- Email: [email protected]
Histopathologic Study of Autosomal Dominant Vitreoretinochoroidopathy
Histopathologic Study of Autosomal Dominant Vitreoretinochoroidopathy Peripheral Annular Pigmentary Dystrophy of the Retina MORTON F. GOLDBERG, MD, FENQ-LIH LEE, MD, MARK O. M. TSO, MD, GERALD A. FISHMAN, MD
Abstract: Autosomal dominant vitreoretinochoroidopathy (ADVIRC), a recently described disease, is clinically characterized by a slowly progressive or stationary circumferential peripheral pigmentary retinopathy with fibrillar condensation of the vitreous . Histopathologic study of an 88-year-old patient with this disease showed disorganization of the peripheral retina with focally atrophic retinal pigment epithelium (RPE). Altered pigment epithelial cells surrounded retinal blood vessels and lined the internal limiting membrane. At the equator, a remarkable and possibly unique multifocalloss of photoreceptor cells was seen. An extensive preretinal membrane, consisting of condensed vitreous with cellular debris and layers of MOiler cells, was demonstrated by electron microscopic examination and immunohistochemistry. Histologically, this entity has some similarities to and some differences from retinitis pigmentosa. The clinical features are distinctive. Ophthalmology 96: 1736-1746, 1989
In 1982 and subsequently in 1984, we described a previously unrecognized peripheral annular pigmentary dystrophy of the ocular fundus that was inherited in two
Originally received: May 8, 1989. Revision accepted: July 6, 1989. From the Department of Ophthalmology, University of Illinois at Chicago College of Medicine, Eye and Ear Infirmary, and Lions of Illinois Eye Re· search Institute, Chicago. Supported in part by core grant EY1792 and training grant EY7038 from the National Institutes of Health, Bethesda, Maryland, unrestricted grants from Research to Prevent Blindness, Inc, New York, New York, the Alcon Research Institute, Fort Worth, Texas, andthe National Retinitis Pigmentosa Foundation Fighting Blindness, Baltimore, Maryland. Reprint requests to Morton F. Goldberg, MD, The Wilmer Ophthalmological Institute, Johns Hopkins Hospital, 600 North Wolfe St, Baltimore, MD 21 205.
1736
unrelated families as an autosomal dominant trait. 1,2 Because of characteristic clinical findings, we used the name autosomal dominant vitreoretinochoroidopathy (ADVIRC). This disease is clinically characterized, to varying extents in different family members, by coarse peripheral hyperpigmentation and hypopigmentation of the fundus for 360 0 (with a relatively discrete posterior border at approximately the equatorial zone); superficial and deep punctate yellowish-white opacities in the fundus; retinal vascular attenuation, transudation, and neovascularization; cystoid macular edema; ophthalmoscopic evidence of choroidal atrophy; vitreous degeneration; and cataract formation. The primary or initiating anatomic site for the pathogenesis of the disease remains unknown. Autosomal dominant vitreoretinochoroidopathy appears to be stable or minimally progressive. Unlike retinitis
GOLDBERG et al
•
AUTOSOMAL DOMINANT VITREORETINOCHOROIDOPATHY
LH
8/28/79
loo~'L
Normal
20ms
30 min.
Scotopic Whit.
30min.
Scotopic Blue
Fig 1. Clinical photographs of ADVIRC. Left. color fundus photograph demonstrates involvement ofthe peripheral fundus. Color fundus photographs of other family members were previously published.'·2 Right. electroretinogram of patient shown in Figure 1, left.
pigmentosa, it is characterized by absence of both significant nyctalopia and defects of the peripheral visual field. Electroretinograms are normal in younger individuals and are only moderately abnormal in older individuals. We recently acquired the postmortem eyes of an elderly woman (case 11-2 in reference 1) who died of unknown causes at 88 years of age. This report concerns the light and electron microscopic findings in both of her eyes.
CASE REPORT Case 11-2. A 79-year-old woman had a best-corrected visual acuity of 20/60-2 in both eyes, with -0.50 + 0.50 X 45 0 in the right eye and -0.25 + 2.00 X 135 0 in the left. Results of slit-lamp examination of the lenses showed trace anterior cortical opacities, 2+ nuclear sclerosis, and trace to 1+ posterior subcapsular cataractous changes bilaterally. Applanation pressures were 16 mmHg in the right eye and 18 mmHg in the left. The pupils reacted normally. There were no cells in the anterior vitreous. The Amsler grid and Goldmann peripheral field testing (isopters 1-4 and V-4) were normal in both eyes. Results of ophthalmoscopic examination of both eyes through dilated pupils showed apparently normal discs. There was mild arteriolar narrowing in both eyes, and extensive bone-spiculelike clumping of pigment was seen at and anterior to the equatorial region (Fig 1). Drusen and epiretinal membranes were not noted, despite subsequent histologic findings. Fluorescein angiography showed some early hyperfluorescence about the left disc, which faded on late views. There was mildto-moderate hyperfluorescence in the foveal region of the right eye, which was interpreted as mild cystoid macular edema. This was not confirmed at the time of histologic examination. The left macula appeared normal on angiography. In the periphery, the area of pigmentary degeneration was characterized by both hyperpigmented and hypopigmented changes in a coarse, irregular pattern. Zones of punctate hyperfluorescence that had the angiographic appearance of drusen (not apparent ophthalmoscopically) were scattered throughout the degenerated area.
METHODS ELECTRORETINOGRAPHY
The electroretinogram was recorded when the patient was 79 years of age with the pupils fully dilated. A BurianAllen unipolar contact lens was used as a recording electrode, while a silver-silver chloride disk was fastened, with the use of electrode paste and adhesive tape, to the midforehead as an indifferent electrode. A similar disk fastened to the right ear served as the ground electrode. A Grass PS-2 photostimulator and xenon-arc lamp placed in a ganzfeld diffusing sphere were used as the stimulus source. Single-flash photopic (cone) responses were recorded with an 1-16 setting on the photostimulator after 5 minutes of adaptation to a background light of 7 to 8 foot lamberts illumination at the patient's pupil. A combined rod and cone response was then obtained after 30 minutes of dark adaptation using the 1-16 white intensity setting. A Wratten 47 blue filter interposed between the light stimulus (1-4 setting on the photostimulator) was then used to measure isolated rod-mediated responses. Psychophysical dark adaptation testing was not performed. PATHOLOGIC FINDINGS
The eyes were obtained within 6 hours after death. The patient had no history of ingestion of retinotoxic drugs. The right eye was fixed in a 1% gluteraldahyde and 4% paraformaldahyde fixative (MacDowell and Trump's). The left eye was fixed in 10% buffered formalin. Portions of the macula, optic disc, posterior pole, and equatorial and peripheral retina were separately embedded in plastic for electron microscopic examination. The pupillary-optic nerve segment of the left eye was embedded in paraffin; the macula was embedded in plastic for electron microscopic examination.
1737
OPHTHALMOLOGY
•
DECEMBER 1989
Thin sections for electron microscopic examination were treated with uranyl acetate and lead citrate. The paraffin sections were stained with hematoxylin-eosin and periodic acid-Schiff. For immunopathologic studies, polyclonal rabbit anti-human carbonic anhydrase isoenzyme C (CA-C, Calbiochem, Inc, La Jolla, CA) or polyclonal rabbit anti-human glial fibrillary acidic protein (GFAP, Dako, Carpinteria, CA) were used as primary antibodies. After overnight incubation at 4°C with either anti-CA-C at 1: 100 dilution or anti-GFAP at 1: 150 dilution, the sections were subsequently incubated with biotinylated goat anti-rabbit IgG diluted in phosphate-buffered saline and collagen extract solution (1 :80 for CA-C, 1: 100 for GFAP) for 30 minutes and rabbit peroxidaseavidin-biotin (1 :500) for 30 minutes at room temperature. The peroxidase reaction was visualized with 3-3' diaminobenzidine as chromogen. A normal human postmortem eye fixed in formalin served as a control. For the negative control, either of the primary antibodies was replaced by nonimmune rabbit serum.
RESULTS ELECTRORETINOGRAPHIC FINDINGS
The patient's photopic (cone) b-wave amplitude response of 70 Jl V was slightly reduced below the lower range of normal for her age (100 Jl V), whereas the b-wave implicit time of 34 mseconds was within the upper range of normal (Fig 1). Her combined rod and cone scotopic b-wave response of 200 Jl V to a bright white light was reduced 50% below the lowest normal limit of 400 Jl V. Her combined scotopic b-wave response implicit time of 50 mseconds was normal (mean for our laboratory, 51 mseconds). The isolated scotopic rod b-wave response of 60 Jl V was considerably reduced, approximately two thirds below the lower normal limit of 190 Jl V. The scotopic rod-isolated b-wave implicit time of 86 mseconds was within normal limits (maximal normal value, 89 mseconds). PATHOLOGIC FINDINGS
The anterior segments of both eyes were unremarkable on gross inspection. The lenses were mildly cataractous. The posterior segment of the right eye showed anterior condensation of the vitreous along the vitreous base. Cobblestone degeneration was seen in the inferior peripheral fundus just posterior to the ora serrata. Bone spicule-like pigmentation, especially around the retinal vasculature, extended from the equator to the ora serrata for 360 0 (Fig 2), and the retinal pigment epithelium (RPE) appeared atrophic. The posterior segment of the left eye showed similar vitreous condensation along the vitreous base, and cobblestone degeneration was seen inferiorly just behind the ora serrata. Bone spicule-like pigmentation also extended along and anterior to the entire equatorial region. The 1738
•
VOLUME 96
•
NUMBER 12
Fig 2. Vitreous traction on the peripheral retina (hematoxylin-eosin; original magnification, X950).
RPE appeared focally hypopigmented between the equator and ora serrata. The gross appearance of the rest of the globe was unremarkable. LIGHT MICROSCOPIC FINDINGS
Histologically, the two eyes appeared similar. The vitreous was condensed anteriorly along the vitreous base. Vitreous traction on the peripheral retina produced retinal tags in the cortical vitreous (Fig 2). In the far periphery, the retina was reduced to a glial membrane with total loss of photo receptors (Fig 3). Proliferated RPE extended into the sensory retina, aggregating around the retinal vessels and lining the surface of the internal limiting membrane. In focal areas, there were losses of RPE. One focus of sub-RPE neovascularization was noted. At the equatorial region, the inner and outer nuclear layers of the retina were thin, and the retinal vasculature appeared sclerotic. In a horizontal section from the posterior pole to the ora serrata, multiple focal areas of absent photo receptors were noted near the equator (Fig 4). As many as nine discrete foci oflost photoreceptor cells were observed in one equatorial area. Wherever there was focal loss of photoreceptor nuclei, the RPE appeared atrophic and depigmented (Fig 5). Focal degeneration in one tissue layer was always accompanied by contiguous degeneration in the other tissue layer. The remaining photoreceptor cell layers in the equatorial region were reduced to two to three nuclei thick; the photoreceptor outer segments were, for the most part, absent. The choriocapillaris in this area appeared mildly atrophic. There was a preretinal membrane covering the retina, macula, and optic disc, which thinned out toward the equator (Fig 6). Immunohistochemical study showed that the cytoplasm of the cells in this membrane reacted focally
GOLDBERG et al
•
AUTOSOMAL DOMINANT VITREORETINOCHOROIDOPATHY
Fig 3. A, the peripheral retina is reduced to a glial membrane. Retinal pigment epithelial cells extend into the sensory retina and line the surface of the intemallimiting membrane (arrows) (hematoxylin-eosin; original magnification, X950). B, the markedly atrophic retina in the periphery shows loss of normal architecture as well as focal absence of RPE cells (hematoxylin-eosin; original magnification, X950).
Fig 4. Multiple discrete foci (arrows) of lost photoreceptor cells at the equatorial region (hematoxylin-eosin; original magnification, X100).
with anti-carbonic anhydrase C antibody and showed patchy staining with anti-glial fibrillary acidic protein antibody. Between the macula and equator, there was mild gliosis in the nerve fiber layer, but the inner and outer nuclear layers appeared normal. Rods and cones and their outer segments seemed morphologically intact, and there was a relatively abrupt transition between this normal zone and the multifocal abnormalities of the equatorial fundus. At the macula, the outer nuclear layer was three to five nuclei thick, and the outer segments of the photoreceptor cells were moderately to severely shortened. Occasional subretinal macrophages were seen. The RPE was markedly irregular in thickness and pigmentation. Bruch's membrane appeared thickened, and there was a mild increase in the width of the intercapillary pillars of the choroid. Retinal capillaries in the posterior pole appeared unremarkable, and no cystoid macular edema was noted. ELECfRON MICROSCOPIC FINDINGS
Ultrastructural evaluation concerned primarily (1) the preretinal membrane and cortical vitreous, (2) the gliotic peripheral retina, (3) the photoreceptor degenerative process 'at the equatorial region, and (4) changes associated with a mild, chronic, inflammatory reaction in the retina. In the peripheral retina, the proliferated RPE replaced the foot-plates of the Muller cells and lined the vitreous cavity (Fig 7). Basement membrane-like material and cellular debris produced by these cells were present in the cortical vitreous. A thin preretinal membrane was noted in the equatorial region and extended, in a more thickened configuration, posteriorly (Fig 8). We believe this mem-
Fig S. At the equatorial retina, a focal loss (arrows) of photoreceptor cells is associated with depigmentation ofRPE and thinning of the inner nuclear layer (hematoxylin-eosin; original magnification, X950).
brane consisted of proliferated Muller cells, because the cells formed zonulae adherentes-like cell junctions, simulating an "external limiting membrane." Villi projected into the vitreous cavity and resembled basket fibers of Schultze. The cytoplasm of the cells contained neurotubuIes and filaments. The ground substance of the cytoplasm appeared relatively electron lucent. The preretinal membrane was thickest in the macular area and consisted of 10 to 13 layers of cells (Fig 9). These cells showed two distinct morphologic appearances. Some ofthe cells had lucent cytoplasm and contained a number of microtubules. Others had dense filamentous cytoplasm. Both types of cells were joined by multiple desmosomes. Vitreous fibers were apparently trapped between the glial cells of the preretinal membrane. In the peripheral retina, anterior to the equator, the normal retinal architecture was replaced by glial cells. Two types of glial cells were again noted: some with lucent cytoplasm containing microtubules and mitochondria; 1739
OPHTHALMOLOGY
•
DECEMBER 1989
•
VOLUME 96
•
NUMBER 12
Fig 6. A, preretinal membrane (arrows) covers the retina of the posterior pole. The underlying architecture of the retina is preserved in this area (hematoxylin-eosin; original magnification, X950). B, at the macular area, a thick preretinal membrane (small arrows) is noted. The photoreceptor outer nuclear layer is three to five nuclei thick, but the outer segments of the photoreceptor cells are short. The RPE cells are markedly irregular in thickness and pigmentation (large arrow). The width of the intercapillary pillars of the choriocapillaries (arrowheads) is slightly increased (hematoxylin-eosin; original magnification, X950).
Fig 7. In the peripheral retina, proliferated RPE cells line the vitreous cavity (V). Basement membrane material (arrows) and cellular debris (arrowheads) have been shed into the cortical vitreous (original magnification, X5200).
others with dense filamentous cytoplasm. Some of the glial cells produced multilaminar basement membrane in a nodular fashion. Interposed between the gliotic cells were nodules of proliferated RPE, which had produced additional nodular basement membrane material at the base of disoriented RPE cells. The photoreceptor cells at the equator showed extensive degenerative changes (Fig 10). Many nuclei had disap1740
peared, and the space was filled with glial processes. Some nuclei of the photoreceptor cells were densified and elongated; others has a crenated nuclear membrane, con-' densed chromatin, and vacuolated cytoplasm. Some rod and cone nuclei appeared to be present (Fig 11). Fragments of disorganized photoreceptor outer segments formed membranous whorls. The RPE showed two forms of changes: some cells were depigmented with densified
GOLDBERG et al
•
AUTOSOMAL DOMINANT VITREORETINOCHOROIDOPATHY
Fig 8. The preretinal membrane at the equatorial region consists of proliferated Muller cells, which formed zonula adherentes-like cell junctions (arrows) facing the vitreous cavity (V). Villi projected into the vitreous cavity. The cytoplasm of the cells contain neurotubules and filaments with relatively lucent ground substance (lLM = internal limiting membrane) (original magnification, x 10,(00). Inset, zonula adherentes-like cell junctions (arrows) border the vitreous cavity (original magnification, x30,(00).
cytoplasm and nuclei; others appeared atrophic and filled with melanolysosomes (Fig 12). Muller cells extended down to the subretinal space and expanded to form a new and condensed external limiting membrane wherever there was extensive loss of photoreceptor cells (Fig 13). The photoreceptor degenerative process in the macula was different from that at the equator. At the macula, the outer segments were moderately to severely shortened and showed tubular-vesicular degeneration. Within the cytoplasm in the inner segments, some membranous degeneration also was seen (Fig 14). The RPE was filled with melanolysosomes, and there was a loss of apical villi. At the base of these cells, drusen-like deposits and various forms of basement membrane deposits were seen. Bruch's membrane was filled with curvilinear profiles and densified vesicles. However, the retinal vasculature in the macula showed no perivascular exudation, nor were there any changes typical of cystoid macular degeneration (Fig 15). Macrophages were observed between Bruch's membrane and the choriocapillaris, in the sensory retina, and in the vitreous cavity, suggesting that a mild inflammatory reaction had existed. Other types of inflammatory cells were absent.
DISCUSSION One of the characteristic microscopic signs of this disease appears to be the discrete, multi focal loss of photoreceptor cells in the equatorial region, associated with thinning of the inner nuclear layer and sclerosis of the peripheral retinal vasculature. Depigmentation and atrophy of the RPE were also present. In the far penphery the retinal architecture was disorganized with reactive changes in astrocytes and Muller cells. The RPE proliferated in nodular form into the inner layers of the retina. Although many of these pathologic changes resemble those of retinitis pigmentosa, there are a number ofstriking differences: the multifocal nature of the disease, the abrupt transition from the abnormal equatorial zone to the normal fundus posterior to the equator (excluding the senescent changes in the macula), the absence of widespread rod and cone degeneration, and the slow or absent clinical progression in various family members. The degeneration of the photo receptors appears to have followed two well-known patterns of cell death, namely, apoptosis and necrosis.3 A few of the photoreceptor cells showed signs of apoptosis with preservation of the retinal 1741
OPHTHALMOLOGY
•
DECEMBER 1989
architecture. These nuclear changes of the photoreceptor cells closely resembled those seen in hereditary macular degeneration of baboons.4 Apoptosis and necrosis also have been observed in retinas of patients with retinitis pigmentosa, although necrosis is more commonly seen. The relative importance ofapoptosis and necrosis ofphotoreceptor cells in ADVIRC, retinitis pigmentosa, and related diseases needs further exploration. It is interesting that GFAP was expressed well by the Muller cells of our patient's gliotic retina and preretinal membrane. Glial fibrillary acidic protein is present in normal retinal astrocytes but is not usually seen in normal Muller cells. 5,6 Sarthy and Fu5 observed GFAP in Muller cells of mice with the rd mutation and after light toxicity. A preliminary study in our laboratory showed that retinal degeneration was not associated with abundant GFAP formation in some cases of retinitis pigmentosa (unpublished data; presented at the Annual Meeting of the Association for Research in Vision and Ophthalmology, May 4, 1989). If these observations are confirmed with more cases of ADVIRC and retinitis pigmentosa, this staining technique may provide a clue to possible differences between retinitis pigmentosa and ADVIRC. The hereditary degeneration of photoreceptor cells in this patient can be contrasted with the age-related macular degeneration observed in the same individual. In the macula, there was shortening of outer segments associated with marked changes in the RPE. The RPE cells were packed with melanolysosomes, but there was no abnormal proliferation ofthese cells. Moreover, there was no widespread death of photoreceptor cells. Tubular and vesicular changes were seen in the outer segments, and membranous degeneration was noted in their cytoplasm, but the basic architecture of the macular region was preserved. The RPE changes in the equatorial retina also were considerably different from those in the posterior pole. Atrophy, depigmentation, necrosis, or proliferation were hallmarks of the hereditary dystrophy, whereas excessive accumulation of melanolysosomes and the presence of subretinal macrophages appeared to characterize the RPE of age-related macular degeneration.
•
VOLUME 96
•
NUMBER 12
Fig 9. Preretinal membrane at the macular area consists of more than ten layers of cells in this section. Some of the cells (M) have lucent cytoplasm and contain a number of microtubules (arrowheads); others have dense filamentous cytoplasm (G). The cells are joined by multiple desmosomes (arrows) (original magnification, X4200) (V = vitreous cavity; ILM = internal limiting membrane). Top right inset, vitreous filaments (V) are trapped within multiple layers of preretinal membrane (original magnification, X5(00). Bottom leji inset, light micrograph shows thick preretinal membrane (arrows) opposite ganglion cells (GC) (original magnification, X950).
Fig 10. Degenerative photoreceptor cells at the equator. A, many nuclei disappear and their spaces are filled with expanded glial processes. Some of the nuclei (N) are densified and pyknotic (original magnification, X3400). B, other photoreceptor nuclei have condensed chromatin with crenated nuclear membranes (arrows) and vacuolated cytoplasm (V) (original magnification, X2800).
1742
GOLDBERG et al
•
AUTOSOMAL DOMINANT VITREORETINOCHOROIDOPATHY
Fig 11. At the equator, both rod (R) and cone (C) photo-
receptor elements are present. Most of the outer segments are absent. The RPE cells appear necrotic and densified. Nodular proliferation of basement membrane (BM) are observed. Focal areas oflong spacing, banded collagen (arrow) are seen in the sub-RPE region. Most of the melanin granules in the RPE are absent (original magnification, X6600).
Fig 12. At the equatorial region, both rod (R) and cone (C) photoreceptor inner segments are present. Fragments of disorganized photoreceptor outer segments (arrowheads) forming membranous whorls are seen. Pigmentladen macrophages (M) are seen in the subretinal space. The RPE cells appear atrophic and are filled with melanolysosomes (arrows) (original magnification ,
X4200).
1743
OPHTHALMOLOGY
•
DECEMBER 1989
The degenerative process excited a mild inflammatory reaction with macrophages in the choroid, retina, and vitreous. No primary inflammatory or other pathogenetic mechanisms could be identified. We suspect that this inflammatory activity may be nonspecific and secondary to the dystrophic process in the retina. The results of this study help explain the pathogenesis of the preretinal membrane. In the peripheral retina, where the disease was most advanced, the shedding of basement membrane-like material and cellular debris into the vitreous cavity by the proliferative pigment epithelium appears to be a possible initiating event in preretinal membrane formation. In the equatorial region, the preretinal membrane consisted entirely of Muller cells, which formed external limiting membrane-like structures lining the vitreous cavity. The presence of Muller cells was confirmed by the immunohistochemical study, which showed carbonic anhydrase C, a characteristic finding in such Muller cells. Clinically, fluorescein leakage was observed in this patient's macular region. The presence of vitreous filaments trapped within the preretinal membrane in this location suggests the presence of traction. Retinal tags pulled into the cortical vitreous were also seen in the fundus periphery. We inferred from both observations that the fluorescein leakage might be secondary to vitreous traction by the preretinal membrane on the underlying retina. 7 Alternatively, the interval between angiographic and histopathologic studies may have permitted spontaneous resolution of vascular incompetence. Although there appear to be some distinguishing microscopic features of ADVIRC, such as the predilection for equatorial and preequatorial regions and its multifocal nature, differentiation from other dominantly inherited retinal dystrophies, such as some forms of retinitis pigmentosa, is based primarily on clinical findings. For example, the coarse pigmentary changes observed ophthalmoscopically as an annular band in the peripheral fundus are highly characteristic of the two unrelated families we have previously reported as examples of ADVIRC I ,2 and may be pathognomonic. Also observed in some members of both pedigrees are punctate yellowish-white deposits in both the superficial and deep fundus; retinal vascular narrowing as well as mild-to-intense leakage of fluorescein; cystoid macular edema; focal areas of preretinal neovascularization; visible choroidal vessels; fibrillar condensation of the vitreous; and presenile cataract formation. Similar changes also are noted in some forms of retinitis pigmentosa. However, unlike retinitis pigmentosa, electroretinographic abnormalities in ADVIRC are only mild to moderate in older individuals and are totally lacking in several younger, affected family members. I •2 Clinical progression, ifany, appears to be extremely slow, and the prognoses for night vision and peripheral vision are excellent. Visual acuity is only mildly to moderately reduced, despite occurrence of cystoid macular edema and vitreous hemorrhage in some patients. Moderately reduced acuity in the current case (20/60-2, both eyes) is probably attributable to the presence of mild age-related macular degeneration. 1744
•
VOLUME 96
•
NUMBER 12
Fig 13. At the equator, focal loss of photoreceptor cells lead to expanded Miiller (M) cells, which form a new and condensed external limiting membrane (arrowheads). A few photoreceptor cells (P) with fragments of outer segments (OS) remain. The RPE cells are atrophic and filled with lipofuscin granules (arrows) (original magnification, X2900).
The microscopic appearance of this patient's eyes showed several possible explanations for the yellowishwhite deposits in the fundus of other family members. These include preretinal tags, preretinal glial membranes, and drusenoid material that was apparently elaborated by RPE cells into the preretinal space. The RPE cells had lost their normal orientation and their basal layers faced the interior of the eye. In addition, more typical drusen (located on Bruch's membrane) as well as hypopigmented RPE cells underlying focal degenerations of photoreceptors also could have contributed to the yellow spots that clinically appeared to be located more deeply in the fundus. 1,2 Although choroidal vessels were abnormally prominent ophthalmoscopically in many family members, histopathologic analysis of our patient's eyes showed only mild degenerative and atrophic choroidal changes compatible with aging. Some focal equatorial changes could have been related to RPE degeneration. It is likely that clinical visualization of choroidal vessels was permitted by atrophy or hypopigmentation of the RPE. Retinal vascular involution also appeared more prominent clinically than microscopically. Only in the far periphery did histologic evidence confirm vascular sclerosis. These findings, in the aggregate, suggest that the primary or initiating site of pathologic involvement in ADVIRC is not in the choroid, retinal vasculature, or vitreous. The available evidence does not, however, allow us to conclude whether cells of the RPE or of the sensory retina are the locus of the primary genetic abnormality. In most degenerated retinal areas, focal loss of photo receptors was accompanied by degeneration or atrophy of underlying RPE cells (and vice versa). Rarely did either of these tissue layers show degeneration without concomitant change in the adjacent tissue. As in the case of many types of retinitis
GOLDBERG et al
•
AUTOSOMAL DOMINANT VITREORETINOCHOROIDOPATHY
Fig 14. The retina at the macular area. A, fragments of outer segments (OS) of photoreceptor cells are seen in the subretinal space. Inner segments of the photoreceptor cells (P) show focal areas of membranous degeneration (MD) (original magnification, X7000). Inset. membranous degeneration (arrows) is seen under higher power magnification (original magnification, X20,OOO). B, RPE cells in the macular area are filled with melanolysosomes (arrow) and melanin granules. The photoreceptor outer segments have disappeared, but inner segments of cone cells (P) remain (original magnification, X4200).
pigmentosa,8-18 preretinal membrane formation was more extensive than anticipated from prior clinical examination. Nonetheless, the vitreous and preretinal abnormalities are probably not primary pathogenetic events. It is of interest that a recent study of autosomal dominant retinitis pigmentosa 17 reinforced the idea that the primary disorder in this disease lay within the photoreceptors. The multifocal nature of the photoreceptor changes in our patient was striking and was seemingly more marked than in previously reported microscopic material from various types of other retinal dystrophies, including retinitis pigmentosa. 8- 3o This may reflect a true distinguishing microscopic feature of ADVIRC. Alternatively, its absence in previously reported cases of retinitis pigmentosa may possibly be due to histologic sampling errors, advanced age (and, therefore, more widespread, rather than focal, loss of photoreceptors) , or other unknown factors. Nonetheless, even in young individuals with retinitis pigmentosa, whose eyes have been evaluated histopathologically,
discrete focal loss of photoreceptor outer segments has not been emphasized. Other more extensive types of patchy retinal degeneration have, however, been reported by Szamier and Berson,15,16 Tucker and Jacobson,17 and Duvall et a1. 20 Patchy retinal atrophy also has been reported by Ghosh et al 31 in a female carrier of choroideremia. In this carrier, however, the transition from normal to abnormal retinal zones was gradual, RPE cells did not extend into the retina, and there were no macrophages in the subretinal space. The multifocal nature of the degenerative process affecting both photo receptors and RPE in the peripheral fundus of our patient probably explains the relatively favorable retinal function and visual prognosis in ADVIRC, even in aged individuals. This stands in contrast to the usually unfavorable effects created by the widespread photoreceptor and RPE degenerations that typify most forms of retinitis pigmentosa (including those affecting younger individuals). Despite careful light- and electron1745
OPHTHALMOLOGY
•
DECEMBER 1989
•
8.
9.
10.
11.
12. 13. 14. 15. 16. 17. Fig 15. Retinal vessels (V) in the macular area appear intact without exudate (G-ganglion cells) (original magnification, X4200).
18.
19.
microscopic evaluation of our ADVIRC patient's eyes, however, we still have little insight into the basic mechanisms underlying the muItifocal retinal degeneration, retinal edema (in other family members), preretinal neo-' vascularization (in other family members) and preretinal membrane formation that occur in this enigmatic syndrome. Microscopic findings do not support primary pathogenetic roles for the choroid or vitreous; therefore, a name for this syndrome that is more accurate than ADVIRC would be autosomal dominant peripheral annular pigmentary dystrophy of the retina.
20.
21.
22. 23.
24.
REFERENCES 25. 1. Kaufman SJ, Goldberg MF, Orth DH, et al. Autosomal dominant vitreoretinochoroidopathy. Arch Ophthalmol 1982; 100:272-8. 2. Blair NP, Goldberg MF, Fishman GA, Salzano T. Autosomal dominant vitreoretinochoroidopathy (ADVIRC). Br J Ophthalmol1984; 68:2-9. 3. Walker NI, Harmon BV, Gobe GC, Keer JFR. Pattems of cell death. Methods Achiev Exp Pathol 1988; 13:18-54. 4. Santos-Anderson RM, Tso MOM. Vainisi SJ. Heredofamilial retinal dystrophy in guinea baboons. II. Electron microscopic observations. Arch Ophthalmol1983; 101:1762-70. 5. Sarthy PV, Fu M. Photoreceptor degeneration leads to induction of the glial intermediate filament protein gene in the mouse retina. In: Piatigorsky J, Shinohara T, Zelenka PS, eds. Molecular Biology of the Eye: Genes, Vision, and Ocular Disease. New York: Alan R. Liss, Inc, 1988; 305-15. 6. Haltia M, Tarkkanen A, Kivela T. Rabies: ocular pathology. Br J Ophthalmol1989; 73:61-7. 7. Goldberg MF. Diseases affecting the inner blood-retinal barrier. In:
1746
26.
27.
28. 29.
30.
31.
VOLUME 96
•
NUMBER 12
Cunha-Vaz JG, ed. The Blood-Retinal Barriers. New York: Plenum, 1980; 309-63. Raybom ME, Moorhead LC, Hollyfield JG. A dominantly inherited chorioretinal degeneration resembling sectoral retinitis pigmentosa. Ophthalmology 1982; 89:1441-54. Rodrigues MM. Wiggert B, Hackett J, et al. Dominantly inherited retinitis pigmentosa: ultrastructure and biochemical analysiS. Ophthalmology 1985; 92:1165-72. Rodrigues MM. Newsome D. Retinitis pigmentosa: electron microscopy and cell culture studies. Birth Defects: Original Article Series: (Genetic Eye Diseases: Retinitis Pigmentosa and Other Inherited Eye Diseases) 1982; 18:81-94. Rodrigues MM, Bardenstein D, Wiggert B, et al. Retinitis pigmentosa with segmental massive retinal gliosis: an immunohistochemical, biochemical, and ultrastructural study. Ophthalmology 1987; 94:180-6. Santos-Anderson RM. Tso MOM. Fishman GA. A histopathologic study of retinitis pigmentosa. Ophthalmic Paediatr Genet 1982; 1:151-68. Szamier RB. Ultrastructure of the preretinal membrane in retinitis pigmentosa. Invest Ophthalmol Vis Sci 1981; 21 :227 -36. Szamier RB, Berson EL. Retinal ultrastructure in advanced retinitis pigmentosa. Invest Ophthalmol Vis Sci 1977; 16:947-62. Szamier RB, Berson EL. Histopathologic study of an unusual form of retinitis pigmentosa. Invest Ophthalmol Vis Sci 1982; 22:559-70. Szamier RB, Berson EL. Retinal histopathology of a carrier of X-chromosome-linked retinitis pigmentosa. Ophthalmology 1985; 92:271-8. Tucker GS, Jacobson SG. Morphological findings in retinitis pigmentosa with early diffuse rod dysfunction. Retina 1988; 8:30-41. Flannery JG, Farber DB, Bird AC, Bok D. Degenerative changes in a retina affected with autosomal dominant retinitis pigmentosa. Invest Ophthalmol Vis Sci 1989; 30:191-211. Bunt-Milam AH, Kalina RE, Pagon RA. Clinical-ultrastructural study of a retinal dystrophy. Invest Ophthalmol Vis Sci 1983; 24:458-69. Duvall J, McKechnie NM, Lee WR, et al. Extensive subretinal pigment epithelial deposit in two brothers suffering from dominant retinitis pigmentosa. A histopathological study. Graefes Arch Clin Exp Ophthalmol 1986; 224:299-309. Farber DB, Flannery JG, Bird AC, et al. Histopathological and biochemical studies on donor eyes affected with retinitis pigmentosa. Prog Clin Bioi Res 1987; 247:53-67. Gartner S, Henkind P. Pathology of retinitis pigmentosa. Ophthalmology 1982; 89:1425-32. Goebel HH, Ikeda K, Eichholtz W, et al. Ultrastructural study of primary canine and human pigmentary retinopathy. OphthalmiC Paediatr Genet 1985; 5:3-11. Kolb H, Gouras P. Electron microscopiC observations of human retinitis pigmentosa, dominantly inherited. Invest Ophthalmol1974; 13:48798. Lahav M, Craft J, Albert DM, Ishii Y. Advanced pigmentary retinal degeneration: an ultrastructural study. Retina 1982; 2:65-75. Meyer KT, Heckenlively JR, Spitznas M, Foos RY. Dominant retinitis pigmentosa: a clinicopathologic correlation. Ophthalmology 1982; 89: 1414-24. Mizuno K, Nishida S. Electron microscopic studies of human retinitis pigmentosa. Part 1. Two cases of advanced retinitis pigmentosa. Am J Ophthalmol1967; 63:791-803. Mizuno K, Nishida S, Takei Y. Pathology of human retinal dystrophy. Prog Clin Bioi Res 1987; 247:21-33. Rodrigues MM, Wiggert B, Tso MOM, Chader GJ. Retinitis pigmentosa: immunohistochemical and biochemical studies of the retina. Can J Ophthalmol 1986; 21:79-83. Szamier RB, Berson EL, Klein R, Meyers S. Sex-linked retinitis pigmentosa: ultrastructure of photoreceptors and pigment epithelium. Invest Ophthalmol Vis Sci 1979; 18:145-60. Ghosh M. McCulloch C, Parker JA. Pathological study in a female carrier of choroideremia. Can J Ophthalmol1988; 23:181-6.
Abstract: Autosomal dominant vitreoretinochoroidopathy (ADVIRC), a recently described disease, is clinically characterized by a slowly progressive or stationary circumferential peripheral pigmentary retinopathy with fibrillar condensation of the vitreous . Histopathologic study of an 88-year-old patient with this disease showed disorganization of the peripheral retina with focally atrophic retinal pigment epithelium (RPE). Altered pigment epithelial cells surrounded retinal blood vessels and lined the internal limiting membrane. At the equator, a remarkable and possibly unique multifocalloss of photoreceptor cells was seen. An extensive preretinal membrane, consisting of condensed vitreous with cellular debris and layers of MOiler cells, was demonstrated by electron microscopic examination and immunohistochemistry. Histologically, this entity has some similarities to and some differences from retinitis pigmentosa. The clinical features are distinctive. Ophthalmology 96: 1736-1746, 1989
In 1982 and subsequently in 1984, we described a previously unrecognized peripheral annular pigmentary dystrophy of the ocular fundus that was inherited in two
Originally received: May 8, 1989. Revision accepted: July 6, 1989. From the Department of Ophthalmology, University of Illinois at Chicago College of Medicine, Eye and Ear Infirmary, and Lions of Illinois Eye Re· search Institute, Chicago. Supported in part by core grant EY1792 and training grant EY7038 from the National Institutes of Health, Bethesda, Maryland, unrestricted grants from Research to Prevent Blindness, Inc, New York, New York, the Alcon Research Institute, Fort Worth, Texas, andthe National Retinitis Pigmentosa Foundation Fighting Blindness, Baltimore, Maryland. Reprint requests to Morton F. Goldberg, MD, The Wilmer Ophthalmological Institute, Johns Hopkins Hospital, 600 North Wolfe St, Baltimore, MD 21 205.
1736
unrelated families as an autosomal dominant trait. 1,2 Because of characteristic clinical findings, we used the name autosomal dominant vitreoretinochoroidopathy (ADVIRC). This disease is clinically characterized, to varying extents in different family members, by coarse peripheral hyperpigmentation and hypopigmentation of the fundus for 360 0 (with a relatively discrete posterior border at approximately the equatorial zone); superficial and deep punctate yellowish-white opacities in the fundus; retinal vascular attenuation, transudation, and neovascularization; cystoid macular edema; ophthalmoscopic evidence of choroidal atrophy; vitreous degeneration; and cataract formation. The primary or initiating anatomic site for the pathogenesis of the disease remains unknown. Autosomal dominant vitreoretinochoroidopathy appears to be stable or minimally progressive. Unlike retinitis
GOLDBERG et al
•
AUTOSOMAL DOMINANT VITREORETINOCHOROIDOPATHY
LH
8/28/79
loo~'L
Normal
20ms
30 min.
Scotopic Whit.
30min.
Scotopic Blue
Fig 1. Clinical photographs of ADVIRC. Left. color fundus photograph demonstrates involvement ofthe peripheral fundus. Color fundus photographs of other family members were previously published.'·2 Right. electroretinogram of patient shown in Figure 1, left.
pigmentosa, it is characterized by absence of both significant nyctalopia and defects of the peripheral visual field. Electroretinograms are normal in younger individuals and are only moderately abnormal in older individuals. We recently acquired the postmortem eyes of an elderly woman (case 11-2 in reference 1) who died of unknown causes at 88 years of age. This report concerns the light and electron microscopic findings in both of her eyes.
CASE REPORT Case 11-2. A 79-year-old woman had a best-corrected visual acuity of 20/60-2 in both eyes, with -0.50 + 0.50 X 45 0 in the right eye and -0.25 + 2.00 X 135 0 in the left. Results of slit-lamp examination of the lenses showed trace anterior cortical opacities, 2+ nuclear sclerosis, and trace to 1+ posterior subcapsular cataractous changes bilaterally. Applanation pressures were 16 mmHg in the right eye and 18 mmHg in the left. The pupils reacted normally. There were no cells in the anterior vitreous. The Amsler grid and Goldmann peripheral field testing (isopters 1-4 and V-4) were normal in both eyes. Results of ophthalmoscopic examination of both eyes through dilated pupils showed apparently normal discs. There was mild arteriolar narrowing in both eyes, and extensive bone-spiculelike clumping of pigment was seen at and anterior to the equatorial region (Fig 1). Drusen and epiretinal membranes were not noted, despite subsequent histologic findings. Fluorescein angiography showed some early hyperfluorescence about the left disc, which faded on late views. There was mildto-moderate hyperfluorescence in the foveal region of the right eye, which was interpreted as mild cystoid macular edema. This was not confirmed at the time of histologic examination. The left macula appeared normal on angiography. In the periphery, the area of pigmentary degeneration was characterized by both hyperpigmented and hypopigmented changes in a coarse, irregular pattern. Zones of punctate hyperfluorescence that had the angiographic appearance of drusen (not apparent ophthalmoscopically) were scattered throughout the degenerated area.
METHODS ELECTRORETINOGRAPHY
The electroretinogram was recorded when the patient was 79 years of age with the pupils fully dilated. A BurianAllen unipolar contact lens was used as a recording electrode, while a silver-silver chloride disk was fastened, with the use of electrode paste and adhesive tape, to the midforehead as an indifferent electrode. A similar disk fastened to the right ear served as the ground electrode. A Grass PS-2 photostimulator and xenon-arc lamp placed in a ganzfeld diffusing sphere were used as the stimulus source. Single-flash photopic (cone) responses were recorded with an 1-16 setting on the photostimulator after 5 minutes of adaptation to a background light of 7 to 8 foot lamberts illumination at the patient's pupil. A combined rod and cone response was then obtained after 30 minutes of dark adaptation using the 1-16 white intensity setting. A Wratten 47 blue filter interposed between the light stimulus (1-4 setting on the photostimulator) was then used to measure isolated rod-mediated responses. Psychophysical dark adaptation testing was not performed. PATHOLOGIC FINDINGS
The eyes were obtained within 6 hours after death. The patient had no history of ingestion of retinotoxic drugs. The right eye was fixed in a 1% gluteraldahyde and 4% paraformaldahyde fixative (MacDowell and Trump's). The left eye was fixed in 10% buffered formalin. Portions of the macula, optic disc, posterior pole, and equatorial and peripheral retina were separately embedded in plastic for electron microscopic examination. The pupillary-optic nerve segment of the left eye was embedded in paraffin; the macula was embedded in plastic for electron microscopic examination.
1737
OPHTHALMOLOGY
•
DECEMBER 1989
Thin sections for electron microscopic examination were treated with uranyl acetate and lead citrate. The paraffin sections were stained with hematoxylin-eosin and periodic acid-Schiff. For immunopathologic studies, polyclonal rabbit anti-human carbonic anhydrase isoenzyme C (CA-C, Calbiochem, Inc, La Jolla, CA) or polyclonal rabbit anti-human glial fibrillary acidic protein (GFAP, Dako, Carpinteria, CA) were used as primary antibodies. After overnight incubation at 4°C with either anti-CA-C at 1: 100 dilution or anti-GFAP at 1: 150 dilution, the sections were subsequently incubated with biotinylated goat anti-rabbit IgG diluted in phosphate-buffered saline and collagen extract solution (1 :80 for CA-C, 1: 100 for GFAP) for 30 minutes and rabbit peroxidaseavidin-biotin (1 :500) for 30 minutes at room temperature. The peroxidase reaction was visualized with 3-3' diaminobenzidine as chromogen. A normal human postmortem eye fixed in formalin served as a control. For the negative control, either of the primary antibodies was replaced by nonimmune rabbit serum.
RESULTS ELECTRORETINOGRAPHIC FINDINGS
The patient's photopic (cone) b-wave amplitude response of 70 Jl V was slightly reduced below the lower range of normal for her age (100 Jl V), whereas the b-wave implicit time of 34 mseconds was within the upper range of normal (Fig 1). Her combined rod and cone scotopic b-wave response of 200 Jl V to a bright white light was reduced 50% below the lowest normal limit of 400 Jl V. Her combined scotopic b-wave response implicit time of 50 mseconds was normal (mean for our laboratory, 51 mseconds). The isolated scotopic rod b-wave response of 60 Jl V was considerably reduced, approximately two thirds below the lower normal limit of 190 Jl V. The scotopic rod-isolated b-wave implicit time of 86 mseconds was within normal limits (maximal normal value, 89 mseconds). PATHOLOGIC FINDINGS
The anterior segments of both eyes were unremarkable on gross inspection. The lenses were mildly cataractous. The posterior segment of the right eye showed anterior condensation of the vitreous along the vitreous base. Cobblestone degeneration was seen in the inferior peripheral fundus just posterior to the ora serrata. Bone spicule-like pigmentation, especially around the retinal vasculature, extended from the equator to the ora serrata for 360 0 (Fig 2), and the retinal pigment epithelium (RPE) appeared atrophic. The posterior segment of the left eye showed similar vitreous condensation along the vitreous base, and cobblestone degeneration was seen inferiorly just behind the ora serrata. Bone spicule-like pigmentation also extended along and anterior to the entire equatorial region. The 1738
•
VOLUME 96
•
NUMBER 12
Fig 2. Vitreous traction on the peripheral retina (hematoxylin-eosin; original magnification, X950).
RPE appeared focally hypopigmented between the equator and ora serrata. The gross appearance of the rest of the globe was unremarkable. LIGHT MICROSCOPIC FINDINGS
Histologically, the two eyes appeared similar. The vitreous was condensed anteriorly along the vitreous base. Vitreous traction on the peripheral retina produced retinal tags in the cortical vitreous (Fig 2). In the far periphery, the retina was reduced to a glial membrane with total loss of photo receptors (Fig 3). Proliferated RPE extended into the sensory retina, aggregating around the retinal vessels and lining the surface of the internal limiting membrane. In focal areas, there were losses of RPE. One focus of sub-RPE neovascularization was noted. At the equatorial region, the inner and outer nuclear layers of the retina were thin, and the retinal vasculature appeared sclerotic. In a horizontal section from the posterior pole to the ora serrata, multiple focal areas of absent photo receptors were noted near the equator (Fig 4). As many as nine discrete foci oflost photoreceptor cells were observed in one equatorial area. Wherever there was focal loss of photoreceptor nuclei, the RPE appeared atrophic and depigmented (Fig 5). Focal degeneration in one tissue layer was always accompanied by contiguous degeneration in the other tissue layer. The remaining photoreceptor cell layers in the equatorial region were reduced to two to three nuclei thick; the photoreceptor outer segments were, for the most part, absent. The choriocapillaris in this area appeared mildly atrophic. There was a preretinal membrane covering the retina, macula, and optic disc, which thinned out toward the equator (Fig 6). Immunohistochemical study showed that the cytoplasm of the cells in this membrane reacted focally
GOLDBERG et al
•
AUTOSOMAL DOMINANT VITREORETINOCHOROIDOPATHY
Fig 3. A, the peripheral retina is reduced to a glial membrane. Retinal pigment epithelial cells extend into the sensory retina and line the surface of the intemallimiting membrane (arrows) (hematoxylin-eosin; original magnification, X950). B, the markedly atrophic retina in the periphery shows loss of normal architecture as well as focal absence of RPE cells (hematoxylin-eosin; original magnification, X950).
Fig 4. Multiple discrete foci (arrows) of lost photoreceptor cells at the equatorial region (hematoxylin-eosin; original magnification, X100).
with anti-carbonic anhydrase C antibody and showed patchy staining with anti-glial fibrillary acidic protein antibody. Between the macula and equator, there was mild gliosis in the nerve fiber layer, but the inner and outer nuclear layers appeared normal. Rods and cones and their outer segments seemed morphologically intact, and there was a relatively abrupt transition between this normal zone and the multifocal abnormalities of the equatorial fundus. At the macula, the outer nuclear layer was three to five nuclei thick, and the outer segments of the photoreceptor cells were moderately to severely shortened. Occasional subretinal macrophages were seen. The RPE was markedly irregular in thickness and pigmentation. Bruch's membrane appeared thickened, and there was a mild increase in the width of the intercapillary pillars of the choroid. Retinal capillaries in the posterior pole appeared unremarkable, and no cystoid macular edema was noted. ELECfRON MICROSCOPIC FINDINGS
Ultrastructural evaluation concerned primarily (1) the preretinal membrane and cortical vitreous, (2) the gliotic peripheral retina, (3) the photoreceptor degenerative process 'at the equatorial region, and (4) changes associated with a mild, chronic, inflammatory reaction in the retina. In the peripheral retina, the proliferated RPE replaced the foot-plates of the Muller cells and lined the vitreous cavity (Fig 7). Basement membrane-like material and cellular debris produced by these cells were present in the cortical vitreous. A thin preretinal membrane was noted in the equatorial region and extended, in a more thickened configuration, posteriorly (Fig 8). We believe this mem-
Fig S. At the equatorial retina, a focal loss (arrows) of photoreceptor cells is associated with depigmentation ofRPE and thinning of the inner nuclear layer (hematoxylin-eosin; original magnification, X950).
brane consisted of proliferated Muller cells, because the cells formed zonulae adherentes-like cell junctions, simulating an "external limiting membrane." Villi projected into the vitreous cavity and resembled basket fibers of Schultze. The cytoplasm of the cells contained neurotubuIes and filaments. The ground substance of the cytoplasm appeared relatively electron lucent. The preretinal membrane was thickest in the macular area and consisted of 10 to 13 layers of cells (Fig 9). These cells showed two distinct morphologic appearances. Some ofthe cells had lucent cytoplasm and contained a number of microtubules. Others had dense filamentous cytoplasm. Both types of cells were joined by multiple desmosomes. Vitreous fibers were apparently trapped between the glial cells of the preretinal membrane. In the peripheral retina, anterior to the equator, the normal retinal architecture was replaced by glial cells. Two types of glial cells were again noted: some with lucent cytoplasm containing microtubules and mitochondria; 1739
OPHTHALMOLOGY
•
DECEMBER 1989
•
VOLUME 96
•
NUMBER 12
Fig 6. A, preretinal membrane (arrows) covers the retina of the posterior pole. The underlying architecture of the retina is preserved in this area (hematoxylin-eosin; original magnification, X950). B, at the macular area, a thick preretinal membrane (small arrows) is noted. The photoreceptor outer nuclear layer is three to five nuclei thick, but the outer segments of the photoreceptor cells are short. The RPE cells are markedly irregular in thickness and pigmentation (large arrow). The width of the intercapillary pillars of the choriocapillaries (arrowheads) is slightly increased (hematoxylin-eosin; original magnification, X950).
Fig 7. In the peripheral retina, proliferated RPE cells line the vitreous cavity (V). Basement membrane material (arrows) and cellular debris (arrowheads) have been shed into the cortical vitreous (original magnification, X5200).
others with dense filamentous cytoplasm. Some of the glial cells produced multilaminar basement membrane in a nodular fashion. Interposed between the gliotic cells were nodules of proliferated RPE, which had produced additional nodular basement membrane material at the base of disoriented RPE cells. The photoreceptor cells at the equator showed extensive degenerative changes (Fig 10). Many nuclei had disap1740
peared, and the space was filled with glial processes. Some nuclei of the photoreceptor cells were densified and elongated; others has a crenated nuclear membrane, con-' densed chromatin, and vacuolated cytoplasm. Some rod and cone nuclei appeared to be present (Fig 11). Fragments of disorganized photoreceptor outer segments formed membranous whorls. The RPE showed two forms of changes: some cells were depigmented with densified
GOLDBERG et al
•
AUTOSOMAL DOMINANT VITREORETINOCHOROIDOPATHY
Fig 8. The preretinal membrane at the equatorial region consists of proliferated Muller cells, which formed zonula adherentes-like cell junctions (arrows) facing the vitreous cavity (V). Villi projected into the vitreous cavity. The cytoplasm of the cells contain neurotubules and filaments with relatively lucent ground substance (lLM = internal limiting membrane) (original magnification, x 10,(00). Inset, zonula adherentes-like cell junctions (arrows) border the vitreous cavity (original magnification, x30,(00).
cytoplasm and nuclei; others appeared atrophic and filled with melanolysosomes (Fig 12). Muller cells extended down to the subretinal space and expanded to form a new and condensed external limiting membrane wherever there was extensive loss of photoreceptor cells (Fig 13). The photoreceptor degenerative process in the macula was different from that at the equator. At the macula, the outer segments were moderately to severely shortened and showed tubular-vesicular degeneration. Within the cytoplasm in the inner segments, some membranous degeneration also was seen (Fig 14). The RPE was filled with melanolysosomes, and there was a loss of apical villi. At the base of these cells, drusen-like deposits and various forms of basement membrane deposits were seen. Bruch's membrane was filled with curvilinear profiles and densified vesicles. However, the retinal vasculature in the macula showed no perivascular exudation, nor were there any changes typical of cystoid macular degeneration (Fig 15). Macrophages were observed between Bruch's membrane and the choriocapillaris, in the sensory retina, and in the vitreous cavity, suggesting that a mild inflammatory reaction had existed. Other types of inflammatory cells were absent.
DISCUSSION One of the characteristic microscopic signs of this disease appears to be the discrete, multi focal loss of photoreceptor cells in the equatorial region, associated with thinning of the inner nuclear layer and sclerosis of the peripheral retinal vasculature. Depigmentation and atrophy of the RPE were also present. In the far penphery the retinal architecture was disorganized with reactive changes in astrocytes and Muller cells. The RPE proliferated in nodular form into the inner layers of the retina. Although many of these pathologic changes resemble those of retinitis pigmentosa, there are a number ofstriking differences: the multifocal nature of the disease, the abrupt transition from the abnormal equatorial zone to the normal fundus posterior to the equator (excluding the senescent changes in the macula), the absence of widespread rod and cone degeneration, and the slow or absent clinical progression in various family members. The degeneration of the photo receptors appears to have followed two well-known patterns of cell death, namely, apoptosis and necrosis.3 A few of the photoreceptor cells showed signs of apoptosis with preservation of the retinal 1741
OPHTHALMOLOGY
•
DECEMBER 1989
architecture. These nuclear changes of the photoreceptor cells closely resembled those seen in hereditary macular degeneration of baboons.4 Apoptosis and necrosis also have been observed in retinas of patients with retinitis pigmentosa, although necrosis is more commonly seen. The relative importance ofapoptosis and necrosis ofphotoreceptor cells in ADVIRC, retinitis pigmentosa, and related diseases needs further exploration. It is interesting that GFAP was expressed well by the Muller cells of our patient's gliotic retina and preretinal membrane. Glial fibrillary acidic protein is present in normal retinal astrocytes but is not usually seen in normal Muller cells. 5,6 Sarthy and Fu5 observed GFAP in Muller cells of mice with the rd mutation and after light toxicity. A preliminary study in our laboratory showed that retinal degeneration was not associated with abundant GFAP formation in some cases of retinitis pigmentosa (unpublished data; presented at the Annual Meeting of the Association for Research in Vision and Ophthalmology, May 4, 1989). If these observations are confirmed with more cases of ADVIRC and retinitis pigmentosa, this staining technique may provide a clue to possible differences between retinitis pigmentosa and ADVIRC. The hereditary degeneration of photoreceptor cells in this patient can be contrasted with the age-related macular degeneration observed in the same individual. In the macula, there was shortening of outer segments associated with marked changes in the RPE. The RPE cells were packed with melanolysosomes, but there was no abnormal proliferation ofthese cells. Moreover, there was no widespread death of photoreceptor cells. Tubular and vesicular changes were seen in the outer segments, and membranous degeneration was noted in their cytoplasm, but the basic architecture of the macular region was preserved. The RPE changes in the equatorial retina also were considerably different from those in the posterior pole. Atrophy, depigmentation, necrosis, or proliferation were hallmarks of the hereditary dystrophy, whereas excessive accumulation of melanolysosomes and the presence of subretinal macrophages appeared to characterize the RPE of age-related macular degeneration.
•
VOLUME 96
•
NUMBER 12
Fig 9. Preretinal membrane at the macular area consists of more than ten layers of cells in this section. Some of the cells (M) have lucent cytoplasm and contain a number of microtubules (arrowheads); others have dense filamentous cytoplasm (G). The cells are joined by multiple desmosomes (arrows) (original magnification, X4200) (V = vitreous cavity; ILM = internal limiting membrane). Top right inset, vitreous filaments (V) are trapped within multiple layers of preretinal membrane (original magnification, X5(00). Bottom leji inset, light micrograph shows thick preretinal membrane (arrows) opposite ganglion cells (GC) (original magnification, X950).
Fig 10. Degenerative photoreceptor cells at the equator. A, many nuclei disappear and their spaces are filled with expanded glial processes. Some of the nuclei (N) are densified and pyknotic (original magnification, X3400). B, other photoreceptor nuclei have condensed chromatin with crenated nuclear membranes (arrows) and vacuolated cytoplasm (V) (original magnification, X2800).
1742
GOLDBERG et al
•
AUTOSOMAL DOMINANT VITREORETINOCHOROIDOPATHY
Fig 11. At the equator, both rod (R) and cone (C) photo-
receptor elements are present. Most of the outer segments are absent. The RPE cells appear necrotic and densified. Nodular proliferation of basement membrane (BM) are observed. Focal areas oflong spacing, banded collagen (arrow) are seen in the sub-RPE region. Most of the melanin granules in the RPE are absent (original magnification, X6600).
Fig 12. At the equatorial region, both rod (R) and cone (C) photoreceptor inner segments are present. Fragments of disorganized photoreceptor outer segments (arrowheads) forming membranous whorls are seen. Pigmentladen macrophages (M) are seen in the subretinal space. The RPE cells appear atrophic and are filled with melanolysosomes (arrows) (original magnification ,
X4200).
1743
OPHTHALMOLOGY
•
DECEMBER 1989
The degenerative process excited a mild inflammatory reaction with macrophages in the choroid, retina, and vitreous. No primary inflammatory or other pathogenetic mechanisms could be identified. We suspect that this inflammatory activity may be nonspecific and secondary to the dystrophic process in the retina. The results of this study help explain the pathogenesis of the preretinal membrane. In the peripheral retina, where the disease was most advanced, the shedding of basement membrane-like material and cellular debris into the vitreous cavity by the proliferative pigment epithelium appears to be a possible initiating event in preretinal membrane formation. In the equatorial region, the preretinal membrane consisted entirely of Muller cells, which formed external limiting membrane-like structures lining the vitreous cavity. The presence of Muller cells was confirmed by the immunohistochemical study, which showed carbonic anhydrase C, a characteristic finding in such Muller cells. Clinically, fluorescein leakage was observed in this patient's macular region. The presence of vitreous filaments trapped within the preretinal membrane in this location suggests the presence of traction. Retinal tags pulled into the cortical vitreous were also seen in the fundus periphery. We inferred from both observations that the fluorescein leakage might be secondary to vitreous traction by the preretinal membrane on the underlying retina. 7 Alternatively, the interval between angiographic and histopathologic studies may have permitted spontaneous resolution of vascular incompetence. Although there appear to be some distinguishing microscopic features of ADVIRC, such as the predilection for equatorial and preequatorial regions and its multifocal nature, differentiation from other dominantly inherited retinal dystrophies, such as some forms of retinitis pigmentosa, is based primarily on clinical findings. For example, the coarse pigmentary changes observed ophthalmoscopically as an annular band in the peripheral fundus are highly characteristic of the two unrelated families we have previously reported as examples of ADVIRC I ,2 and may be pathognomonic. Also observed in some members of both pedigrees are punctate yellowish-white deposits in both the superficial and deep fundus; retinal vascular narrowing as well as mild-to-intense leakage of fluorescein; cystoid macular edema; focal areas of preretinal neovascularization; visible choroidal vessels; fibrillar condensation of the vitreous; and presenile cataract formation. Similar changes also are noted in some forms of retinitis pigmentosa. However, unlike retinitis pigmentosa, electroretinographic abnormalities in ADVIRC are only mild to moderate in older individuals and are totally lacking in several younger, affected family members. I •2 Clinical progression, ifany, appears to be extremely slow, and the prognoses for night vision and peripheral vision are excellent. Visual acuity is only mildly to moderately reduced, despite occurrence of cystoid macular edema and vitreous hemorrhage in some patients. Moderately reduced acuity in the current case (20/60-2, both eyes) is probably attributable to the presence of mild age-related macular degeneration. 1744
•
VOLUME 96
•
NUMBER 12
Fig 13. At the equator, focal loss of photoreceptor cells lead to expanded Miiller (M) cells, which form a new and condensed external limiting membrane (arrowheads). A few photoreceptor cells (P) with fragments of outer segments (OS) remain. The RPE cells are atrophic and filled with lipofuscin granules (arrows) (original magnification, X2900).
The microscopic appearance of this patient's eyes showed several possible explanations for the yellowishwhite deposits in the fundus of other family members. These include preretinal tags, preretinal glial membranes, and drusenoid material that was apparently elaborated by RPE cells into the preretinal space. The RPE cells had lost their normal orientation and their basal layers faced the interior of the eye. In addition, more typical drusen (located on Bruch's membrane) as well as hypopigmented RPE cells underlying focal degenerations of photoreceptors also could have contributed to the yellow spots that clinically appeared to be located more deeply in the fundus. 1,2 Although choroidal vessels were abnormally prominent ophthalmoscopically in many family members, histopathologic analysis of our patient's eyes showed only mild degenerative and atrophic choroidal changes compatible with aging. Some focal equatorial changes could have been related to RPE degeneration. It is likely that clinical visualization of choroidal vessels was permitted by atrophy or hypopigmentation of the RPE. Retinal vascular involution also appeared more prominent clinically than microscopically. Only in the far periphery did histologic evidence confirm vascular sclerosis. These findings, in the aggregate, suggest that the primary or initiating site of pathologic involvement in ADVIRC is not in the choroid, retinal vasculature, or vitreous. The available evidence does not, however, allow us to conclude whether cells of the RPE or of the sensory retina are the locus of the primary genetic abnormality. In most degenerated retinal areas, focal loss of photo receptors was accompanied by degeneration or atrophy of underlying RPE cells (and vice versa). Rarely did either of these tissue layers show degeneration without concomitant change in the adjacent tissue. As in the case of many types of retinitis
GOLDBERG et al
•
AUTOSOMAL DOMINANT VITREORETINOCHOROIDOPATHY
Fig 14. The retina at the macular area. A, fragments of outer segments (OS) of photoreceptor cells are seen in the subretinal space. Inner segments of the photoreceptor cells (P) show focal areas of membranous degeneration (MD) (original magnification, X7000). Inset. membranous degeneration (arrows) is seen under higher power magnification (original magnification, X20,OOO). B, RPE cells in the macular area are filled with melanolysosomes (arrow) and melanin granules. The photoreceptor outer segments have disappeared, but inner segments of cone cells (P) remain (original magnification, X4200).
pigmentosa,8-18 preretinal membrane formation was more extensive than anticipated from prior clinical examination. Nonetheless, the vitreous and preretinal abnormalities are probably not primary pathogenetic events. It is of interest that a recent study of autosomal dominant retinitis pigmentosa 17 reinforced the idea that the primary disorder in this disease lay within the photoreceptors. The multifocal nature of the photoreceptor changes in our patient was striking and was seemingly more marked than in previously reported microscopic material from various types of other retinal dystrophies, including retinitis pigmentosa. 8- 3o This may reflect a true distinguishing microscopic feature of ADVIRC. Alternatively, its absence in previously reported cases of retinitis pigmentosa may possibly be due to histologic sampling errors, advanced age (and, therefore, more widespread, rather than focal, loss of photoreceptors) , or other unknown factors. Nonetheless, even in young individuals with retinitis pigmentosa, whose eyes have been evaluated histopathologically,
discrete focal loss of photoreceptor outer segments has not been emphasized. Other more extensive types of patchy retinal degeneration have, however, been reported by Szamier and Berson,15,16 Tucker and Jacobson,17 and Duvall et a1. 20 Patchy retinal atrophy also has been reported by Ghosh et al 31 in a female carrier of choroideremia. In this carrier, however, the transition from normal to abnormal retinal zones was gradual, RPE cells did not extend into the retina, and there were no macrophages in the subretinal space. The multifocal nature of the degenerative process affecting both photo receptors and RPE in the peripheral fundus of our patient probably explains the relatively favorable retinal function and visual prognosis in ADVIRC, even in aged individuals. This stands in contrast to the usually unfavorable effects created by the widespread photoreceptor and RPE degenerations that typify most forms of retinitis pigmentosa (including those affecting younger individuals). Despite careful light- and electron1745
OPHTHALMOLOGY
•
DECEMBER 1989
•
8.
9.
10.
11.
12. 13. 14. 15. 16. 17. Fig 15. Retinal vessels (V) in the macular area appear intact without exudate (G-ganglion cells) (original magnification, X4200).
18.
19.
microscopic evaluation of our ADVIRC patient's eyes, however, we still have little insight into the basic mechanisms underlying the muItifocal retinal degeneration, retinal edema (in other family members), preretinal neo-' vascularization (in other family members) and preretinal membrane formation that occur in this enigmatic syndrome. Microscopic findings do not support primary pathogenetic roles for the choroid or vitreous; therefore, a name for this syndrome that is more accurate than ADVIRC would be autosomal dominant peripheral annular pigmentary dystrophy of the retina.
20.
21.
22. 23.
24.
REFERENCES 25. 1. Kaufman SJ, Goldberg MF, Orth DH, et al. Autosomal dominant vitreoretinochoroidopathy. Arch Ophthalmol 1982; 100:272-8. 2. Blair NP, Goldberg MF, Fishman GA, Salzano T. Autosomal dominant vitreoretinochoroidopathy (ADVIRC). Br J Ophthalmol1984; 68:2-9. 3. Walker NI, Harmon BV, Gobe GC, Keer JFR. Pattems of cell death. Methods Achiev Exp Pathol 1988; 13:18-54. 4. Santos-Anderson RM, Tso MOM. Vainisi SJ. Heredofamilial retinal dystrophy in guinea baboons. II. Electron microscopic observations. Arch Ophthalmol1983; 101:1762-70. 5. Sarthy PV, Fu M. Photoreceptor degeneration leads to induction of the glial intermediate filament protein gene in the mouse retina. In: Piatigorsky J, Shinohara T, Zelenka PS, eds. Molecular Biology of the Eye: Genes, Vision, and Ocular Disease. New York: Alan R. Liss, Inc, 1988; 305-15. 6. Haltia M, Tarkkanen A, Kivela T. Rabies: ocular pathology. Br J Ophthalmol1989; 73:61-7. 7. Goldberg MF. Diseases affecting the inner blood-retinal barrier. In:
1746
26.
27.
28. 29.
30.
31.
VOLUME 96
•
NUMBER 12
Cunha-Vaz JG, ed. The Blood-Retinal Barriers. New York: Plenum, 1980; 309-63. Raybom ME, Moorhead LC, Hollyfield JG. A dominantly inherited chorioretinal degeneration resembling sectoral retinitis pigmentosa. Ophthalmology 1982; 89:1441-54. Rodrigues MM. Wiggert B, Hackett J, et al. Dominantly inherited retinitis pigmentosa: ultrastructure and biochemical analysiS. Ophthalmology 1985; 92:1165-72. Rodrigues MM. Newsome D. Retinitis pigmentosa: electron microscopy and cell culture studies. Birth Defects: Original Article Series: (Genetic Eye Diseases: Retinitis Pigmentosa and Other Inherited Eye Diseases) 1982; 18:81-94. Rodrigues MM, Bardenstein D, Wiggert B, et al. Retinitis pigmentosa with segmental massive retinal gliosis: an immunohistochemical, biochemical, and ultrastructural study. Ophthalmology 1987; 94:180-6. Santos-Anderson RM. Tso MOM. Fishman GA. A histopathologic study of retinitis pigmentosa. Ophthalmic Paediatr Genet 1982; 1:151-68. Szamier RB. Ultrastructure of the preretinal membrane in retinitis pigmentosa. Invest Ophthalmol Vis Sci 1981; 21 :227 -36. Szamier RB, Berson EL. Retinal ultrastructure in advanced retinitis pigmentosa. Invest Ophthalmol Vis Sci 1977; 16:947-62. Szamier RB, Berson EL. Histopathologic study of an unusual form of retinitis pigmentosa. Invest Ophthalmol Vis Sci 1982; 22:559-70. Szamier RB, Berson EL. Retinal histopathology of a carrier of X-chromosome-linked retinitis pigmentosa. Ophthalmology 1985; 92:271-8. Tucker GS, Jacobson SG. Morphological findings in retinitis pigmentosa with early diffuse rod dysfunction. Retina 1988; 8:30-41. Flannery JG, Farber DB, Bird AC, Bok D. Degenerative changes in a retina affected with autosomal dominant retinitis pigmentosa. Invest Ophthalmol Vis Sci 1989; 30:191-211. Bunt-Milam AH, Kalina RE, Pagon RA. Clinical-ultrastructural study of a retinal dystrophy. Invest Ophthalmol Vis Sci 1983; 24:458-69. Duvall J, McKechnie NM, Lee WR, et al. Extensive subretinal pigment epithelial deposit in two brothers suffering from dominant retinitis pigmentosa. A histopathological study. Graefes Arch Clin Exp Ophthalmol 1986; 224:299-309. Farber DB, Flannery JG, Bird AC, et al. Histopathological and biochemical studies on donor eyes affected with retinitis pigmentosa. Prog Clin Bioi Res 1987; 247:53-67. Gartner S, Henkind P. Pathology of retinitis pigmentosa. Ophthalmology 1982; 89:1425-32. Goebel HH, Ikeda K, Eichholtz W, et al. Ultrastructural study of primary canine and human pigmentary retinopathy. OphthalmiC Paediatr Genet 1985; 5:3-11. Kolb H, Gouras P. Electron microscopiC observations of human retinitis pigmentosa, dominantly inherited. Invest Ophthalmol1974; 13:48798. Lahav M, Craft J, Albert DM, Ishii Y. Advanced pigmentary retinal degeneration: an ultrastructural study. Retina 1982; 2:65-75. Meyer KT, Heckenlively JR, Spitznas M, Foos RY. Dominant retinitis pigmentosa: a clinicopathologic correlation. Ophthalmology 1982; 89: 1414-24. Mizuno K, Nishida S. Electron microscopic studies of human retinitis pigmentosa. Part 1. Two cases of advanced retinitis pigmentosa. Am J Ophthalmol1967; 63:791-803. Mizuno K, Nishida S, Takei Y. Pathology of human retinal dystrophy. Prog Clin Bioi Res 1987; 247:21-33. Rodrigues MM, Wiggert B, Tso MOM, Chader GJ. Retinitis pigmentosa: immunohistochemical and biochemical studies of the retina. Can J Ophthalmol 1986; 21:79-83. Szamier RB, Berson EL, Klein R, Meyers S. Sex-linked retinitis pigmentosa: ultrastructure of photoreceptors and pigment epithelium. Invest Ophthalmol Vis Sci 1979; 18:145-60. Ghosh M. McCulloch C, Parker JA. Pathological study in a female carrier of choroideremia. Can J Ophthalmol1988; 23:181-6.