Purpose
To analyze the outer retinal and retinal pigment epithelium (RPE) features of reticular pattern dystrophy of the retina using spectral-domain optical coherence tomography (SDOCT).
Design
Retrospective observational case series.
Methods
Consecutive patients with reticular pattern dystrophy of the retina underwent a complete ophthalmologic examination, including assessment of best-corrected visual acuity (BCVA), fundus biomicroscopy, fluorescein angiography (FA), and SDOCT.
Results
Twenty-two eyes of 13 patients (6 men, 7 women, mean age 68.6 ± 14.5 years) were included. In the foveal area, the RPE layer appeared normal in 45.5% of eyes, while small RPE elevations and RPE bumps were detected in 31.8% and 22.7% of eyes, respectively. The SDOCT scans showed disruption of inner segment/outer segment (IS/OS) junction in 54.6% of eyes, a slight elevation in 59.1% of eyes, and an absence in 45.5% of eyes. The outer limiting membrane (OLM) appeared disrupted in 50.0% of eyes, absent in 22.7% of eyes, and elevated in 63.6% of eyes. Hyper-reflective subretinal material accumulation or hyporeflective subretinal lesions in the retrofoveolar region were detected in 70% and in 20% of eyes, respectively. SDOCT showed hyporeflective retinal pseudocysts in 13.6% of eyes.
Conclusion
In this study on reticular pattern dystrophy of the retina, SDOCT provided a description of the material deposits and the alterations of the RPE and the different retinal layers. We observe that the lesions present specific features distinct from other macular dystrophies, but closer to those reported in fundus flavimaculatus than those reported in adult-onset foveomacular vitelliform dystrophy. Further analyses are needed, particularly to analyze the progression of the lesions.
Pattern dystrophies are a heterogeneous group of inherited disorders of the retinal pigment epithelium (RPE) affecting both eyes, predominantly at the macula, and are considered to have a chronic progressive course. Each entity is characterized by specific RPE alterations; several forms have been identified, including adult-onset foveomacular vitelliform dystrophy, butterfly-shaped pigment dystrophy, reticular dystrophy of the pigment epithelium, and pattern dystrophy simulating fundus flavimaculatus or fundus pulverulentus. Pattern dystrophy has also been associated with other systemic disease. On fundus examination, pattern dystrophy is characterized by accumulation of a yellowish, orange, or brown material at the level of the RPE and by RPE alterations in the macular area. Reticular pattern dystrophy was first described in 5 children of a Swedish family. Actually, the diagnosis of reticular pattern dystrophy is usually found in the course of routine ophthalmoscopic examination in patients with no obvious complaints, since visual function is preserved or minimally affected even in advanced stages. Nevertheless, the development of atrophic changes or choroidal neovascularization (CNV) can lead to loss of central vision.
Diagnosis of reticular pattern dystrophy is generally based on the presence of yellowish material deposits on the macula with a reticular pattern at fundus examination. The material deposits are hyper-autofluorescent on fundus autofluorescence (FAF). The pattern dystrophy lesions appear hypofluorescent on fluorescein angiography (FA) surrounded by hyperfluorescent lesion borders in early and late frames.
High-resolution spectral-domain optical coherence tomography (SDOCT) has recently become available, allowing a quasi-histologic assessment of the ocular fundus in vivo. Combination of confocal scanning laser ophthalmoscopy (cSLO) and SDOCT along with real-time eye tracking technology in Spectralis SDOCT (Spectralis HRAOCT; Heidelberg Engineering, Heidelberg, Germany) allows for precise orientation of the scan toward the region of interest and simultaneous recordings of cross-sectional OCT images with various topographic imaging modalities, including near-infrared reflectance, FAF, and FA (ie, integrated imaging analysis).
The purpose of this study was to analyze the specific outer retinal and RPE features in macular reticular pattern dystrophy using SDOCT.
Patients and Methods
In this retrospective observational case series, we studied patients with diagnosis of reticular pattern dystrophy who consecutively presented at the Department of Ophthalmology of the Centre Hospitalier Intercommunal de Creteil between February 2010 and May 2012 and who underwent SDOCT. Informed consent was obtained from all patients in accordance with the Declaration of Helsinki for research involving human subjects. French Society of Ophthalmology Institutional Review Board approval was obtained for this study. Past medical history (such as diabetes or hypoacousia) or familial history of pattern dystrophy was recorded. The criteria for reticular pattern dystrophy diagnosis were the presence of a yellowish material deposit on the macula with a reticular pattern at fundus examination, showing hyper-autofluorescent lesions on FAF. Exclusion criteria were presence of geographic atrophy, signs of CNV, or subretinal fibrosis. All patients harboring signs of fundus flavimaculatus flecks in FAF frames were also excluded. All patients were submitted to a complete ophthalmologic examination, including assessment of best-corrected visual acuity (BCVA) using Early Treatment Diabetic Retinopathy Study (ETDRS) charts, fundus biomicroscopy, and FA. SDOCT examination was performed with a Spectralis SDOCT device (Spectralis HRA+SD−OCT; Heidelberg Engineering, Heidelberg, Germany). Minimum protocol of acquisition for SDOCT consisted of 19 horizontal lines (6 × 6-mm area centered on the fovea), each composed of 1024 A-scans per line. The line scans were saved for analysis after up to 100 frames were averaged, using the automatic averaging and eye tracking features of the proprietary device. For each eye, we analyzed SDOCT line scans centered on the fovea as well as the scans located 720 μm superiorly and 720 μm inferiorly, except in Case 1, in which the patient underwent only 1 line scan centered on the fovea in 1 eye. Thus, we analyzed 22 foveal scans and 42 extrafoveal scans, for a total of 64 scans. Several peculiar features associated with the reticular pattern were reported on SDOCT scans. The analyses of the scans were performed independently by 3 retinal specialists (J.Z., G.Q., and N.M.). We analyzed the RPE, the Verhoeff membrane, the inner segment/outer segment (IS/OS) junction, the outer limiting membrane (OLM), the presence and the appearance of the material, and presence of hyperreflective clumps and pseudocysts. Disagreement regarding interpretation of the different features was resolved by open adjudication.
Comparisons of mean BCVA (converted to the logarithm of the minimal angle of resolution [logMAR]) according to IS/OS status (presence or absence of abnormalities), presence or absence of material, presence or absence of bumps, thickened Verhoeff membrane (presence or absence), hyperreflective clumps (presence or absence), and presence or absence of cysts were performed using logistic generalized estimating equation (GEE) models, which allow taking into account the data from both eyes and their intra-individual correlations. GEE models were also used to assess associations between IS/OS status (presence or absence of irregularities), presence of material, presence of bumps, and thickened Verhoeff membrane. The chosen level of statistical significance was P < .05. All statistical analyses were performed using SAS version 9.3 (SAS Institute Inc, Cary, North Carolina, USA; procedure GENMOD for the GEE analysis).
Results
Twenty-two eyes of 13 patients (6 men, 7 women, mean age 68.6 ± 14.5 years) from 13 different families were included for analysis. At presentation logMAR BCVA was 0.34 ± 0.31 (range 1.1-0.0). No patient reported familial history of pattern dystrophy. Three patients, who were previously diagnosed with reticular pattern dystrophy, underwent ophthalmic assessment in our department at mean 11.5 ± 30.8 months prior.
Reticular pattern dystrophy was bilateral in 9 cases. Two eyes of 2 patients were excluded because they were previously diagnosed with CNV-complicating reticular pattern dystrophy, and 2 eyes of 2 patients because of geographic macular atrophy. At presentation, all reticular lesions were symmetric except for the 4 cases showing CNV or geographic atrophy in the fellow eyes. Retrospective analysis (11.5 ± 30.8 months) of bilateral cases (n = 3) revealed that all reticular lesions were synchronic. None of these cases developed CNV or geographic atrophy over time.
The mean size of the reticular lesions measured by a circle on infrared frames was 4531 μm. We also measured the mean height and width of retrofoveolar lesions on OCT scans. The mean height of the retrofoveolar lesions was 69 ± 19 μm and the mean width was 495 ± 305 μm.
FAF showed hyper-autofluorescence of the reticular material deposits ( Figures 1-5 ), and near-infrared reflectance revealed the reticular lesions as hyperreflective ( Figures 1 , 4 , 6 ). On FA the reticular lesion appeared hypofluorescent from early to late phase of the examination, with hyperfluorescent borders ( Figures 1 , 2 , 4-6 ).
We analyzed a total of 22 foveolar scans and 42 extrafoveolar scans, which revealed several peculiar features associated with the reticular pattern dystrophy ( Tables 1 and 2 ):
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Retinal pigment epithelium elevations and retinal pigment epithelium bumps: Small drusen-like RPE elevations and RPE bumps (corresponding to focal thickenings of the RPE) were detected on SDOCT scans, both centered on the fovea and superiorly/inferiorly to the fovea ( Figures 1-4, 6 ; Table 2 ).
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Thickening of the Verhoeff membrane: The thin hyperreflective optical layer located between the RPE and the IS/OS interface, referred to as Verhoeff membrane, appeared thickened in a high proportion of eyes for both scans centered on the fovea and extrafoveal scans ( Figures 1 and 6 ; Table 2 ).
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Subretinal accumulation of hyperreflective/hyporeflective material: Subretinal material, detected in scans centered on the fovea and the extrafoveal scans, was more often hyperreflective and homogenous ( Figures 5 and 6 ; Table 2 ). Hyporeflective and mixed hyper-/hyporeflective subretinal material was rarely detected in both the scans centered on the fovea and the extrafoveolar region ( Table 2 ).
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Disruption, elevations, and loss of the inner segment/outer segment interface and outer limiting membrane: IS/OS and OLM disruption/loss and elevation were frequently observed in scans both centered on the fovea and superiorly and inferiorly to the fovea (extrafoveal scans) ( Figures 1-6 ; Table 2 ). Eyes showing IS/OS interface alterations had a worse BCVA compared to eyes showing absence of IS/OS alterations (mean logMAR BCVA 0.39 ± 0.32 vs 0.1 ± 0.82, respectively; P = .02).
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Hyperreflective retinal clumps: The retinal clumps, small round hyperreflective lesions, were detected in the inner retinal layers in 9 of 22 scans (40.9% of eyes) centered on the fovea and in 18 of 42 (42.9%) superiorly and inferiorly to the fovea ( Figures 4-6 ; Table 2 ). The retinal clumps were located in the outer nuclear layer (ONL) in 9 of 9 scans centered on the fovea, and in the inner retinal layer for the scans superiorly and inferiorly to the fovea (7/18) ( Figure 6 ).
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Hyporeflective retinal pseudocysts: Small optically empty retinal spaces (retinal pseudocysts) were rarely observed, both in scans centered on the fovea and in the extrafoveolar scans ( Figure 4 ; Table 2 ).
| Study Eye | BCVA (LogMAR) | IS/OS Irregularities | Presence of Bumps | Thickened Verhoeff | Hyperreflective Clumps | Presence of Materiel | Homogenous | Hypo- or Hyperreflective Material | Presence of Cysts | |
|---|---|---|---|---|---|---|---|---|---|---|
| Case 1 | OD | 1.1 | Y | N | Y | Y | Y | Y | Hyper | N |
| OS | 0.8 | Y | Y | Y | Y | Y | Y | Hyper | N | |
| Case 2 | OD | 0.2 | N | N | N | N | N | – | – | N |
| OS | 0.0 | N | N | N | N | N | – | – | N | |
| Case 3 | OD | 0.1 | Y | N | Y | N | N | – | – | N |
| OS | 0.3 | Y | N | Y | N | Y | N | Hyper | N | |
| Case 4 | OD | 0.6 | Y | N | N | N | Y | N | Hyper and hypo | N |
| OS | 0.4 | Y | Y | Y | Y | Y | N | Hypo | Y | |
| Case 5 | OD | 0.1 | Y | N | N | Y | N | – | – | Y |
| Case 6 | OD | 0.00 | Y | N | N | N | Y | Y | Hyper | N |
| OS | 0.00 | Y | Y | N | N | Y | Y | Hyper | N | |
| Case 7 | OD | 0.2 | Y | N | Y | Y | N | – | – | N |
| OS | 0.5 | Y | Y | Y | Y | Y | Y | Hyper | N | |
| Case 8 | OD | 0.1 | Y | N | N | N | N | – | – | N |
| OS | 0.1 | Y | N | N | N | N | – | – | N | |
| Case 9 | OD | 0.8 | Y | Y | Y | N | Y | Y | Hyper | N |
| OS | 0.5 | Y | N | Y | N | N | N | |||
| Case 10 | OS | 0.4 | Y | N | N | Y | N | – | – | N |
| Case 11 | OS | 0.8 | Y | N | N | Y | N | Y | Hypo | N |
| Case 12 | OD | 0.1 | N | N | N | N | N | – | – | N |
| OS | 0.1 | N | N | N | N | N | – | – | N | |
| Case 13 | OD | 1.3 | Y | N | N | N | N | – | – | N |
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