- Email: [email protected]
Leber's Congenital Amaurosis
LEBER'S
CONGENITAL
AMAUROSIS
K . M I Z U N O , M . D . , AND Y . T A K E I , M . D .
Sendai,
Japan
AND
M . L. SEARS, M . D . , W . S. P E T E R S O N , M . D . ,
R O N A L D E . C A R R , M . D . , AND L . M . J A M P O L , M . D .
New Haven,
Leber's congenital amaurosis, initially described as a variant of retinitis pigmentosa, is a hereditary disorder characterized by blindness or near-blindness from birth or shortly thereafter, reduced or absent pupillary reactions, often nystagmus and photophobia, and a variable ophthalmoscopic a p p e a r a n c e . The end-stage fundus changes may be those of a typical pigmentary retinal degeneration. Initially, however, an almost normal ophthalmoscopic appearance is common, requiring electroretinographic abnormalities for diagnosis. Subsequently, atypical granularity of the fundus may also be seen, as well as pigmentation and depigmentation, especially in the peripheral fundus, different from that seen classically. Most striking of all is a rare "marbelized f u n d u s " with an unusual mosaic pattern and periarteriolar distribution of relatively well-demarcated depigmented lesions deep to the retinal vessels but separated from them by clear or somewhat reddish z o n e s . ' A frequent association of Leber's congenital amaurosis with neurological disorders, especially mental retardation and epilepsy, has been noted, as well as association with cataract and keratoconus. An autosomal-
recessive pattern of inheritance is probable. Although it is clinically apparent that this form of congenital blindness originates in the retina, with significant early abnormalities of the retinal photoreceptors, histopathologic information is scanty, difficult to interpret, and unavailable from early c a s e s . This report presents clinical observations from two patients with early cases of Leber's congenital amaurosis, as well as detailed histopathologic observations from one of these patients.
1,2
3-13
1 7 - 2 2
CASE REPORTS
Case 1—This 7-month-old girl had consanguineous parents. The pregnancy was normal, the parents were healthy, and the family history revealed no evidence of hereditary visual disturbance. The birth weight was normal. When she was first seen at Tohoku University Hospital, the child would not respond to her environment. Pupillary reactions were sluggish, nystagmus was present, and slight edema in the macular area resembled a cherry-red spot. Psychomotor retardation was apparent with delayed milestones. She needed support to sit and could not pronounce words. At 9 months of age, the eyes showed an oscillatory movement, but motility was otherwise grossly normal. The pupils were dilated and unresponsive to light, and the media were clear. The electroretinographic response was completely extinguished. Ophthalmoscopic examination revealed multiple round or oval white spots with indistinct edges, localized beneath the retinal vessels and distributed throughout the entire fundus except for the macular region (Figs. 1 and 2). These lesions were present bilaterally and distributed symmetrically. The optic disks and retinal vessels appeared essentially normal. Neurologic examination revealed abnormalities of hearing and of the motor system, and positive Babinski reflexes were present. Urinalysis, hemogram, serum proteins, fasting blood glucose, lipid profile, urinary amino acids, and radiographs of the chest, skull, and skeleton were normal. An electro-
1 1 1 3 , 1 4
15
Connecticut
16
11
3
From the Department of Ophthalmology, Tohoku University School of Medicine, Sendai, Japan (Drs. Mizuno and Takei), and the Department of Ophthalmology and Visual Science, Yale University School of Medicine, New Haven, Connecticut (Drs. Sears, Peterson, Carr, and Jampol). Reprint requests to Marvin L. Sears, M.D., Department of Ophthalmology, Yale Medical School, New Haven, CT 06510. 32
Fig. 1 (Mizuno and associates). Case 1. Right eye at 9 months. Isolated, deepseated, opaque, round to oval lesions are seen in the paramacular area, with a cherryred spot in the macular region.
Fig. 2 (Mizuno and associates). Case 1. Equatorial region of the right eye at 12 months. Lesions are larger, more numerous, and more confluent.
Fig. 3 (Mizuno and associates). Case 1. Left eye at 15 months. Optic disk is atrophic and vessels are narrower.
VOL. 83, NO. 1
L E B E R ' S CONGENITAL AMAUROSIS
encephalogram (EEG) revealed polymorphous dysrhythmia, suggesting diffuse organic brain damage with epilepsy. At 12 months of age, ophthalmoscopy revealed a tendency toward enlargement and confluence of the whitish lesions. However, they became smaller (Fig. 3). Diameters of 30 white lesions located in the equatorial region clinically were 0.34 ± 0.12 mm (standard deviation). The white spots in the midperiphery were intermingled with fine pigmentation. The optic disks appeared to be pale. The retinal vessels remained essentially normal. After 16 months of age, the patient had frequent dyspneic episodes, and she died of cardiac arrest at 18 months of age. The eyes were obtained for postmortem examination. Case 2—This 9-month-old white boy was the child of nonconsanguineous parents. The pregnancy was complicated by intermittent episodes of vaginal bleeding and maternal syncope, lasted IOV2 months, and labor was induced by rupture of the fetal membranes; apparent meconium staining of the amniotic fluid was then noted. Delivery was by forceps. The patient weighed 3,402 g (7 lb, 9V2 oz) at birth but the APGAR rating was not recorded. The patient whose developmental milestones were normal for five months developed defective vision, hyperacusis, and a loss of previously attained developmental milestones. One month later, the patient had an episode of spiking fevers, vomiting, and diarrhea that lasted for several days. No definite diagnosis was made. The patient's development regressed significantly with listlessness and unresponsiveness to his environment. Ophthalmological examination at this time was normal. At 9 months of age the patient was hospitalized and examined extensively. Urinalysis, hemogram, and multiple routine blood chemistries were normal. No inclusion bodies or amino acids were present in the urine. A tine test was negative. An electrocardiogram, bone marrow analysis, lumbar puncture, electromyogram, and E E G were within normal limits. Radiographic views of the skull, spine, chest, and long bones were also normal, as well as intravenous pyelography, esophagram, and brain scan. Evaluation on admission showed only delayed milestones with what was felt to be psychomotor retardation. Degenerative neurologic disease of uncertain cause was suspected. Subsequently, some progression in the patient's milestones was noted, with development of the ability to hold his head up and to speak some words, but overall psychomotor retardation persisted. At examination here, the 21-month-old patient appeared to follow a hand light with either eye. Examination was done when the child was awake and then under ketamine anesthesia. External examination showed an intermittent right exotropia but was otherwise normal. Pupillary reactions were present but sluggish. Slit-lamp examination showed Mittendorf dots. Intraocular pressures measured by Schi0tz tonometry were 4.5 scale units with 5.5 gram weight in both eyes. Retinoscopy was R.E.: +9.50 sphere, and L.E.: +10.50 = - 1 . 7 5 x 180°. Ophthal-
35
moscopy revealed multiple, relatively wellcircumscribed, irregular linear depigmented lesions distributed bilaterally and symmetrically in the midperipheries, but not in the posterior poles and the far peripheries. These lesions were located beneath the retinal vessels and appeared to be at the level of the retinal pigment epithelium. Fluorescein angiography showed fluorescence of the lesions during the choroidal phase but no leakage or staining was apparent. An electroretinogram showed a moderately decreased photopic response with a minimal scotopic increment. By about 3V2 years of age, the child seemed to be able to follow toys with both eyes, but visual acuity was grossly poor. The fundi were essentially unchanged with apparent sparing of the posterior poles. Moderate to severe psychomotor retardation persisted. MATERIAL AND METHODS
T h e eyes from C a s e 1 were obtained three hours after death. T h e left eye was p l a c e d in 1 0 % formaldehyde solution, e m b e d d e d in paraffin, sectioned, stained with hematoxylin and eosin, and examined by light microscopy. T h e right eye was cut into small sagittal sections and fixed for one hour in 1 % osmium tetroxide containing 0 . 2 5 M sucrose buffered to p H 7.4 with phosphate buffer at 4 ° C . T h e y were then dehydrated serially in ethanol and e m b e d d e d in E p o n 8 1 2 . One-micron sections were stained with toluidine blue and examined by light microscopy. Ultrathin sections were cut on a Porter-Blum ultramicrotome, stained with uranyl acetate and lead citrate, and examined with a J E M - 1 0 0 C electron m i c r o s c o p e . Light microscopy—In 6-|x thick paraffin sections prepared for light microscopy, the pigment epithelial cells in the equatorial region were proliferated and intermingled with outer and inner nuclear layers, migrating to the essentially intact nerve fiber layer ( F i g . 4 ) . T h e pigment epithelial layer and the neurosensory retina, however, were artifactitiously separated so that details of the outer retinal layers were observed only in E p o n sections. In 1-u. thick E p o n sections prepared for light microscopy, there were fewer gan-
36
AMERICAN JOURNAL O F OPHTHALMOLOGY
Fig. 4 (Mizuno and associates). Histologic section from periphery of right eye. Proliferation of pigment epithelial cells from outer nuclear layer to nerve fiber layer (hematoxylin and eosin, x 130).
glion cells, and a marked hypertrophy o f the Müller fibers was found. T h e inner plexiform and inner nuclear layers were well developed. E v i d e n c e of significant cellular undifferentiation, however, was observed from the outer nuclear layer to the pigment epithelial layer. Cell bodies of photoreceptors were larger than normal and oval, resembling nuclei o f the outer neuroblastic layer in the human embryonal stage o f development. T h e nuclei were sparsely distributed, with only two to four rows in the equatorial region (Figs. 5-7). In a wide zone extending beyond the macula were elements undoubtedly belonging solely to the cones.
Fig. 5 (Mizuno and associates). Histologic section near that shown in Figure 4. Layers from inner limiting membrane to outer plexiform layer are normal. Circumscribed deposit is seen in subretinal space (x60).
JANUARY, 1977
Fig. 6 (Mizuno and associates). Histologic section near that shown in Figure 4 shows hypertrophic Müller fiber layer, rarefaction of outer nuclear layers, disorganized visual cell layer, wavy pigment epithelium, and thicker choroid. Subretinal deposits (arrows) indent pigmented epithelium outward (toluidine blue, x60).
T h e rod outer segments were generally absent throughout the retina. T h e most striking finding observed in the photoreceptor layer was the widespread presence of peculiar large deposits. T h e s e consisted of debris from photoreceptors and phagocytes and displaced the outer limiting membrane inward and the pigment epithelial layer outward. Sixteen of these deposits, measured through about 6 0 serial 8-u. sections, were 0.35 ±
Fig. 7 (Mizuno and associates). Higher magnification of Figure 6. Undifferentiated oval nuclei are less numerous in outer nuclear layer. Cones are intact. No rods are visible. Circumscribed deposit indents pigment epithelium outward. Undifferentiated pigment epithelium is more cuboidal and contains inwardly displaced pigment granules. There are fewer capillaries in the choriocapillaris than normal (toluidine blue, x220).
VOL. 83, NO. 1
LEBER'S CONGENITAL AMAUROSIS
0.02 mm (standard deviation). T h e pigment epithelium was regular and intact, but its undifferentiation was shown by its cuboidal shape and displacement o f pigment granules toward the apical border (Fig. 7). T h e choroid was thickened and poorly pigmented, with generalized undifferentiation. T h e choriocapillaris was present everywhere, but the capillaries were poorly developed and were not patent. Bruch's membrane was intact (Figs. 6 and 7). Electron microscopy—Nuclei o f the outer nuclear layer were oval or spindleshaped (Fig. 8). All of the photoreceptors, even the cones near the macula, were abnormal. T h e outer segments near the posterior pole were markedly shorter than
Fig. 8 (Mizuno and associates). Electron micrograph near outer limiting membrane (OLM). Nuclei of photoreceptor cells are oval. Cytoplasmic organelle of Müller cell (M) is scanty. Mitochondria of inner segment (Is) are vacuolated (x3,500).
37
normal and had disorganized and disoriented disks even at the base of the outer segment ( F i g . 9 ) . Variably throughout the equatorial region, the outer segments completely disappeared so that the tips of the inner segments were in direct contact with the apical portions o f the pigment epithelial cells (Figs. 10 and 11). T h e outer part of the inner segments was wider than normal and ballooned out, containing only ribosomes and a few glycogen particles, but no mitochondria. In contrast, the inner part was packed with mitochondria, although most mitochondria in the rods had become vacuolated and deteriorated (Figs. 10 and 11). In the large subretinal deposits identified by light microscopy, the layer o f rods and cones was replaced by an accumulation of fragments of inner segments, apical processes of pigment epithelial cells, and macrophages. T h e macrophages contained many kinds of lysosomes, swollen mitochondria, and amorphous material (Figs. 10 and 12). T h e pigment epithelial cells lacked a normal arrangement o f microvilli and showed vesicular disorganization (Figs. 10-12). Mitochondria, smooth-surfaced endoplasmic reticulum, and melanin granules were distributed throughout the cytoplasm of the cells. Much phagocytosed outer segment material, as membrane-bound phagosomes and other lysosomes, was found in the cytoplasm (Figs. 13 and 14). O n e large lysosome contained debris o f a probable 1amellated body and melanin granules (Fig. 15). T h e undifferentiated basal surfaces of the pigment epithelial cells were not delicately invaginated but slightly undulating, resembling an ordinary cell surface (Figs. 10 and 14). Bruch's membrane was fairly well differentiated. In the choroid, however, most capillaries and larger vessels were sparse and poorly developed. In their place, a number of round or oval-shaped cells, probably representing fibroblasts, were noted (Fig. 14).
Fig. 9 (Mizuno and associates). Electron micrograph near posterior pole. Swelling of the outer part of the inner segment without mitochondria indicates prematurity of rod and cone inner segment (Is). Immature outer segment (Os) is disorganized; bar gauge = l(i (x4,400).
DISCUSSION
T h e clinical entity of L e b e r ' s congenital amaurosis has not been fully defined, with the relationship o f earlier to later changes particularly o b s c u r e . In both of our cases, essentially normal fundi were present initially. Later, white dots and flecks appeared, eventually associated with some fine pigmentation. In neither of these early cases did the advanced pigmentary tapetoretinal degeneration described in L e b e r ' s original patients occur, although the possible future course is unknown in both cases. E v e n in the early stages, however, diffuse pathophysiologic disturbances were apparent. 1 - 1 4
1 , 2
Fig. 10 (Mizuno and associates). Electron micrograph of outer retina corresponding to white spot. Deposit located between inner segment (Is) and pigment epithelium (PE) contains macrophage (Mp), debris of outer segments, apical part of pigment epithelium, and amorphous material. Bruch's membrane (Br) and choriocapillaris ( C C ) appear normal ( x 1,700).
Fig. 11 (Mizuno and associates). Electron micrograph near equatorial region. Tips of swollen and immature inner segments (Is) of rods and cones directly contact pigment epithelium (PE); bar gauge = In (x6,600).
Fig. 12 (Mizuno and associates). Electron micrograph of subretinal deposit (inset) shows debris (D) of inner segment and pigment epithelium (PE), and macrophage (Mp) that contains lysosomes and the debris; bar gauge = lp. (x4,400).
Fig. 13 (Mizuno and associates). Electron micrograph of retinal pigment epithelium (PE). Cellular architecture exhibits large amount of phagocytosed outer segment material as phagosome (arrows); bar gauge = lu. (x 14,400).
Fig. 14 (Mizuno and associates). Electron micrograph of proximal pigment epithelium (PE) and choroid. Basal infolding in not developed so that basal surface of pigment epithelium appears wavy. Capillary in choriocapillaris (CC) is barely developed and fibrocyte-like cell (F) appears instead. Bruch's membrane (Br) appears normal; bar gauge = lji (x4,400).
VOL. 83, NO. 1
LEBER'S CONGENITAL AMAUROSIS
41
Fig. 15 (Mizuno and associates). Electron micrograph of pigment epithelial cell. Large lysosome (Ly) contains fragmented probable disk membrane and melanin granule; bar gauge = lu. (x 15,000).
Clinical observations, including the intensity of the disorder at birth and electroretinographic data, suggest significant early impairment of the photoreceptor elements, and we speculate that the neurosensory retina fails to develop functionally during prenatal development. T h e curious oval-shaped nuclei found in the outer nuclear layer and the abnormal fine structure of the inner segments are evidence of this immaturity and undifferentiation of the neurosensory retina. T h e lack of basal infoldings in the retinal pigment epithelium, however, indicates that this layer is also immature and undifferentiated, and the poorly developed choriocapillaris with diffuse fibroblastlike cells in the choroidal stroma suggests that the choroid is also impaired. T h e innermost retinal layers appeared to b e spared by the pathologic process.
T h a t neurosensory retina, pigment epithelium, and choroid are involved in postnatal degenerative abnormalities in this disorder seems to b e supported by our observations. W e saw many degenerative changes o f the photoreceptor elements. T h e white fundus lesions appearing after birth correspond to subretinal deposits consisting o f undeveloped and degenerated elements from both the outer retinal layers and the retinal pigment epithelium. T h e marked pigmentary changes noted in some patients, especially as the disease progresses, are not surprising, and may b e the end result o f these earlier pathogenetic processes. Although the factors influencing the ultimate course in any given case are not known, Leber's original concept remains—that cases in which there is the development o f a primarily pigmen-
42
AMERICAN JOURNAL O F OPHTHALMOLOGY
tary retinopathy, as well as the more atypical cases later described b y W a l d e n burg as "neuroepithelial dysgenesis," represent a single clinical spectrum. L e ber's congenital amaurosis may, therefore, b e considered a hereditary disorder characterized b y primary dystrophic and secondary degenerative changes o f neurosensory retina, retinal pigment epithelium, and choroid, with its polymorphic c l i n i c a l and pathologic expressions o f variable pathophysiologic progression. 4
SUMMARY
An early stage o f L e b e r ' s congenital amaurosis, characterized by white spots or lines in the fundus, occurred in two children. L i g h t m i c r o s c o p i c examination o f eyes obtained from one child, a 1 6 month-old J a p a n e s e girl, revealed subretinal deposits corresponding to the white spots and lines in the fundus deposits. L i g h t and electron m i c r o s c o p i c examination o f the eye showed distinctive changes in the outer retinal layers and choroid, w h i l e the inner retinal layers were nearly normal. Characteristic early lesions o f congenital amaurosis appeared to b e produced by deposits consisting o f loose outer segments and apical processes o f the pigmental epithelial cell and macrophages. Undifferentiation in the n u c l e i o f the photoreceptor cell, the inner segment, the pigment epithelial cell, and the choriocapillaris were likely characteristics o f the early changes o f congenital amaurosis. REFERENCES
1. Leber, T.: Uber retinitis pigmentosa und angeborene Amaurose. Albrecht von Graefe's Arch. Klin. Ophthalmol. 15:3.1, 1869. 2. : Uber anomale Formen der retinitis pigmentosa. Albrecht von Graefe's Arch. Klin. Ophthalmol. 17:314, 1871. 3. Alström, C. H., and Olson, O.: Heredo-
JANUARY, 1977
retinopathia congenitalis monohybrida recessiva autosomialis. Hereditas 43:1, 1957. 4. Wâardenburg, P. J.: Does agenesis or dysgenesis neuroepithelialis retinae whether or not related to keratoglobus exist? Ophthalmologica 133:454,1957. 5. Sorsby, A., and Williams, C. E.: Retinal aplasia as a clinical entity. Br. Med. J. 1:293, 1960. 6. Franceschetti, A., François, J., and Babel, J . : Chorioretinal Heredodegenerations, 1st ed. Springfield, Charles C Thomas, 1974, p. 307. 7. Winkelman, J. E . , and Horsten, G. P. M.: The ERG of premature and full-term born infants during theirfirstdays of life. Ophthalmologica 143:92,1962. 8. Schappert-Kimmijser, J . , Henkes, H. E . , and van den Bosch, J . : Amaurosis congenita (Leber). Arch. Ophthalmol. 61:211, 1959; Ophthalmologica 137:420, 1959. 9. Wâardenburg, P. J., and Schappert-Kimmijser, J.: On various recessive biotypes of Leber's congenital amaurosis. Acta Ophthalmol. 41:317, 1963. 10. Gillespie, F . D.: Congenital amaurosis of Leber. Am. J. Ophthalmol. 61:874, 1966. 11. Dekaban, A., and Carr, R. E . : Congenital amaurosis of retinal origin. Frequent association with neurological disorders. Arch. Neurol. Psychtr. 14:294, 1966. 12. Jöhr, P.: A propose de 4 cas d'amaurose tapétorétinienne (type Leber) dans une famille de 9 enfants issue de parents sains (Forme congenitale?). Probl. Act. Ophtalmol. 1;559, 1957. 13. Franceschetti, A., and Forni, S.: Dégénérescence tapéto-rétinienne (type Leber) avec aspect marbré du fond de l'oeil périphérique. Ophthalmologica 135:610, 1958. 14. Brand, L: Eine seltene Netzhautveränderung beim Lawrenee-Biedlschen Syndrom. Klin. Monatsbl. Augenheilkd. 116:337, 1950. 15. Hirose, T., and Wand, O.: Amaurosis congenita (Leber). Ann. Ophthalmol. 7:59, 1975. 16. Flynn, J . T., and Cullen, R. F.: Disc oedema in congenital amaurosis of Leber. Br. J. Ophthalmol. 59:497, 1975. 17. Aubineau, M.: Rétinite pigmentaire congénitale familiäre Examen anatomique. Ann. Oculistique 29:432, 1903. 18. Vrabec, F.: Un case de dégénérescence pigmentaire congénitale de la rétine, examiné histologiquement. Ophthalmologica 122:65, 1951. 19. Horsten, G. P. M., and Winkelman, J . E . : Development of the ERG in relation to histological differentiation of the retina in man and animals. Arch. Ophthalmol. 63:232, 1960. 20. Senior, B., Friedmann, A. I., and Braudo, J. L.: Juvenile familial nephropathy with tapetoretinal degeneration. Am. J. Ophthalmol. 52:625, 1961. 21. Babel, J . : Constatations histologiques dans l'amaurose infantile de Leber et diverses formes d'héméralopie. Ophthalmologica 145:399, 1963. 22. Kroll, A. J., and Kuwabara, T.: Electron microscopy of a retinal abiotrophy. Arch. Ophthalmol. 71:683, 1964.
CONGENITAL
AMAUROSIS
K . M I Z U N O , M . D . , AND Y . T A K E I , M . D .
Sendai,
Japan
AND
M . L. SEARS, M . D . , W . S. P E T E R S O N , M . D . ,
R O N A L D E . C A R R , M . D . , AND L . M . J A M P O L , M . D .
New Haven,
Leber's congenital amaurosis, initially described as a variant of retinitis pigmentosa, is a hereditary disorder characterized by blindness or near-blindness from birth or shortly thereafter, reduced or absent pupillary reactions, often nystagmus and photophobia, and a variable ophthalmoscopic a p p e a r a n c e . The end-stage fundus changes may be those of a typical pigmentary retinal degeneration. Initially, however, an almost normal ophthalmoscopic appearance is common, requiring electroretinographic abnormalities for diagnosis. Subsequently, atypical granularity of the fundus may also be seen, as well as pigmentation and depigmentation, especially in the peripheral fundus, different from that seen classically. Most striking of all is a rare "marbelized f u n d u s " with an unusual mosaic pattern and periarteriolar distribution of relatively well-demarcated depigmented lesions deep to the retinal vessels but separated from them by clear or somewhat reddish z o n e s . ' A frequent association of Leber's congenital amaurosis with neurological disorders, especially mental retardation and epilepsy, has been noted, as well as association with cataract and keratoconus. An autosomal-
recessive pattern of inheritance is probable. Although it is clinically apparent that this form of congenital blindness originates in the retina, with significant early abnormalities of the retinal photoreceptors, histopathologic information is scanty, difficult to interpret, and unavailable from early c a s e s . This report presents clinical observations from two patients with early cases of Leber's congenital amaurosis, as well as detailed histopathologic observations from one of these patients.
1,2
3-13
1 7 - 2 2
CASE REPORTS
Case 1—This 7-month-old girl had consanguineous parents. The pregnancy was normal, the parents were healthy, and the family history revealed no evidence of hereditary visual disturbance. The birth weight was normal. When she was first seen at Tohoku University Hospital, the child would not respond to her environment. Pupillary reactions were sluggish, nystagmus was present, and slight edema in the macular area resembled a cherry-red spot. Psychomotor retardation was apparent with delayed milestones. She needed support to sit and could not pronounce words. At 9 months of age, the eyes showed an oscillatory movement, but motility was otherwise grossly normal. The pupils were dilated and unresponsive to light, and the media were clear. The electroretinographic response was completely extinguished. Ophthalmoscopic examination revealed multiple round or oval white spots with indistinct edges, localized beneath the retinal vessels and distributed throughout the entire fundus except for the macular region (Figs. 1 and 2). These lesions were present bilaterally and distributed symmetrically. The optic disks and retinal vessels appeared essentially normal. Neurologic examination revealed abnormalities of hearing and of the motor system, and positive Babinski reflexes were present. Urinalysis, hemogram, serum proteins, fasting blood glucose, lipid profile, urinary amino acids, and radiographs of the chest, skull, and skeleton were normal. An electro-
1 1 1 3 , 1 4
15
Connecticut
16
11
3
From the Department of Ophthalmology, Tohoku University School of Medicine, Sendai, Japan (Drs. Mizuno and Takei), and the Department of Ophthalmology and Visual Science, Yale University School of Medicine, New Haven, Connecticut (Drs. Sears, Peterson, Carr, and Jampol). Reprint requests to Marvin L. Sears, M.D., Department of Ophthalmology, Yale Medical School, New Haven, CT 06510. 32
Fig. 1 (Mizuno and associates). Case 1. Right eye at 9 months. Isolated, deepseated, opaque, round to oval lesions are seen in the paramacular area, with a cherryred spot in the macular region.
Fig. 2 (Mizuno and associates). Case 1. Equatorial region of the right eye at 12 months. Lesions are larger, more numerous, and more confluent.
Fig. 3 (Mizuno and associates). Case 1. Left eye at 15 months. Optic disk is atrophic and vessels are narrower.
VOL. 83, NO. 1
L E B E R ' S CONGENITAL AMAUROSIS
encephalogram (EEG) revealed polymorphous dysrhythmia, suggesting diffuse organic brain damage with epilepsy. At 12 months of age, ophthalmoscopy revealed a tendency toward enlargement and confluence of the whitish lesions. However, they became smaller (Fig. 3). Diameters of 30 white lesions located in the equatorial region clinically were 0.34 ± 0.12 mm (standard deviation). The white spots in the midperiphery were intermingled with fine pigmentation. The optic disks appeared to be pale. The retinal vessels remained essentially normal. After 16 months of age, the patient had frequent dyspneic episodes, and she died of cardiac arrest at 18 months of age. The eyes were obtained for postmortem examination. Case 2—This 9-month-old white boy was the child of nonconsanguineous parents. The pregnancy was complicated by intermittent episodes of vaginal bleeding and maternal syncope, lasted IOV2 months, and labor was induced by rupture of the fetal membranes; apparent meconium staining of the amniotic fluid was then noted. Delivery was by forceps. The patient weighed 3,402 g (7 lb, 9V2 oz) at birth but the APGAR rating was not recorded. The patient whose developmental milestones were normal for five months developed defective vision, hyperacusis, and a loss of previously attained developmental milestones. One month later, the patient had an episode of spiking fevers, vomiting, and diarrhea that lasted for several days. No definite diagnosis was made. The patient's development regressed significantly with listlessness and unresponsiveness to his environment. Ophthalmological examination at this time was normal. At 9 months of age the patient was hospitalized and examined extensively. Urinalysis, hemogram, and multiple routine blood chemistries were normal. No inclusion bodies or amino acids were present in the urine. A tine test was negative. An electrocardiogram, bone marrow analysis, lumbar puncture, electromyogram, and E E G were within normal limits. Radiographic views of the skull, spine, chest, and long bones were also normal, as well as intravenous pyelography, esophagram, and brain scan. Evaluation on admission showed only delayed milestones with what was felt to be psychomotor retardation. Degenerative neurologic disease of uncertain cause was suspected. Subsequently, some progression in the patient's milestones was noted, with development of the ability to hold his head up and to speak some words, but overall psychomotor retardation persisted. At examination here, the 21-month-old patient appeared to follow a hand light with either eye. Examination was done when the child was awake and then under ketamine anesthesia. External examination showed an intermittent right exotropia but was otherwise normal. Pupillary reactions were present but sluggish. Slit-lamp examination showed Mittendorf dots. Intraocular pressures measured by Schi0tz tonometry were 4.5 scale units with 5.5 gram weight in both eyes. Retinoscopy was R.E.: +9.50 sphere, and L.E.: +10.50 = - 1 . 7 5 x 180°. Ophthal-
35
moscopy revealed multiple, relatively wellcircumscribed, irregular linear depigmented lesions distributed bilaterally and symmetrically in the midperipheries, but not in the posterior poles and the far peripheries. These lesions were located beneath the retinal vessels and appeared to be at the level of the retinal pigment epithelium. Fluorescein angiography showed fluorescence of the lesions during the choroidal phase but no leakage or staining was apparent. An electroretinogram showed a moderately decreased photopic response with a minimal scotopic increment. By about 3V2 years of age, the child seemed to be able to follow toys with both eyes, but visual acuity was grossly poor. The fundi were essentially unchanged with apparent sparing of the posterior poles. Moderate to severe psychomotor retardation persisted. MATERIAL AND METHODS
T h e eyes from C a s e 1 were obtained three hours after death. T h e left eye was p l a c e d in 1 0 % formaldehyde solution, e m b e d d e d in paraffin, sectioned, stained with hematoxylin and eosin, and examined by light microscopy. T h e right eye was cut into small sagittal sections and fixed for one hour in 1 % osmium tetroxide containing 0 . 2 5 M sucrose buffered to p H 7.4 with phosphate buffer at 4 ° C . T h e y were then dehydrated serially in ethanol and e m b e d d e d in E p o n 8 1 2 . One-micron sections were stained with toluidine blue and examined by light microscopy. Ultrathin sections were cut on a Porter-Blum ultramicrotome, stained with uranyl acetate and lead citrate, and examined with a J E M - 1 0 0 C electron m i c r o s c o p e . Light microscopy—In 6-|x thick paraffin sections prepared for light microscopy, the pigment epithelial cells in the equatorial region were proliferated and intermingled with outer and inner nuclear layers, migrating to the essentially intact nerve fiber layer ( F i g . 4 ) . T h e pigment epithelial layer and the neurosensory retina, however, were artifactitiously separated so that details of the outer retinal layers were observed only in E p o n sections. In 1-u. thick E p o n sections prepared for light microscopy, there were fewer gan-
36
AMERICAN JOURNAL O F OPHTHALMOLOGY
Fig. 4 (Mizuno and associates). Histologic section from periphery of right eye. Proliferation of pigment epithelial cells from outer nuclear layer to nerve fiber layer (hematoxylin and eosin, x 130).
glion cells, and a marked hypertrophy o f the Müller fibers was found. T h e inner plexiform and inner nuclear layers were well developed. E v i d e n c e of significant cellular undifferentiation, however, was observed from the outer nuclear layer to the pigment epithelial layer. Cell bodies of photoreceptors were larger than normal and oval, resembling nuclei o f the outer neuroblastic layer in the human embryonal stage o f development. T h e nuclei were sparsely distributed, with only two to four rows in the equatorial region (Figs. 5-7). In a wide zone extending beyond the macula were elements undoubtedly belonging solely to the cones.
Fig. 5 (Mizuno and associates). Histologic section near that shown in Figure 4. Layers from inner limiting membrane to outer plexiform layer are normal. Circumscribed deposit is seen in subretinal space (x60).
JANUARY, 1977
Fig. 6 (Mizuno and associates). Histologic section near that shown in Figure 4 shows hypertrophic Müller fiber layer, rarefaction of outer nuclear layers, disorganized visual cell layer, wavy pigment epithelium, and thicker choroid. Subretinal deposits (arrows) indent pigmented epithelium outward (toluidine blue, x60).
T h e rod outer segments were generally absent throughout the retina. T h e most striking finding observed in the photoreceptor layer was the widespread presence of peculiar large deposits. T h e s e consisted of debris from photoreceptors and phagocytes and displaced the outer limiting membrane inward and the pigment epithelial layer outward. Sixteen of these deposits, measured through about 6 0 serial 8-u. sections, were 0.35 ±
Fig. 7 (Mizuno and associates). Higher magnification of Figure 6. Undifferentiated oval nuclei are less numerous in outer nuclear layer. Cones are intact. No rods are visible. Circumscribed deposit indents pigment epithelium outward. Undifferentiated pigment epithelium is more cuboidal and contains inwardly displaced pigment granules. There are fewer capillaries in the choriocapillaris than normal (toluidine blue, x220).
VOL. 83, NO. 1
LEBER'S CONGENITAL AMAUROSIS
0.02 mm (standard deviation). T h e pigment epithelium was regular and intact, but its undifferentiation was shown by its cuboidal shape and displacement o f pigment granules toward the apical border (Fig. 7). T h e choroid was thickened and poorly pigmented, with generalized undifferentiation. T h e choriocapillaris was present everywhere, but the capillaries were poorly developed and were not patent. Bruch's membrane was intact (Figs. 6 and 7). Electron microscopy—Nuclei o f the outer nuclear layer were oval or spindleshaped (Fig. 8). All of the photoreceptors, even the cones near the macula, were abnormal. T h e outer segments near the posterior pole were markedly shorter than
Fig. 8 (Mizuno and associates). Electron micrograph near outer limiting membrane (OLM). Nuclei of photoreceptor cells are oval. Cytoplasmic organelle of Müller cell (M) is scanty. Mitochondria of inner segment (Is) are vacuolated (x3,500).
37
normal and had disorganized and disoriented disks even at the base of the outer segment ( F i g . 9 ) . Variably throughout the equatorial region, the outer segments completely disappeared so that the tips of the inner segments were in direct contact with the apical portions o f the pigment epithelial cells (Figs. 10 and 11). T h e outer part of the inner segments was wider than normal and ballooned out, containing only ribosomes and a few glycogen particles, but no mitochondria. In contrast, the inner part was packed with mitochondria, although most mitochondria in the rods had become vacuolated and deteriorated (Figs. 10 and 11). In the large subretinal deposits identified by light microscopy, the layer o f rods and cones was replaced by an accumulation of fragments of inner segments, apical processes of pigment epithelial cells, and macrophages. T h e macrophages contained many kinds of lysosomes, swollen mitochondria, and amorphous material (Figs. 10 and 12). T h e pigment epithelial cells lacked a normal arrangement o f microvilli and showed vesicular disorganization (Figs. 10-12). Mitochondria, smooth-surfaced endoplasmic reticulum, and melanin granules were distributed throughout the cytoplasm of the cells. Much phagocytosed outer segment material, as membrane-bound phagosomes and other lysosomes, was found in the cytoplasm (Figs. 13 and 14). O n e large lysosome contained debris o f a probable 1amellated body and melanin granules (Fig. 15). T h e undifferentiated basal surfaces of the pigment epithelial cells were not delicately invaginated but slightly undulating, resembling an ordinary cell surface (Figs. 10 and 14). Bruch's membrane was fairly well differentiated. In the choroid, however, most capillaries and larger vessels were sparse and poorly developed. In their place, a number of round or oval-shaped cells, probably representing fibroblasts, were noted (Fig. 14).
Fig. 9 (Mizuno and associates). Electron micrograph near posterior pole. Swelling of the outer part of the inner segment without mitochondria indicates prematurity of rod and cone inner segment (Is). Immature outer segment (Os) is disorganized; bar gauge = l(i (x4,400).
DISCUSSION
T h e clinical entity of L e b e r ' s congenital amaurosis has not been fully defined, with the relationship o f earlier to later changes particularly o b s c u r e . In both of our cases, essentially normal fundi were present initially. Later, white dots and flecks appeared, eventually associated with some fine pigmentation. In neither of these early cases did the advanced pigmentary tapetoretinal degeneration described in L e b e r ' s original patients occur, although the possible future course is unknown in both cases. E v e n in the early stages, however, diffuse pathophysiologic disturbances were apparent. 1 - 1 4
1 , 2
Fig. 10 (Mizuno and associates). Electron micrograph of outer retina corresponding to white spot. Deposit located between inner segment (Is) and pigment epithelium (PE) contains macrophage (Mp), debris of outer segments, apical part of pigment epithelium, and amorphous material. Bruch's membrane (Br) and choriocapillaris ( C C ) appear normal ( x 1,700).
Fig. 11 (Mizuno and associates). Electron micrograph near equatorial region. Tips of swollen and immature inner segments (Is) of rods and cones directly contact pigment epithelium (PE); bar gauge = In (x6,600).
Fig. 12 (Mizuno and associates). Electron micrograph of subretinal deposit (inset) shows debris (D) of inner segment and pigment epithelium (PE), and macrophage (Mp) that contains lysosomes and the debris; bar gauge = lp. (x4,400).
Fig. 13 (Mizuno and associates). Electron micrograph of retinal pigment epithelium (PE). Cellular architecture exhibits large amount of phagocytosed outer segment material as phagosome (arrows); bar gauge = lu. (x 14,400).
Fig. 14 (Mizuno and associates). Electron micrograph of proximal pigment epithelium (PE) and choroid. Basal infolding in not developed so that basal surface of pigment epithelium appears wavy. Capillary in choriocapillaris (CC) is barely developed and fibrocyte-like cell (F) appears instead. Bruch's membrane (Br) appears normal; bar gauge = lji (x4,400).
VOL. 83, NO. 1
LEBER'S CONGENITAL AMAUROSIS
41
Fig. 15 (Mizuno and associates). Electron micrograph of pigment epithelial cell. Large lysosome (Ly) contains fragmented probable disk membrane and melanin granule; bar gauge = lu. (x 15,000).
Clinical observations, including the intensity of the disorder at birth and electroretinographic data, suggest significant early impairment of the photoreceptor elements, and we speculate that the neurosensory retina fails to develop functionally during prenatal development. T h e curious oval-shaped nuclei found in the outer nuclear layer and the abnormal fine structure of the inner segments are evidence of this immaturity and undifferentiation of the neurosensory retina. T h e lack of basal infoldings in the retinal pigment epithelium, however, indicates that this layer is also immature and undifferentiated, and the poorly developed choriocapillaris with diffuse fibroblastlike cells in the choroidal stroma suggests that the choroid is also impaired. T h e innermost retinal layers appeared to b e spared by the pathologic process.
T h a t neurosensory retina, pigment epithelium, and choroid are involved in postnatal degenerative abnormalities in this disorder seems to b e supported by our observations. W e saw many degenerative changes o f the photoreceptor elements. T h e white fundus lesions appearing after birth correspond to subretinal deposits consisting o f undeveloped and degenerated elements from both the outer retinal layers and the retinal pigment epithelium. T h e marked pigmentary changes noted in some patients, especially as the disease progresses, are not surprising, and may b e the end result o f these earlier pathogenetic processes. Although the factors influencing the ultimate course in any given case are not known, Leber's original concept remains—that cases in which there is the development o f a primarily pigmen-
42
AMERICAN JOURNAL O F OPHTHALMOLOGY
tary retinopathy, as well as the more atypical cases later described b y W a l d e n burg as "neuroepithelial dysgenesis," represent a single clinical spectrum. L e ber's congenital amaurosis may, therefore, b e considered a hereditary disorder characterized b y primary dystrophic and secondary degenerative changes o f neurosensory retina, retinal pigment epithelium, and choroid, with its polymorphic c l i n i c a l and pathologic expressions o f variable pathophysiologic progression. 4
SUMMARY
An early stage o f L e b e r ' s congenital amaurosis, characterized by white spots or lines in the fundus, occurred in two children. L i g h t m i c r o s c o p i c examination o f eyes obtained from one child, a 1 6 month-old J a p a n e s e girl, revealed subretinal deposits corresponding to the white spots and lines in the fundus deposits. L i g h t and electron m i c r o s c o p i c examination o f the eye showed distinctive changes in the outer retinal layers and choroid, w h i l e the inner retinal layers were nearly normal. Characteristic early lesions o f congenital amaurosis appeared to b e produced by deposits consisting o f loose outer segments and apical processes o f the pigmental epithelial cell and macrophages. Undifferentiation in the n u c l e i o f the photoreceptor cell, the inner segment, the pigment epithelial cell, and the choriocapillaris were likely characteristics o f the early changes o f congenital amaurosis. REFERENCES
1. Leber, T.: Uber retinitis pigmentosa und angeborene Amaurose. Albrecht von Graefe's Arch. Klin. Ophthalmol. 15:3.1, 1869. 2. : Uber anomale Formen der retinitis pigmentosa. Albrecht von Graefe's Arch. Klin. Ophthalmol. 17:314, 1871. 3. Alström, C. H., and Olson, O.: Heredo-
JANUARY, 1977
retinopathia congenitalis monohybrida recessiva autosomialis. Hereditas 43:1, 1957. 4. Wâardenburg, P. J.: Does agenesis or dysgenesis neuroepithelialis retinae whether or not related to keratoglobus exist? Ophthalmologica 133:454,1957. 5. Sorsby, A., and Williams, C. E.: Retinal aplasia as a clinical entity. Br. Med. J. 1:293, 1960. 6. Franceschetti, A., François, J., and Babel, J . : Chorioretinal Heredodegenerations, 1st ed. Springfield, Charles C Thomas, 1974, p. 307. 7. Winkelman, J. E . , and Horsten, G. P. M.: The ERG of premature and full-term born infants during theirfirstdays of life. Ophthalmologica 143:92,1962. 8. Schappert-Kimmijser, J . , Henkes, H. E . , and van den Bosch, J . : Amaurosis congenita (Leber). Arch. Ophthalmol. 61:211, 1959; Ophthalmologica 137:420, 1959. 9. Wâardenburg, P. J., and Schappert-Kimmijser, J.: On various recessive biotypes of Leber's congenital amaurosis. Acta Ophthalmol. 41:317, 1963. 10. Gillespie, F . D.: Congenital amaurosis of Leber. Am. J. Ophthalmol. 61:874, 1966. 11. Dekaban, A., and Carr, R. E . : Congenital amaurosis of retinal origin. Frequent association with neurological disorders. Arch. Neurol. Psychtr. 14:294, 1966. 12. Jöhr, P.: A propose de 4 cas d'amaurose tapétorétinienne (type Leber) dans une famille de 9 enfants issue de parents sains (Forme congenitale?). Probl. Act. Ophtalmol. 1;559, 1957. 13. Franceschetti, A., and Forni, S.: Dégénérescence tapéto-rétinienne (type Leber) avec aspect marbré du fond de l'oeil périphérique. Ophthalmologica 135:610, 1958. 14. Brand, L: Eine seltene Netzhautveränderung beim Lawrenee-Biedlschen Syndrom. Klin. Monatsbl. Augenheilkd. 116:337, 1950. 15. Hirose, T., and Wand, O.: Amaurosis congenita (Leber). Ann. Ophthalmol. 7:59, 1975. 16. Flynn, J . T., and Cullen, R. F.: Disc oedema in congenital amaurosis of Leber. Br. J. Ophthalmol. 59:497, 1975. 17. Aubineau, M.: Rétinite pigmentaire congénitale familiäre Examen anatomique. Ann. Oculistique 29:432, 1903. 18. Vrabec, F.: Un case de dégénérescence pigmentaire congénitale de la rétine, examiné histologiquement. Ophthalmologica 122:65, 1951. 19. Horsten, G. P. M., and Winkelman, J . E . : Development of the ERG in relation to histological differentiation of the retina in man and animals. Arch. Ophthalmol. 63:232, 1960. 20. Senior, B., Friedmann, A. I., and Braudo, J. L.: Juvenile familial nephropathy with tapetoretinal degeneration. Am. J. Ophthalmol. 52:625, 1961. 21. Babel, J . : Constatations histologiques dans l'amaurose infantile de Leber et diverses formes d'héméralopie. Ophthalmologica 145:399, 1963. 22. Kroll, A. J., and Kuwabara, T.: Electron microscopy of a retinal abiotrophy. Arch. Ophthalmol. 71:683, 1964.