Morphologic Changes in Patients with Geographic Atrophy Assessed with a Novel Spectral OCT–SLO Combination

SUBRETINAL LIPID GLOBULES AN EARLY BIOMARKER OF MACULAR NEOVASCULARIZATION IN EYES WITH INTERMEDIATE AGE-RELATED MACULAR DEGENERATION

PURPOSE

To explore the association between subretinal lipid globules (SLGs) detected in eyes with intermediate age-related macular degeneration with the presence of nonexudative macular neovascularization.

METHODS

This was a retrospective analysis of 113 consecutive patients with bilateral intermediate age-related macular degeneration (226 eyes) followed for a least 6 months. All eyes underwent multimodal imaging with fundus autofluorescence, spectral-domain optical coherence tomography, and optical coherence tomography angiography. Subretinal lipid globules were identified on spectral-domain optical coherence tomography as round hyporeflective lesions measuring 31 to 157 µ m located between the ellipsoid zone and the retinal pigment epithelium/Bruch membrane complex. Nonexudative macular neovascularization was detected with optical coherence tomography angiography. The features of NE-MNV lesions detected in eyes with SLGs were compared with those in eyes without SLGs.

RESULTS

Subretinal lipid globules were identified in 15 eyes of which 14 eyes (93.3%) demonstrated NE-MNV on optical coherence tomography angiography. In the remaining 98 eyes without SLGs, 18 (18.4%) displayed NE-AMD on optical coherence tomography angiography. The macular neovascularization area was larger in the SLG subgroup (+0.38 vs. +0.21 mm 2 , P = 0.008) and showed faster horizontal growth (+727 µ m, CI 95% 250.4, 1,205.4) than MNV in eyes without SLGs (+64.9 µ m, CI 95%, 24.3, 154) on optical coherence tomography B-scans. After a mean of 11.6 months, the conversion rate to exudative MNV was similar between eyes with SLGs and those without SLGs [8/26 (38.5%) versus 3/13 (27.3%), P = 0.56)].

CONCLUSION

The detection of SLGs in eyes with intermediate age-related macular degeneration was strongly correlated with the presence of NE-MNV. Although these MNV lesions were larger and grew faster than NE-MNV detected in eyes lacking SLGs, the rates of conversion to exudative MNV appeared similar.

Exploring the pathogenesis of age-related macular degeneration: A review of the interplay between retinal pigment epithelium dysfunction and the innate immune system

Age-related macular degeneration (AMD) is a leading cause of irreversible vision loss in the older population. Classical hallmarks of early and intermediate AMD are accumulation of drusen, a waste deposit formed under the retina, and pigmentary abnormalities in the retinal pigment epithelium (RPE). When the disease progresses into late AMD, vision is affected due to death of the RPE and the light-sensitive photoreceptors. The RPE is essential to the health of the retina as it forms the outer blood retinal barrier, which establishes ocular immune regulation, and provides support for the photoreceptors. Due to its unique anatomical position, the RPE can communicate with the retinal environment and the systemic immune environment. In AMD, RPE dysfunction and the accumulation of drusen drive the infiltration of retinal and systemic innate immune cells into the outer retina. While recruited endogenous or systemic mononuclear phagocytes (MPs) contribute to the removal of noxious debris, the accumulation of MPs can also result in chronic inflammation and contribute to AMD progression. In addition, direct communication and indirect molecular signaling between MPs and the RPE may promote RPE cell death, choroidal neovascularization and fibrotic scarring that occur in late AMD. In this review, we explore how the RPE and innate immune cells maintain retinal homeostasis, and detail how RPE dysfunction and aberrant immune cell recruitment contribute to AMD pathogenesis. Evidence from AMD patients will be discussed in conjunction with data from preclinical models, to shed light on future therapeutic targets for the treatment of AMD.

Do biometric parameters improve the quality of optic nerve head measurements with spectral domain optical coherence tomography?

Background

Spectral domain optical coherence tomography (SD-OCT) is a widely applied non-invasive technique for evaluating optic nerve head parameters. The aim of this study was to evaluate the impact of biometric parameters such as the spherical equivalent (SE) and the anterior corneal curvature (ACC) on the peripapillary retinal nerve fiber layer (pRNFL), Bruch’s membrane opening (BMO), and the minimum rim width (MRW) measurements performed by spectral domain optical coherence tomography (SD-OCT) in glaucomatous and healthy eyes.

Methods

In this cross-sectional, case–control prospective pilot study, the glaucoma group consisted of 50 patients with previously diagnosed and treated glaucoma and one healthy group of 50 subjects. Two consecutive examinations of pRNFL, BMO, and MRW with SD-OCT for every patient were performed without ACC and objective refraction (imaging 1) and with them (imaging 2).

Results

The interclass correlation coefficient (ICC) reflected high agreement between imaging 1 and imaging 2 in both groups. The ICC in the glaucoma and healthy groups for pRNFL (0.99 vs. 0.98), BMO (0.95 vs. 0.97), and MRW (1.0 vs. 1.0) was comparable.

Conclusions

Our preliminary data from a small number of eyes showed that the measurements of pRNFL, MRW, and BMO reflected high agreement between both imaging techniques with ACC and objective refraction and without these parameters in subjects with a refractive error up to ± 6.0 diopters. Further studies with participants with higher refractive error are necessary to evaluate the impact of biometric parameters such as SE and ACC on measurements with SD-OCT.

Automated foveal location detection on spectral-domain optical coherence tomography in geographic atrophy patients

PURPOSE

To develop a fully automated algorithm for accurate detection of fovea location in atrophic age-related macular degeneration (AMD), based on spectral-domain optical coherence tomography (SD-OCT) scans.

METHODS

Image processing was conducted on a cohort of patients affected by geographic atrophy (GA). SD-OCT images (cube volume) from 55 eyes (51 patients) were extracted and processed with a layer segmentation algorithm to segment Ganglion Cell Layer (GCL) and Inner Plexiform Layer (IPL). Their en face thickness projection was convolved with a 2D Gaussian filter to find the global maximum, which corresponded to the detected fovea. The detection accuracy was evaluated by computing the distance between manual annotation and predicted location.

RESULTS

The mean total location error was 0.101±0.145mm; the mean error in horizontal and vertical en face axes was 0.064±0.140mm and 0.063±0.060mm, respectively. The mean error for foveal and extrafoveal retinal pigment epithelium and outer retinal atrophy (RORA) was 0.096±0.070mm and 0.107±0.212mm, respectively. Our method obtained a significantly smaller error than the fovea localization algorithm inbuilt in the OCT device (0.313±0.283mm, p <.001) or a method based on the thinnest central retinal thickness (0.843±1.221, p <.001). Significant outliers are depicted with the reliability score of the method.

CONCLUSION

Despite retinal anatomical alterations related to GA, the presented algorithm was able to detect the foveal location on SD-OCT cubes with high reliability. Such an algorithm could be useful for studying structural-functional correlations in atrophic AMD and could have further applications in different retinal pathologies.

Role of Optical Coherence Tomography Imaging in Predicting Progression of Age-Related Macular Disease: A Survey

In developed countries, age-related macular degeneration (AMD), a retinal disease, is the main cause of vision loss in the elderly. Optical Coherence Tomography (OCT) is currently the gold standard for assessing individuals for initial AMD diagnosis. In this paper, we look at how OCT imaging can be used to diagnose AMD. Our main aim is to examine and compare automated computer-aided diagnostic (CAD) systems for diagnosing and grading of AMD. We provide a brief summary, outlining the main aspects of performance assessment and providing a basis for current research in AMD diagnosis. As a result, the only viable alternative is to prevent AMD and stop both this devastating eye condition and unwanted visual impairment. On the other hand, the grading of AMD is very important in order to detect early AMD and prevent patients from reaching advanced AMD disease. In light of this, we explore the remaining issues with automated systems for AMD detection based on OCT imaging, as well as potential directions for diagnosis and monitoring systems based on OCT imaging and telemedicine applications.

Strongest Correlation Between Contrast Sensitivity and Morphological Characteristics in Bilateral nAMD

In patients with neovascular age-related macular degeneration (nAMD) there is often an inconsistency between their subjective visual impairment and a still relatively preserved standard Early Treatment of Diabetic Retinopathy Study (ETDRS) best corrected visual acuity. Therefore, in order to better capture the specific functional defects in nAMD, other tests need to be evaluated. In a previous study, we reported contrast sensitivity of the better eye to best correlate with near distance and distance vision related quality of life in patients with bilateral nAMD. Here, we evaluated Pelli-Robson contrast sensitivity, ETDRS visual acuity, low luminance visual acuity and Radner maximum reading speed and correlated them with several morphologic parameters as measured on fundus autofluorescence imaging, optical coherence tomography and optical tomography angiography in 54 patients. A multiple regression analysis was performed which correlated each visual function parameter with the anatomic features. The results showed the strongest correlations between the total area of macular geographic atrophy as well as the percentage of geographic atrophy in the central 1 mm and contrast sensitivity. Further, the regression model selected the total area of macular geographic atrophy, the photoreceptor inner and outer segments interface disruption score, the presence of subretinal fibrosis in the central 1 mm and the central retinal thickness as the variables that explained 71% of the variation in contrast sensitivity when including all eyes. Hence, our results suggest that among the evaluated measures of vision, contrast sensitivity is best correlated with the morphologic impairment in bilateral nAMD. Thus, contrast sensitivity may complement ETDRS visual acuity in clinical trials and serve as a standard diagnostic tool in clinical practice.

Relationship between morphological and vascular alterations in geographic atrophy using a multimodal imaging approach

PURPOSE

To assess geographic atrophy (GA) using a multimodal imaging approach, focusing on alterations at the level of the retinal pigment epithelium (RPE) and the choriocapillaris (CC) layers, by lesion demarcation, and assessment of morphological alterations within the atrophic area and in the transition zone.

METHODS

Fifty-seven eyes of 34 patients with atrophic age-related macular degeneration (AMD) were included in this prospective, observational, cross-sectional study. Multimodal imaging using wide-field polarization-sensitive optical coherence tomography (PS-OCT), optical coherence tomography angiography (OCT-A) and fundus autofluorescence (FAF) was performed. The images were overlaid and used to analyse and compare alterations in the retina and the CC.

RESULTS

Mean atrophic lesion size was 8.15 mm² (range: 2.23-17.23 mm² ). In 52 of 57 eyes (91%), OCT-A displayed focal hypodense areas at the CC level in the transition zone of GA, as well as increased focal depolarizing material (e.g. melanin-containing structures) showed in PS-OCT en face depolarizing material maps. These regions of increased depolarizing material at the transition zone corresponded to the hypodense areas on OCT-A scans. All 57 eyes presented with abnormal FAF patterns at the transition zone. All 57 eyes showed distinct alterations of CC flow pattern architecture. Six eyes (11%) demonstrated reduced and three eyes (5%) a complete loss of CC flow pattern architecture across the entire area of GA, while 48 of 57 eyes (84%) presented with irregular mixed patterns of different focal alterations of CC flow architecture within the area of GA. Reduced CC patterns exceeding GA lesion margins into the transitional zone were found in all eyes.

CONCLUSIONS

Optical coherence tomography angiography images revealed different degrees of flow impairment within the atrophic lesion area and its transition zone. Alterations in RPE morphology and tissue integrity resulting in accumulation of depolarizing material, such as melanin, could result in misinterpretation of OCT-A imaging in areas in the shadow of depolarizing material. These changes seem to be partially independent from autofluorescence altering processes.

Outer Retinal Thickness and Fundus Autofluorescence in Geographic Atrophy

PURPOSE

Most studies of fundus autofluorescence (FAF) in geographic atrophy (GA) have been nonquantitative, with inadequate registration of image modalities. Furthermore, as pointed out in the recent Consensus Definition for Atrophy Associated with Age-Related Macular Degeneration on OCT, it is unclear whether decreased FAF would be correlated exclusively with a single category of OCT-defined atrophy. We sought to determine how FAF intensity in eyes with GA correlates with structural changes of the outer retina and choroid as seen on co-registered spectral domain OCT (SD-OCT) images.

DESIGN

Retrospective cross-sectional.

PARTICIPANTS

Twenty eyes of 11 patients with GA secondary to non-neovascular age-related macular degeneration (AMD).

METHODS

Spectral domain OCT and FAF images for each eye were co-registered using MATLAB (MathWorks Inc, Natick, MA). On B-scans, the choroid, retinal pigment epithelium (RPE), photoreceptor (PR) layer, and outer nuclear layer (ONL) were segmented. Regions of interest (ROIs) including all atrophic and border regions were selected manually on the FAF scans. Regions of interest were subdivided into quartiles of FAF level to correlate with retinal thickness measurements taken along the B-scans. Mean choroid, RPE, PR, and ONL thicknesses were compared across quartiles using an analysis of variance factorial design testing for interaction effects, adjusted for repeated measures (on both eyes) with a within-subjects factor.

RESULTS

Seventeen eyes of 10 patients were selected for analysis. The mean choroidal thicknesses were not significantly different across FAF quartiles, but the overall differences in mean RPE, PR layer, and ONL thicknesses across quartiles were statistically significant (analysis of variance, P < 0.001, P < 0.001, and P = 0.015, respectively). Post hoc analysis demonstrated significant differences in thickness among quartiles 1, 2, and 3 for the RPE and PR layers (Tukey, P < 0.01 in each case). The FAF quartiles within GA did not correlate exclusively with single categories of Consensus Definition for Atrophy Associated with Age-Related Macular Degeneration-defined atrophy.

CONCLUSIONS

Not only RPE but also PR layer thickness on SD-OCT varies significantly with FAF levels in GA. This suggests that although the RPE cells are losing thickness and function, evidenced by decreased FAF from fluorophores, delicate PR cells also succumb early in the disease process. These relationships should be pursued as a possibly better-detailed mechanism in GA.

Correlations between Choriocapillaris Flow Deficits around Geographic Atrophy and Enlargement Rates Based on Swept-Source OCT Imaging

PURPOSE

To determine the possible correlation between the annual enlargement rates (ERs) of geographic atrophy (GA) with the percentage and size of the choriocapillaris (CC) flow deficits (FDs) surrounding GA, measured with swept-source OCT angiography (SS-OCTA) images.

DESIGN

Prospective, observational case series.

PARTICIPANTS

Patients with GA secondary to nonexudative AMD.

METHODS

Patients were imaged with a 100-kHz SS-OCTA instrument (PLEX Elite 9000, Carl Zeiss Meditec, Dublin, CA) using a 6×6-mm field of view scan pattern. The GA area measurements were obtained from en face SS-OCT sub-retinal pigment epithelium (RPE) slab images. Visualization of the CC and quantification of FDs were performed using a previously published validated algorithm based on a 20-μm thickness slab with the inner boundary located beneath Bruch's membrane. The percentage of CC FDs (FD%) and the average FD area measurements were calculated in different regions around the GA.

MAIN OUTCOME MEASURES

The correlation between the CC FDs and the ERs of GA.

RESULTS

Twenty-two eyes from 15 patients were eligible for the analysis. The annual square root ERs for GA ranged from 0.07 to 0.75 mm/year. The CC FD% and average FD area measurements were highly correlated with each other (P < 0.001), with the highest FD values found in the region closest to the margin of GA. The ERs correlated best with the average CC FD area measurements in the total scan area minus the area of GA (Pearson r = 0.747; P < 0.001) than those in the regions immediately surrounding the GA (r = 0.544; P = 0.009).

CONCLUSIONS

Contrary to expectations, the global CC FD measurements had a better correlation with the ERs of GA than those in the regions immediately around the GA. The most likely explanation for this outcome is that normal age-related increases in FDs within the central macula confound the correlations between the ERs of GA and FDs, whereas the regions furthest away from the margins of GA are less affected by normal age-related changes and reflect FD alterations related to AMD severity.

Sphingosine Kinase-1 Is Essential for Maintaining External/Outer Limiting Membrane and Associated Adherens Junctions in the Aging Retina

Sphingosine-1-phosphate (S1P) produced by sphingosine kinases (SPHK1 and SPHK2) is a signaling molecule involved in cell proliferation and formation of cellular junctions. In this study, we characterized the retinas of Sphk1 knockout (KO) mice by electron microscopy and immunocytochemistry. We also tested cultured Müller glia for their response to S1P. We found that S1P plays an important role in retinal and retinal pigment epithelial (RPE) structural integrity in aging mice. Ultrastructural analysis of Sphk1 KO mouse retinas aged to 15 months or raised with moderate light stress revealed a degenerated outer limiting membrane (OLM). This membrane is formed by adherens junctions between neighboring Müller glia and photoreceptor cells. We also show that Sphk1 KO mice have reduced retinal function in mice raised with moderate light stress. In vitro assays revealed that exogenous S1P modulated cytoskeletal rearrangement and increased N-cadherin production in human Müller glia cells. Aged mice also had morphological degeneration of the RPE, as well as increased lipid storage vacuoles and undigested phagosomes reminiscent of RPE in age-related macular degeneration. These findings show that SPHK1 and S1P play a vital role in the structural maintenance of the mammalian retina and retinal pigmented epithelium by supporting the formation of adherens junctions.

Fundus Autofluorescence in Age-related Macular Degeneration

: Fundus autofluorescence (FAF) provides detailed insight into the health of the retinal pigment epithelium (RPE). This is highly valuable in age-related macular degeneration (AMD) as RPE damage is a hallmark of the disease. The purpose of this paper is to critically appraise current clinical descriptions regarding the appearance of AMD using FAF and to integrate these findings into a chair-side reference. A wide variety of FAF patterns have been described in AMD, which is consistent with the clinical heterogeneity of the disease. In particular, FAF imaging in early to intermediate AMD has the capacity to reveal RPE alterations in areas that appear normal on funduscopy, which aids in the stratification of cases and may have visually significant prognostic implications. It can assist in differential diagnoses and also represents a reliable, sensitive method for distinguishing reticular pseudodrusen. FAF is especially valuable in the detection, evaluation, and monitoring of geographic atrophy and has been used as an endpoint in clinical trials. In neovascular AMD, FAF reveals distinct patterns of classic choroidal neovascularization noninvasively and may be especially useful for determining which eyes are likely to benefit from therapeutic intervention. FAF represents a rapid, effective, noninvasive imaging method that has been underutilized, and incorporation into the routine assessment of AMD cases should be considered. However, the practicing clinician should also be aware of the limitations of the modality, such as in the detection of foveal involvement and in the distinction of phenotypes (hypo-autofluorescent drusen from small areas of geographic atrophy).

Infrared reflectance imaging in age-related macular degeneration

PURPOSE

The purpose of this article is to describe the appearance of age-related macular degeneration (AMD) phenotypes using infrared (IR) reflectance imaging. IR reflectance imaging of the retina has the potential to highlight specific sub-retinal features and pathology. However, its role in macular disease, specifically AMD, is often underestimated and requires clarification.

RECENT FINDINGS

Recent advances in clinical methods, imaging and scientific knowledge may be integrated to improve the accuracy of disease stratification in AMD. In particular, IR imaging holds an underutilised sensitivity to detect reticular pseudodrusen, which have been repeatedly described as a high-risk sign for late AMD.

SUMMARY

This article provides clinically relevant descriptions of AMD phenotypes using IR reflectance imaging. The findings are integrated with images from cases seen at the Centre for Eye Health. As primary eye-care providers assume a critical role in the detection, diagnosis and management of AMD, we also provide a chair-side reference to assist clinicians in interpreting IR images in AMD.

Quantitative Characteristics of Spectral-Domain Optical Coherence Tomography in Corresponding Areas of Increased Autofluorescence at the Margin of Geographic Atrophy in Patients With Age-Related Macular Degeneration

BACKGROUND AND OBJECTIVE

To evaluate the spectral-domain optical coherence tomography (SD-OCT) characteristics of the junctional zone corresponding to areas of increased autofluorescence (IAF) at the margin of geographic atrophy (GA) in patients with age-related macular degeneration (AMD).

PATIENTS AND METHODS

SD-OCT and fundus autofluorescence (FAF) images from untreated eyes with GA available from archived studies at Doheny Image Reading Center were evaluated. Areas of definite decreased autofluorescence (DDAF) corresponding to GA, and areas of IAF at the margins of the GA were manually segmented. Eyes with evidence of IAF were selected. Following manual registration of FAF and OCT data, areas of IAF and normal fluorescence were correlated with OCT features at these locations.

RESULTS

Thirty eyes were included. The mean retinal pigment epithelium (RPE) thickness in areas of IAF was 40.6 µm ± 7.69 µm, compared to 28.8 µm ± 7.09 µm in normal adjacent areas (P < .001).

CONCLUSION

Regions of IAF at the junctional zone of GA lesions appear to correspond to thickening of the presumed RPE band on OCT. [Ophthalmic Surg Lasers Imaging Retina. 2016;47:523-527.].

Associations Between Retinal Pigment Epithelium and Drusen Volume Changes During the Lifecycle of Large Drusenoid Pigment Epithelial Detachments

Purpose

Drusenoid pigment epithelial detachments (PEDs) are a defined path to atrophy in age-related macular degeneration (AMD). We analyzed the relationships between retinal pigment epithelium (RPE) and drusen volume changes during the PED lifecycle, using spectral-domain optical coherence tomography (SD-OCT).

Methods

Twenty-one cases of drusenoid PED tracked using SD-OCT through periods of growth and collapse were evaluated. Volumetric calculations and piece-wise linear regression analysis were used to determine the breakpoint between growth and collapse. Spectral-domain OCT scans were independently evaluated for the appearance of intraretinal hyperreflective foci, acquired vitelliform lesions (AVLs), and disruptions to the RPE+basal lamina band. Timing of these events with respect to the breakpoint was statistically evaluated. Morphometric characteristics of drusenoid PEDs were correlated with rate of PED collapse and final visual acuity.

Results

Mean age of subjects was 75.3 years and mean period of follow up was 4.1 years (median 4.5 years; range, 0.6–6.6 years). The lifecycle of drusenoid PEDs was asymmetric, in that the rate of collapse (0.199 mm³/month) is significantly faster (P < 0.001) than the rate of growth (0.022 mm³/month). Appearance of intraretinal hyperreflective foci and AVLs preceded the breakpoint (both P < 0.001). The timing of disruptions to the RPE+basal lamina band did not differ from the breakpoint (P = 0.510). Maximal height, volume, and diameter of drusenoid PEDs were inversely correlated with final visual acuity (all P < 0.001) and positively correlated with the rate of PED collapse (all P < 0.001).

Conclusions

Spectral-domain OCT signatures, plausibly attributable to anteriorly migrated RPE and disintegration of the RPE layer, precede or occur simultaneously with changes in volume of drusenoid PED during the lifecycle of this lesion.

VISUALIZING RETINAL PIGMENT EPITHELIUM PHENOTYPES IN THE TRANSITION TO GEOGRAPHIC ATROPHY IN AGE-RELATED MACULAR DEGENERATION

PURPOSE

To inform the interpretation of clinical optical coherence tomography and fundus autofluorescence imaging in geographic atrophy (GA) of age-related macular degeneration by determining the distribution of retinal pigment epithelium (RPE) phenotypes in the transition from health to atrophy in donor eyes.

METHODS

In RPE-Bruch membrane flat mounts of two GA eyes, the terminations of organized RPE cytoskeleton and autofluorescent material were compared. In high-resolution histological sections of 13 GA eyes, RPE phenotypes were assessed at ±500 and ±100 μm from the descent of the external limiting membrane (ELM) toward Bruch membrane. The ELM descent was defined as curved, reflected, or oblique in shape. Thicknesses of RPE, basal laminar deposit (BLamD), and RPE plus BLamD were measured.

RESULTS

A border of atrophy that can be precisely delimited is the ELM descent, as opposed to the termination of the RPE layer itself, because of dissociated RPE in the atrophic area. Approaching the ELM descent, the percentage of abnormal RPE morphologies increases, the percentage of age-normal cells decreases, overall RPE thickens, and BLamD does not thin. The combination of RPE plus BLamD is 19.7% thicker at -100 μm from the ELM descent than that at -500 μm (23.1 ± 10.7 μm vs. 19.3 ± 8.2 μm; P = 0.05).

CONCLUSION

The distribution of RPE phenotypes at the GA transition supports the idea that these morphologies represent defined stages of a degeneration sequence. The idea that RPE dysmorphia including rounding and stacking helps explain variable autofluorescence patterns in GA is supported. The ELM descent and RPE plus BLamD thickness profile may have utility as spectral domain optical coherence tomography metrics in clinical trials.

Retinal Pigment Epithelium Degeneration Associated With Subretinal Drusenoid Deposits in Age-Related Macular Degeneration

PURPOSE

To test whether increased light transmission (hypertransmission) through subretinal drusenoid deposits (SDD) into the choroid in age-related macular degeneration (AMD) represented retinal pigment epithelium (RPE) degeneration.

DESIGN

Cross-sectional study.

METHODS

Nineteen eyes of 12 patients with early- to intermediate-stage AMD and 18 eyes of 12 normal subjects were evaluated with color fundus photography, optical coherence tomography (OCT), and high-resolution adaptive optics scanning laser ophthalmoscopy (AOSLO) at baseline and 24 months later. SDD were classified using an OCT-based 3-stage grading system. Hypertransmission beneath SDD into the choroid was examined in OCT. SDD microstructure was assessed with AOSLO. To characterize the hypertransmission-associated chorioretinal degeneration, choroidal thickness and photoreceptor length were measured in OCT at 1 mm and 2 mm superior, inferior, temporal, and nasal to the foveal center.

RESULTS

OCT disclosed hypertransmission beneath stage 3 SDD in 8 eyes. These lesions showed a distinctive regressing structure in AOSLO, compared with stage 3 lesions without hypertransmission. The phenomenon persisted at follow-up, and new hypertransmission developed as SDD advanced. In eyes with hypertransmission, choroids were thinner than those of normal eyes at all sites (by 44%-56%, P ≤ .0028) and those of eyes with SDD but without hypertransmission at superior and temporal sites (by 31%-46%, P ≤ .039). Photoreceptors were significantly shorter than those in normal eyes (by 6%-26%, P ≤ .0379).

CONCLUSIONS

Hypertransmission into the choroid, accompanied with SDD regression and thinning of choroid and photoreceptor layers, indicates RPE degeneration associated with advanced stages in the SDD life cycle.

LOSS OF EXTERNAL LIMITING MEMBRANE INTEGRITY PREDICTS PROGRESSION OF HYDROXYCHLOROQUINE RETINAL TOXICITY AFTER DRUG DISCONTINUATION

PURPOSE

To quantify external limiting membrane (ELM) disruption and photoreceptor volume over time, using spectral domain optical coherence tomography in eyes with hydroxychloroquine (HCQ) toxic effects after discontinuation.

METHODS

We performed a retrospective chart review of patients who were screened for toxic effects of HCQ between January 1, 2009 and August 31, 2014, and identified 10 patients diagnosed as having HCQ retinal toxic effects. Intact ELM and the Bruch membrane were manually traced using ImageJ software and their lengths from each scan of the spectral domain optical coherence tomography macular volume were summed. The ratio of intact ELM length/Bruch membrane length was calculated. We measured the two-dimensional photoreceptor area between the intact ELM and Bruch membrane in every cross-sectional B-scan. We calculated the total volume of photoreceptors in a volumetric OCT by multiplying photoreceptor area by the distance between B-scans.

RESULTS

Of the 10 patients (120 eyes), 1 eye was excluded because of the presence of vitreomacular traction. The mean cumulative dose of HCQ was 1,951 g (range, 584-3,650 g). The mean follow-up duration was 34.1 months (range, 11-64 months). Based on the extent of ELM integrity at diagnosis of HCQ toxicity, we classified eyes into 2 groups: 1) 12 eyes showed severe ELM disruption and 2) 7 eyes had intact ELM. All 19 eyes showed characteristic signs of HCQ toxicity on the visual field examination at the baseline. Seven of 12 eyes with ELM disruption showed progressive ELM changes, including 7 eyes that additionally developed progressive photoreceptor volume decline, whereas 5 eyes remained stable. All 7 eyes with intact ELM remained stable over time.

CONCLUSION

Intact ELM status at the time of HCQ discontinuation is a good prognostic sign, and ELM status may allow clinicians to predict patients at risk for progression of retinopathy. Quantitative measurements of ELM disruption and photoreceptors volume may provide an objective tool to monitor outer retinal changes due to HCQ.

Structural Characteristics of Retinal Layers Adjacent to Geographic Atrophy

BACKGROUND AND OBJECTIVE

To compare the anatomy of different retinal layers adjacent to areas of geographic atrophy (GA) to those of eyes with no known ocular diseases.

PATIENTS AND METHODS

Spectral-domain optical coherence tomography (SD-OCT) scans from eyes with GA were retrospectively reviewed. Two scans with no findings suggestive of GA changes on OCT were selected from immediately above and/or below the edge of the lesions. Thickness values of the retinal layers were calculated and compared to values obtained from normal subjects.

RESULTS

Forty-four eyes (30 patients) were compared to 20 healthy eyes. Retinal pigment epithelium (RPE), inner nuclear layer (INL), and full retinal thickness (FRT) values were significantly lower in patients compared to healthy subjects. Thicknesses of all other layers were not significantly different.

CONCLUSION

Clinically appearing, non-involved RPE and INL layers of eyes with GA demonstrate significant thinning compared to corresponding layers in eyes with no known ocular diseases.

Relating Retinal Morphology and Function in Aging and Early to Intermediate Age-related Macular Degeneration Subjects

PURPOSE

To evaluate relationships between age-related macular degeneration (AMD) morphology on spectral-domain optical coherence tomography (SDOCT) and visual function.

DESIGN

Cross-sectional, observational.

METHODS

From the Alabama Study on Early AMD baseline visit, visual acuity, cone-mediated sensitivity, rod-mediated dark adaptation, and SDOCT were obtained in 1 eye per subject with no apparent retinal aging (n = 15), normal aging (n = 15), early AMD (n = 15), and intermediate AMD (n = 46). The volumes of retinal pigment epithelium (RPE)-drusen complex, RPE-drusen complex abnormal thinning, RPE-drusen complex abnormal thickening, and inner and outer retina were calculated in specified regions using semi-automated SDOCT segmentation.

RESULTS

Better cone-mediated sensitivity was associated with greater RPE-drusen complex volume (r = 0.34, P < .001) and less RPE-drusen complex abnormal thinning volume (r = -0.31, P = .003). Longer rod-mediated dark adaptation time, the duration for rod-mediated sensitivity to recover from photo-bleach exposure, correlated with lower RPE-drusen complex volume (r = -0.34, P = .005) and greater RPE-drusen complex abnormal thinning volume (r = 0.280, P = .023). In 19 eyes with subretinal drusenoid deposits (SDD) vs 47 eyes without SDD, rod-mediated dark adaptation time was longer (mean ± SD 13.5 ± 7.0 vs 10.2 ± 3.1 minutes, P = .004), RPE-drusen complex abnormal thinning volume was greater (P < .0001), and visual acuity and cone sensitivity did not differ.

CONCLUSION

Decreased function relates to structural markers on SDOCT in AMD. Because the RPE-drusen complex includes the interdigitation of outer segments and RPE apical processes and SDD in eyes with AMD, slower dark adaptation might be related to structural abnormalities of the RPE, the RPE-photoreceptor interface, or both.

Ultrahigh-Speed, Swept-Source Optical Coherence Tomography Angiography in Nonexudative Age-Related Macular Degeneration with Geographic Atrophy

PURPOSE

To investigate ultrahigh-speed, swept-source optical coherence tomography (SSOCT) angiography for visualizing vascular changes in eyes with nonexudative age-related macular degeneration (AMD) with geographic atrophy (GA).

DESIGN

Observational, prospective, cross-sectional study.

PARTICIPANTS

A total of 63 eyes from 32 normal subjects and 12 eyes from 7 patients with nonexudative AMD with GA.

METHODS

A 1050-nm, 400-kHz A-scan rate SSOCT system was used to perform volumetric optical coherence tomography angiography (OCTA) of the retinal and choriocapillaris (CC) vasculatures in normal subjects and patients with nonexudative AMD with GA. Optical coherence tomography angiography using variable interscan time analysis (VISTA) was performed to assess CC alteration and differentiate varying degrees of CC flow impairment.

MAIN OUTCOME MEASURES

Qualitative comparison of retinal and CC vasculatures in normal subjects versus those in patients with a clinical diagnosis of nonexudative AMD with GA.

RESULTS

In all 12 eyes with GA, OCTA showed pronounced CC flow impairment within the region of GA. In 10 of the 12 eyes with GA, OCTA with VISTA showed milder CC flow impairment extending beyond the margin of GA. Of the 5 eyes exhibiting foveal-sparing GA, OCTA showed CC flow within the region of foveal sparing in 4 of the eyes.

CONCLUSIONS

The ability of ultrahigh-speed, swept-source OCTA to noninvasively visualize alterations in the retinal and CC vasculatures makes it a promising tool for assessing nonexudative AMD with GA. Optical coherence tomography angiography using VISTA can distinguish varying degrees of CC alteration and flow impairment and may be useful for elucidating disease pathogenesis, progression, and response to therapy.

Prognostic implications of imaging in atrophic macular degeneration and its use in clinical practice and clinical trial design

Clinical prognostic markers in atrophic age-related macular degeneration include the extent of existing atrophy, fundus autofluorescence (FAF) patterns and optical coherence tomography changes in the outer retina/retinal pigment epithelium interface. The prognostic implications of these findings may be used to determine not just the rate of disease progression but also influence the likelihood, magnitude and clinical relevance of therapy responses. FAF phenotypes have been extensively investigated; however, the pathophysiological mechanisms behind their appearance have not been fully elucidated. Optical coherence tomography imaging is additive to FAF imaging in atrophic age-related macular degeneration, allowing the visualization of detail not available through FAF imaging whilst also displaying subtle changes correlating with the FAF phenotypes themselves, thereby giving clues to their histological determinates. The developing understanding of these imaging modalities and consequent development of prognostically useful classification systems have widespread implication in clinical care and clinical trial design.

Optical coherence tomography difference maps and average macular volume for geographic atrophy

PURPOSE

To demonstrate the ability to monitor geographic atrophy (GA) volumetrically through all retinal layers with high-resolution optical coherence tomography difference maps and average macular volume.

METHODS

Observational case report.

RESULTS

Two patients diagnosed with GA were followed up for multiple years with consecutive high-resolution optical coherence tomography studies along with fundus photography and fluorescein angiography or fundus autofluorescence. Difference maps visually reflect macular thinning associated with expansion of GA witnessed on alternative studies. In addition, these maps show progressive macular thinning within previously delineated areas of GA. Average macular volume quantitatively demonstrates the decreasing volume associated with the expanding atrophy.

CONCLUSION

Difference maps and average macular volume allow quantitative analysis of GA and may be a useful tool for patient care and clinical trials.

Fundus Autofluorescence and RPE Lipofuscin in Age-Related Macular Degeneration

Genes that increase susceptibility to age-related macular degeneration (AMD) have been identified; however, since many individuals carrying these risk alleles do not develop disease, other contributors are involved. One additional factor, long implicated in the pathogenesis of AMD, is the lipofuscin of retinal pigment epithelium (RPE). The fluorophores that constitute RPE lipofuscin also serve as a source of autofluorescence (AF) that can be imaged by confocal laser ophthalmoscopy. The AF originating from lipofuscin is excited by the delivery of short wavelength (SW) light. A second autofluorescence is emitted from the melanin of RPE (and choroid) upon near-infrared (NIR-AF) excitation. SW-AF imaging is currently used in the clinical management of retinal disorders and the advantages of NIR-AF are increasingly recognized. Here we visit the damaging properties of RPE lipofuscin that could be significant when expressed on a background of genetic susceptibility. To advance interpretations of disease-related patterns of fundus AF in AMD, we also consider the photochemical and spectrophotometric features of the lipofuscin compounds responsible for generating the fluorescence emission.

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.

Metamorphopsia and letter recognition

Acuity is the most commonly used measure of visual function, and reductions in acuity are associated with most eye diseases. Metamorphopsia--a perceived distortion of visual space--is another common symptom of visual impairment and is currently assessed qualitatively using Amsler (1953) charts. In order to quantify the impact of metamorphopsia on acuity, we measured the effect of physical spatial distortion on letter recognition. Following earlier work showing that letter recognition is tuned to specific spatial frequency (SF) channels, we hypothesized that the effect of distortion might depend on the spatial scale of visual distortion just as it depends on the spatial scale of masking noise. Six normally sighted observers completed a 26 alternate forced choice (AFC) Sloan letter identification task at five different viewing distances, and the letters underwent different levels of spatial distortion. Distortion was controlled using spatially band-pass filtered noise that spatially remapped pixel locations. Noise was varied over five spatial frequencies and five magnitudes. Performance was modeled with logistic regression and worsened linearly with increasing distortion magnitude and decreasing letter size. We found that retinal SF affects distortion at midrange frequencies and can be explained with the tuning of a basic contrast sensitivity function, while object-centered distortion SF follows a similar pattern of letter object recognition sensitivity and is tuned to approximately three cycles per letter (CPL). The interaction between letter size and distortion makes acuity an unreliable outcome for metamorphopsia assessment.

The cellular origins of the outer retinal bands in optical coherence tomography images

PURPOSE

To test the recently proposed hypothesis that the second outer retinal band, observed in clinical OCT images, originates from the inner segment ellipsoid, by measuring: (1) the thickness of this band within single cone photoreceptors, and (2) its respective distance from the putative external limiting membrane (band 1) and cone outer segment tips (band 3).

METHODS

Adaptive optics-optical coherence tomography images were acquired from four subjects without known retinal disease. Images were obtained at foveal (2°) and perifoveal (5°) locations. Cone photoreceptors (n = 9593) were identified and segmented in three dimensions using custom software. Features corresponding to bands 1, 2, and 3 were automatically identified. The thickness of band 2 was assessed in each cell by fitting the longitudinal reflectance profile of the band with a Gaussian function. Distances between bands 1 and 2, and between 2 and 3, respectively, were also measured in each cell. Two independent calibration techniques were employed to determine the depth scale (physical length per pixel) of the imaging system.

RESULTS

When resolved within single cells, the thickness of band 2 is a factor of three to four times narrower than in corresponding clinical OCT images. The distribution of band 2 thickness across subjects and eccentricities had a modal value of 4.7 μm, with 48% of the cones falling between 4.1 and 5.2 μm. No significant differences were found between cells in the fovea and perifovea. The distance separating bands 1 and 2 was found to be larger than the distance between bands 2 and 3, across subjects and eccentricities, with a significantly larger difference at 5° than 2°.

CONCLUSIONS

On the basis of these findings, we suggest that ascription of the outer retinal band 2 to the inner segment ellipsoid is unjustified, because the ellipsoid is both too thick and proximally located to produce the band.

A longitudinal comparison of spectral-domain optical coherence tomography and fundus autofluorescence in geographic atrophy

PURPOSE

To identify reliable criteria based on spectral-domain optical coherence tomography (SD OCT) to monitor disease progression in geographic atrophy attributable to age-related macular degeneration (AMD) compared with lesion size determination based on fundus autofluorescence (FAF).

DESIGN

Prospective longitudinal observational study.

METHODS

setting: Institutional. study population: A total of 48 eyes in 24 patients with geographic atrophy. observation procedures: Eyes with geographic atrophy were included and examined at baseline and at months 3, 6, 9, and 12. At each study visit best-corrected visual acuity (BCVA), FAF, and SD OCT imaging were performed. FAF images were analyzed using the region overlay device. Planimetric measurements in SD OCT, including alterations or loss of outer retinal layers and the RPE, as well as choroidal signal enhancement, were performed with the OCT Toolkit. main outcome measures: Areas of interest in patients with geographic atrophy measured from baseline to month 12 by SD OCT compared with the area of atrophy measured by FAF.

RESULTS

Geographic atrophy lesion size increased from 8.88 mm² to 11.22 mm² based on quantitative FAF evaluation. Linear regression analysis demonstrated that results similar to FAF planimetry for determining lesion progression can be obtained by measuring the areas of outer plexiform layer thinning (adjusted R(2) = 0.93), external limiting membrane loss (adjusted R(2) = 0.89), or choroidal signal enhancement (R(2) = 0.93) by SD OCT.

CONCLUSIONS

SD OCT allows morphologic markers of disease progression to be identified in geographic atrophy and may improve understanding of the pathophysiology of atrophic AMD.

Optical coherence tomography-defined changes preceding the development of drusen-associated atrophy in age-related macular degeneration

PURPOSE

To characterize the pathological changes preceding the development of drusen-associated atrophy in eyes with age-related macular degeneration (AMD) using spectral-domain optical coherence tomography (SD-OCT).

DESIGN

Longitudinal and cross-sectional retrospective observational study.

PARTICIPANTS

A total of 181 participants with intermediate AMD in at least 1 eye (141 unilateral, 40 bilateral) were assessed longitudinally. A total of 230 participants with bilateral intermediate AMD (40 longitudinal participants with an additional 190 participants) were analyzed cross-sectionally.

METHODS

Spectral-domain OCT, color fundus photography (CFP), near-infrared reflectance, and fundus autofluorescence imaging were performed in all participants at cross-section and every 3 months for up to 30 months in the longitudinal study. Spectral-domain OCT volume scans were examined for features that portend the development of drusen-associated atrophy, and the topography, prevalence, and risk factors of these features were determined through cross-sectional analysis.

MAIN OUTCOME MEASURES

The pathological features on SD-OCT preceding the development of drusen-associated atrophy and the characteristics of these features.

RESULTS

Twenty areas from 16 eyes of 16 participants developed drusen-associated atrophy after an average of 20 months (range, 8-30 months). Spectral-domain OCT features unique in these areas included: subsidence of the outer plexiform layer (OPL) and inner nuclear layer (INL), and development of a hyporeflective wedge-shaped band within the limits of the OPL. These characteristics were termed "nascent geographic atrophy" (nGA), describing features that portend the development of drusen-associated atrophy. Cross-sectional examination of participants with bilateral intermediate AMD revealed that independent risk factors for the presence of nGA included the presence of pigmentary changes (odds ratio [OR], 16.84; 95% confidence interval [CI], 2.42-117.24) and nGA in the fellow eye (OR, 4.15; 95% CI, 1.12-15.34); nGA was present in 21.9% of participants with drusen >125 μm and pigmentary changes in both eyes.

CONCLUSIONS

This study identified pathological changes occurring before the development of drusen-associated atrophy using SD-OCT, which we defined as nGA. Although nGA is undetectable on CFP, it is important for determining the risk of future vision loss in AMD and could be used as an earlier surrogate end point in interventional trials targeting the early stages of AMD.

Geographic atrophy: a histopathological assessment

IMPORTANCE

Geographic atrophy (GA) is the major cause of blind registration in Western communities, although, with few exceptions, it is less common than choroidal neovascular disease. The variation of phenotype implies that age-related macular degeneration (AMD) does not follow the same course from one case to another and that phenotyping may be important before initiating a therapeutic trial.

OBJECTIVE

To document photoreceptor and retinal pigment epithelium (RPE) cell loss and other changes at the RPE-choroid interface in donated human eyes in which visual loss was deemed to be due to GA.

DESIGN, SETTING, AND PARTICIPANTS

Histological study of a consecutive series of eyes donated by individuals previously diagnosed clinically as having GA. Donors were chosen on the basis of available clinical records (from MidAmerica Transplant Services, St Louis, Missouri; the Iowa Lions Eye Bank, Iowa City; and the Utah Lions Eye Bank, Salt Lake City) and selected were those considered to have GA due to AMD. Tissues in the regions of atrophy were examined with light, electron, and autofluorescence microscopy.

RESULTS

In most of the 37 donors examined, there was marked loss of photoreceptor cells for variable distances distal from the edge of the GA. Rod loss was greater than cone loss. An inverse relationship existed between the quantity of autofluorescent inclusions in the RPE and the thickness of sub-RPE basal laminar deposit. Integrity of the choroid varied from one eye to another and was not related strictly to photoreceptor survival. In some eyes, photoreceptor loss existed in the absence of obvious morphological changes in the Bruch membrane or RPE.

CONCLUSIONS AND RELEVANCE

The findings support the view that photoreceptor loss occurs early in AMD in a proportion of cases and imply that photoreceptor-cell loss may contribute to the functional loss recorded in early stages of AMD at least in part. The variation of changes from one eye to another implies that patients selected for a specific prophylactic therapy for early AMD should be chosen on the basis of the characteristics of their disease.

The relationship between inner retinal cavitation, photoreceptor disruption, and the integrity of the outer limiting membrane in macular telangiectasia type 2

PURPOSE

The authors analyzed the relationship between the integrity of the outer limiting membrane (OLM) and the presence of inner retinal cavitation and photoreceptor disruption in eyes with macular telangiectasia Type 2 (MacTel Type 2).

METHODS

Cirrus optical coherence tomography images were analyzed with attention to the presence or absence of inner and outer retinal cavities, photoreceptor loss, or disruption and OLM integrity.

RESULTS

Ninety-seven eyes with MacTel Type 2 that were suitable for analysis were identified. The OLM was intact in all 48 eyes with inner retinal cavities without photoreceptor disruption. By contrast, the OLM was absent or disrupted in 8 of 10 eyes with photoreceptor disruption.

CONCLUSION

If Müller cell disruption contributes to inner retinal cavitation, it does not appear to affect the OLM, which is the only part of the Müller cell that is visible clinically. By contrast, the integrity of both the OLM and photoreceptors appear to be closely linked in MacTel Type 2. This observation is consistent with the hypothesis that Müller cell dysfunction plays a role in the pathogenesis of MacTel.

Semi-automatic geographic atrophy segmentation for SD-OCT images

Geographic atrophy (GA) is a condition that is associated with retinal thinning and loss of the retinal pigment epithelium (RPE) layer. It appears in advanced stages of non-exudative age-related macular degeneration (AMD) and can lead to vision loss. We present a semi-automated GA segmentation algorithm for spectral-domain optical coherence tomography (SD-OCT) images. The method first identifies and segments a surface between the RPE and the choroid to generate retinal projection images in which the projection region is restricted to a sub-volume of the retina where the presence of GA can be identified. Subsequently, a geometric active contour model is employed to automatically detect and segment the extent of GA in the projection images. Two image data sets, consisting on 55 SD-OCT scans from twelve eyes in eight patients with GA and 56 SD-OCT scans from 56 eyes in 56 patients with GA, respectively, were utilized to qualitatively and quantitatively evaluate the proposed GA segmentation method. Experimental results suggest that the proposed algorithm can achieve high segmentation accuracy. The mean GA overlap ratios between our proposed method and outlines drawn in the SD-OCT scans, our method and outlines drawn in the fundus auto-fluorescence (FAF) images, and the commercial software (Carl Zeiss Meditec proprietary software, Cirrus version 6.0) and outlines drawn in FAF images were 72.60%, 65.88% and 59.83%, respectively.

Association between fluorescein leakage and optical coherence tomographic characteristics of microaneurysms in diabetic retinopathy

PURPOSE

To evaluate the characteristics of microaneurysms seen on color fundus photography, fluorescein angiography, and spectral-domain optical coherence tomography in diabetic retinopathy.

METHODS

One hundred and thirty-two consecutive eyes of 92 patients with diabetic retinopathy were reviewed retrospectively. The characteristics of microaneurysms, including capsular structure (ring sign), hyperreflective spots in the lumen, the retinal layers in which they are located, and adjacent cystoid spaces, were documented on spectral-domain optical coherence tomography as sectional images. Their appearance on fundus photographs and focal fluorescein leakage were recorded. The association among these characteristics was evaluated.

RESULTS

Eighty-eight of 118 microaneurysms (74.6%) with no capsular structure had focal fluorescein leakage, whereas 7 of 34 microaneurysms (20.6%) with complete capsular structure had leakage (P < 0.001). Focal leakage from the microaneurysms correlated positively with hyperreflective spots in the lumen and nearby cystoid spaces (P = 0.013 and P < 0.001, respectively) but not in the layers in which they were located. Multicolored microaneurysms contained hyperreflective spots in the lumens more frequently than whitish or reddish spots (P = 0.038), compared with no significant associations between the appearance and the other optical coherence tomography characteristics.

CONCLUSION

Focal fluorescein leakage from microaneurysms was associated positively with the absence of a capsular structure, hyperreflective spots, and nearby cystoid spaces.

Mice lacking Period 1 and Period 2 circadian clock genes exhibit blue cone photoreceptor defects

Many aspects of retinal physiology are modulated by circadian clocks, but it is unclear whether clock malfunction impinges directly on photoreceptor survival, differentiation or function. Eyes from wild-type (WT) and Period1 (Per1) and Period2 (Per2) mutant mice (Per1(Brdm1) Per2(Brdm1) ) were examined for structural (histology, in vivo imaging), phenotypical (RNA expression, immunohistochemistry) and functional characteristics. Transcriptional levels of selected cone genes [red/green opsin (Opn1mw), blue cone opsin (Opn1sw) and cone arrestin (Arr3)] and one circadian clock gene (RORb) were quantified by real-time polymerase chain reaction. Although there were no changes in general retinal histology or visual responses (electroretinograms) between WT and Per1(Brdm1) Per2(Brdm1) mice, compared with age-matched controls, Per1(Brdm1) Per2(Brdm1) mice showed scattered retinal deformations by fundus inspection. Also, mRNA expression levels and immunostaining of blue cone opsin were significantly reduced in mutant mice. Especially, there was an alteration in the dorsal-ventral patterning of blue cones. Decreased blue cone opsin immunoreactivity was present by early postnatal stages, and remained throughout maturation. General photoreceptor differentiation was retarded in young mutant mice. In conclusion, deletion of both Per1 and Per2 clock genes leads to multiple discrete changes in retina, notably patchy tissue disorganization, reductions in cone opsin mRNA and protein levels, and altered distribution. These data represent the first direct link between Per1 and Per2 clock genes, and cone photoreceptor differentiation and function.

Multimodal adaptive optics retinal imager: design and performance

Optical coherence tomography (OCT) and scanning laser ophthalmoscopy (SLO) are complementary imaging modalities, the combination of which can provide clinicians with a wealth of information to detect retinal diseases, monitor disease progression, or assess new therapies. Adaptive optics (AO) is a tool that enables correction of wavefront distortions from ocular aberrations. We have developed a multimodal adaptive optics system (MAOS) for high-resolution multifunctional use in a variety of research and clinical applications. The system integrates both OCT and SLO imaging channels into an AO beam path. The optics and hardware were designed with specific features for simultaneous SLO/OCT output, for high-fidelity AO correction, for use in humans, primates, and small animals, and for efficient location and orientation of retinal regions of interest. The MAOS system was tested on human subjects and rodents. The design, performance characterization, and initial representative results from the human and animal studies are presented and discussed.

Retinal nerve fibre layer loss in hereditary spastic paraplegias is restricted to complex phenotypes

Background

Reduction of retinal nerve fibre layer (RNFL) thickness was shown as part of the neurodegenerative process in a range of different neurodegenerative pathologies including Alzheimer′s disease (AD), idiopathic Parkinson’s disease (PD), spinocerebellar ataxia (SCA) and multiple system atrophy (MSA). To further clarify the specificity of RNFL thinning as a potential marker of neurodegenerative diseases we investigated RNFL thickness in Hereditary Spastic Paraplegia (HSP), an axonal, length-dependent neurodegenerative pathology of the upper motor neurons.

Methods

Spectral domain optical coherence tomography (OCT) was performed in 28 HSP patients (clinically: pure HSP = 22, complicated HSP = 6; genetic subtypes: SPG4 = 13, SPG5 = 1, SPG7 = 3, genetically unclassified: 11) to quantify peripapillary RNFL thickness. Standardized examination assessed duration of disease, dependency on assistive walking aids and severity of symptoms quantified with Spastic Paraplegia Rating Scale (SPRS).

Results

HSP patients demonstrated no significant thinning of global RNFL (p_global = 0.61). Subgroup analysis revealed significant reduction in temporal and temporal inferior sectors for patients with complex (p<0.05) but not pure HSP phenotypes. Two of three SPG7-patients showed severe temporal and temporal inferior RNFL loss. Disease duration, age and severity of symptoms were not significantly correlated with global RNFL thickness.

Conclusion

Clinically pure HSP patients feature no significant reduction in RNFL, whereas complex phenotypes display an abnormal thinning of temporal and temporal inferior RNFL. Our data indicate that RNFL thinning does not occur unspecifically in all neurodegenerative diseases but is in HSP restricted to subtypes with multisystemic degeneration.

Modified protocol for in vivo imaging of wild-type mouse retina with customized miniature spectral domain optical coherence tomography (SD-OCT) device

This protocol outlines and evaluates a modified scanning procedure for a customized spectral domain optical coherence tomography (SD-OCT) imaging apparatus within the wild-type C57Bl/6 mouse posterior segment. This modified protocol allows for the capture of a 50 degree field of view spanning 3 mm by 3 mm perimeter with the optic disc as the central point. By utilizing this scanning protocol a more reliable measurement of retinal thickness can be achieved outside the fluctuating region of the optic disc. This protocol, when applied to this high resolution device, enables non-invasive in vivo histological imaging and biometric assessment of the various layers of the rodent posterior segment within a 20 - 30 min procedural time-frame. This protocol could establish a standardized method for evaluating morphological changes, with this commercial SDOCT device, when assessing longitudinal disease pathophysiology and treatment response in mouse models for future vision science research.

Morphologic changes in acute central serous chorioretinopathy using spectral domain optical coherence tomography

Purpose

To investigate morphologic changes of acute central serous chorioretinopathy (CSC) using spectral domain optical coherence tomography (SD-OCT) and confocal scanning laser ophthalmoscopy.

Methods

This retrospective study included 63 eyes of 63 patients with unilateral acute CSC. All patients underwent simultaneous SD-OCT and fluorescein angiography examination using Spectralis HRA+OCT.

Results

The external limiting membrane could be seen on SD-OCT, although the junction between photoreceptor inner and outer segments (IS/OS) was not detected in all eyes with retinal detachment (RD). However, IS/OS became visible after resolution of serous RD in 51 eyes (81.0%). SD-OCT images at the leakage sites showed a bump of retinal pigment epithelium (RPE) in in 47 cases (68.1%) and pigment epithelial detachment (PED) in 22 of 69 leakage sites (31.9%). In 14 of 69 leakage sites (20.3%), highly reflective areas suggesting fibrinous exudate were observed in the subretinal space. In nine leakage sites (13.0%), sagging or dipping of the posterior retinal layer was seen. Abnormal RPE changes such as RPE bump and PED were observed in 12 of 22 fellow eyes (54.5%).

Conclusions

A variety of morphologic changes could be identified on SD-OCT, and those findings may contribute more information to our understanding of the pathophysiology of CSC.

Relationship between perifoveal capillaries and pathomorphology in macular oedema associated with branch retinal vein occlusion

PURPOSE

To study the relationship between macular ischaemia on fluorescein angiography (FA) and pathomorphology at the foveal centre delineated by spectral-domain optical coherence tomography (OCT) in macular oedema (MO) associated with branch retinal vein occlusion (BRVO).

METHODS

One hundred and five consecutive eyes of 105 patients with MO (centre point thickness (CPT) ≥ 300 μm) associated with BRVO in which FA using Heidelberg Retinal Angiography 2 and Spectralis OCT were performed on the same day were retrospectively reviewed. We evaluated the foveal pathomorphology using OCT images and the association with macular ischaemia.

RESULTS

Within 1 year from symptom onset, 94 eyes were classified with perfused macula (34 eyes) or non-perfused macula (60 eyes). Eyes with perfused macula had better visual acuity and less CPT than those with non-perfused macula (P=0.024 and P<0.001, respectively). Fourteen eyes with perfused macula had serous retinal detachment (SRD) alone at the presumed foveal centre (SRD type); seven, a sponge-like swelling at that area (retinal swelling type); 11, foveal cystoid spaces alone (cystoid MO (CMO) type), and 2, with both SRD and foveal cystoid spaces (SRD+CMO type). However, 58 eyes with non-perfused macula had foveal cystoid spaces (42 of CMO type and 16 of SRD+CMO type), with a significant association between them (P<0.001). Among 11 eyes with symptoms exceeding 1 year, 6 eyes had perfused macula, and none had the SRD type.

CONCLUSION

Most eyes without foveal cystoid spaces have perfused macula in MO associated with BRVO.