Choriocapillaris' alterations in the presence of reticular pseudodrusen compared to drusen: study based on OCTA findings

Optical Coherence Tomography in Inherited Macular Dystrophies: A Review

Macular dystrophies (MDs) constitute a collection of hereditary retina disorders leading to notable visual impairment, primarily due to progressive macular atrophy. These conditions are distinguished by bilateral and relatively symmetrical abnormalities in the macula that significantly impair central visual function. Recent strides in fundus imaging, especially optical coherence tomography (OCT), have enhanced our comprehension and diagnostic capabilities for MD. OCT enables the identification of neurosensory retinal disorganization patterns and the extent of damage to retinal pigment epithelium (RPE) and photoreceptor cells in the dystrophies before visible macular pathology appears on fundus examinations. It not only helps us in diagnostic retinal and choroidal pathologies but also guides us in monitoring the progression of, staging of, and response to treatment. In this review, we summarize the key findings on OCT in some of the most common MD.

Correlation between ellipsoid zone thickness and the presence of subretinal drusenoid deposits in age-related macular degeneration

PURPOSE

Subretinal drusenoid deposits (SDDs) in age-related macular degeneration (AMD) are associated with systemic vascular diseases that compromise ocular perfusion. We demonstrate that SDDs are associated with decreased ellipsoid zone (EZ) thickness, further evidence of hypoxic damage.

METHODS

Post hoc analysis of a cross-sectional study. 165 AMD subjects (aged 51-100; 61% women). Spectral-domain optical coherence tomography was obtained in both eyes. Masked readers assigned subjects to three groups: drusen only, SDD+drusen (SDD+D) and SDD only. EZ thickness was measured subfoveally and 2000 µm nasally, temporally, superiorly and inferiorly from the fovea. Univariate testing was performed using two-tailed t-tests with Bonferroni correction.

RESULTS

The mean EZ thickness differences between the SDD+D and drusen-only groups were (in μm) 1.10, 0.67, 1.21, 1.10 and 0.50 at the foveal, nasal, temporal, superior and inferior locations, respectively (p=0.08 inferiorly, otherwise p≤0.01); between the SDD-only and drusen-only groups, the differences were 3.48, 2.48, 2.42, 2.08 and 1.42 (p≤0.0002). Differences in EZ thicknesses across all subjects and between groups were not significantly different based on gender, race or age.

CONCLUSION

Subjects with SDDs (±drusen) had thinner EZs than those with drusen only, and the inferior EZ was least affected. EZs were thinnest in SDD-only subjects. This thinning gradation is consistent with progressive destruction of highly oxygen-sensitive mitochondria in the EZ from hypoxia. These findings support the reduced ophthalmic perfusion hypothesis for the formation of SDDs secondary to high-risk systemic vasculopathy.

Central macular choriocapillaris impairment as a manifestation of microvascular disease in eyes with subretinal drusenoid deposits

BACKGROUND/OBJECTIVES

Microvascular alterations and choroidal impairment are emerging as a pathologic pathway in age-related macular degeneration (AMD). This study aimed to evaluate the central macular choriocapillaris (CC) in eyes with subretinal drusenoid deposits (SDD) and the retinal microvasculature in patients with early AMD phenotypes.

SUBJECTS/METHODS

This was an institutional, multicentric observational cross-sectional study. Ninety-nine eyes of 99 subjects; 33 eyes with SDD only, 33 eyes with conventional drusen (CD) only, and 33 eyes of healthy age-matched subjects were included. Comprehensive ophthalmologic examination and optical coherence tomography angiography (OCTA) was performed. The central macular flow area of the CC was analysed in the SDD group and the vessel density of the retinal superficial capillary plexus (SCP) and deep capillary plexus (DCP) was analysed in the SDD and CD groups using automated OCTA output parameters.

RESULTS

The flow area of the CC in the SDD group was significantly reduced (p ≤ 0.001) with respect to the healthy control group. There was a trend of reduction of vessel density of the SCP and the DCP in the SDD and CD group with respect to controls, although this did not reach statistical significance.

CONCLUSIONS

OCTA data in the present report corroborate the role of vascular damage in early AMD with CC impairment in the central macular area in eyes with SDD.

Association between Subretinal Drusenoid Deposits and Age-Related Macular Degeneration in Multimodal Retinal Imaging

Multimodal retinal imaging enables the detection of subretinal drusenoid deposits (SDD) with significantly greater accuracy compared to fundus photography. The study aimed to analyze a relationship between the presence of SDD, the clinical picture of AMD, and disease progression in a 3 year follow-up. A total of 602 eyes of 339 patients with a diagnosis of AMD, of which 121 (55%) had SDD confirmed in multimodal retinal imaging, were enrolled in the study. SDD was related to a more advanced stage of AMD (p = 0.008), especially with the presence of geographic atrophy (OR = 4.11, 95% CI 2.02-8.38, p < 0.001). Eyes with SDD presented significantly lower choroidal and retinal thickness (ATC: 210.5 μm, CRT: 277 μm, respectively) and volume (AVC: 0.17 mm3, CRV: 8.29 mm3, p < 0.001, respectively) compared to SDD-negative eyes (ATC: 203 μm, CRT: 277 μm; AVC: 7.08 mm3, 8.54 mm3, p < 0.001). Accordingly, the prevalence of pachychoroids and pachyvessels was significantly lower in the SDD present group than in eyes without SDD (p = 0.004; p = 0.04, respectively). Neither demographic factors, lipid profile, genetic predisposition, systemic vascular disease comorbidities, nor parameters of retinal vessels were affected by the presence of SDD. We found no effect of SDD presence on AMD progression (p = 0.12). The presence of SDD appeared to be related to local rather than systemic factors.

Inner Retinal Thickness and Vasculature in Patients with Reticular Pseudodrusen

INTRODUCTION

The aim of this study was to investigate retinal layer thickness and vessel density differences between patients with reticular pseudodrusen (RPD) and intermediate dry age-related macular degeneration (iAMD).

METHODS

Participants included in the study were patients diagnosed by retinal specialists with RPD, iAMD, and both RPD and iAMD at our academic referral center, seen from May 2021 until February 2022. The central 3 mm retinal thickness was measured using spectral-domain optical coherence tomography (Heidelberg Spectralis HRA+OCT System; Heidelberg Engineering, Heidelberg, Germany). Individual retinal thickness measurements were obtained from the innermost layer (nerve fiber layer) until the outermost layer (retinal pigment epithelium [RPE]). Each thickness measurement was subdivided into nine Early Treatment Diabetic Retinopathy Study (ETDRS) sectors. For the vessel density, OCT angiography from the Heidelberg Spectralis System was measured using proprietary third-party software (AngioTool; National Institutes of Health, National Cancer Institute, Bethesda, MD). Clinical and demographic characteristics were compared across the three groups (iAMD, RPD, iAMD and RPD) and analyzed with necessary adjustments. Linear mixed-effects models with necessary corrections were employed to compare continuous eye-level measurements between our three groups as well as in pairwise fashion using the R statistical programming software (R version 4.2.1).

RESULTS

A total of 25 eyes of 17 patients with RPD, 20 eyes of 15 patients with iAMD, and 14 eyes of 9 patients with both iAMD and RPD were analyzed. Retinal thickness analysis identified that the superior inner (p = 0.028) and superior outer (p = 0.027) maculas of eyes with both iAMD and RPD were significantly thinner than those with iAMD alone. In eyes with RPD, the superior inner and superior outer RPE (p = 0.011 and p = 0.05, respectively), outer plexiform layer (p = 0.003 and p = 0.013, respectively), and inner nuclear layer (p = 0.034 and p = 0, respectively) were noted to be thinner compared to eyes with iAMD alone. In addition, the macular deep capillary plexus vessel density was significantly reduced in eyes with RPD compared to eyes with iAMD (p = 0.017).

CONCLUSION

Patients with RPD had inner retinal structural as well as vascular changes compared to iAMD patients. Inner retinal vascular attenuation should be investigated further to see if there is a causal association with retinal thinning.

Decreased Macular Choriocapillaris Perfusion in Eyes With Macular Reticular Pseudodrusen Imaged With Swept-Source OCT Angiography

Purpose

To determine if macular reticular pseudodrusen (RPD) were associated with markers of impaired macular choroidal perfusion, we investigated measurements of macular choriocapillaris (CC) flow deficits (FDs), CC thickness, and mean choroidal thickness (MCT) in eyes with macular RPD compared with normal eyes and eyes with soft drusen.

Methods

Eyes with intermediate age-related macular degeneration (iAMD) and normal eyes underwent 6 × 6 mm swept-source optical coherence tomography angiography (SS-OCTA) imaging to diagnose macular RPD, occupying over 25% of the fovea-centered 5 mm diameter circle, and measure outer retinal layer (ORL) thickness, CC FDs, CC thickness, MCT, and choroidal vascularity index (CVI) using previously published strategies within the same fovea-centered 5 mm circle.

Results

Ninety eyes were included; 30 normal eyes, 30 eyes with soft drusen, and 30 eyes with macular RPD. The RPD eyes showed higher macular CC FDs than normal eyes (P < 0.001) and soft drusen eyes (P = 0.019). Macular CC thickness was decreased in RPD eyes compared with normal eyes (P < 0.001) and soft drusen eyes (P = 0.016). Macular MCT in RPD eyes was thinner than normal eyes (P = 0.005) and soft drusen eyes (P < 0.001). No statistically and clinically significant differences were found in the ORL thickness and CVI measurements between RPD eyes and the other two groups (all P > 0.05).

Conclusions

Eyes with macular RPD had decreased macular CC perfusion, decreased CC thickness, and decreased MCT measurements compared with normal and soft drusen eyes, suggesting that RPD may result from impaired choroidal perfusion.

Computerized Texture Analysis of Optical Coherence Tomography Angiography of Choriocapillaris in Normal Eyes of Young and Healthy Subjects

Computerized texture analysis uses higher-order mathematics to identify patterns beyond what the naked eye can recognize. We tested its feasibility in optical coherence tomography angiography imaging of choriocapillaris. Our objective was to determine sets of parameters that provide coherent and consistent output when applied to a homogeneous, healthy group of patients. This observational cross-sectional study involved 19 eyes of 10 young and healthy Caucasian subjects. En-face macular optical coherence tomography angiography of superficial choriocapillaris was obtained by the RTVue-XR Avanti system. Various algorithms were used to extract texture features. The mean and standard deviation were used to assess the distribution and dispersion of data points in each metric among eyes, which included: average gray level, gray level yielding 70% threshold and 30% threshold, balance, skewness, energy, entropy, contrast, edge mean gradient, root-mean-square variation, and first moment of power spectrum, which was compared between images, showing a highly concordant homology between all eyes of participants. We conclude that computerized texture analysis for en-face optical coherence tomography angiography images of choriocapillaris is feasible and provides values that are coherent and tightly distributed around the mean in a homogenous, healthy group of patients. Homology of blob size among subjects may represent a “repeat pattern” in signal density and thus a perfusion in the superficial choriocapillaris of healthy young individuals of the same ethnic background.

Swept-Source Optical Coherence Tomography Detection of Bruch's Membrane and Choriocapillaris Abnormalities in Sorsby Macular Dystrophy

PURPOSE

Swept-source optical coherence tomography angiography (SS-OCTA) was used to analyze Bruch's membrane (BM) and choriocapillaris (CC) abnormalities in undiagnosed family members with Sorsby macular dystrophy (SMD).

METHODS

In a family with SMD (TIMP3 Tyr191Cys), SS-OCTA imaging was performed using the 6X6mm scan patter and previously validated algorithms to detect abnormalities in BM and the CC, as well as the presence of reticular pseudodrusen (RPD) and macular neovascularization (MNV). Genetic analyses were performed for TIMP3 mutations.

RESULTS

Of eight family members, two were previously diagnosed with SMD and six were asymptomatic. SS-OCTA imaging of the 33-year-old proband revealed type 1 MNV in the left eye and bilateral RPD, thickening of BM, CC thinning, and increases in CC flow deficits (FDs). A TIMP3 mutation was confirmed. His niece, despite having no clinical evidence of SMD, showed BM thickening and CC thinning on SS-OCTA. A TIMP3 mutation was confirmed. The proband's younger nephew and niece also carried the TIMP3 mutation without clinical evidence of SMD. Two additional members had normal exams, unremarkable SS-OCTA findings, and no TIMP3 mutation.

CONCLUSIONS

SS-OCTA imaging can detect BM and CC abnormalities in vivo in subjects unaware of their TIMP3 status in a family with SMD.

An Update on the Hemodynamic Model of Age-Related Macular Degeneration

PURPOSE

To provide an update on the hemodynamic model of age-related macular degeneration (AMD).

DESIGN

Evidence-based perspective.

METHODS

Review of the literature and experience of the authors.

RESULTS

Choroidal hemodynamics are not the primary cause of AMD as proposed by Ephraim Friedman in 1997. However, evidence is accumulating to suggest that choroidal perfusion is an important environmental influence that contributes to our understanding of disease progression in this complex genetic disorder. Although early and intermediate AMD seem to be influenced to a large extent by the underlying genetics, the asymmetry of disease progression to the later stages of AMD cannot be explained by genetics alone. The progression of disease and the asymmetry of this progression seem to correlate with abnormalities in choroidal perfusion that can be documented by optical coherence tomography. These perfusion abnormalities in the setting of a thickened Bruch's membrane are thought to exacerbate the impaired nutritional exchange between the retinal pigment epithelium and the choriocapillaris. We propose that the genetic susceptibility to develop AMD combined with age-related changes in macular choroidal hemodynamics, such as increasing choriocapillaris perfusion deficits and decreasing choroidal vascular densities, play an important role in disease progression and may help to explain the asymmetry between eyes, particularly in the later stages of AMD.

CONCLUSIONS

This updated hemodynamic model of AMD focuses on disease progression and highlights the importance of age-related changes in the choroidal circulation as a major environmental influence on disease severity in eyes that are genetically susceptible to develop AMD.

The RAP study, report 4: morphological and topographical characteristics of multifocal macular neovascularization type 3

PURPOSE

To report on the morphological characteristics and regional distribution of multifocal macular neovascularization type 3 (mMNV3).

METHODS

Twenty-two consecutive eyes of 21 patients with mMNV3 were included using multimodal imaging. The count and stage of lesions of all MNV types and the existence of exudate and hemorrhage were determined. Also, we addressed the regional distribution of MNV3 lesions between the superior-inferior and the nasal-temporal halves of the macula, and the range of the distance of the lesions from the central fovea. Furthermore, we explored the number of feeding vessels including the cilioretinal artery.

RESULTS

We found 51 lesions in 22 eyes of 21 patients. They were bifocal in 16 (73%) eyes, trifocal in 5 (23%), and quadrifocal in one (4%). No lesion of MNV1 or 2 was found. Fifteen (68%), 2 (9%), and 16 (73%) eyes were associated with retinal hard exudate, subretinal pigment epithelium exudate, and intraretinal hemorrhage, respectively. Thirty (59%) lesions were located in the temporal half of the macula, whereas 21 (41%) were located nasally (p = 0.07). One (2%) lesion was closer than 500 µm, 49 (96%) between 500 and 1500 µm, and one (2%) between 1500 and 3000 µm. The lesions were supplied by one arteriole in one (4%) eye, two arterioles in 16 (73%) eyes, and 3 arterioles in 5 (23%) eyes. The CRA contributed as a feeding vessel in 5 (23%) eyes.

CONCLUSION

The multifocal variant of MNV3 has specific morphological and topographical characteristics. Multimodal imaging allows the understanding of the pathomorphological condition in more detail.

Choriocapillaris Vascular Density Changes: Healthy vs. Advanced Exudative Age-Related Macular Degeneration Previously Treated with Multiple Anti-VEGF Intravitreal Injections

Purpose: To assess choriocapillaris vascular density (VD) in healthy and advanced exudative age-related macular degeneration (ae-AMD) patients by new full-range optical coherence tomography angiography (OCT-A). Method: In this observational, cross-sectional study, 21 healthy and 21 ae-AMD eyes, already treated with anti-VEGF, were enrolled. Angio-View retina patterns centered on fovea (6.4 × 6.4 mm) were acquired for all participants using Solix full-range OCT (Optovue Inc., Freemont, CA, USA). The main outcome was to compare choriocapillaris VD between healthy and ae-AMD eyes. Automated measurements of whole image choriocapillaris VD (%) and fovea grid-based (%) were collected for the analysis. Angio-View patterns were used to assess the flow area (mm²) of macular neovascularization (MNV) by contour flow measure algorithm. Best-corrected visual acuity (BCVA) of both groups was also used for the statistical analysis. Results: The mean age was 60.9 (±8.3) in healthy and 73.33 (±15.05) in ae-AMD eyes. The mean BCVA (ETDRS letters) was 98.47 (±1.50) in healthy and 7.04 (±5.96) in ae-AMD eyes. The Mann–Whitney test comparing choriocapillaries VD for whole and fovea healthy and ae-AMD eyes showed statistical significance (p < 0.0001 (t = 4.91; df = 40) and p < 0.0001 (t = 6.84; df = 40), respectively). Regarding, the correlation between MNV and VD of choriocapillaries, neither whole nor fovea areas were statistically significant (F = 0.38 (R² = 0.01) and 1.68 (R² = 0.08), respectively). Conclusions: Choriocapillaris VD showed a statistically significant reduction in comparison to healthy eyes in ae-AMD eyes. Choriocapillaris impairment can be seen in the early phase of MNV pathogenesis.

Vascular and structural alterations of the choroid evaluated by optical coherence tomography angiography and enhanced-depth imaging optical coherence tomography in eyes with reticular pseudodrusen and soft drusen

BACKGROUND

To assess the vascularity of choriocapillaris and structural choroidal differences in eyes with reticular pseudodrusen (RPD) and soft drusen.

METHODS

21 eyes with RPD (group 1), 17 eyes with soft drusen (group 2), and 19 eyes as a control group (group 3) were included in this study. Choriocapillaris vascular density and flow area were measured by optical coherence tomography angiography. Total choroidal area, luminal area, stromal area, and lumen/stroma ratios were measured on optical coherence tomography B-scans converted to binary images.

RESULTS

Mean choriocapillaris vascular density was higher in group 3 than other groups (group 1 vs 3, p = 0.001; group 2 vs 3, p = 0.003). Mean flow area in choriocapillaris was higher in group 3 than other groups (group 1 vs 3, p = 0.001; group 2 vs 3, p = 0.001). Mean luminal, stromal, and total choroidal areas decreased in group 1 and group 2 compared to controls (p < 0.001, p < 0.001, and p < 0.001, respectively). The stroma ratio decreased in group 1 compared to group 3 (p = 0.013). The lumen ratio and lumen/stroma ratio increased in group 1 compared to group 3 (p = 0.012 and p = 0.008, respectively).

CONCLUSIONS

The choroid of eyes with RPD and soft drusen was affected in both choriocapillaris and whole choroid layer.

Integrative analysis of the choroid by quantifying Haller vessel and choriocapillaris parameters in different drusen subtypes

This study aimed to quantify the Haller vessel and choriocapillaris (CC) parameters in drusen subtypes in nonexudative age-related macular degeneration (AMD) and pachydrusen. Ninety-five eyes of 80 patients and 28 control eyes were categorized into soft drusen, subretinal drusenoid deposit (SDD), soft drusen plus SDD, pachydrusen, and control groups. The diameter, length and intersections of Haller vessels and the total area, size and number of CC flow voids were quantified using en face optical coherence tomography (OCT) or OCT angiography. The pachydrusen group showed the largest Haller vessel area and diameter and shortest total length but similar CC parameters to those in the control group. The soft drusen plus SDD group showed the largest CC flow void area and size, while the Haller parameters were similar to those in the control group. The area and size of the flow voids in the SDD group were smaller than those in the soft drusen plus SDD group. Based on unsupervised machine learning, the eyes were classified into 4 clusters—the control, pachydrusen, soft drusen plus SDD and soft drusen plus SDD groups. Cluster 3 showed a larger diameter and shorter total length of the Haller vessels than cluster 4.

Validation of a Compensation Strategy Used to Detect Choriocapillaris Flow Deficits Under Drusen With Swept Source OCT Angiography

PURPOSE

A compensation strategy that was developed to measure the choriocapillaris (CC) flow deficits (FDs) under drusen was tested in eyes with large drusen from age-related macular degeneration (AMD) before and after the drusen spontaneously resolved without evidence of disease progression.

DESIGN

Prospective, observational consecutive case series.

METHODS

Patients with AMD were enrolled in a prospective swept-source optical coherence tomography (SS-OCT) imaging study. Consecutive eyes with large drusen were followed, and eyes that underwent spontaneous collapse of drusen without evidence of disease progression were identified retrospectively. The drusen-resolved regions were manually outlined. CC FDs were measured using a previously published compensation strategy that adjusted for the decreased signal intensity underlying drusen. Both the percentage of FDs (FD%) and the mean FD sizes (MFDSs) were measured before and after drusen resolution.

RESULTS

Resolution of drusen was identified in 8 eyes from 8 patients. The average interval between the 2 visits was 7.8 months. The average drusen volumes measured between visits were 0.23 and 0.04 mm³, respectively. After the drusen resolved, the average follow-up time without evidence of disease progression was 10.1 months. When the 2 visits were compared, there were no statistically significant differences in any of the CC parameters within the drusen resolved regions once the compensation strategy was applied (all P values >.22).

CONCLUSIONS

In this naturally occurring experiment in which drusen collapsed without evidence of disease progression, the CC parameters were similar once our compensation strategy was applied both before and after the drusen resolved.

The role of optical coherence tomography angiography in reticular pseudodrusen

BACKGROUND

To investigate the changes in retinal and choriocapillaris vessel density (VD) in patients effected by early age-related macular degeneration (AMD) and reticular pseudodrusen (RPD), using Optical Coherence Tomography Angiography (OCTA).

METHODS

A total of seventy-eight eyes of 78 patients (43 male, 35 female, mean age 72.61 ± 5.15) with non-neovascular AMD (38 eyes with early AMD and 40 eyes with RPD) was recruited in this observational prospective study. Forty eyes of 40 healthy subjects represented the control group. The VD was measured in superficial capillary plexus (SCP), deep capillary plexus (DCP) and choriocapillaris in different macular regions.

RESULTS

There were no significant differences in VD of the SCP and DCP among the controls and the two study groups (p > 0.05). The VD of the choriocapillaris revealed a statistically significant reduction in early AMD and RPD groups respect to controls (p < 0.001). Furthermore, the patients with RPD showed a significantly decreased VD respect to patients with early AMD in different macular regions (p < 0.001).

CONCLUSIONS

The quantitative analysis of retinal and choriocapillaris blood flow by OCTA provided useful information regarding the vascular changes in non-neovascular AMD patients suggesting that the choriocapillaris loss is mainly involved in the pathogenesis of RPD.

Macular Functional and Morphological Changes in Intermediate Age-Related Maculopathy

Purpose

The purpose of this study was to evaluate macular preganglionic function and to verify its relationship with retinal and choroidal morphology in patients with intermediate age-related macular degeneration (iAMD) patients.

Methods

All included patients performed multifocal electroretinogram (mfERG) for investigating on macular function from the central 15° of foveal eccentricity, spectral domain optical coherence tomography (SD-OCT) for studying retinal structure, enhanced depth imaging OCT (EDI-OCT) for the measure of choroidal vascularity index (CVI), and OCT-angiography (OCTA) for the evaluation of vessel density (VD) in the superficial and deep capillary plexus, and choriocapillaris (CC) layer.

Results

Twenty-seven patients with iAMD and 20 age-matched control eyes were analyzed. Significantly (P < 0.01) delayed and reduced mfERG responses in the central 0 to 2.5°, paracentral 2.5 to 5°, and overall 0 to 5° areas, as well as increased CVI values in both foveal (1 mm centered to the fovea) and fovea + parafovea areas (3 mm centered to the fovea), increased foveal and parafoveal (annular area of 1-3 mm centered to the fovea) retinal pigment epithelium thickness, and volume and parafoveal outer retinal volume were found in iAMD eyes as compared to controls. Moreover, iAMD eyes showed significantly (P < 0.01) reduced foveal and parafoveal OCTA-VD values in the CC layer when compared to controls. In the iAMD group, not significant (P > 0.01) correlations were found between morphological and functional parameters.

Conclusions

Our findings support a dysfunction of photoreceptors and bipolar cells in both foveal and parafoveal areas in the presence of outer retina, CC, and choroidal structural changes, however, not significantly correlated. The observed enlargement of luminal choroidal area (measured by CVI) is possibly compensatory to CC vascular insufficiency.

A novel TIMP3 mutation associated with a retinitis pigmentosa-like phenotype

BACKGROUND

Sorsby Fundus Dystrophy is an inherited macular degeneration caused by pathogenic variants in the TIMP3 gene. Clinical exam findings typically drusen -like deposits beneath the RPE or reticular pseudo drusen deposits above the RPE with a majority of patients developing choroidal neovascularization.

MATERIALS AND METHODS

Case report of two members of a family that present with atypical clinical exam findings. Protein modeling of the novel Y137CTIMP3 variant was performed and compared with other known variants.

RESULTS

In this study we describe a father and son initially diagnosed with retinitis pigmentosa of unknown genetic origin. More recent genetic testing of the patients, identified a novel c.410A>G; p.Tyr137Cys variant of uncertain clinical significance in the Tissue Inhibitor of Metalloproteinase-3 (TIMP3) gene. The atypical clinical findings led us to compare the theoretical molecular effects of this variant on the TIMP3 protein structure and interactions with other proteins using homology modeling and machine learning predictions.

CONCLUSIONS

It is important to consider mutations in TIMP3 in atypical cases of Retinitis Pigmentosa particularly in the absence of known variants.

Relationship between vascular densities of choriocapillaris and the whole choroid using OCTA

PURPOSE

To study the vascular density (VD) of choriocapillaris and the whole choroid using optical coherence tomography-angiography (OCTA).

METHODS

Cross-sectional study enrolling healthy individuals between 18 and 35 years old and with an axial length (AL) lower than 26 mm, who were examined with swept-source OCTA Triton DRI (Topcon). Color pictures of both VD were obtained from a fovea-centered 6 × 6 mm macular exam, which were divided into 900 squares and codified into numbers.

RESULTS

A total of 50 patients (100 eyes) with a mean age of 27.29 ± 3.90 years and a mean AL of 23.67 ± 0.74 mm were analyzed. The highest choroidal VD was found in juxtapapillary macula, being followed by the most temporal macula and fovea. The lowest was found in superior and inferior perifoveal areas. The highest VD in choriocapillaris was in the fovea. VD in this layer was uniform, with a decrease from temporal toward nasal. Both VD differed and but correlated, especially in the fovea and in inferior-temporal macula.

CONCLUSION

VD of choriocapillaris and the whole choroid are not similar. The former is maximal in the fovea, and the latter is maximal in the juxtapapillary macula. In general lines, choroidal VD is higher than that of choriocapillaris. Both VD are directly correlated.

FEATURES OF THE MACULAR AND PERIPAPILLARY CHOROID AND CHORIOCAPILLARIS IN EYES WITH NONEXUDATIVE AGE-RELATED MACULAR DEGENERATION

PURPOSE

We investigated macular and peripapillary choroidal thickness (CT) and flow voids in the choriocapillaris in eyes with nonexudative age-related macular degeneration.

METHODS

We retrospectively reviewed the medical records of patients with nonexudative age-related macular degeneration and classified their eyes into three categories: pachydrusen, drusen, and subretinal drusenoid deposit. Mean macular and peripapillary CT and choriocapillaris flow void area were compared among the three groups.

RESULTS

The three groups included 29, 33, and 33 patients, respectively. The mean macular and peripapillary CT findings were 260.64 ± 75.85 µm and 134.47 ± 46.28 µm for the pachydrusen group; 163.63 ± 64.08 µm and 93.47 ± 39.07 µm for the drusen group; and 95.33 ± 28.87 µm and 56.06 ± 11.64 µm for the subretinal drusenoid deposit group (all, P < 0.001). Mean macular and peripapillary flow void area varied among the subretinal drusenoid deposit group (57.07 ± 6.16% and 55.38 ± 6.65%), drusen group (58.30 ± 6.98% and 49.11 ± 9.11%) and pachydrusen group (50.09 ± 5.77% and 45.47 ± 8.06%) (all P < 0.001).

CONCLUSION

The peripapillary CT and flow voids in the choriocapillaris varied according to the features of drusen in nonexudative age-related macular degeneration eyes. Greater flow voids and thinner CT in eyes with subretinal drusenoid deposits may suggest that these eyes have diffuse choroidal abnormalities both in and outside the macula.

Correlations Between Different Choriocapillaris Flow Deficit Parameters in Normal Eyes Using Swept Source OCT Angiography

PURPOSE

Choriocapillaris (CC) imaging of normal eyes with swept-source optical coherence tomographic angiography (SS-OCTA) was performed, and the percentage of CC flow deficits (FD%) and the average area of CC flow deficits (FDa) were compared within the given macular regions.

DESIGN

A prospective, cross-sectional study.

METHODS

Subjects with normal eyes ranging in age from their 20s through their 80s were imaged with SS-OCTA (PLEX Elite 9000; Carl Zeiss Meditec, Dublin, California, USA) using both 3×3-mm and 6×6-mm macular scan patterns. The CC images were generated using a previously published and validated algorithm. In both 3×3-mm and 6×6-mm scans, the CC FD% and FDa were measured in circular regions centered on the fovea with diameters as 1 mm and 2.5 mm (C1 and C2.5). In 6×6-mm scans, the FD% and FDa were measured within an additional circular region with diameter as 5 mm (C5). The correlations between FD% and FDa from each region were analyzed with Pearson correlation coefficients.

RESULTS

A total of 164 eyes were analyzed. There was excellent correlation between CC FDa and FD% measurements from each region. In the 3×3-mm scans, the correlations in the C1 and C2.5 regions were 0.83 and 0.90, respectively. In the 6×6-mm scans, the correlations in C1, C2.5, and C5 regions were 0.90, 0.89, and 0.89, respectively.

CONCLUSIONS

When measuring CC FDs, we found excellent correlations between FDa and FD% in regions from 3×3-mm and 6×6-mm scans. Further studies are needed to determine if one parameter is more useful when studying diseased eyes.

Age-dependent Changes in the Macular Choriocapillaris of Normal Eyes Imaged With Swept-Source Optical Coherence Tomography Angiography

PURPOSE

Swept-source optical coherence tomography angiography (SS-OCTA) was used to measure the age-dependent changes in macular choriocapillaris (CC) flow deficits (FDs) in normal eyes.

DESIGN

A prospective, cross-sectional study.

METHODS

Subjects with normal eyes ranging in age from their 20s to their 80s were imaged using a 100-kHz SS-OCTA instrument (PLEX Elite 9000, Carl Zeiss Meditec, Dublin, California, USA). Both 3 × 3-mm and 6 × 6-mm scans were used to image the macular CC. Visualization of the CC and quantification of FDs were performed using a previously validated algorithm. The percentage of FDs (FD%) in the central 1-mm circle (C₁), 1.5-mm rim (R_1.5), and 2.5-mm circle (C_2.5) from the 3 × 3-mm and 6 × 6-mm scans and FD% in the 2.5-mm rim (R_2.5) and 5-mm circle (C₅) from the 6 × 6-mm scans were measured and correlated with age and axial length.

RESULTS

A total of 164 subjects were enrolled, with at least 10 subjects from each decade of life. No meaningful correlations were found between FD% and axial length (|r| < 0.30). FD% in all fields increased with increasing age (all r > 0.50; all P < .001); however, the greatest increases were found in the central macula C₁ regions and the smallest increases in the peripheral macula R_2.5 regions.

CONCLUSIONS

In normal aging, the FD% increased with age across the central 5 mm of the macula, but the greatest increase was found in the central 1-mm region of the macula.

Sorsby fundus dystrophy: Insights from the past and looking to the future

Sorsby fundus dystrophy (SFD), an autosomal dominant, fully penetrant, degenerative disease of the macula, is manifested by symptoms of night blindness or sudden loss of visual acuity, usually in the third to fourth decades of life due to choroidal neovascularization (CNV). SFD is caused by specific mutations in the Tissue Inhibitor of Metalloproteinase-3, (TIMP3) gene. The predominant histo-pathological feature in the eyes of patients with SFD are confluent 20-30 m thick, amorphous deposits found between the basement membrane of the retinal pigment epithelium (RPE) and the inner collagenous layer of Bruch's membrane. SFD is a rare disease but it has generated significant interest because it closely resembles the exudative or "wet" form of the more common age-related macular degeneration (AMD). In addition, in both SFD and AMD donor eyes, sub-retinal deposits have been shown to accumulate TIMP3 protein. Understanding the molecular functions of wild-type and mutant TIMP3 will provide significant insights into the patho-physiology of SFD and perhaps AMD. This review summarizes the current knowledge on TIMP3 and how mutations in TIMP3 cause SFD to provide insights into how we can study this disease going forward. Findings from these studies could have potential therapeutic implications for both SFD and AMD.

Choriocapillaris changes in dry age-related macular degeneration and geographic atrophy: a review

Age-related macular degeneration (AMD) is a leading cause of central vision loss worldwide. The progression of dry AMD from early to intermediate stages is primarily characterized by increasing drusen formation and adverse impact on outer retinal cells. Late stage AMD consists of either geographic atrophy (GA), the non-exudative (dry) AMD subtype, or choroidal neovascularization, the exudative (wet) AMD subtype. GA is characterized by outer retinal and choroidal atrophy, specifically the photoreceptor layer, RPE, and choriocapillaris. Much remains to be discovered regarding the pathogenesis of AMD progression and subsequent development of GA. As the functionality of all three layers is closely linked, the temporal sequence of events that end up in atrophy is important in the understanding of the pathogenic pathway of the disease. The advent of OCTA, and particularly of swept-source technology, has allowed for depth-resolved imaging of retinal vasculature and the choriocapillaris. With the use of OCTA, recent studies demonstrate that choriocapillaris flow alterations are closely associated with the development and progression of AMD. Such changes may even possibly offer predictive value in determining progression of GA. This article reviews studies demonstrating choriocapillaris changes in dry AMD and summarizes the existing literature on the potential role of the choriocapillaris as a key factor in the pathogenesis of AMD.