Three-dimensional distribution of the vitelliform lesion, photoreceptors, and retinal pigment epithelium in the macula of patients with best vitelliform macular dystrophy

Peak Cone Density Predicted from Outer Segment Length Measured on Optical Coherence Tomography

PURPOSE

To compare peak cone density predicted from outer segment length measured on optical coherence tomography with direct measures of peak cone density from adaptive optics scanning light ophthalmoscopy.

METHODS

Data from 42 healthy participants with direct peak cone density measures and optical coherence tomography line scans available were used in this study. Longitudinal reflectivity profiles were analyzed using two methods of identifying the boundaries of the ellipsoid and interdigitation zones to estimate maximum outer segment length: peak-to-peak and the slope method. These maximum outer segment length values were then used to predict peak cone density using a previously described geometrical model. A comparison between predicted and direct peak cone density measures was then performed.

RESULTS

The mean bias between observers for estimating maximum outer segment length across methods was less than 2 µm. Cone density predicted from the peak-to-peak method against direct cone density measures showed a mean bias of 6,812 cones/mm2 with 50% of participants displaying a 10% difference or less between predicted and direct cone density values. Cone density derived from the slope method showed a mean bias of -17,929 cones/mm2 relative to direct cone density measures, with only 41% of participants demonstrating less than a 10% difference between direct and predicted cone density values.

CONCLUSION

Predicted foveal cone density derived from peak-to-peak outer segment length measurements using commercial optical coherence tomography show modest agreement with direct measures of peak cone density from adaptive optics scanning light ophthalmoscopy. The methods used here are imperfect predictors of cone density, however, further exploration of this relationship could reveal a clinically relevant marker of cone structure.

Multimodal imaging in Best Vitelliform Macular Dystrophy: Literature review and novel insights

Best Vitelliform Macular Dystrophy (BVMD) is a dominantly inherited retinal disease caused by dominant variants in the BEST1 gene. The original classification of BVMD is based on biomicroscopy and color fundus photography (CFP); however, advancements in retinal imaging provided unique structural, vascular, and functional data and novel insights on disease pathogenesis. Quantitative fundus autofluorescence studies informed us that lipofuscin accumulation, the hallmark of BVMD, is unlikely to be a primary effect of the genetic defect. It could be due to a lack of apposition between photoreceptors and retinal pigment epithelium in the macula with subsequent accumulation of shed outer segments over time. Optical Coherence Tomography (OCT) and adaptive optics imaging revealed that vitelliform lesions are characterized by progressive changes in the cone mosaic corresponding to a thinning of the outer nuclear layer and then disruption of the ellipsoid zone, which are associated with a decreased sensitivity and visual acuity. Therefore, an OCT staging system based on lesion composition, thus reflecting disease evolution, has been recently developed. Lastly, the emerging role of OCT Angiography proved a greater prevalence of macular neovascularization, the majority of which are non-exudative and develop in late disease stages. In conclusion, effective diagnosis, staging, and clinical management of BVMD will likely require a deep understanding of the multimodal imaging features of this disease.

A pathogenic in-frame deletion-insertion variant in BEST1 phenocopies Stargardt disease

Here, we describe affected members of a 2-generation family with a Stargardt disease-like phenotype caused by a 2-base pair deletion insertion, c.1014_1015delGAinsCT;p.(Trp338_Asn339delinsCysTyr), in BEST1. The variant was identified by whole-exome sequencing, and its pathogenicity was verified through chloride channel recording using WT and transfected mutant HEK293 cells. Clinical examination of both patients revealed similar phenotypes at 2 different disease stages that were attributable to differences in their age at presentation. Hyperautofluorescent flecks along the arcades were observed in the proband, while the affected mother exhibited more advanced retinal pigment epithelium (RPE) loss in the central macula. Full-field electroretinogram testing was unremarkable in the daughter; however, moderate attenuation of generalized cone function was detected in the mother. Results from electrooculogram testing in the daughter were consistent with widespread dysfunction of the RPE characteristic of Best disease. Whole-cell patch-clamp recordings revealed a statistically significant decrease in chloride conductance of the mutant compared with WT cells. This report on a mother and daughter with a BEST1 genotype that phenocopies Stargardt disease broadens the clinical spectrum of BEST1-associated retinopathy.

Microstructural changes of photoreceptor layers detected by ultrahigh-resolution SD-OCT in patients with autosomal recessive bestrophinopathy

Purpose

To determine the changes in the microstructures of the photoreceptors in patients with autosomal recessive bestrophinopathy (ARB) by ultrahigh-resolution spectral-domain optical coherence tomography (UHR-SD-OCT).

Methods

Five eyes of 4 patients with ARB were studied. Cross-sectional images of the fovea were recorded by the UHR-SD-OCT system with a depth resolution of <2.0 μm.

Results

The UHR-SD-OCT images revealed changes in the outer retinal structures that were dependent on the severity of the photoreceptor atrophy. There was an increase in the reflectivity and appearance of small hyperreflective dots (HRDs) in the outer segments, followed by an irregularity and decrease in the length of the outer segments, then a disruption of the ellipsoid zone (EZ) band, and appearance of large HRDs corresponding to the segmented ellipsoids. Finally, there was a disappearance of the large HRDs followed by a localized thinning of the outer nuclear layer and appearance of hyperreflective foci above the region of the disrupted EZ.

Conclusions

UHR-SD-OCT can record images that show detailed changes of the microstructures of the photoreceptors at different stages of ARB. These observations should help in determining the mechanisms involved in retinal pathology and should provide important information on the effectiveness of treatments.

Photoreceptor Function and Structure in Autosomal Dominant Vitelliform Macular Dystrophy Caused by BEST1 Mutations

Purpose

The purpose of this study was to evaluate rod and cone function and outer retinal structure within macular lesions, and surrounding extralesional areas of patients with autosomal dominant Best vitelliform macular dystrophy caused by BEST1 mutations.

Methods

Seventeen patients from seven families were examined with dark- and light-adapted chromatic perimetry and optical coherence tomography. Subsets of patients had long-term follow-up (14-22 years, n = 6) and dark-adaptation kinetics measured (n = 5).

Results

Within central lesions with large serous retinal detachments, rod sensitivity was severely reduced but visual acuity and cone sensitivity were relatively retained. In surrounding extralesional areas, there was a mild but detectable widening of the subretinal space in some patients and some retinal areas. Available evidence was consistent with subretinal widening causing slower dark-adaptation kinetics. Over long-term follow-up, some eyes showed formation of de novo satellite lesions at retinal locations that years previously demonstrated subretinal widening. A subclinical abnormality consisting of a retina-wide mild thickening of the outer nuclear layer was evident in many patients and thickening increased in the subset of patients with long-term follow-up.

Conclusions

Outcome measures for future clinical trials should include evaluations of rod sensitivity within central lesions and quantitative measures of outer retinal structure in normal-appearing regions surrounding the lesions.

Photoreceptor and Retinal Pigment Epithelium Relationships in Eyes With Vitelliform Macular Dystrophy Revealed by Multimodal Adaptive Optics Imaging

Purpose

To assess the structure of cone photoreceptors and retinal pigment epithelial (RPE) cells in vitelliform macular dystrophy (VMD) arising from various genetic etiologies.

Methods

Multimodal adaptive optics (AO) imaging was performed in 11 patients with VMD using a custom-assembled instrument. Non-confocal split detection and AO-enhanced indocyanine green were used to visualize the cone photoreceptor and RPE mosaics, respectively. Cone and RPE densities were measured and compared across BEST1-, PRPH2-, IMPG1-, and IMPG2-related VMD.

Results

Within macular lesions associated with VMD, both cone and RPE densities were reduced below normal, to 37% of normal cone density (eccentricity 0.2 mm) and to 8.4% of normal RPE density (eccentricity 0.5 mm). Outside of lesions, cone and RPE densities were slightly reduced (both to 92% of normal values), but with high degree of variability in the individual measurements. Comparison of juxtalesional cone and RPE measurements (<1 mm from the lesion edge) revealed significant differences in RPE density across the four genes (P < 0.05). Overall, cones were affected to a greater extent than RPE in patients with IMPG1 and IMPG2 pathogenic variants, but RPE was affected more than cones in BEST1 and PRPH2 VMD. This trend was observed even in contralateral eyes from a subset of five patients who presented with macular lesions in only one eye.

Conclusions

Assessment of cones and RPE in retinal locations outside of the macular lesions reveals a pattern of cone and RPE disruption that appears to be gene dependent in VMD. These findings provide insight into the cellular pathogenesis of disease in VMD.

Correlation of features on OCT with visual acuity and Gass lesion type in Best vitelliform macular dystrophy

OBJECTIVE

To correlate structural features seen on optical coherence tomography (OCT) with best-corrected visual acuity (BCVA) and Gass lesion type in patients with Best vitelliform macular dystrophy (BVMD).

METHODS AND ANALYSIS

This is a retrospective case series of consecutive patients with molecularly confirmed BEST1-associated BVMD. OCT scans were reviewed for lesion status and presence of subretinal pillar, focal choroidal excavation (FCE), intraretinal fluid or atrophy. Available OCT angiography images were used to evaluate for the presence of choroidal neovascularisation (CNV). These features were then correlated with BCVA and Gass lesion type.

RESULTS

95 eyes from 48 patients (mean age 38.9 years, range 4-87) were included. The presence of a pillar (24.2%), FCE (20.0%) and atrophy (7.4%) were associated with poor BCVA (p<0.05). Gass lesion type 1 eyes were correlated with good BCVA (LogMAR <0.4) whereas type 5 eyes had poor BCVA (LogMAR >0.4). Among 65 eyes with longitudinal data (mean follow-up 5.1 years), 7 eyes (10.8%) reverted from higher to lower Gass lesion type; of these, 4 eyes (57.1%) had CNV responsive to intravitreal anti-vascular endothelial growth factor treatment.

CONCLUSION

OCT-based structural features are readily identifiable in patients with BVMD and have prognostic importance due to their correlation with BCVA.

Best disease presenting as subretinal pigment epithelium hyperreflectivite lesion on spectral-domain optical coherence tomography: Multimodal imaging features

PURPOSE

To report clinical and multimodal imaging features of Best disease in patients presenting with subretinal pigment epithelium hyperreflective lesions.

DESIGN

Retrospective study.

METHODS

Clinical examination findings and multimodal imaging features, including color fundus photography, spectral-domain optical coherence tomography (SD-OCT), fundus autofluorescence, fluorescein and indocyanine green angiography (ICGA), and optical coherence tomography angiography (OCTA) images were evaluated retrospectively.

RESULTS

We assessed 27 eyes of 16 patients with the diagnosis of Best disease. Only patients presenting with serous macular detachment and subretinal pigment epithelium hyperreflective lesion in one or both eyes were included in this study. In 17 of 27 eyes (63%), fibrosis was identified by multimodal imaging techniques. Although there was no sign of active neovascularization on fundus examination or SD-OCT, a vascular network could be identified in 7 eyes (26%) (in 1 eye with OCTA only and in 6 eyes with both OCTA and ICGA). Active neovascularization was seen in 3 eyes (11%). Treatment was recommended for eyes with active neovascularization, and follow-up was scheduled for eyes with quiescent neovascularization and fibrosis.

CONCLUSION

Eyes with Best disease with subretinal pigment epithelium hyperreflective lesion and serous macular detachment may show fibrosis, quiescent neovascularization, or active neovascularization. Multimodal imaging techniques are very important for differentiation of these lesions.

Cellular Changes in Retinas From Patients With BEST1 Mutations

Best disease (BD), also known as vitelliform macular dystrophy, is an inherited disease of the central retina caused by more than 300 pathogenic variants in the BEST1 gene. The phenotype of BD is variable, and there are just a few reports on the histopathology of eyes from donors with BD. Here, we describe the histopathological comparison of donor’s eyes from two patients with BD. Eyes obtained from 85-year-old (donor 1) and 65-year-old (donor 2) donors were fixed within 25 h postmortem. Perifoveal and peripheral retinal regions were processed for histology and immunocytochemistry using retinal-specific and retinal pigment epithelium (RPE)-specific antibodies. Three age-matched normal eyes were used as controls. DNA was obtained from donor blood samples. Sequence analysis of the entire BEST1 coding region was performed and identified a c.886A > C (p.Asn296His) variant in donor 1 and a c.602T > C (p.Ile201Thr) variant in donor 2; both mutations were heterozygous. Fundus examination showed that donor 1 displayed a macular lesion with considerable scarring while donor 2 displayed close to normal macular morphology. Our studies of histology and molecular pathology in the perifovea and periphery of these two BD donor eyes revealed panretinal abnormalities in both photoreceptors and RPE cellular levels in the periphery; donor 1 also displayed macular lesion. Our findings confirm the phenotypic variability of BD associated with BEST1 variants.

Altered ellipsoid zone reflectivity and deep capillary plexus rarefaction correlate with progression in Best disease

AIMS

To evaluate the effects of neurovascular damage in patients with the typical vitelliform lesion of Best vitelliform macular dystrophy (BVMD) in the attempt to identify different progression patterns.

METHODS

Prospective, observational case series. Patients in the vitelliform stage of BVMD and healthy controls underwent complete ophthalmological examination on a yearly basis, including best-corrected visual acuity (BCVA), biomicroscopy, optical coherence tomography (OCT) and OCT angiography (OCT-A). 4.5×4.5 mm OCT-A slabs were imported into ImageJ software and their vessel density (VD) was calculated. Similarly, the ellipsoid zone (EZ) was manually outlined and the reflectivity was measured above the vitelliform lesion and in the 500 µm external to it. Retinal pigment epithelium-Bruch's membrane complex was taken as internal reference.

RESULTS

34 eyes (24 patients) and 34 matched controls were included in the study. Mean follow-up was of 28.4±5.8 months, with 12 eyes showing signs of stage progression at the end follow-up. The EZ overlying the vitelliform lesion and in the peri-lesional area disclosed a significant reduction in reflectivity when compared with the foveal and para-foveal EZ of controls, respectively. VD resulted meaningfully decreased only at the deep capillary plexus. Of notice, more extensive EZ (reflectivity <0.7) and vascular alterations (VD <0.4) at baseline strongly correlated with worse BCVA and were associated with a more rapid progression at follow-up.

CONCLUSIONS

Both EZ reflectivity and VD at deep capillary plexus may prove valuable biomarkers to assess BVMD severity and detect progression. In this view, 'rapid progressors' might benefit the most from timely genetic therapies in the future.

In vivo electroretinographic differentiation of rod, short-wavelength and long/medium-wavelength cone responses in dogs using silent substitution stimuli

The canine species has dichromatic color vision comprising short-wavelength (S-) and long/medium (L/M-) wavelength-sensitive cones with peak spectral sensitivity of 429-435 nm and 555 nm respectively. Although differentiation of rod- and cone-mediated responses by electroretinogram (ERG) in dogs is commonly performed, and standards have been developed based on standards for human observers, methods to differentiate S- and L/M-cone responses in dogs have not been described. We developed flicker protocols derived from previously published rod and cone spectral sensitivities. We used a double silent substitution paradigm to isolate responses from each of the 3 photoreceptor subclasses. ERG responses were measured to sine-wave modulation of photoreceptor excitation at different temporal frequencies (between 4 and 56 Hz) and mean luminance (between 3.25 and 130 cd/m²) on 6 different normal dogs (3 adult female, and 3 adult male beagles) and one female beagle dog with suspected hereditary congenital stationary night blindness (CSNB). Peak rod driven response amplitudes were achieved with low frequency (4 Hz, maximal range 4-12 Hz) and low mean luminance (3.25 cd/m²). In contrast, peak L/M-cone driven response amplitudes were achieved with high frequency (32 Hz, maximal range 28-44 Hz) and high mean luminance (32.5-130 cd/m²). Maximal S-cone driven responses were obtained with low frequency stimuli (4 Hz, maximal range 4-12 Hz) and 32.5-130 cd/m² mean luminance. The dog with CSNB had reduced rod- and S-cone-driven responses, but normal/supernormal L/M cone-driven responses. We have developed methods to differentiate rod, S- and L/M-cone function in dogs using silent substitution methods. The influence of temporal frequency and mean luminance on the ERGs originating in each photoreceptor type can now be studied independently. Dogs and humans have similar L/M cone responses, whereas mice have significantly different L/M responses. This work will facilitate a greater understanding of canine retinal electrophysiology and will complement the study of canine models of human hereditary photoreceptor disorders.

Chromatic pupilloperimetry for objective diagnosis of Best vitelliform macular dystrophy

Purpose

To determine the pupil response of Best vitelliform macular dystrophy (BVMD) patients for focal blue and red light stimuli presented at 76 test points in a 16.2° visual field (VF) using a chromatic pupilloperimeter.

Methods

An observational study was conducted in 16 participants: 7 BVMD patients with a heterozygous BEST1 mutation and 9 similar-aged controls. All participants were tested for best-corrected visual acuity, chromatic pupilloperimetry and Humphrey perimetry. Percentage of pupil contraction (PPC), maximal pupil contraction velocity (MCV) and latency of MCV (LMCV) were determined.

Results

The mean PPC and MCV recorded in BVMD patients in response to red stimuli were lower by >2 standard errors (SEs) from the mean of controls in 47% and 43% of VF test points, respectively. The mean PPC and MCV recorded in the patients in response to blue stimuli were lower by >2 SEs from the mean of controls in 36% and 24% of VF test points, respectively. The patients’ mean and median MCV recorded in response to red light correlated with their Humphrey mean deviation score (r=−0.714, P=0.071 and r=−0.821, P=0.023, respectively) and visual acuity (r=0.709, P=0.074 and r=0.655, P=0.111, respectively). A substantially shorter mean LMCV was recorded in BVMD patients compared to controls in 54% and 93% of VF test points in response to red and blue light, respectively. Receiver operating characteristic analysis for LMCV in response to red light identified a test point at the center of the VF with high diagnostic accuracy (area under the curve of 0.94).

Conclusion

Chromatic pupilloperimetry may potentially be used for objective noninvasive assessment of rod and cone cell function in different locations of the retina in BVMD patients.

Atypical presentation of Best Disease

CLINICAL CASE

A 43-year-old man was treated for reduced visual acuity, initially attributed to strabismic amblyopia. On fundus examination, bilateral neurosensory detachments (NSD) were observed in posterior pole, surrounded by deposits of lipofuscin. His 3-year-old son was also examined and circumscribed NSD was observed with the presence of pseudohypopyon in OD and a fibrosis scar in OS. The Arden ratio were decreased in electrooculography (EOG) in both patients, and genetic studies revealed a single mutation of the BEST1 gene.

DISCUSSION

The existence of extensive bilateral NSD may be an unusual form of presentation of Best disease. Family history, EOG, and genetic study supported this diagnosis.

SPECTRAL DOMAIN OPTICAL COHERENCE TOMOGRAPHY FEATURES IN DIFFERENT STAGES OF BEST VITELLIFORM MACULAR DYSTROPHY

PURPOSE

To provide a systematic classification of findings regarding the different stages of vitelliform macular dystrophy on spectral domain optical coherence tomography (SD-OCT).

METHODS

Ninety-four eyes of 47 patients were recruited in a prospective cross-sectional study. All patients underwent a complete ophthalmologic examination, including best-corrected visual acuity using Early Treatment Diabetic Retinopathy Study (ETDRS) charts, biomicroscopy, and SD-OCT. The findings assessed included vitelliform material, neurosensory detachment, status of external limiting membrane, ellipsoid zone and retinal pigment epithelium, choroidal excavation, foveal cavitation, choroidal neovascularization, vitreomacular traction, and macular hole. The primary outcome measure was the identification of SD-OCT findings in each vitelliform macular dystrophy stage. Secondary outcomes included the correlations between SD-OCT features and visual acuity changes.

RESULTS

The outer retinal layers (external limiting membrane, ellipsoid zone, and retinal pigment epithelium) were found to be more commonly disrupted in Stages 2 to 4 (range: 86%-100%), whereas their absence was more typical of Stage 5 (71%-86%). Vitelliform material was found in 100% of Stages 2 and 3, 93% of Stage 4, and interestingly in 43% of Stage 5. Eyes characterized by vitelliform material showed a greater correlation with higher best-corrected visual acuity than eyes without it (0.35 logarithm of the minimum angle of resolution vs. 0.80 ± 0.36 logarithm of the minimum angle of resolution, approximately 20/45 and 20/125 Snellen equivalent, respectively) (t = 3.726, P < 0.05). Moreover, its absence was associated with a best-corrected visual acuity of 0.5 logarithm of the minimum angle of resolution or worse (approximately 20/63 Snellen equivalent; P < 0.05). Subretinal fluid was more common in Stages 3 and 4 (72.7% and 75%, respectively) than Stages 2 and 5 (P = 0.004). Eyes with subretinal fluid were significantly associated with a visual acuity of 0.2 logarithm of the minimum angle of resolution or worse (approximately 20/32 Snellen equivalent; P = 0.04).

CONCLUSION

Spectral domain optical coherence tomography assessment primarily indicates an outer retinal layer disruption in Stages 2 to 4, along with the presence of vitelliform material extending into the more advanced clinical stages too. Eyes characterized by the persistence of vitelliform material show better best-corrected visual acuity. Future investigations based on a longitudinal follow-up are warranted to correlate SD-OCT modifications with functional responses to identify SD-OCT indicators for prognostic and therapeutic purposes.

BEST1 gene therapy corrects a diffuse retina-wide microdetachment modulated by light exposure

One of the most common forms of monogenic macular degeneration worldwide is caused by dominant or recessive bestrophinopathies associated with mutations in the BEST1 gene. Disease expression is known to start with a retina-wide electrophysiological defect leading to localized vitelliform and atrophic lesions and vision loss. To develop lasting therapies for this incurable disease, there is a need for greater understanding of the early pathophysiology before lesion formation. Here we find that the loss of retinal pigment epithelium apical microvilli and resulting microdetachment of the retina represent the earliest features of canine bestrophinopathies. We show that retinal light exposure expands, and dark adaptation contracts, the microdetachments. Subretinal adeno-associated virus-based gene therapy corrects both the vitelliform lesions and the light-modulated microdetachments.

Mutations in the BEST1 gene cause detachment of the retina and degeneration of photoreceptor (PR) cells due to a primary channelopathy in the neighboring retinal pigment epithelium (RPE) cells. The pathophysiology of the interaction between RPE and PR cells preceding the formation of retinal detachment remains not well-understood. Our studies of molecular pathology in the canine BEST1 disease model revealed retina-wide abnormalities at the RPE-PR interface associated with defects in the RPE microvillar ensheathment and a cone PR-associated insoluble interphotoreceptor matrix. In vivo imaging demonstrated a retina-wide RPE–PR microdetachment, which contracted with dark adaptation and expanded upon exposure to a moderate intensity of light. Subretinal BEST1 gene augmentation therapy using adeno-associated virus 2 reversed not only clinically detectable subretinal lesions but also the diffuse microdetachments. Immunohistochemical analyses showed correction of the structural alterations at the RPE–PR interface in areas with BEST1 transgene expression. Successful treatment effects were demonstrated in three different canine BEST1 genotypes with vector titers in the 0.1-to-5E11 vector genomes per mL range. Patients with biallelic BEST1 mutations exhibited large regions of retinal lamination defects, severe PR sensitivity loss, and slowing of the retinoid cycle. Human translation of canine BEST1 gene therapy success in reversal of macro- and microdetachments through restoration of cytoarchitecture at the RPE–PR interface has promise to result in improved visual function and prevent disease progression in patients affected with bestrophinopathies.

Underdeveloped RPE Apical Domain Underlies Lesion Formation in Canine Bestrophinopathies

Canine bestrophinopathy (cBest) is an important translational model for BEST1-associated maculopathies in man that recapitulates the broad spectrum of clinical and molecular disease aspects observed in patients. Both human and canine bestrophinopathies are characterized by focal to multifocal separations of the retina from the RPE. The lesions can be macular or extramacular, and the specific pathomechanism leading to formation of these lesions remains unclear. We used the naturally occurring canine BEST1 model to examine factors that underlie formation of vitelliform lesions and addressed the susceptibility of the macula to its primary detachment in BEST1-linked maculopathies.

PHOTORECEPTOR INNER SEGMENT MORPHOLOGY IN BEST VITELLIFORM MACULAR DYSTROPHY

Supplemental Digital Content is Available in the Text.

Outer retinal cellular structure in best vitelliform macular dystrophy was assessed using novel adaptive optics retinal imaging, revealing that photoreceptor morphology is highly variable depending on the stage of disease. Photoreceptor structure is still present even at advanced stages of disease, and longitudinal assessment shows that the photoreceptor mosaic is not static.

Purpose:

To characterize outer retina structure in best vitelliform macular dystrophy (BVMD) and to determine the effect of macular lesions on overlying and adjacent photoreceptors.

Methods:

Five individuals with BVMD were followed prospectively with spectral domain optical coherence tomography and confocal and nonconfocal split-detector adaptive optics scanning light ophthalmoscopy (AOSLO). The AOSLO cone photoreceptor mosaic images were obtained within and around retinal lesions. Cone density was measured inside and outside lesions. In 2 subjects, densities were compared with published measurements acquired ∼2.5 years before. One subject was imaged 3 times over a 5-month period.

Results:

The AOSLO imaging demonstrated that photoreceptor morphology within BVMD retinal lesions was highly variable depending on the disease stage, with photoreceptor structure present even in advanced disease. The AOSLO imaging was repeatable even in severe disease over short-time and long-time intervals. Photoreceptor density was normal in retinal areas immediately adjacent to lesions and stable over ∼2.5 years. Mobile disk-like structures possibly representing subretinal macrophages were also observed.

Conclusion:

Combined confocal and nonconfocal split-detector AOSLO imaging reveals substantial variability within clinical lesions in all stages of BVMD. Longitudinal cellular photoreceptor imaging could prove a powerful tool for understanding disease progression and monitoring emerging therapeutic treatment response in inherited degenerations such as BVMD.

Bestrophinopathy: An RPE-photoreceptor interface disease

Bestrophinopathies, one of the most common forms of inherited macular degenerations, are caused by mutations in the BEST1 gene expressed in the retinal pigment epithelium (RPE). Both human and canine BEST1-linked maculopathies are characterized by abnormal accumulation of autofluorescent material within RPE cells and bilateral macular or multifocal lesions; however, the specific mechanism leading to the formation of these lesions remains unclear. We now provide an overview of the current state of knowledge on the molecular pathology of bestrophinopathies, and explore factors promoting formation of RPE-neuroretinal separations, using the first spontaneous animal model of BEST1-associated retinopathies, canine Best (cBest). Here, we characterize the nature of the autofluorescent RPE cell inclusions and report matching spectral signatures of RPE-associated fluorophores between human and canine retinae, indicating an analogous composition of endogenous RPE deposits in Best Vitelliform Macular Dystrophy (BVMD) patients and its canine disease model. This study also exposes a range of biochemical and structural abnormalities at the RPE-photoreceptor interface related to the impaired cone-associated microvillar ensheathment and compromised insoluble interphotoreceptor matrix (IPM), the major pathological culprits responsible for weakening of the RPE-neuroretina interactions, and consequently, formation of vitelliform lesions. These salient alterations detected at the RPE apical domain in cBest as well as in BVMD- and ARB-hiPSC-RPE model systems provide novel insights into the pathological mechanism of BEST1-linked disorders that will allow for development of critical outcome measures guiding therapeutic strategies for bestrophinopathies.

Optical coherence tomography in Best vitelliform macular dystrophy

PURPOSE

To analyze spectral-domain optical coherence tomography (SD-OCT)-specific findings in the different stages of vitelliform macular dystrophy (VMD).

METHODS

Thirty-seven patients were prospectively recruited. All the patients underwent a complete ophthalmologic examination, including best-corrected visual acuity (BCVA), biomicroscopy, and SD-OCT. The examined findings were vitelliform material, neurosensory detachment, intraretinal hyperreflective foci, and the status of external limiting membrane, ellipsoid zone, and retinal pigment epithelium. The primary outcome was the stratification of SD-OCT findings in each VMD stage. Secondary outcomes included the description of different characteristics related to intraretinal hyperreflective foci.

RESULTS

Outer retinal layers were preserved almost exclusively in stage 1 (range 70%-100%), whereas their disruption and absence were typical of stages 2 to 4 (83%-100%) and stage 5 (67%-83%), respectively. Vitelliform material was found always in stages 2 and 3, 89% of stage 4, and rarely in stage 5 (33%). Neurosensory detachment was to some extent representative of stages 3 and 4 (80% and 72%, respectively) when compared with the other stages (p<0.001). Hyperreflective foci (16% of all eyes) demonstrated a progressive increase across stages 2 to 4, with slightly reduced figure in stage 5. These foci were located in the outer nuclear and plexiform layers, showed different sizes, and were not associated with a visual acuity reduction (p = 0.64).

CONCLUSIONS

A progressive deterioration of the outer retinal layers was noticeable in more advanced stages of VMD. The reduction of vitelliform material from stage 3 to 4 was paralleled by an increased evidence of neurosensory detachment. Although showing different size and location, hyperreflective foci did not correlate with worse BCVA.

Fundus autofluorescence applications in retinal imaging

Fundus autofluorescence (FAF) is a relatively new imaging technique that can be used to study retinal diseases. It provides information on retinal metabolism and health. Several different pathologies can be detected. Peculiar AF alterations can help the clinician to monitor disease progression and to better understand its pathogenesis. In the present article, we review FAF principles and clinical applications.

Clinical and genetic heterogeneity in Slovenian patients with BEST disease

PURPOSE

To determine the spectrum of BEST1 mutations and to study the phenotype in Slovenian families with Best vitelliform macular dystrophy (BVMD) to identify genotype-phenotype correlations.

METHODS

Twenty patients from five families underwent the ophthalmological examination including electrooculogram (EOG; N = 17), fundus autofluorescence imaging (N = 16) and optical coherence tomography (N = 14). Mutational screening was performed by direct DNA sequencing of the BEST1 gene.

RESULTS

Mutation c.43G>C (p.Gly15Arg) was detected in three patients from family M presenting with different clinical stages of Best disease. Mutation c.313G>C (p.Arg105Gly) was found in families K, ST, S, B and was associated with incomplete clinical penetrance and variable retinal changes, including extramacular and multifocal lesions. In three patients from family K, an atypical form of BVMD was observed; there were additional peripheral lesions outside of the vascular arcades in addition to the typical macular lesions. Multiple alterations between the vitelliruptive and pseudohypopyon stages over a period of 11 years were seen in one patient.

CONCLUSION

Two previously unreported disease-associated variants in the BEST1 gene (p.Gly15Arg and p.Arg105Gly) were found in Slovenian patients with Best disease. Our data expand the mutation spectrum of the BEST1 gene and further support the broad phenotypic variability observed clinically and with optical coherence tomography (OCT) and AF imaging.

Differential cytotoxic effects of 7-dehydrocholesterol-derived oxysterols on cultured retina-derived cells: Dependence on sterol structure, cell type, and density

Tissue accumulation of 7-dehydrocholesterol (7DHC) is a hallmark of Smith-Lemli-Opitz Syndrome (SLOS), a human inborn error of the cholesterol (CHOL) synthesis pathway. Retinal 7DHC-derived oxysterol formation occurs in the AY9944-induced rat model of SLOS, which exhibits a retinal degeneration characterized by selective loss of photoreceptors and associated functional deficits, Müller cell hypertrophy, and engorgement of the retinal pigment epithelium (RPE) with phagocytic inclusions. We evaluated the relative effects of four 7DHC-derived oxysterols on three retina-derived cell types in culture, with respect to changes in cellular morphology and viability. 661W (photoreceptor-derived) cells, rMC-1 (Müller glia-derived) cells, and normal diploid monkey RPE (mRPE) cells were incubated for 24 h with dose ranges of either 7-ketocholesterol (7kCHOL), 5,9-endoperoxy-cholest-7-en-3β,6α-diol (EPCD), 3β,5α-dihydroxycholest-7-en-6-one (DHCEO), or 4β-hydroxy-7-dehydrocholesterol (4HDHC); CHOL served as a negative control (same dose range), along with appropriate vehicle controls, while staurosporine (Stsp) was used as a positive cytotoxic control. For 661W cells, the rank order of oxysterol potency was: EPCD > 7kCHOL >> DHCEO > 4HDHC ≈ CHOL. EC50 values were higher for confluent vs. subconfluent cultures. 661W cells exhibited much higher sensitivity to EPCD and 7kCHOL than either rMC-1 or mRPE cells, with the latter being the most robust when challenged, either at confluence or in sub-confluent cultures. When tested on rMC-1 and mRPE cells, EPCD was again an order of magnitude more potent than 7kCHOL in compromising cellular viability. Hence, 7DHC-derived oxysterols elicit differential cytotoxicity that is dose-, cell type-, and cell density-dependent. These results are consistent with the observed progressive, photoreceptor-specific retinal degeneration in the rat SLOS model, and support the hypothesis that 7DHC-derived oxysterols are causally linked to that retinal degeneration as well as to SLOS.

Automated Segmentability Index for Layer Segmentation of Macular SD-OCT Images

PURPOSE

To automatically identify which spectral-domain optical coherence tomography (SD-OCT) scans will provide reliable automated layer segmentations for more accurate layer thickness analyses in population studies.

METHODS

Six hundred ninety macular SD-OCT image volumes (6.0 × 6.0 × 2.3 mm3) were obtained from one eyes of 690 subjects (74.6 ± 9.7 [mean ± SD] years, 37.8% of males) randomly selected from the population-based Rotterdam Study. The dataset consisted of 420 OCT volumes with successful automated retinal nerve fiber layer (RNFL) segmentations obtained from our previously reported graph-based segmentation method and 270 volumes with failed segmentations. To evaluate the reliability of the layer segmentations, we have developed a new metric, segmentability index SI, which is obtained from a random forest regressor based on 12 features using OCT voxel intensities, edge-based costs, and on-surface costs. The SI was compared with well-known quality indices, quality index (QI), and maximum tissue contrast index (mTCI), using receiver operating characteristic (ROC) analysis.

RESULTS

The 95% confidence interval (CI) and the area under the curve (AUC) for the QI are 0.621 to 0.805 with AUC 0.713, for the mTCI 0.673 to 0.838 with AUC 0.756, and for the SI 0.784 to 0.920 with AUC 0.852. The SI AUC is significantly larger than either the QI or mTCI AUC (P < 0.01).

CONCLUSIONS

The segmentability index SI is well suited to identify SD-OCT scans for which successful automated intraretinal layer segmentations can be expected.

TRANSLATIONAL RELEVANCE

Interpreting the quantification of SD-OCT images requires the underlying segmentation to be reliable, but standard SD-OCT quality metrics do not predict which segmentations are reliable and which are not. The segmentability index SI presented in this study does allow reliable segmentations to be identified, which is important for more accurate layer thickness analyses in research and population studies.

Autosomal Recessive Bestrophinopathy Is Not Associated With the Loss of Bestrophin-1 Anion Channel Function in a Patient With a Novel BEST1 Mutation

PURPOSE

Mutations in BEST1, encoding bestrophin-1 (Best1), cause autosomal recessive bestrophinopathy (ARB). Encoding bestrophin-1 is a pentameric anion channel localized to the basolateral plasma membrane of the RPE. Here, we characterize the effects of the mutations R141H (CGC > CAC) and I366fsX18 (c.1098_1100+7del), identified in a patient in our practice, on Best1 trafficking, oligomerization, and channel activity.

METHODS

Currents of Cl- were assessed in transfected HEK293 cells using whole-cell patch clamp. Best1 localization was assessed by confocal microscopy in differentiated, human-induced pluripotent stem cell-derived RPE (iPSC-RPE) cells following expression of mutants via adenovirus-mediated gene transfer. Oligomerization was evaluated by coimmunoprecipitation in iPSC-RPE and MDCK cells.

RESULTS

Compared to Best1, Best1 I366fsX18 currents were increased while Best1 R141H Cl- currents were diminished. Coexpression of Best1 R141H with Best1 or Best1 I366fsX18 resulted in rescued channel activity. Overexpressed Best1, Best1 R141H, and Best1 I366fsX18 were all properly localized in iPSC-RPE cells; Best1 R141H and Best1 I366fsX18 coimmunoprecipitated with endogenous Best1 in iPSC-RPE cells and with each other in MDCK cells.

CONCLUSIONS

The first 366 amino acids of Best1 are sufficient to mediate channel activity and homo-oligomerization. The combination of Best1 and Best1 R141H does not cause disease, while Best1 R141H together with Best1 I366fsX18 causes ARB. Since both combinations generate comparable Cl- currents, this indicates that ARB in this patient is not caused by a loss of channel activity. Moreover, Best1 I366fsX18 differs from Best1 in that it lacks most of the cytosolic C-terminal domain, suggesting that the loss of this region contributes significantly to the pathogenesis of ARB in this patient.

Using Stem Cells to Model Diseases of the Outer Retina

Retinal degeneration arises from the loss of photoreceptors or retinal pigment epithelium (RPE). It is one of the leading causes of irreversible blindness worldwide with limited effective treatment options. Generation of induced pluripotent stem cell (IPSC)-derived retinal cells and tissues from individuals with retinal degeneration is a rapidly evolving technology that holds a great potential for its use in disease modelling. IPSCs provide an ideal platform to investigate normal and pathological retinogenesis, but also deliver a valuable source of retinal cell types for drug screening and cell therapy. In this review, we will provide some examples of the ways in which IPSCs have been used to model diseases of the outer retina including retinitis pigmentosa (RP), Usher syndrome (USH), Leber congenital amaurosis (LCA), gyrate atrophy (GA), juvenile neuronal ceroid lipofuscinosis (NCL), Best vitelliform macular dystrophy (BVMD) and age related macular degeneration (AMD).

Complement activation and choriocapillaris loss in early AMD: implications for pathophysiology and therapy

Age-related macular degeneration (AMD) is a common and devastating disease that can result in severe visual dysfunction. Over the last decade, great progress has been made in identifying genetic variants that contribute to AMD, many of which lie in genes involved in the complement cascade. In this review we discuss the significance of complement activation in AMD, particularly with respect to the formation of the membrane attack complex in the aging choriocapillaris. We review the clinical, histological and biochemical data that indicate that vascular loss in the choroid occurs very early in the pathogenesis of AMD, and discuss the potential impact of vascular dropout on the retinal pigment epithelium, Bruch's membrane and the photoreceptor cells. Finally, we present a hypothesis for the pathogenesis of early AMD and consider the implications of this model on the development of new therapies.

Near-infrared fundus autofluorescence in subclinical best vitelliform macular dystrophy

PURPOSE

To describe fundus autofluorescence (FAF) on short-wavelength FAF and near-infrared FAF in the subclinical form of Best vitelliform macular dystrophy.

DESIGN

Cross-sectional prospective study.

METHODS

Patients affected by the subclinical form of Best vitelliform macular dystrophy (positive testing for BEST1 gene mutation, fully preserved best-corrected visual acuity, normal fundus appearance) were recruited. Each patient underwent a complete ophthalmologic examination, including electro-oculogram (EOG), short-wavelength FAF, near-infrared FAF, spectral-domain OCT (SD OCT), and microperimetry. Main outcome measure was the identification of abnormal FAF patterns.

RESULTS

Forty-six patients showing mutations in the BEST1 gene were examined. Forty patients presented a bilateral Best vitelliform macular dystrophy, 2 patients showed a unilateral Best vitelliform macular dystrophy, and 4 patients had a bilateral subclinical form. Patients with the unilateral form (2 eyes) and patients with the subclinical form (8 eyes) were analyzed. Three BEST1 sequence variants were identified: c.73C>T (p.Arg25Trp), c.28G>A (p.Ala10Thr), and c.652C>G (p.Arg218Gly). Short-wavelength FAF was normal in all eyes. Near-infrared FAF detected a pattern consisting of a central hypo-autofluorescence surrounded by a round area of hyper-autofluorescence. A bilateral reduced EOG response was detected in 1 patient. SD OCT revealed a thicker, well-defined, and more reflective interdigitation zone in 2 patients (4 eyes, 40%). Microperimetry of the central 10 degrees revealed a slight, diffuse reduction of retinal sensitivity. Mean retinal sensitivity within the central 2 and 4 degrees was lower and matched the hypo-autofluorescent area detected on near-infrared FAF. Additional relative scotomata were detected within the 10-degree area. No change in clinical, functional, or FAF pattern was found over the follow-up.

CONCLUSIONS

Subclinical Best vitelliform macular dystrophy is characterized by the absence of biomicroscopic fundus abnormality and fully preserved visual acuity, but shows an abnormal near-infrared FAF pattern, with central hypo-autofluorescence.

Patient-specific induced pluripotent stem cells (iPSCs) for the study and treatment of retinal degenerative diseases

Vision is the sense that we use to navigate the world around us. Thus it is not surprising that blindness is one of people's most feared maladies. Heritable diseases of the retina, such as age-related macular degeneration and retinitis pigmentosa, are the leading cause of blindness in the developed world, collectively affecting as many as one-third of all people over the age of 75, to some degree. For decades, scientists have dreamed of preventing vision loss or of restoring the vision of patients affected with retinal degeneration through drug therapy, gene augmentation or a cell-based transplantation approach. In this review we will discuss the use of the induced pluripotent stem cell technology to model and develop various treatment modalities for the treatment of inherited retinal degenerative disease. We will focus on the use of iPSCs for interrogation of disease pathophysiology, analysis of drug and gene therapeutics and as a source of autologous cells for cell transplantation and replacement.

Fundus autofluorescence patterns in Best vitelliform macular dystrophy

PURPOSE

To provide a systematic classification of fundus autofluorescence (FAF) patterns in patients affected by Best vitelliform macular dystrophy.

DESIGN

Cross-sectional prospective study.

METHODS

Patients affected by Best vitelliform macular dystrophy at different stages of the disease were prospectively enrolled from January 2012 to July 2013. Eighty eyes of 40 patients were included in the study. All patients underwent a complete ophthalmologic examination, including genetic characterization, short-wavelength FAF, and near-infrared FAF. Main outcome measures were the recognition of the FAF patterns in the different stages and the identification of a relationship between FAF patterns and best-corrected visual acuity (BCVA).

RESULTS

Six FAF patterns for both short-wavelength and near-infrared FAF were identified, including normal, hyper-autofluorescent, hypo-autofluorescent, patchy, multifocal, and spoke-like patterns. Applying Gass's classification for defining consecutive stages of Best vitelliform macular dystrophy (namely vitelliform, pseudohypopyon, vitelliruptive, atrophic, and cicatricial) identified no pattern as stage-specific. Patchy patterns had the highest prevalence. A statistically significant difference (Kruskal-Wallis ANOVA) was found among hyper-autofluorescent, patchy, and hypo-autofluorescent patterns, both in short-wavelength (P = .001) and near-infrared FAF (P = .001). Hyper-autofluorescent and hypo-autofluorescent patterns were associated with better and worse BCVA, respectively.

CONCLUSIONS

Six main patterns on both short-wavelength and near-infrared FAF were identified in Best vitelliform macular dystrophy. No FAF pattern can be considered stage-specific. Although a difference in the BCVA among the FAF patterns was registered, only a longitudinal study designed to evaluate the clinical and FAF modifications over the follow-up will help clarify the prognostic implications of each FAF pattern.

Multimodal analysis of the progression of Best vitelliform macular dystrophy

PURPOSE

To investigate the multimodal morphological features in the different stages of Best vitelliform macular dystrophy (VMD) in subjects harboring mutations in the BEST1 gene, and their changes during the progression of the disease.

METHODS

In this retrospective observational study performed between January 2007 and December 2012, 21 patients (42 eyes) with Best VMD from eight families with the BEST1 mutation were included. Best-corrected visual acuity (BCVA), fundus autofluorescence (FAF), and spectral domain optical coherence tomography (SDOCT) were evaluated at study entry and at last visit.

RESULTS

The mean age of patients was 26.3±17.4 years. Seven new missense mutations in BEST1 were identified. Mean follow-up was 41.1±18.5 months. Mean BCVA was 0.34±0.34 LogMAR at study entry and 0.32±0.33 LogMAR at last follow-up visit (p = 0.2). The overall lesion area on FAF increased from 6.62±4.9 mm² to 7.34±6.1 mm² (p = 0.05). At study entry, on SD-OCT, photoreceptor inner segment ellipsoid portion (ellipsoid zone, EZ) was normal in 15 eyes, disrupted in 14 eyes, and absent in 13 eyes. In two eyes, EZ changed from normal to disrupted during follow-up. Three eyes of three patients showing pseudohypopyon lesions at study entry progressed to vitelliruptive lesions at the last follow-up visit. Three eyes of three patients showing vitelliruptive lesion at study entry reverted to pseudohypopyon lesion with overall enlargement of the lesion size.

CONCLUSIONS

Multimodal analysis allowed documenting a continuous material accumulation and reabsorption in Best VMD progression. Blue FAF and SD-OCT could represent noninvasive imaging techniques to monitor Best VMD.

Quantitative fundus autofluorescence and optical coherence tomography in best vitelliform macular dystrophy

PURPOSE

Quantitative fundus autofluorescence (qAF), spectral domain optical coherence tomography (SD-OCT) segmentation, and multimodal imaging were performed to elucidate the pathogenesis of Best vitelliform macular dystrophy (BVMD) and to identify abnormalities in lesion versus nonlesion fundus areas.

METHODS

Sixteen patients with a clinical diagnosis of BVMD were studied. Autofluorescence images (30°, 488-nm excitation) were acquired with a confocal scanning laser ophthalmoscope equipped with an internal fluorescent reference to account for variable laser power and detector sensitivity. The grey levels (GLs) of each image were calibrated to the reference, zero GL, magnification, and normative optical media density, to yield qAF. Horizontal SD-OCT scans were obtained and retinal layers manually segmented. Additionally, color and near-infrared reflectance (NIR-R) images were registered to AF images. All patients were screened for mutations in BEST1. In three additional BVMD patients, in vivo spectrofluorometric measurements were obtained within the vitelliform lesion.

RESULTS

Mean nonlesion qAF was within normal limits for age. Maximum qAF within the lesion was markedly increased compared with controls. By SD-OCT segmentation, outer segment equivalent thickness was increased and outer nuclear layer thickness decreased in the lesion. Changes were also present in a transition zone beyond the lesion border. In subclinical patients, no abnormalities in retinal layer thickness were identified. Fluorescence spectra recorded from the vitelliform lesion were consistent with those of retinal pigment epithelial cell lipofuscin.

CONCLUSIONS

Based on qAF, mutations in BEST1 do not cause increased lipofuscin levels in nonlesion fundus areas.

Outer retinal structure in best vitelliform macular dystrophy

IMPORTANCE

Demonstrating the utility of adaptive optics scanning light ophthalmoscopy (AOSLO) to assess outer retinal structure in Best vitelliform macular dystrophy (BVMD).

OBJECTIVE

To characterize outer retinal structure in BVMD using spectral-domain optical coherence tomography (SD-OCT) and AOSLO.

DESIGN, SETTING, AND PARTICIPANTS

Prospective, observational case series. Four symptomatic members of a family with BVMD with known BEST1 mutation were recruited at the Advanced Ocular Imaging Program research lab at the Medical College of Wisconsin Eye Institute, Milwaukee.

INTERVENTION

Thickness of 2 outer retinal layers corresponding to photoreceptor inner and outer segments was measured using SD-OCT. Photoreceptor mosaic AOSLO images within and around visible lesions were obtained, and cone density was assessed in 2 subjects.

MAIN OUTCOME AND MEASURE

Photoreceptor structure.

RESULTS

Each subject was at a different stage of BVMD, with photoreceptor disruption evident by AOSLO at all stages. When comparing SD-OCT and AOSLO images from the same location, AOSLO images allowed for direct assessment of photoreceptor structure. A variable degree of retained photoreceptors was seen within all lesions. The photoreceptor mosaic immediately adjacent to visible lesions appeared contiguous and was of normal density. Fine hyperreflective structures were visualized by AOSLO, and their anatomical orientation and size were consistent with Henle fibers.

CONCLUSIONS

AND RELEVANCE: The AOSLO findings indicate that substantial photoreceptor structure persists within active lesions, accounting for good visual acuity in these patients. Despite previous reports of diffuse photoreceptor outer segment abnormalities in BVMD, our data reveal normal photoreceptor structure in areas adjacent to clinical lesions. This study demonstrates the utility of AOSLO for understanding the spectrum of cellular changes that occur in inherited degenerations such as BVMD. Photoreceptors are often significantly affected at various stages of inherited degenerations, and these changes may not be readily apparent with current clinical imaging instrumentation.

Human photoreceptor outer segments shorten during light adaptation

PURPOSE

Best disease is a macular dystrophy caused by mutations in the BEST1 gene. Affected individuals exhibit a reduced electro-oculographic (EOG) response to changes in light exposure and have significantly longer outer segments (OS) than age-matched controls. The purpose of this study was to investigate the anatomical changes in the outer retina during dark and light adaptation in unaffected and Best disease subjects, and to compare these changes to the EOG.

METHODS

Unaffected (n = 11) and Best disease patients (n = 7) were imaged at approximately 4-minute intervals during an approximately 40-minute dark-light cycle using spectral domain optical coherence tomography (SD-OCT). EOGs of two subjects were obtained under the same conditions. Automated three-dimensional (3-D) segmentation allowed measurement of light-related changes in the distances between five retinal surfaces.

RESULTS

In normal subjects, there was a significant decrease in outer segment equivalent length (OSEL) of -2.14 μm (95% confidence interval [CI], -1.77 to -2.51 μm) 10 to 20 minutes after the start of light adaptation, while Best disease subjects exhibited a significant increase in OSEL of 2.07 μm (95% CI, 1.79-2.36 μm). The time course of the change in OS length corresponded to that of the EOG waveform.

CONCLUSIONS

Our results strongly suggest that the light peak phase of the EOG is temporally related to a decreased OSEL in normal subjects, and the lack of a light peak phase in Best disease subjects is associated with an increase in OSEL. One potential role of Bestrophin-1 is to trigger an increase in the standing potential that approximates the OS to the apical surface of the RPE to facilitate phagocytosis.

Optical coherence tomography for multifocal vitelliform macular dystrophy

PURPOSE

To describe the optical coherence tomography (OCT) features of multifocal vitelliform macular dystrophy (VMD).

METHODS

Five patients (10 eyes) with multifocal VMD were examined by slit lamp biomicroscopy, fundus photography, and OCT.

RESULTS

Serous retinal detachment was present in the macular area in all eyes. A hyperreflective inner/outer segment interface was observed in the macula in nine of them. High reflectivity was homogeneous in six eyes of three patients with no prominent macular lesion. Retinoschisis-like changes could be clearly seen in four eyes evaluated by high-resolution OCT. A hyporeflectivity corresponded to the inner nuclear layer in two eyes. In four eyes with prominent macular lesions, a hyperreflective area between the hyporeflective outer nuclear layer and the hyperreflective retinal pigment epithelium layer was detectable.

CONCLUSIONS

Although the fundus appearance of multifocal VMD is quite variable, OCT features of the disease are relatively uniform. Optical coherence tomography could help the pathological interpretation and facilitate the diagnosis of VMD.