MICROPERIMETRY IN BEST VITELLIFORM MACULAR DYSTROPHY

Inner retinal thickness in Stargardt disease

PURPOSE

To analyze the alterations at the level of the inner retina in patients affected by Stargardt disease (STGD1).

METHODS

Cross-sectional investigation involving STGD1 patients with genetically confirmed diagnosis, who underwent optical coherence tomography (OCT), optical coherence tomography angiography (OCTA), and microperimetry.

RESULTS

Overall, 31 patients (62 eyes) with genetically confirmed STGD1 were included in the study. Mean inner retinal thickness, vessel density of plexa, and retinal sensitivity resulted significantly reduced in STGD patients, compared with healthy controls (p < 0.05), both in the outer and in the inner ETDRS rings. Overall, 43% of eyes revealed an inner retinal thinning, whereas 21% and 35% showed a thicker or within normal range inner retina.

CONCLUSIONS

Inner retina is irregularly altered in STGD1, showing variable quantitative alterations as detected on OCT. Inner retinal status might represent a useful biomarker to better characterize STGD1 and to ascertain the effects of new treatment approaches.

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.

Retinal sensitivity and fundus autofluorescence in adult-onset foveomacular vitelliform dystrophy

The present study aimed to compare retinal sensitivity (RS) at each stage and to evaluate the relationship between RS and fundus autofluorescence (FAF) pattern in adult-onset foveomacular vitelliform dystrophy (AOFVD). We retrospectively reviewed 17 eyes of 13 patients with AOFVD. In addition to best-corrected visual acuity (VA), RS within the affected lesion and optical coherence tomography (OCT) measurements were carried out in each participant. All the examined eyes were classified into 4 stages and 3 FAF patterns. RS was superimposed on OCT fundus image and RS within the affected lesion was calculated in each eye. The relationships between visual functions (VA and RS within the affected lesion) and stages and also FAF patterns were analyzed using the linear mixed model. As a result, RS within the affected lesion was significantly associated with FAF pattern, but not with stage. In contrast, VA was correlated with neither stages nor FAF patterns. Our current result suggested that RS within the affected lesion was related to FAF patterns but this was not the case with VA in eyes with AOFVD, demonstrating the usefulness of measuring RS, not only VA, to comprehend the disease status in AOFVD.

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.

Morphological and functional involvement of the inner retina in retinitis pigmentosa

BACKGROUND

To investigate the morphological retinal parameters associated with retinal sensitivity status in retinitis pigmentosa (RP) through a quantitative multimodal imaging approach.

METHODS

The study was designed as an observational, prospective case series, including RP patients and healthy controls. Multimodal imaging included fundus autofluorescence (FAF), structural optical coherence tomography (OCT), OCT angiography (OCTA) and microperimetry (MP). The follow-up lasted 12 months. For each imaging modality, we performed an overall quantitative analysis and a detailed investigation based on the ETDRS-9 sectors grid. Quantitative parameters included the thickness of each retinal and choroidal layer, vessel density (VD), choriocapillaris porosity (CCP), FAF intensity and MP retinal sensitivity.

RESULTS

We included 40 eyes (40 patients) affected by RP and 40 healthy eyes (40 controls). Mean baseline BCVA was 0.14 ± 0.18 LogMAR, with 0.18 ± 0.24 LogMAR after 1-year of follow-up. RP eyes showed statistically significant alterations of retinal and choroidal layers on the ETDRS-9 sectors grid, significant reduction of VD values and MP retinal sensitivity, and significantly higher CCP than controls. The inner retinal layers proved closely associated with the functional integrity of the posterior pole. In addition, our ROC analysis provided quantitative cutoffs connected significantly with a high probability of observing a partial sparing of MP retinal sensitivity.

CONCLUSIONS

The inner retinal layers are closely associated with the functional integrity of the posterior pole in RP. FAF intensity reduction may be interpreted as lipofuscin metabolism impairment inducing increased phototoxic distress for retinal structures. Vascular involvement contributes to the morpho-functional deterioration of the macular region in RP.

The pseudohypopyon stage in adult-onset foveomacular vitelliform dystrophy

PURPOSE

To gain insight into the pathogenesis of adult-onset foveomacular vitelliform dystrophy (AFVD) via assessment of its pseudohypopyon stage (PHS).

METHODS

Retrospectively, data were collected in a tertiary center from established cohorts of a genetically evaluated AFVD and best vitelliform macular dystrophy (BVMD) eyes in the pseudohypopyon stage. Best-corrected visual acuity (BCVA, LogMAR), lesion characterization, including lesion dimensions, liquefaction areas and patterns (altitudinal or lateral), and ellipsoid zone integrity were analyzed from spectral-domain optical coherence tomography images.

RESULTS

Out of 167 eyes of 90 AFVD patients and 56 eyes of 28 BVMD patients, 8 eyes of six AFVD patients and five eyes of four BVMD patients were at the PHS were included. The mean LogMAR BCVA ± SD was 0.21 ± 0.20 and 0.41 ± 0.10 in AFVD and BVMD diseases, respectively (p = 0.13). Seven AFVD eyes (87.5%) demonstrated lateral liquefaction, while all BVMD eyes demonstrated an altitudinal pattern (p = 0.005). Maximal horizontal lesion diameters were 1.41 ± 0.46 mm and 2.64 ± 0.77 mm in AFVD and BVMD, respectively (p = 0.02). AFVD patients were older (69 ± 14) than BVMD patients (22 ± 13; p = 0.009).

CONCLUSION

The pseudohypopyon stage in AFVD is often characterized by a lateral liquefaction pattern, unlike the altitudinal pattern characterizing BVMD. Age, lesion size, or pathogenesis pathways may underline the different pseudohypopyon stage patterns in AFVD and BVMD.

Vitelliform maculopathy: Diverse etiologies originating from one common pathway

Vitelliform lesions (VLs) are associated with a wide array of macular disorders but are the result of one common pathway: retinal pigment epithelium (RPE) impairment and phagocytic dysfunction. VLs are defined by the accumulation of yellowish subretinal material. In the era of multimodal advanced retinal imaging, VLs can be further characterized by subretinal hyperreflectivity with optical coherence tomography and hyperautofluorescence with fundus autofluorescence. VLs can be the result of genetic or acquired retinal diseases. In younger patients, VLs usually occur in the setting of Best disease. Additional genetic causes of VL include pattern dystrophy or adult-onset vitelliform macular dystrophy. In older patients, acquired VLs can be associated with a broad spectrum of etiologies, including tractional, paraneoplastic, toxic, and degenerative disorders. The main cause of visual morbidity in eyes with VLs is the onset of macular atrophy and macular neovascularization. Histopathological studies have provided new insights into the location, nature, and lifecycle of the vitelliform material comprised of melanosomes, lipofuscin, melanolipofuscin, and outer segment debris located between the RPE and photoreceptor layer. Impaired phagocytosis by the RPE cells is the unifying pathway leading to VL development. We discuss and summarize the nature, pathogenesis, multimodal imaging characteristics, etiologies, and natural course of vitelliform maculopathies.

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.

Clinical Correlation Between Optical Coherence Tomography Biomarkers and Retinal Sensitivity in Best Vitelliform Macular Dystrophy

Purpose

To investigate the clinical and imaging features associated with retinal sensitivity in Best vitelliform macular dystrophy (BVMD).

Methods

This was a cross-sectional, single-center, observational study. Each patient underwent optical coherence tomography (OCT), near-infrared fundus autofluorescence, and OCT angiography. Macular integrity assessment microperimetry under mesopic conditions was performed to obtain retinal sensitivity thresholds from 68 testing points in the central macula. Structural OCT was used to classify BVMD lesions into four types according to their composition: vitelliform, mixed, subretinal fluid, and atrophy. Multilevel, mixed-effects linear regression was used to determine the factors associated with retinal sensitivity.

Results

The study included 57 eyes of 30 patients with BVMD, 48 of which (84%) were in a clinical stage. Mean retinal sensitivity varied according to the composition of the lesion: the vitelliform type registering the highest (22 ± 4.1 dB), followed by mixed (18.73 ± 2.7 dB), subretinal fluid (15.68 ± 4.2 dB), and atrophy types (11.85 ± 4.6 dB). The factors most strongly associated with mean retinal sensitivity in BVMD proved to be the OCT lesion type and outer nuclear layer thickness.

Conclusions

Retinal sensitivity in BVMD is influenced by lesion composition and outer nuclear layer thickness. Further studies with long-term follow-up are warranted to examine retinal sensitivity over time and to validate retinal sensitivity changes as biomarkers for BVMD.

Translational Relevance

Assessing retinal sensitivity in BVMD provides a new instrument in the clinical characterization of the disease and offers the opportunity to identify imaging biomarkers for use as outcome measures in future clinical trials.

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.

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.

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

PURPOSE

The vitelliform stage is the typical phenotypic manifestation of Best vitelliform macular dystrophy (BVMD). As yet, no study has focused specifically on the clinical changes occurring in the vitelliform stage over the follow-up.

METHODS

The survey takes the form of a prospective observational study with a 5-year follow-up. Twenty-one eyes of 11 patients in the vitelliform stage were examined annually. The primary outcome was the identification of the changes in the vitelliform lesion over a 5-year follow-up. Secondary outcomes included changes in structural optical coherence tomography (OCT) parameters and the correlation with the BCVA variation over the follow-up.

RESULTS

Spectral domain OCT at baseline showed one subform characterized by solid vitelliform deposition, in 81% of eyes, and another subform characterized by a combination of solid deposition and subretinal fluid, in 19% of eyes. Overall, 62% of eyes showed an increase in the area of vitelliform deposition. Once the maximal area was reached, a progressive flattening of the vitelliform deposition took place, with subsequent flattening of the vitelliform lesion and formation of subretinal fluid. Hyperreflective foci (HF) increased in number as long as the vitelliform area continued to expand, with no variation in HF when the vitelliform lesion flattened or the subretinal fluid formed.

CONCLUSIONS

The vitelliform stage reveals more subforms with clinical variations over the follow-up. Our data suggest that the substage before the flattening of the lesion, thus before the so-called subretinal fluid accumulates and when the visual acuity is still high, might offer the best opportunity for an optimal therapeutic approach.

Structure-Function Correlation Using OCT Angiography And Microperimetry In Diabetic Retinopathy

Purpose

To evaluate macular vasculature in diabetic retinopathy (DR) with optical coherence tomography angiography (OCTA) and to correlate vessel density (VD) with retinal sensitivity (RS) as a way to assess structural and functional findings in DR.

Design

Prospective observational cross-sectional study.

Methods

Diabetic patients with DR but no clinically significant diabetic macular edema (DME) and healthy subjects were included in this study. All of them underwent comprehensive ophthalmic examination, best corrected visual acuity (BCVA), OCTA with RS-3000 Advance AngioScan (Nidek, Gamagori, Japan) and microperimetry with MP-3 (Nidek, Gamagori, Japan). Retinal vascular density measured by OCT angiography in 9 areas was correlated with RS in the same 9 areas by Spearman correlation.

Results

In this study, 50 subjects were enrolled: 25 eyes of diabetic patients with DR and 25 eyes of non-diabetic subjects. Diabetic patients mean age was 51.88±13.62 years; non-diabetic subjects were 43.48±13.42 years. The BCVA was 20/25 in the diabetic group and 20/20 in the non-diabetic group. Mean RS was decreased in the DR group (27.68±2.71 dB) compared to the non-diabetic group (31.68±1.46 dB) (p<0.05) and in the 9 studied areas (p<0.05). Mean VD was decreased in the DR group compared to non-diabetics (p<0.05) and in 7 of the 9 areas (except temporal superior and inferior squares) (p<0.05). Correlations by areas between VD and RS were assessed, we found moderate correlation in the area temporal to the fovea (r=0.501, p=0.01) in the DR group but not in the non-diabetic subjects. There were no other statistical significant correlations with this pattern.

Conclusion

DR without DME results in a retinal VD decreased that might be the cause of a reduction of RS in one of the studied areas. Microangiopathic changes are correlated with microperimetry sensitivity drop in the temporal to the fovea grid but not in the other studied grids.

Multimodal Imaging in Best Vitelliform Macular Dystrophy

Purpose

In patients diagnosed with Best vitelliform macular dystrophy (BVMD), quantitative fundus autofluorescence (qAF), near-infrared fundus autofluorescence (NIR-AF), and spectral-domain optical coherence tomography (SD-OCT) were used to elucidate pathogenic mechanisms.

Methods

Fourteen patients heterozygous for BEST1 mutations were recruited. qAF was analyzed using short-wavelength fundus autofluorescence (SW-AF) images. Mean gray levels (GL) were determined in nonlesion areas (7 to 9° eccentricity) and adjusted by GL measured in an internal fluorescent reference. NIR-AF images (787 nm; sensitivity of 96) were captured and saved in non-normalized mode. Horizontal SD-OCT images also were acquired and BVMD was staged according to the OCT findings.

Results

In the pre-vitelliform stage, NIR-AF imaging revealed an area of reduced fluorescence, whereas in the vitelliruptive stage, puncta of elevated NIR-AF signal were present. In both SW-AF and NIR-AF images, the vitelliform lesion in the atrophic stage was marked by reduced signal. At all stages of BVMD, nonlesion qAF was within the 95% confidence intervals for healthy eyes. Similarly, the NIR-AF intensity measurements outside the vitelliform lesion were comparable to the healthy control eye. SD-OCT scans revealed a fluid-filled detachment between the ellipsoid zone and the hyperreflectivity band attributable to RPE/Bruch's membrane.

Conclusions

NIR-AF imaging can identify the pre-vitelliform stage of BVMD. Mutations in BEST1 are not associated with increased levels of SW-AF outside the vitelliform lesion. Elevated SW-AF within the fluid-filled lesion likely reflects the inability of RPE to phagocytose outer segments due to separation of RPE from photoreceptor cells, together with progressive photoreceptor cell impairment.

Fibrotic pillar leads to focal choroidal excavation in Best vitelliform dystrophy

PURPOSE

To study focal choroidal excavations in patients with Best vitelliform dystrophy using optical coherence tomography and their topographical relation with fibrotic pillars.

METHODS

This is a retrospective cross-sectional study of consecutive patients diagnosed with Best vitelliform dystrophy at a tertiary eye care center. Records of patients with Best vitelliform dystrophy were reviewed for best-corrected visual acuity, color fundus photographs, shortwave autofluorescence, optical coherence tomography, and electrooculogram with special emphasis on the presence of focal choroidal excavation (FCE) and fibrotic pillar. Main outcome measure was to study the fibrotic pillar in relation to the FCE.

RESULTS

Thirty-eight eyes of 19 patients with mean age of 34.6 years were enrolled in the study. FCE was seen in eight eyes of six patients. Two patients had bilateral FCE and all the FCEs were located in the area of vitelliform lesion. Six out of eight eyes with FCE were in vitelliruptive stage of disease; one was in pseudohypopyon stage and one in atrophic stage. A fibrotic pillar was seen lying directly above the FCE in seven eyes. In one eye, hyper-reflective material not amounting to fibrotic pillar was seen lying above the FCE.

CONCLUSION

A focal choroidal excavation in the setting of Best vitelliform dystrophy is seen predominantly in the vitelliruptive stage of the disease. Fibrotic pillars appear to play a role in the formation of these FCEs.