Natural course of the vitelliform stage in best vitelliform macular dystrophy: a five-year follow-up study

Associations Between Contrast Sensitivity, Optical Coherence Tomography Features and Progression From Intermediate to Late Age-related Macular Degeneration

PURPOSE

Establishing associations between structure, function, and clinical outcomes in intermediate age-related macular degeneration (iAMD) remains an unmet need. This study aims to (1) cross-sectionally investigate the relationships between optical coherence tomography (OCT) biomarkers and quantitative contrast sensitivity function (qCSF)-measured contrast sensitivity (CS), and (2) longitudinally assess their relationship with progression from iAMD to late stages of the disease.

DESIGN

Cross-sectional and cohort study.

METHODS

Our study was conducted at Massachusetts Eye and Ear (Boston, MA, USA) and included eyes with (1) baseline diagnosis of iAMD, (2) same-day OCT and qCSF test, (3) visual acuity ≥20/200 Snellen, and (4) 24+ months of follow-up. qCSF metrics included the area under the logCSF curve, contrast acuity, and CS thresholds at 1- to 18-cycle-per-degree (cpd). Two independent graders reviewed macular OCT scans for various biomarkers, and outer nuclear layer (ONL) thickness and retinal pigment epithelium (RPE) volume were measured. Progression to wet AMD or geographic atrophy (GA) was confirmed using imaging studies. Generalized linear mixed-effects models assessed associations between qCSF and OCT biomarkers, while Cox regression models evaluated their association with progression to late AMD.

RESULTS

We included 205 iAMD eyes from 134 patients (age: 73 [69-78] years; 63% female). Higher RPE volume in the central subfield and a greater number of intraretinal hyperreflective foci were associated with reduced area under the logCSF curve, contrast acuity, and CS at 6 to 12 cpd (P < .05). ONL thinning in the inner ring and a greater number of intraretinal hyperreflective foci were associated with reduced CS at 1 and 3 cpd (P < .05). During follow-up, 35 eyes developed wet AMD (17%) and 53 progressed to GA (26%). subretinal drusenoid deposit, ONL thinning in the inner ring, and reduced CS at 1.5 cpd were associated with wet AMD (P < .05). Higher RPE volume in the inner ring, hyporeflective drusen cores, subretinal drusenoid deposit, higher HRF count, and reduced CS at 1 cpd were associated with GA (P < .05).

CONCLUSIONS

Our study reveals significant structure-function relationships between OCT biomarkers and qCSF-measured CS in iAMD. These findings highlight the impact of AMD alterations on CS function and offer valuable insights for patient stratification and prognostication in research and clinical settings.

Clinical, Genotypic, and Imaging Characterization of the Spectrum of ABCA4 Retinopathies

PURPOSE

To investigate the clinical and genotypic differences in the spectrum of ABCA4-associated retinopathies (ABCA4Rs).

DESIGN

Observational, cross sectional case series.

PARTICIPANTS

Sixty-six patients (132 eyes) carrying biallelic ABCA4 variants.

METHODS

Patients underwent visual acuity measurement and multimodal imaging. Clinical records were reviewed for age at onset, presenting symptoms, genetic variants, and electroretinogram (ERG). Each eye was assigned to a phenotype based on age at onset, imaging and ERG: cone dystrophy-bull's-eye maculopathy (CD-BEM, 40 eyes), cone-rod dystrophy (CRD, 12 eyes), Stargardt disease (SD, 28 eyes), late-onset SD (LO-SD, 38 eyes), and fundus flavimaculatus (14 eyes). Images were analyzed for: peripapillary sparing, retinal pigment epithelium (RPE) atrophy (definitely decreased autofluorescence, DDAF), flecks patterns using autofluorescence; type of atrophy according to Classification of Atrophy Meeting reports, macular and choroidal thickness on OCT; and choriocapillaris flow deficits on OCT angiography.

MAIN OUTCOME MEASURES

Primary outcome was to report the demographic, genotypic, and imaging characteristics of the different ABCA4R phenotypes. Secondary objectives included the assessment of imaging biomarkers as outcome measures for clinical trials.

RESULTS

Age at onset was lower in CRD (12 ± 8 years) and higher in patients with LO-SD (59 ± 9 years) (all P < 0.01). Central vision loss was a common presenting symptom in CD-BEM and SD, whereas patients with LO-SD primarily complained of difficult dark adaptation. Missense variants were more frequent in CD-BEM, and splice site in CRD and LO-SD (P < 0.05). Peripapillary sparing was absent in 3 eyes with LO-SD (8%). Cone dystrophy-bull's-eye maculopathy eyes typically had complete outer retinal atrophy alterations (98%), whereas CRD and SD eyes showed both complete outer retinal atrophy and complete RPE and outer retinal atrophy (cRORA) (71%-100%). Patients with LO-SD had larger areas of DDAF (100% cRORA) and of choriocapillaris flow deficits (all P < 0.01). Repeatability of DDAF measurements was low for some phenotypes (CD-BEM and CRD) and atrophic areas <7.5 mm2. Resorbed flecks were significantly associated with CRD and LO-SD (P < 0.01).

CONCLUSIONS

This research provides a thorough evaluation of the spectrum of ABCA4R. Our findings suggest that certain phenotypes show preferential photoreceptor degeneration (e.g., CD-BEM), whereas others have substantial RPE and choriocapillaris alterations (e.g., LO-SD). We recommend that clinical trial end points take into consideration these imaging features to improve the interpretation of their results.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

The Retinal Phenotype Associated with the p.Pro101Thr BEST1 Variant

PURPOSE

To describe the retinal phenotype associated with the p.Pro101Thr BEST1 variant.

DESIGN

Retrospective, observational case series.

PARTICIPANTS

Patients diagnosed with bestrophinopathies in which molecular genetic testing identified the p.Pro101Thr BEST1 as well as healthy carriers among their first-degree relatives.

METHODS

Medical records were reviewed to obtain data on family history and ophthalmic examinations, including retinal imaging. The imaging protocol included OCT and fundus autofluorescence using Spectralis HRA + OCT (Heidelberg Engineering). Genetic analysis was performed by next-generation sequencing.

MAIN OUTCOME MEASURES

Results of ophthalmic examinations and multimodal imaging features of retinal phenotypes.

RESULTS

The c.301C>A, p.Pro101Thr BEST1 missense variant was identified as the causative variant in 8 individuals (all men) from 5 families, accounting for 13% of cases (8/61) and 10% of pathogenic alleles (9/93) in our cohort of patients affected by bestrophinopathies. Seven individuals (14 eyes) had the variant in heterozygous status: all eyes had a hyperopic refractive error (median spherical equivalent of + 3.75 diopters [D]) and 4 individuals had a macular dystrophy with mildly reduced visual acuity (median of 20/25 Snellen), whereas the other 3 were asymptomatic carriers. On multimodal retinal imaging, 5 (36%) out of 14 eyes had subclinical bestrophinopathy, 4 (29%) had typical findings of adult-onset foveomacular vitelliform dystrophy (AOFVD), and the remaining 5 (36%) displayed a pattern dystrophy-like phenotype. Follow-up data were available for 6 subjects, demonstrating clinical stability up to 11 years, in both subclinical and clinical forms. An additional patient with autosomal recessive bestrophinopathy was found to harbor the p.Pro101Thr variant in homozygosity.

CONCLUSIONS

The p.Pro101Thr BEST1 variant is likely a frequent cause of bestrophinopathy in the Italian population and can result in autosomal dominant macular dystrophies with incomplete penetrance and mild clinical manifestations as well as autosomal recessive bestrophinopathy. The spectrum of autosomal dominant maculopathy includes the typical AOFVD and a pattern dystrophy-like phenotype.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Fixation Location and Stability in Best Vitelliform Macular Dystrophy

Purpose

To analyze fixation location and stability in best vitelliform macular dystrophy (BVMD) and test their association with best-corrected visual acuity (BCVA).

Design

Observational, cross-sectional study.

Participants

Thirty patients (55 eyes) affected by genetically confirmed BVMD were followed up at the Retinal Heredodystrophies Unit of IRCCS San Raffaele Scientific Institute, Milan.

Methods

Patients underwent testing with macular integrity assessment (MAIA) microperimeter. Fixation location was measured as distance in degrees (°) between preferred retinal locus (PRL) and estimated fovea location (EFL); fixation was defined as eccentric when the distance between PRL and EFL exceeded 2°. Fixation stability was graded as stable, relatively unstable, or unstable and expressed as bivariate contour ellipse area (BCEA, °²).

Main Outcome Measures

Fixation location and stability.

Results

The median distance of the PRL from the anatomic fovea was 0.7°, and fixation location was eccentric in 27% of eyes. Fixation was graded as stable in 64% of eyes, relatively unstable in 13%, and unstable in 24%, with a median 95% BCEA of 6.2°². The atrophic/fibrotic stage was associated with worse fixation parameters (all P < 0.01). Both PRL eccentricity and fixation stability were linearly associated with BCVA: every 1° increase in PRL eccentricity was associated with a 0.07 logarithm of the minimum angle of resolution (logMAR) worse BCVA (P < 0.0001) while every 1°² increase in 95% BCEA was associated with a 0.01 logMAR worse BCVA (P < 0.001). No significant intereye correlation was found for PRL eccentricity and fixation stability, as well as no association between the patient's age and fixation parameters.

Conclusions

We demonstrated that most eyes affected by BVMD retain a central stable fixation and provided evidence that both fixation eccentricity and stability are strongly associated with visual acuity in BVMD. These parameters may serve as secondary end points for future clinical trials.

Financial Disclosures

Proprietary or commercial disclosure may be found after the references.

Disease expression caused by different variants in the BEST1 gene: genotype and phenotype findings in bestrophinopathies

Purpose:

To analyse the spectrum of clinical features and molecular genetic data in a series of patients carrying likely disease-associated variants in the BEST1 gene.

Methods:

Retrospective observational analysis of clinical data extracted from the medical records of visual function, multimodal imaging and electrophysiology of 62 eyes of 31 patients. Molecular genetic analysis was performed by means of panel-based NGS or Sanger sequencing.

Results:

The spectrum of variants in the BEST1 gene comprised 19 different variants and three of which are novel. Fundus photographs and OCT images allowed categorization of 52 eyes as Best vitelliform macular dystrophy (BVMD) with stages 1 to 5 and 10 eyes with autosomal recessive bestrophinopathy (ARB), with more severe phenotype. One patient was shown to be heterozygous for a variant, which has so far been described only in ARB, but this patient had the BVMD phenotype. There was no significant progression of the visual acuity during the follow-up period of 5 years both in BVMD and ARB. The most prevalent pattern of fundus autofluorescence (FAF) in BVMD was ‘patchy’. There were diverse visual field defects in static automated perimetry (SAP) depending on the stage. The Arden ratio was significantly lower in ARB patients and in eyes with stage 5 of BVMD.

Conclusions:

The genotype does not always predict the phenotype in patients with BVMD and ARB; however, having two mutations in the BEST1 gene causes a more severephenotype. FAFhelped to distinguish ARB from BVMD. Most of the observed eyesdidnotprogressfunctionallyduringthefollow-up.ARBandtheatrophicstageof BVMD as the disease end-stage had the worst visual functions and EOG results.

The Role of Optical Coherence Tomography Angiography (OCTA) in Detecting Choroidal Neovascularization in Different Stages of Best Macular Dystrophy: A Case Series

Best macular dystrophy (BMD) is an autosomal dominant macular dystrophy of childhood onset characterized by bilateral and symmetric vitelliform lesions. Several stages of disease have been well-described in the literature. Choroidal neovascularization (CNV) has traditionally been considered a hallmark of end-stage disease, and anti-vascular endothelial growth factor (anti-VEGF) agents have been used to improve visual prognosis. While CNV was historically detected with fluorescein angiography, optical coherence tomography angiography (OCTA) has recently been employed as a novel mechanism for identifying CNV in BMD. In this case series, we discuss our institutional experience with using OCTA to detect CNV in BMD and contextualize this experience within the broader emerging literature. While OCTA allows for the identification of CNV in less severe stages of BMD, the management of this CNV remains uncertain.

Optical Coherence Tomography Angiography Quantitative Assessment of Macular Neovascularization in Best Vitelliform Macular Dystrophy

Purpose

To describe quantitative characteristics of macular neovascularization (MNV) in vitelliform macular dystrophy (VMD) patients by means of optical coherence tomography angiography (OCTA).

Methods

The study design was a prospective case series. All patients underwent complete ophthalmologic assessment, optical coherence tomography, and OCTA. The quantitative OCTA parameters examined included vessel tortuosity and vessel dispersion of the MNV. The primary outcome was OCTA characterization of MNV in VMD. Secondary outcomes included the evolution of MNV over the follow-up.

Results

A total of 78 eyes were recruited for the study. MNV was identified in 50 eyes (64%) at baseline and in 51 eyes (65%) at the end of the follow-up (mean follow-up, 24.7 ± 9.7 months). MNV was detected in four out of the 30 eyes classified as stages 2 and 3 (13%), showing exudative manifestations and undergoing ranibizumab treatment, leading to clinical stabilization. OCTA detected MNV in 46 out of 48 eyes (96%) classified as stages 4 and 5, showing no evidence of exudative manifestation. All of the non-exudative MNVs were merely observed over the follow-up and received no treatment. At the end of the follow-up, 47 out of 48 eyes displayed MNV (98%). Non-exudative MNVs remained stable over the follow-up. Statistically significant differences were found when comparing vessel tortuosity and vessel dispersion in the two MNV subforms.

Conclusions

VMD is characterized by two MNV subforms. Exudative MNV is rare and may develop in the early stages of the disease, in association with bleeding and fluid formation. Non-exudative MNV develops very commonly in the advanced stage of VMD, without any exudative manifestation.

Multimodal imaging in subclinical best vitelliform macular dystrophy

BACKGROUND

To analyse multimodal imaging alterations in the subclinical form of best vitelliform macular dystrophy (BVMD).

METHODS

The study was designed as an observational, cross-sectional case series. Eleven eyes of 7 subclinical patients with BVMD and 12 age-matched and sex-matched controls were included. Multimodal imaging included fundus blue-light autofluorescence, near-infrared autofluorescence (NIR-AF), structural optical coherence tomography (OCT) and OCT angiography (OCTA). The quantitative analysis included the calculation of the following parameters: vessel density (VD), vessel tortuosity (VT), vessel dispersion (Vdisp), vessel rarefaction (VR), foveal avascular zone (FAZ) area, reflectivity of the outer retinal bands and choriocapillaris porosity (CCP).

RESULTS

Mean best-corrected visual acuity was 0.0±0.0 LogMAR in both groups. The round central hypoautofluorescent alteration on NIR-AF corresponded to a significant reflectivity attenuation of the outer retinal bands on structural OCT (0.55±0.18 vs 0.75±0.08; p<0.001). VD, VT, VR and Vdisp were normal compared with controls (all p>0.05). The FAZ area turned out to be significantly restricted at the level of the deep capillary plexus in subclinical BVMD eyes (p<0.001). Furthermore, quantitative OCTA revealed a significant central increase of CCP, compared with controls (18.25±2.43 vs 4.58±1.36; p<0.001).

CONCLUSIONS

The subclinical stage of BVMD is characterised by significant alterations of the outer retinal bands and the choriocapillaris. Quantitative multimodal imaging assessment suggests that subclinical BVMD is affected by the functional impairment of the outer retinal structures, leading to an alteration in melanin and growth factor production.

Anti-VEGF and Retinal Dystrophies

The therapeutic approach based on anti-vascular endothelial growth factor (anti-VEGF) molecules can be used to treat two important complications of retinal dystrophies: choroidal neovascularization and macular edema. The macular involvement in retinal dystrophies can lead to further visual deterioration in patients at a young age and already affected by functional limitations. The study reports the effect of anti-VEGF treatment in several subforms of retinal dystrophies, critically discussing advantages and limitations.