- Email: [email protected]
Spectral-Domain Optical Coherence Tomography in Wagner Syndrome: Characterization of Vitreoretinal Interface and Foveal Changes
Spectral-Domain Optical Coherence Tomography in Wagner Syndrome: Characterization of Vitreoretinal Interface and Foveal Changes PIERRE-RAPHAEL ROTHSCHILD, CYRIL BURIN-DES-ROZIERS, ISABELLE AUDO, BRIGITTE NEDELEC, SOPHIE VALLEIX, AND ANTOINE P. BRE´ZIN PURPOSE:
To evaluate the spectrum of morphologic abnormalities in patients with Wagner syndrome by spectral-domain optical coherence tomography (SD OCT). DESIGN: Retrospective comparative case study. METHODS: Institutional study of patients entered into the French Vitreoretinopathy Study Group database. Twelve eyes of 9 patients from 3 unrelated families with genetically confirmed Wagner syndrome and 28 eyes from 15 age- and sex-matched healthy family controls were scanned by SD OCT. Morphology and layer thickness of the total retina, inner retinal layers, outer retinal layers, and photoreceptor layer at different degrees of eccentricity from the fovea were compared between the 2 groups. RESULTS: A thick multilayered membrane adherent to the perifovea but completely detached from the fovea, thus forming a bridge over the foveal pit, was observed in 84% of eyes from patients with Wagner syndrome. At the equatorial area, SD OCT imaging allowed visualization of the architecture of an avascular vitreous veil with localized retinal traction. Most retinal layers were significantly thinner in patients with Wagner syndrome Accepted for publication Aug 8, 2015. From Assistance Publique–Hoˆpitaux de Paris, Groupe Hospitalier Cochin-Hoˆtel-Dieu, Service d’ophtalmologie, Universite´ Paris Descartes, Sorbonne Paris Cite´, Paris, France (P.R.R., A.P.B.); Institut National de la Sante´ et de la Recherche Me´dicale, Centre de Recherche des Cordeliers, Unite´ Mixte de Recherche 1138, e´quipe 17, Paris, France (P.R.R., S.V.); Institut National de la Sante´ et de la Recherche Me´dicale, Unite´ Mixte de Recherche 1163, Institut Imagine, Laboratoire de Ge´ne´tique Ophtalmologique, Universite´ Paris Descartes, Sorbonne Paris Cite´, Paris, France (C.B., B.N.); Institut National de la Sante´ et de la Recherche Me´dicale, Unite´ Mixte de Recherche _S968, Paris, France (I.A.); Centre National de la Recherche Scientifique, Unite´ Mixte de Recherche 7210, Paris, France (I.A.); Universite´ Pierre et Marie Curie Paris 6, Institut de la Vision, Paris, France (I.A.); Centre Maladies Rares/Centre d’Investigations Cliniques 503 Institut National de la Sante´ et de la Recherche Me´dicale, Centre Hospitalier National d’Ophtalmologie des Quinze-Vingts, Paris, France (I.A.); Department of Molecular Genetics, Institute of Ophthalmology, London, United Kingdom (I.A.); and Universite´ Paris-Descartes, Sorbonne Paris Cite´, Assistance Publique–Hoˆpitaux de Paris, Laboratoire de Biologie et Ge´ne´tique Mole´culaire, Hoˆpital Cochin, Paris, France (S.V.). Inquiries to Pierre-Raphael Rothschild, Service d’ophtalmologie, Hoˆpital Hoˆtel Dieu, 1 Place du Parvis de Notre-Dame, 75004 Paris, France; e-mail: [email protected] 0002-9394/$36.00 http://dx.doi.org/10.1016/j.ajo.2015.08.012
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2015 BY
compared to the control group, except at the foveal center where abnormal persistence of 1 or more inner retinal layers could be observed. CONCLUSION: SD OCT provides better structural insight into the range of retinal defects at the vitreoretinal interface and fovea, which is not only useful for improving diagnosis and management, but also for understanding the pathogenesis of Wagner syndrome. (Am J Ophthalmol 2015;160(5):1065–1072. Ó 2015 by Elsevier Inc. All rights reserved.)
W
AGNER SYNDROME (OMIM#143200) IS A VERY
rare vitreoretinal degenerative disorder with no systemic features, inherited as an autosomal dominant trait, and only 14 families have been reported worldwide with a molecularly confirmed diagnosis. This genetic disorder is caused by splice mutations in the versican (VCAN) gene, coding for a chondroitin sulfate proteoglycan named versican whose exact role in ocular tissues is largely unknown. The pattern of expression of versican during retinal development and in the adult retina supports a role in vitreous architecture and vitreoretinal interface, as well as in the maintenance of photoreceptor cells, and in the regulation of neurite formation and growth of the nerve fiber layer and inner plexiform layer where neural networks of ganglion cells are being formed.1–3 The clinical spectrum of the disease is very large and age-dependent, with a highly variable expressivity even among affected members within a same family, making diagnosis of this disease very challenging.4–6 The disease usually manifests in childhood, and affected patients show an optically empty vitreous with a characteristic fibrillary aspect of the vitreous core and an abnormal vitreous cortex with avascular peripheral veils.7,8 Other features variably include moderate congenital myopia,7,9–13 early-onset cataract,7,10–14 glaucoma,7,10–13 uveitis,4,8,15 and foveal ectopia responsible for pseudostrabismus.14,16,17 The severity of the disease is related to the progressive chorioretinal degeneration with atrophy and the occurrence of retinal detachments, both of these complications being the leading causes of visual loss in patients with Wagner syndrome.7 Although retinal detachment has long been an unrecognized manifestation and is not
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TABLE 1. Summary of Clinical, Spectral-Domain Optical Coherence Tomography, and Molecular Findings in Patients With Wagner Syndrome
Family ID
A
B
C
VCAN Mutation
c.4004-2A>T
c.4004-6A>T
c.9265þ1G>A
References 4
Bre´zin et al
Rothschild et al8
Rothschild et al9
Patient ID
Sex
Age (y)
A.IV.7 A.IV.8 A.V.5
M M F
61.9 51 35.9
A.V.6 B.I.2 B.II.1 B.II.4
F F F F
40.7 72.6 44.7 47.4
C.II.1 C.III.1
M F
30.5 3
Eye
BCVA (LogMAR)
AL (mm)
SE (Diopters)
OD OS OD OS OD OS OD OD OS OS OD OS
0.4 0.1 0.1 0.1 0.2 0.2 0.2 0.1 0.1 0 0.5 0.5
25.05 24.77 23.84 24.1 27.05
7.75 3.375 5.5 5.625
21.97
26.7
1 0.875 0.75 3.125 3 6.375
IOP
ExRM
Grade 1 FH
Grade 2 FH
17 11 16 16 16 17 17 16 17 17
Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No
Yes Yes No No No No No No Yes Yes Yes Yes
Yes No No No No No No No No Yes No No
AL¼ axial length; BCVA ¼ best-corrected visual acuity; ExRM ¼ extraretinal membrane; FH ¼ foveal hypoplasia; IOP ¼ intraocular pressure; SE ¼ spherical equivalent; VCAN ¼ versican gene.
as frequent in Wagner syndrome as in Stickler, all recent studies have reported retinal detachment in affected patients.4,14 Visual acuity is reported to be normal or subnormal in young patients with Wagner syndrome but is constantly severely affected in older patients. To gain insight into the qualitative and quantitative defects in the retina and at the vitreoretinal interface in Wagner syndrome, a retrospective intrafamilial comparative case study was conducted using the in vivo spectraldomain optical coherence tomography (SD OCT) imaging method.18 The retinal structural information provided by SD OCT may help in clarifying the underlying pathologic mechanisms at play in Wagner syndrome, which remain poorly understood thus far.
SPECTRAL-DOMAIN OPTICAL COHERENCE TOMOGRAPHY ANALYSIS: The SD OCT acquisition protocol
METHODS INSTITUTIONAL REVIEW BOARD APPROVALS FOR RETRO-
spective chart reviews were obtained commensurate with the respective institutional requirements prior to the beginning of the study. Described research was approved by the Ethics Committee of the French Society of Ophthalmology and adhered to the tenets of the Declaration of Helsinki. Fully written informed consent was obtained for all patients. This intrafamilial case-control study included patients followed for hereditary vitreoretinal diseases at a single institution, a university teaching hospital at Groupe Hospitalier Cochin Hoˆtel-Dieu, Paris, France. Patients enrolled in our cohort (The French Vitreoretinopathy Study Group) were offered standardized ophthalmic examination and genetic testing. Patients with a clinical picture of Wagner syndrome and positive for a pathogenic mutation in the VCAN gene were 1066
enrolled in this study (cases). The control population included clinically unaffected family members who were non-carriers of VCAN mutations (controls). ETDRS bestcorrected visual acuity (BCVA), slit-lamp biomicroscopy, intraocular pressure measurements, dilated fundus examination, and spherical equivalent and axial length measurement (IOLMaster; Carl Zeiss Meditec AG, Jena, Germany) was performed for all studied patients (cases and controls) and findings have been partly reported elsewhere (Table 1).4,8,9 SD OCT was performed using the Spectralis OCT (Heidelberg Engineering, Heidelberg, Germany). Patients with no SD OCT data; with a history of retinal detachment, macular edema, or premature birth; or with low-quality SD OCT images were excluded from the analysis (see Figure 1 for inclusion flow chart details).
included a horizontal and vertical 9-mm central linear scan (passing through the fovea). At least 30 scans were averaged to reduce the signal-to-noise ratio and lowquality images (signal-to-noise ratio below 25 dB) were discarded. Qualitative OCT image analysis included the quoting of the presence or absence of a membrane-like structure forming a bridge over the foveal pit according to our previous description in time-domain OCT of Wagner syndrome patients.4 We also graded foveal abnormalities as previously described by others.19 In brief, we noted the absence of extrusion of the plexiform layers (grade 1) from the central fovea, the absence of foveal pit (grade 2), the absence of outer segment lengthening (grade 3), and finally the absence of widening of the outer nuclear layer (grade 4). Quantitative analysis included manual segmentation of several retinal layers using the built-in caliper of the viewing software (HRA Spectralis viewing software version 5.6.4.0).
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TABLE 2. Demographic Characteristics of Patients With Wagner Syndrome and Control Patients
Number of patients Number of eyes Age (y, mean 6 SD) Male-to-female ratio BCVA (logMAR 6 SD) Spherical equivalent (diopters, mean 6 SD) Axial length (mm, mean 6 SD)
Control Group
Wagner Group
P Value
15 28 31 (6 18.3) 8:7 060 0.3 (6 1.2)
9 12 37.5 (6 22.6) 4:5 0.2 6 0.16 3.5 (6 2.8)
.5 NS .67 NS .0001 .001
23.4 (6 0.7)
24.8 (6 1.7)
.026
BCVA ¼ best-corrected visual acuity; NS ¼ not significant.
FIGURE 1. Patients with Wagner syndrome selection flow chart for spectral-domain optical coherence tomography (SD OCT) study. VCAN is the symbol for the Versican gene.
FIGURE 2. Point estimates of the thickness of several retinal layers in control subjects (Top) and in patients with Wagner syndrome (Bottom). Measures of the total retinal thickness (TRT), inner retinal layers (IRL), outer retinal layers (ORL), and photoreceptor layer (PRL) as well as the foveal pit depth (FPD) were performed in the center of the fovea and at 1000 mm of eccentricity along the horizontal line scan.
We defined the following layers: (1) total retinal thickness (TRT), as the distance from the inner limiting membrane (ILM) to the inner aspect of the Bruch membrane (BM); (2) inner retinal layers (IRL), as the distance from the ILM to the outer plexiform layer (not included); (3) outer retinal layers (ORL), as the distance from the inner aspect of BM to the outer plexiform layer (included); and (4) photoreceptor layer (PRL), as the distance from the inner aspect of the retinal pigment epithelium (RPE) to the outer limiting membrane (Figure 2). These measures were VOL. 160, NO. 5
performed at the center of the fovea and at 1000 mm of eccentricity from the center along the OCT 9-mm central line in the nasal, temporal (horizontal line), and superior quadrant (vertical line). We computed as previously described by others the superior foveal-to-perifoveal ratio for the inner retinal layers (foveal-to-perifoveal IRL ratio) and for the photoreceptor layers (foveal-to-perifoveal PRL ratio) measurements.20 Briefly, the foveal-to-perifoveal ratios are computed by dividing the values of a studied layer thickness, here the inner and photoreceptor layer, at the foveal center and at 1000 mm of eccentricity along the vertical scan line in the superior quadrant. These ratios have been used to respectively describe the centrifugal displacement of inner retinal layers from the fovea and the retinal outer layer widening at the fovea during embryogenesis. Finally, we measured the foveal pit depth (FPD) as the distance between a 1-mm line tangential to the retinal surface and the ILM at the center of the fovea (Figure 2). This parameter is another marker of the centrifugal displacement of the inner retinal layers that occurs during embryogenesis. When this phenomenon fails to occur, a shallow foveal pit in adult patients is present, as reflected by a decrease of foveal pit depth. STATISTICAL ANALYSIS:
Categorical variables were expressed as numbers (percentages) and comparisons were performed using the x2 test or the Fisher exact test when appropriate. For continuous variables, mean 6 standard deviation (SD) was provided, and means were compared using the Mann-Whitney test. Correlations were performed using the Spearman correlation coefficient. P < .05 was considered significant. Analyses were performed using XLSTAT software (Addinsoft, Paris, France) version 2014.4.06.
MOLECULAR
ANALYSIS: Molecular analysis of the VCAN gene have been conducted as previously described.4 In brief, DNAs were extracted from venous blood samples, using the QIAamp DNA mini kit (Qiagen, Valencia,
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FIGURE 3. Vitreomacular interface abnormalities in patients with Wagner syndrome. Affected patients presented with a highly reflective thick multilayered membrane, completely detached from the fovea but remaining attached to the perifoveal area and forming a bridge above the foveal pit. Note the thin membrane overlying the center of the fovea and probably corresponding to the partially detached posterior vitreous cortex.
FIGURE 4. Vitreoretinal interface and retinal abnormalities in patients with Wagner syndrome. Note the barely visible extra retinal membrane (Top row and Second row, left), the inversion of optic nerve or ‘‘situs inversus’’ (Second row, right), and the absence of extra retinal membrane, although vitreoschisis was present in both eyes of the same patient (Bottom row). Also note the presence of the outer plexiform layer at the foveal center except for 1 eye (Second row, right).
California, USA). Intron-exon boundaries for exons 6, 7, 8, and 9 of the VCAN gene were amplified by polymerase chain reaction. Sanger sequencing reactions were performed in an automatic genetic analyzer (ABI PRISM 3100 genetic analyzer; Applied Biosystems, Foster City, California, USA) using the BigDye terminator cycle sequencing kit (DNA sequencing kit; Applied Biosystems).
RESULTS A TOTAL OF 12 EYES OF 9 PATIENTS FROM 3 UNRELATED
families with a clinical picture of Wagner syndrome and carriers of a pathogenic VCAN mutation were included in this study; and 28 eyes from 15 unaffected family members, VCAN mutation negative, were selected to serve as controls (see Figure 1 for inclusion flow chart details). 1068
The clinical and molecular data of all included patients with Wagner syndrome are summarized in Table 1 with corresponding references to our previous descriptions. Baseline characteristics of both groups are shown in Table 2. In summary, no significant differences were found for age (31 6 18 3 years and 37 6 22 6 years) in the control and Wagner groups (P ¼ .5; Mann-Whitney test) or for sex ratio (male-to-female ratio was, respectively, 8:7 and 4:5 [P ¼ .6; x2 test]). Spherical equivalent (0.3 6 1.2 diopters and 3.5 6 2.8 diopters) as well as axial length (23.4 6 0.7 mm and 24.8 6 1.7 mm) were significantly different between the control group and Wagner group (P ¼.001 and P ¼ .026, respectively). BCVA was 0 6 0 logMAR units for control patients and 0.2 6 0.16 logMAR units for patients with Wagner syndrome (P ¼ .0001). Among the patients with Wagner syndrome, 6 were pseudophakic and 6 were phakic with a clear crystalline lens. We found no significant difference between phakic and pseudophakic patients regarding all the above studied parameters.
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FIGURE 5. Spectral-domain optical coherence tomography aspect of the circumferential peripheral avascular veil in patients with Wagner syndrome. Note the localized tractional retinal schisis seen at the site of the insertion of the vitreous veil, which corresponds to the posterior vitreous cortex.
Qualitative SD OCT assessment showed in 10 eyes (10/12, 84%) from 8 patients with Wagner syndrome a macular thick hyperreflective structure attached to the perifovea in an annular aspect with no or limited attachment to the inner (superficial) layer of the underlying fovea, sometimes forming a bridge over the foveal pit. The outer (deep) aspect of the multilayered membrane was either partially detached (Figure 3) from the retina (posterior vitreous detachment) or attached (Figure 4). Total absence of this posterior membrane was observed for only 1 patient with Wagner syndrome (individual C.III.1), but abnormal vitreoretinal interface abnormalities in the form of vitreoschisis were present in the perifoveal region of both of her eyes (Figure 4, Bottom). Of note, 1 patient with Wagner syndrome (individual A.IV.7) had an optic nerve inverted nasally, or situs inversus of the optic disc and retinal vessels (Figure 4). Peripheral, mid-equatorial SD OCT images of the detached avascular vitreous veil, a characteristic pathologic feature of the vitreous in Wagner syndrome, showed that this structure corresponded to a vitreous cortex detachVOL. 160, NO. 5
ment with localized tractional retinal schisis at its site of attachment to the retina (Figure 5). SD OCT imaging was also used to evaluate the foveal architecture from patients with Wagner syndrome when compared with control subjects. As shown in Figure 4, variable inner retinal layers, absent at the center of the fovea of control patients, were aberrantly present in 6 eyes (6/12, 50%) of patients with Wagner syndrome. In detail, 4 eyes had nonextrusion of the plexiform layers (grade 1 foveal hypoplasia) and 2, in addition, had no foveal pit depression (grade 2 foveal hypoplasia). Quantitative analysis of retinal layers in patients with Wagner syndrome as compared to controls is shown in Table 3. In brief, central total retinal thickness between the control group (234 6 14.6 mm) and Wagner group (229 6 39.2 mm) was not significantly different (P ¼ .7). However, layer-specific assessment showed that central inner retinal layers were significantly thicker in patients with Wagner syndrome (36 6 13.4 mm) as compared to controls (15.4 6 12.9 mm) (P ¼ .0001). Foveal pit depth for patients
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TABLE 3. Mean Retinal Thickness (mm) in Controls and in Patients With Wagner Syndrome Control Group (Mean 6 SD)
Central thickness Total retinal thickness Inner retinal layers Outer retinal layers Photoreceptor layer Nasal thickness Total retinal thickness Inner retinal layers Outer retinal layers Photoreceptor layer Temporal thickness Total retinal thickness Inner retinal layers Outer retinal layers Photoreceptor layer Foveal-to-perifoveal ratio For inner retinal layers For photoreceptor layer Foveal pit depth
Wagner Group (Mean 6 SD)
P Value
234 (6 14.6) 229 (6 39.2) .7 NS 15.4 (6 12.9) 36 (6 13.4) <.0001 218.6 (6 11.8) 193 (6 32.7) .004 101.6 (6 6.2) 91.3 (6 9.4) .001 362.6 (6 10.2) 301 (6 38.7) <.0001 167.9 (6 10.7) 147.5 (6 16.9) .0001 194.7 (6 10.8) 153.5 (6 30.0) <.0001 87.8 (6 5.6) 73.1 (6 17.2) .0001 341.5 (6 11.3) 149.3 (6 9.8) 192.3 (6 9.7) 87.1 (6 4.4)
281.8 (6 35.9) <.0001 127.9 (6 20.0) .001 153.8 (6 27.8) <.0001 72.4 (6 12.9) <.0001
0.1 (6 0.1) 0.3 (6 0.1) <.0001 1.1 (6 0.1) 1.3 (6 0.2) .002 118.6 (6 19.7) 69.9 (6 34.1) .0001
NS ¼ not significant.
with Wagner syndrome was significantly decreased as compared to controls: 69.9 6 34.1 mm and 118.6 6 19.7 mm, respectively (P ¼ .0001). Conversely, central outer retinal layers and photoreceptor layers, as well as all other studied layers in the temporal or nasal retina, were significantly thinner in patients with Wagner syndrome as compared to controls (Table 3). We found no significant difference between myopic and nonmyopic control patients for the above parameters, suggesting that the foveal changes were not related to the myopia but rather to the Wagner syndrome status. The foveal-to-perifoveal inner retinal layer and fovealto-perifoveal photoreceptor layer ratios were increased in patients with Wagner syndrome as compared to controls. Finally, we found a significant linear correlation between foveal-to-perifoveal inner retinal layer ratio and BCVA (R2 ¼ 0.525, P ¼ .0001) (Figure 6).
DISCUSSION SD OCT HAS EMERGED IN THE LAST DECADE AS A POWERFUL
noninvasive method to investigate structural changes in the retina and the vitreoretinal interface. We took advantage of this technology to evaluate the pathologic features of patients with Wagner syndrome. Wagner syndrome is a rare autosomal dominant degenerative vitreoretinal disease caused by splice mutations in the 1070
VCAN gene coding a large extracellular chondroitin sulfate proteoglycan, named versican. Versican is a component of the vitreous core and vitreous cortex, known to play a central role in the spatial regulation of fibrillar structures, and suspected to participate in vitreoretinal interface adhesion. The pathogenic mechanism of Wagner syndrome is poorly understood and is thought to result from abnormal interactions of versican with vitreous components responsible for pathologic liquefaction of the vitreous, leading to syneresis with optically empty vitreous and synchisis with a fibrillary aspect of the core vitreous. Herein, SD OCT provided high-resolution images of the vitreoretinal interface, allowing the revealing of the presence of a dense packed posterior vitreous with membranous multilayered structures of high reflectivity and variable thickness at the vitreoretinal interface in a large majority of eyes from patients with Wagner syndrome. These membranous structures are detached from the vitreofoveal interface in an annular configuration with persistent attachments to the perifoveal area, thus forming a bridge over the foveal pit. This posterior vitreous detachment in patients with Wagner syndrome seems to differ from age-related posterior vitreous detachment (PVD), which has been shown to start in a perifoveal location while maintaining residual attachments to the fovea, so-called vitreomacular adhesion (VMA), and then extends further to eventually encompass the fovea itself.21 These SD OCT findings suggest that the pathogenic mechanisms in Wagner syndrome cause a weakening of the vitreoretinal adhesion, particularly in the foveal area, and also predispose to membrane formation.22 As for the more common epiretinal membrane (ERM), it is still unclear whether the membrane formation precedes and predisposes to foveal PVD or if the ERM develops after the PVD owing to the vitreoschisis hypothesis.23 SD OCT also provided structural information on the circumferential equatorial avascular veil, a clinical feature unique to Wagner syndrome, also corresponding to abnormal vitreous cortex detachment and showing localized tractional retinal schisis. Patients with Wagner syndrome, as compared to control subjects, had significantly reduced retinal thickness at the posterior pole in almost all layers, consistent with posterior chorioretinal atrophy observed in the fundus of patients with Wagner syndrome. Of importance, central inner retinal layer thickness was significantly increased (Figure 4 and Table 1). SD OCT images detected, in some patients with Wagner syndrome, the presence of plexiform layers at the center of the fovea, normally absent when the maturation of the fovea is properly accomplished. In this study, the foveal-to-perifoveal ratio of the inner retinal layer, for patients with Wagner syndrome, a surrogate marker for failed centrifugal displacement of bipolar cells,24 was comparable to ratios of premature neonates reported by Maldonado and associates.20 Although the sample size studied was small, we found a significant correlation between these foveal defects and visual acuity. Foveal hypoplasia, defined by abnormal persistence of central inner retinal layers with an
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FIGURE 6. Linear regression analysis of the best-corrected visual acuity (expressed in logMAR units) and the superior foveal-toperifoveal inner retinal layer ratio, showing a significant linear correlation between the 2 variables (R2 [ 0.525, P [ .0001). The gray dashed line represents the confidence interval of the mean and the solid gray line the confidence interval of the observations.
absent or shallow foveal pit, has been reported in several ocular conditions such as albinism, aniridia, in retinopathy of prematurity,19,20 but the literature in terms of description and in terms of visual significance of these findings is controversial. Marmor and associates coined the term fovea plana, and found no correlation with visual acuity loss in albinism patients.25 Consistently, Tick and associates demonstrated that a significant proportion of the normal population could exhibit fovea plana with normal visual function.26 More recently, Thomas and associates proposed a classification for foveal hypoplasia based on SD OCT data,19 and found a correlation between the grade of hypoplasia and visual loss. Although these foveal defects remain to be confirmed on a larger population of patients with Wagner syndrome, the existence of other yet well documented foveal developmental abnormalities in Wagner
syndrome, such as foveal ectopia, raises some unanswered questions about the role of versican in early embryogenesis, where a transient but significant expression of versican is found in inner retinal layers when networks of ganglion cells are being formed.1,2 Owing to the rarity of this genetic disease, a large-scale longitudinal study with different subgroups according to age, sex, axial length, and disease duration was not possible, and further SD OCT analysis on additional patients with Wagner syndrome worldwide is needed to refine the retinal dysfunction in Wagner syndrome. To conclude, SD OCT imaging in Wagner syndrome may be helpful in clarifying the changes and the mechanisms underlying this vitreoretinal interface disorder, and this method is also useful for clinicians in the diagnosis, management, and monitoring of disease progression.
FUNDING/SUPPORT: NO FUNDING OR GRANT SUPPORT. FINANCIAL DISCLOSURES: THE FOLLOWING AUTHORS HAVE NO financial disclosures: Pierre-Raphael Rothschild, Cyril Burin-Des-Roziers, Isabelle Audo, Brigitte Nedelec, Sophie Valleix, and Antoine P. Bre´zin. All authors attest that they meet the current ICMJE criteria for authorship. The authors thank Alain Gaudric, MD (Hoˆpital Lariboisie`re, Paris, France) for sharing expertise on OCT data acquisition, analysis, and interpretation; and Vale´rie Beunardeau (Bibliothe`que Javal/Centre de Documentation Ophtalmologique de la Socie´te´ Franc¸aise d’Ophtalmologie, Paris, France) for reference management assistance.
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GeneReviews [Internet]. Seattle (WA): University of Washington, Seattle; 2009:1993–2015. Graemiger RA, Niemeyer G, Schneeberger SA, Messmer EP. Wagner vitreoretinal degeneration. Follow-up of the original pedigree. Ophthalmology 1995;102(12):1830–1839. Rothschild PR, Brezin AP, Nedelec B, et al. A family with Wagner syndrome with uveitis and a new versican mutation. Mol Vis 2013;19(1):2040–2049. Rothschild PR, Audo I, Nedelec B, et al. De novo splice mutation in the versican gene in a family with Wagner syndrome. JAMA Ophthalmol 2013;131(6):805–807. Kloeckener-Gruissem B, Bartholdi D, Abdou MT, Zimmermann DR, Berger W. Identification of the genetic defect in the original Wagner syndrome family. Mol Vis 2006;12(1):350–355. Kloeckener-Gruissem B, Neidhardt J, Magyar I, et al. Novel VCAN mutations and evidence for unbalanced alternative splicing in the pathogenesis of Wagner syndrome. Eur J Hum Genet 2013;21(3):352–356. Zech JC, Morle L, Vincent P, et al. Wagner vitreoretinal degeneration with genetic linkage refinement on chromosome 5q13-q14. Graefes Arch Clin Exp Ophthalmol 1999; 237(5):387–393. Fryer AE, Upadhyaya M, Littler M, et al. Exclusion of COL2A1 as a candidate gene in a family with Wagner-Stickler. J Med Genet 1990;27(2):91–93. Miyamoto T, Inoue H, Sakamoto Y, et al. Identification of a novel splice site mutation of the CSPG2 gene in a Japanese family with Wagner syndrome. Invest Ophthalmol Vis Sci 2005;46(8):2726–2735. Meredith SP, Richards AJ, Flanagan DW, Scott JD, Poulson AV, Snead MP. Clinical characterisation and molecular analysis of Wagner syndrome. Br J Ophthalmol 2007; 91(5):655–659.
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16. Maumenee IH, Stoll HU, Mets MB. The Wagner syndrome versus hereditary arthroophthalmopathy. Trans Am Ophthalmol Soc 1982;80(1):349–365. 17. Maumenee IH. Vitreoretinal degeneration as a sign of generalized connective tissue diseases. Am J Ophthalmol 1979;88(3 Pt1):432–449. 18. Huang D, Swanson EA, Lin CP, et al. Optical coherence tomography. Science 1991;254(5035):1178–1181. 19. Thomas MG, Kumar A, Mohammad S, et al. Structural grading of foveal hypoplasia using spectral-domain optical coherence tomography a predictor of visual acuity? Ophthalmology 2011;118(8):1653–1660. 20. Maldonado RS, O’Connell RV, Sarin N, et al. Dynamics of human foveal development after premature birth. Ophthalmology 2011;118(12):2315–2325. 21. Uchino E, Uemura A, Ohba N. Initial stages of posterior vitreous detachment in healthy eyes of older persons evaluated by optical coherence tomography. Arch Ophthalmol 2001; 119(10):1475–1479. 22. Manschot WA. Pathology of hereditary conditions related to retinal detachment. Ophthalmologica 1971;162(4):223–234. 23. Sebag J. Anomalous posterior vitreous detachment: a unifying concept in vitreo-retinal disease. Graefes Arch Clin Exp Ophthalmol 2004;242(8):690–698. 24. Provis JM, Dubis AM, Maddess T, Carroll J. Adaptation of the central retina for high acuity vision: cones, the fovea and the avascular zone. Prog Retin Eye Res 2013;35(1):63–81. 25. Marmor MF, Choi SS, Zawadzki RJ, Werner JS. Visual insignificance of the foveal pit: reassessment of foveal hypoplasia as fovea plana. Arch Ophthalmol 2008;126(7): 907–913. 26. Tick S, Rossant F, Ghorbel I, et al. Foveal shape and structure in a normal population. Invest Ophthalmol Vis Sci 2011;52(8): 5105–5110.
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Biosketch Pierre-Raphael Rothschild, MD, is a medical and surgical vitreoretinal fellow at the Hotel Dieu Cochin Hospital, Paris, France. He is a graduate of Paris VI University, France. He completed a comprehensive ophthalmology residency and is now in his last year of PhD thesis on the mechanisms of diabetic retinopathy. He also has a particular interest on diagnosis and management of hereditary forms retinal detachment whether polygenic or monogenic especially Stickler and Wagner syndrome.
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To evaluate the spectrum of morphologic abnormalities in patients with Wagner syndrome by spectral-domain optical coherence tomography (SD OCT). DESIGN: Retrospective comparative case study. METHODS: Institutional study of patients entered into the French Vitreoretinopathy Study Group database. Twelve eyes of 9 patients from 3 unrelated families with genetically confirmed Wagner syndrome and 28 eyes from 15 age- and sex-matched healthy family controls were scanned by SD OCT. Morphology and layer thickness of the total retina, inner retinal layers, outer retinal layers, and photoreceptor layer at different degrees of eccentricity from the fovea were compared between the 2 groups. RESULTS: A thick multilayered membrane adherent to the perifovea but completely detached from the fovea, thus forming a bridge over the foveal pit, was observed in 84% of eyes from patients with Wagner syndrome. At the equatorial area, SD OCT imaging allowed visualization of the architecture of an avascular vitreous veil with localized retinal traction. Most retinal layers were significantly thinner in patients with Wagner syndrome Accepted for publication Aug 8, 2015. From Assistance Publique–Hoˆpitaux de Paris, Groupe Hospitalier Cochin-Hoˆtel-Dieu, Service d’ophtalmologie, Universite´ Paris Descartes, Sorbonne Paris Cite´, Paris, France (P.R.R., A.P.B.); Institut National de la Sante´ et de la Recherche Me´dicale, Centre de Recherche des Cordeliers, Unite´ Mixte de Recherche 1138, e´quipe 17, Paris, France (P.R.R., S.V.); Institut National de la Sante´ et de la Recherche Me´dicale, Unite´ Mixte de Recherche 1163, Institut Imagine, Laboratoire de Ge´ne´tique Ophtalmologique, Universite´ Paris Descartes, Sorbonne Paris Cite´, Paris, France (C.B., B.N.); Institut National de la Sante´ et de la Recherche Me´dicale, Unite´ Mixte de Recherche _S968, Paris, France (I.A.); Centre National de la Recherche Scientifique, Unite´ Mixte de Recherche 7210, Paris, France (I.A.); Universite´ Pierre et Marie Curie Paris 6, Institut de la Vision, Paris, France (I.A.); Centre Maladies Rares/Centre d’Investigations Cliniques 503 Institut National de la Sante´ et de la Recherche Me´dicale, Centre Hospitalier National d’Ophtalmologie des Quinze-Vingts, Paris, France (I.A.); Department of Molecular Genetics, Institute of Ophthalmology, London, United Kingdom (I.A.); and Universite´ Paris-Descartes, Sorbonne Paris Cite´, Assistance Publique–Hoˆpitaux de Paris, Laboratoire de Biologie et Ge´ne´tique Mole´culaire, Hoˆpital Cochin, Paris, France (S.V.). Inquiries to Pierre-Raphael Rothschild, Service d’ophtalmologie, Hoˆpital Hoˆtel Dieu, 1 Place du Parvis de Notre-Dame, 75004 Paris, France; e-mail: [email protected] 0002-9394/$36.00 http://dx.doi.org/10.1016/j.ajo.2015.08.012
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2015 BY
compared to the control group, except at the foveal center where abnormal persistence of 1 or more inner retinal layers could be observed. CONCLUSION: SD OCT provides better structural insight into the range of retinal defects at the vitreoretinal interface and fovea, which is not only useful for improving diagnosis and management, but also for understanding the pathogenesis of Wagner syndrome. (Am J Ophthalmol 2015;160(5):1065–1072. Ó 2015 by Elsevier Inc. All rights reserved.)
W
AGNER SYNDROME (OMIM#143200) IS A VERY
rare vitreoretinal degenerative disorder with no systemic features, inherited as an autosomal dominant trait, and only 14 families have been reported worldwide with a molecularly confirmed diagnosis. This genetic disorder is caused by splice mutations in the versican (VCAN) gene, coding for a chondroitin sulfate proteoglycan named versican whose exact role in ocular tissues is largely unknown. The pattern of expression of versican during retinal development and in the adult retina supports a role in vitreous architecture and vitreoretinal interface, as well as in the maintenance of photoreceptor cells, and in the regulation of neurite formation and growth of the nerve fiber layer and inner plexiform layer where neural networks of ganglion cells are being formed.1–3 The clinical spectrum of the disease is very large and age-dependent, with a highly variable expressivity even among affected members within a same family, making diagnosis of this disease very challenging.4–6 The disease usually manifests in childhood, and affected patients show an optically empty vitreous with a characteristic fibrillary aspect of the vitreous core and an abnormal vitreous cortex with avascular peripheral veils.7,8 Other features variably include moderate congenital myopia,7,9–13 early-onset cataract,7,10–14 glaucoma,7,10–13 uveitis,4,8,15 and foveal ectopia responsible for pseudostrabismus.14,16,17 The severity of the disease is related to the progressive chorioretinal degeneration with atrophy and the occurrence of retinal detachments, both of these complications being the leading causes of visual loss in patients with Wagner syndrome.7 Although retinal detachment has long been an unrecognized manifestation and is not
ELSEVIER INC. ALL
RIGHTS RESERVED.
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TABLE 1. Summary of Clinical, Spectral-Domain Optical Coherence Tomography, and Molecular Findings in Patients With Wagner Syndrome
Family ID
A
B
C
VCAN Mutation
c.4004-2A>T
c.4004-6A>T
c.9265þ1G>A
References 4
Bre´zin et al
Rothschild et al8
Rothschild et al9
Patient ID
Sex
Age (y)
A.IV.7 A.IV.8 A.V.5
M M F
61.9 51 35.9
A.V.6 B.I.2 B.II.1 B.II.4
F F F F
40.7 72.6 44.7 47.4
C.II.1 C.III.1
M F
30.5 3
Eye
BCVA (LogMAR)
AL (mm)
SE (Diopters)
OD OS OD OS OD OS OD OD OS OS OD OS
0.4 0.1 0.1 0.1 0.2 0.2 0.2 0.1 0.1 0 0.5 0.5
25.05 24.77 23.84 24.1 27.05
7.75 3.375 5.5 5.625
21.97
26.7
1 0.875 0.75 3.125 3 6.375
IOP
ExRM
Grade 1 FH
Grade 2 FH
17 11 16 16 16 17 17 16 17 17
Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No
Yes Yes No No No No No No Yes Yes Yes Yes
Yes No No No No No No No No Yes No No
AL¼ axial length; BCVA ¼ best-corrected visual acuity; ExRM ¼ extraretinal membrane; FH ¼ foveal hypoplasia; IOP ¼ intraocular pressure; SE ¼ spherical equivalent; VCAN ¼ versican gene.
as frequent in Wagner syndrome as in Stickler, all recent studies have reported retinal detachment in affected patients.4,14 Visual acuity is reported to be normal or subnormal in young patients with Wagner syndrome but is constantly severely affected in older patients. To gain insight into the qualitative and quantitative defects in the retina and at the vitreoretinal interface in Wagner syndrome, a retrospective intrafamilial comparative case study was conducted using the in vivo spectraldomain optical coherence tomography (SD OCT) imaging method.18 The retinal structural information provided by SD OCT may help in clarifying the underlying pathologic mechanisms at play in Wagner syndrome, which remain poorly understood thus far.
SPECTRAL-DOMAIN OPTICAL COHERENCE TOMOGRAPHY ANALYSIS: The SD OCT acquisition protocol
METHODS INSTITUTIONAL REVIEW BOARD APPROVALS FOR RETRO-
spective chart reviews were obtained commensurate with the respective institutional requirements prior to the beginning of the study. Described research was approved by the Ethics Committee of the French Society of Ophthalmology and adhered to the tenets of the Declaration of Helsinki. Fully written informed consent was obtained for all patients. This intrafamilial case-control study included patients followed for hereditary vitreoretinal diseases at a single institution, a university teaching hospital at Groupe Hospitalier Cochin Hoˆtel-Dieu, Paris, France. Patients enrolled in our cohort (The French Vitreoretinopathy Study Group) were offered standardized ophthalmic examination and genetic testing. Patients with a clinical picture of Wagner syndrome and positive for a pathogenic mutation in the VCAN gene were 1066
enrolled in this study (cases). The control population included clinically unaffected family members who were non-carriers of VCAN mutations (controls). ETDRS bestcorrected visual acuity (BCVA), slit-lamp biomicroscopy, intraocular pressure measurements, dilated fundus examination, and spherical equivalent and axial length measurement (IOLMaster; Carl Zeiss Meditec AG, Jena, Germany) was performed for all studied patients (cases and controls) and findings have been partly reported elsewhere (Table 1).4,8,9 SD OCT was performed using the Spectralis OCT (Heidelberg Engineering, Heidelberg, Germany). Patients with no SD OCT data; with a history of retinal detachment, macular edema, or premature birth; or with low-quality SD OCT images were excluded from the analysis (see Figure 1 for inclusion flow chart details).
included a horizontal and vertical 9-mm central linear scan (passing through the fovea). At least 30 scans were averaged to reduce the signal-to-noise ratio and lowquality images (signal-to-noise ratio below 25 dB) were discarded. Qualitative OCT image analysis included the quoting of the presence or absence of a membrane-like structure forming a bridge over the foveal pit according to our previous description in time-domain OCT of Wagner syndrome patients.4 We also graded foveal abnormalities as previously described by others.19 In brief, we noted the absence of extrusion of the plexiform layers (grade 1) from the central fovea, the absence of foveal pit (grade 2), the absence of outer segment lengthening (grade 3), and finally the absence of widening of the outer nuclear layer (grade 4). Quantitative analysis included manual segmentation of several retinal layers using the built-in caliper of the viewing software (HRA Spectralis viewing software version 5.6.4.0).
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TABLE 2. Demographic Characteristics of Patients With Wagner Syndrome and Control Patients
Number of patients Number of eyes Age (y, mean 6 SD) Male-to-female ratio BCVA (logMAR 6 SD) Spherical equivalent (diopters, mean 6 SD) Axial length (mm, mean 6 SD)
Control Group
Wagner Group
P Value
15 28 31 (6 18.3) 8:7 060 0.3 (6 1.2)
9 12 37.5 (6 22.6) 4:5 0.2 6 0.16 3.5 (6 2.8)
.5 NS .67 NS .0001 .001
23.4 (6 0.7)
24.8 (6 1.7)
.026
BCVA ¼ best-corrected visual acuity; NS ¼ not significant.
FIGURE 1. Patients with Wagner syndrome selection flow chart for spectral-domain optical coherence tomography (SD OCT) study. VCAN is the symbol for the Versican gene.
FIGURE 2. Point estimates of the thickness of several retinal layers in control subjects (Top) and in patients with Wagner syndrome (Bottom). Measures of the total retinal thickness (TRT), inner retinal layers (IRL), outer retinal layers (ORL), and photoreceptor layer (PRL) as well as the foveal pit depth (FPD) were performed in the center of the fovea and at 1000 mm of eccentricity along the horizontal line scan.
We defined the following layers: (1) total retinal thickness (TRT), as the distance from the inner limiting membrane (ILM) to the inner aspect of the Bruch membrane (BM); (2) inner retinal layers (IRL), as the distance from the ILM to the outer plexiform layer (not included); (3) outer retinal layers (ORL), as the distance from the inner aspect of BM to the outer plexiform layer (included); and (4) photoreceptor layer (PRL), as the distance from the inner aspect of the retinal pigment epithelium (RPE) to the outer limiting membrane (Figure 2). These measures were VOL. 160, NO. 5
performed at the center of the fovea and at 1000 mm of eccentricity from the center along the OCT 9-mm central line in the nasal, temporal (horizontal line), and superior quadrant (vertical line). We computed as previously described by others the superior foveal-to-perifoveal ratio for the inner retinal layers (foveal-to-perifoveal IRL ratio) and for the photoreceptor layers (foveal-to-perifoveal PRL ratio) measurements.20 Briefly, the foveal-to-perifoveal ratios are computed by dividing the values of a studied layer thickness, here the inner and photoreceptor layer, at the foveal center and at 1000 mm of eccentricity along the vertical scan line in the superior quadrant. These ratios have been used to respectively describe the centrifugal displacement of inner retinal layers from the fovea and the retinal outer layer widening at the fovea during embryogenesis. Finally, we measured the foveal pit depth (FPD) as the distance between a 1-mm line tangential to the retinal surface and the ILM at the center of the fovea (Figure 2). This parameter is another marker of the centrifugal displacement of the inner retinal layers that occurs during embryogenesis. When this phenomenon fails to occur, a shallow foveal pit in adult patients is present, as reflected by a decrease of foveal pit depth. STATISTICAL ANALYSIS:
Categorical variables were expressed as numbers (percentages) and comparisons were performed using the x2 test or the Fisher exact test when appropriate. For continuous variables, mean 6 standard deviation (SD) was provided, and means were compared using the Mann-Whitney test. Correlations were performed using the Spearman correlation coefficient. P < .05 was considered significant. Analyses were performed using XLSTAT software (Addinsoft, Paris, France) version 2014.4.06.
MOLECULAR
ANALYSIS: Molecular analysis of the VCAN gene have been conducted as previously described.4 In brief, DNAs were extracted from venous blood samples, using the QIAamp DNA mini kit (Qiagen, Valencia,
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FIGURE 3. Vitreomacular interface abnormalities in patients with Wagner syndrome. Affected patients presented with a highly reflective thick multilayered membrane, completely detached from the fovea but remaining attached to the perifoveal area and forming a bridge above the foveal pit. Note the thin membrane overlying the center of the fovea and probably corresponding to the partially detached posterior vitreous cortex.
FIGURE 4. Vitreoretinal interface and retinal abnormalities in patients with Wagner syndrome. Note the barely visible extra retinal membrane (Top row and Second row, left), the inversion of optic nerve or ‘‘situs inversus’’ (Second row, right), and the absence of extra retinal membrane, although vitreoschisis was present in both eyes of the same patient (Bottom row). Also note the presence of the outer plexiform layer at the foveal center except for 1 eye (Second row, right).
California, USA). Intron-exon boundaries for exons 6, 7, 8, and 9 of the VCAN gene were amplified by polymerase chain reaction. Sanger sequencing reactions were performed in an automatic genetic analyzer (ABI PRISM 3100 genetic analyzer; Applied Biosystems, Foster City, California, USA) using the BigDye terminator cycle sequencing kit (DNA sequencing kit; Applied Biosystems).
RESULTS A TOTAL OF 12 EYES OF 9 PATIENTS FROM 3 UNRELATED
families with a clinical picture of Wagner syndrome and carriers of a pathogenic VCAN mutation were included in this study; and 28 eyes from 15 unaffected family members, VCAN mutation negative, were selected to serve as controls (see Figure 1 for inclusion flow chart details). 1068
The clinical and molecular data of all included patients with Wagner syndrome are summarized in Table 1 with corresponding references to our previous descriptions. Baseline characteristics of both groups are shown in Table 2. In summary, no significant differences were found for age (31 6 18 3 years and 37 6 22 6 years) in the control and Wagner groups (P ¼ .5; Mann-Whitney test) or for sex ratio (male-to-female ratio was, respectively, 8:7 and 4:5 [P ¼ .6; x2 test]). Spherical equivalent (0.3 6 1.2 diopters and 3.5 6 2.8 diopters) as well as axial length (23.4 6 0.7 mm and 24.8 6 1.7 mm) were significantly different between the control group and Wagner group (P ¼.001 and P ¼ .026, respectively). BCVA was 0 6 0 logMAR units for control patients and 0.2 6 0.16 logMAR units for patients with Wagner syndrome (P ¼ .0001). Among the patients with Wagner syndrome, 6 were pseudophakic and 6 were phakic with a clear crystalline lens. We found no significant difference between phakic and pseudophakic patients regarding all the above studied parameters.
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FIGURE 5. Spectral-domain optical coherence tomography aspect of the circumferential peripheral avascular veil in patients with Wagner syndrome. Note the localized tractional retinal schisis seen at the site of the insertion of the vitreous veil, which corresponds to the posterior vitreous cortex.
Qualitative SD OCT assessment showed in 10 eyes (10/12, 84%) from 8 patients with Wagner syndrome a macular thick hyperreflective structure attached to the perifovea in an annular aspect with no or limited attachment to the inner (superficial) layer of the underlying fovea, sometimes forming a bridge over the foveal pit. The outer (deep) aspect of the multilayered membrane was either partially detached (Figure 3) from the retina (posterior vitreous detachment) or attached (Figure 4). Total absence of this posterior membrane was observed for only 1 patient with Wagner syndrome (individual C.III.1), but abnormal vitreoretinal interface abnormalities in the form of vitreoschisis were present in the perifoveal region of both of her eyes (Figure 4, Bottom). Of note, 1 patient with Wagner syndrome (individual A.IV.7) had an optic nerve inverted nasally, or situs inversus of the optic disc and retinal vessels (Figure 4). Peripheral, mid-equatorial SD OCT images of the detached avascular vitreous veil, a characteristic pathologic feature of the vitreous in Wagner syndrome, showed that this structure corresponded to a vitreous cortex detachVOL. 160, NO. 5
ment with localized tractional retinal schisis at its site of attachment to the retina (Figure 5). SD OCT imaging was also used to evaluate the foveal architecture from patients with Wagner syndrome when compared with control subjects. As shown in Figure 4, variable inner retinal layers, absent at the center of the fovea of control patients, were aberrantly present in 6 eyes (6/12, 50%) of patients with Wagner syndrome. In detail, 4 eyes had nonextrusion of the plexiform layers (grade 1 foveal hypoplasia) and 2, in addition, had no foveal pit depression (grade 2 foveal hypoplasia). Quantitative analysis of retinal layers in patients with Wagner syndrome as compared to controls is shown in Table 3. In brief, central total retinal thickness between the control group (234 6 14.6 mm) and Wagner group (229 6 39.2 mm) was not significantly different (P ¼ .7). However, layer-specific assessment showed that central inner retinal layers were significantly thicker in patients with Wagner syndrome (36 6 13.4 mm) as compared to controls (15.4 6 12.9 mm) (P ¼ .0001). Foveal pit depth for patients
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TABLE 3. Mean Retinal Thickness (mm) in Controls and in Patients With Wagner Syndrome Control Group (Mean 6 SD)
Central thickness Total retinal thickness Inner retinal layers Outer retinal layers Photoreceptor layer Nasal thickness Total retinal thickness Inner retinal layers Outer retinal layers Photoreceptor layer Temporal thickness Total retinal thickness Inner retinal layers Outer retinal layers Photoreceptor layer Foveal-to-perifoveal ratio For inner retinal layers For photoreceptor layer Foveal pit depth
Wagner Group (Mean 6 SD)
P Value
234 (6 14.6) 229 (6 39.2) .7 NS 15.4 (6 12.9) 36 (6 13.4) <.0001 218.6 (6 11.8) 193 (6 32.7) .004 101.6 (6 6.2) 91.3 (6 9.4) .001 362.6 (6 10.2) 301 (6 38.7) <.0001 167.9 (6 10.7) 147.5 (6 16.9) .0001 194.7 (6 10.8) 153.5 (6 30.0) <.0001 87.8 (6 5.6) 73.1 (6 17.2) .0001 341.5 (6 11.3) 149.3 (6 9.8) 192.3 (6 9.7) 87.1 (6 4.4)
281.8 (6 35.9) <.0001 127.9 (6 20.0) .001 153.8 (6 27.8) <.0001 72.4 (6 12.9) <.0001
0.1 (6 0.1) 0.3 (6 0.1) <.0001 1.1 (6 0.1) 1.3 (6 0.2) .002 118.6 (6 19.7) 69.9 (6 34.1) .0001
NS ¼ not significant.
with Wagner syndrome was significantly decreased as compared to controls: 69.9 6 34.1 mm and 118.6 6 19.7 mm, respectively (P ¼ .0001). Conversely, central outer retinal layers and photoreceptor layers, as well as all other studied layers in the temporal or nasal retina, were significantly thinner in patients with Wagner syndrome as compared to controls (Table 3). We found no significant difference between myopic and nonmyopic control patients for the above parameters, suggesting that the foveal changes were not related to the myopia but rather to the Wagner syndrome status. The foveal-to-perifoveal inner retinal layer and fovealto-perifoveal photoreceptor layer ratios were increased in patients with Wagner syndrome as compared to controls. Finally, we found a significant linear correlation between foveal-to-perifoveal inner retinal layer ratio and BCVA (R2 ¼ 0.525, P ¼ .0001) (Figure 6).
DISCUSSION SD OCT HAS EMERGED IN THE LAST DECADE AS A POWERFUL
noninvasive method to investigate structural changes in the retina and the vitreoretinal interface. We took advantage of this technology to evaluate the pathologic features of patients with Wagner syndrome. Wagner syndrome is a rare autosomal dominant degenerative vitreoretinal disease caused by splice mutations in the 1070
VCAN gene coding a large extracellular chondroitin sulfate proteoglycan, named versican. Versican is a component of the vitreous core and vitreous cortex, known to play a central role in the spatial regulation of fibrillar structures, and suspected to participate in vitreoretinal interface adhesion. The pathogenic mechanism of Wagner syndrome is poorly understood and is thought to result from abnormal interactions of versican with vitreous components responsible for pathologic liquefaction of the vitreous, leading to syneresis with optically empty vitreous and synchisis with a fibrillary aspect of the core vitreous. Herein, SD OCT provided high-resolution images of the vitreoretinal interface, allowing the revealing of the presence of a dense packed posterior vitreous with membranous multilayered structures of high reflectivity and variable thickness at the vitreoretinal interface in a large majority of eyes from patients with Wagner syndrome. These membranous structures are detached from the vitreofoveal interface in an annular configuration with persistent attachments to the perifoveal area, thus forming a bridge over the foveal pit. This posterior vitreous detachment in patients with Wagner syndrome seems to differ from age-related posterior vitreous detachment (PVD), which has been shown to start in a perifoveal location while maintaining residual attachments to the fovea, so-called vitreomacular adhesion (VMA), and then extends further to eventually encompass the fovea itself.21 These SD OCT findings suggest that the pathogenic mechanisms in Wagner syndrome cause a weakening of the vitreoretinal adhesion, particularly in the foveal area, and also predispose to membrane formation.22 As for the more common epiretinal membrane (ERM), it is still unclear whether the membrane formation precedes and predisposes to foveal PVD or if the ERM develops after the PVD owing to the vitreoschisis hypothesis.23 SD OCT also provided structural information on the circumferential equatorial avascular veil, a clinical feature unique to Wagner syndrome, also corresponding to abnormal vitreous cortex detachment and showing localized tractional retinal schisis. Patients with Wagner syndrome, as compared to control subjects, had significantly reduced retinal thickness at the posterior pole in almost all layers, consistent with posterior chorioretinal atrophy observed in the fundus of patients with Wagner syndrome. Of importance, central inner retinal layer thickness was significantly increased (Figure 4 and Table 1). SD OCT images detected, in some patients with Wagner syndrome, the presence of plexiform layers at the center of the fovea, normally absent when the maturation of the fovea is properly accomplished. In this study, the foveal-to-perifoveal ratio of the inner retinal layer, for patients with Wagner syndrome, a surrogate marker for failed centrifugal displacement of bipolar cells,24 was comparable to ratios of premature neonates reported by Maldonado and associates.20 Although the sample size studied was small, we found a significant correlation between these foveal defects and visual acuity. Foveal hypoplasia, defined by abnormal persistence of central inner retinal layers with an
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FIGURE 6. Linear regression analysis of the best-corrected visual acuity (expressed in logMAR units) and the superior foveal-toperifoveal inner retinal layer ratio, showing a significant linear correlation between the 2 variables (R2 [ 0.525, P [ .0001). The gray dashed line represents the confidence interval of the mean and the solid gray line the confidence interval of the observations.
absent or shallow foveal pit, has been reported in several ocular conditions such as albinism, aniridia, in retinopathy of prematurity,19,20 but the literature in terms of description and in terms of visual significance of these findings is controversial. Marmor and associates coined the term fovea plana, and found no correlation with visual acuity loss in albinism patients.25 Consistently, Tick and associates demonstrated that a significant proportion of the normal population could exhibit fovea plana with normal visual function.26 More recently, Thomas and associates proposed a classification for foveal hypoplasia based on SD OCT data,19 and found a correlation between the grade of hypoplasia and visual loss. Although these foveal defects remain to be confirmed on a larger population of patients with Wagner syndrome, the existence of other yet well documented foveal developmental abnormalities in Wagner
syndrome, such as foveal ectopia, raises some unanswered questions about the role of versican in early embryogenesis, where a transient but significant expression of versican is found in inner retinal layers when networks of ganglion cells are being formed.1,2 Owing to the rarity of this genetic disease, a large-scale longitudinal study with different subgroups according to age, sex, axial length, and disease duration was not possible, and further SD OCT analysis on additional patients with Wagner syndrome worldwide is needed to refine the retinal dysfunction in Wagner syndrome. To conclude, SD OCT imaging in Wagner syndrome may be helpful in clarifying the changes and the mechanisms underlying this vitreoretinal interface disorder, and this method is also useful for clinicians in the diagnosis, management, and monitoring of disease progression.
FUNDING/SUPPORT: NO FUNDING OR GRANT SUPPORT. FINANCIAL DISCLOSURES: THE FOLLOWING AUTHORS HAVE NO financial disclosures: Pierre-Raphael Rothschild, Cyril Burin-Des-Roziers, Isabelle Audo, Brigitte Nedelec, Sophie Valleix, and Antoine P. Bre´zin. All authors attest that they meet the current ICMJE criteria for authorship. The authors thank Alain Gaudric, MD (Hoˆpital Lariboisie`re, Paris, France) for sharing expertise on OCT data acquisition, analysis, and interpretation; and Vale´rie Beunardeau (Bibliothe`que Javal/Centre de Documentation Ophtalmologique de la Socie´te´ Franc¸aise d’Ophtalmologie, Paris, France) for reference management assistance.
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Biosketch Pierre-Raphael Rothschild, MD, is a medical and surgical vitreoretinal fellow at the Hotel Dieu Cochin Hospital, Paris, France. He is a graduate of Paris VI University, France. He completed a comprehensive ophthalmology residency and is now in his last year of PhD thesis on the mechanisms of diabetic retinopathy. He also has a particular interest on diagnosis and management of hereditary forms retinal detachment whether polygenic or monogenic especially Stickler and Wagner syndrome.
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