Progression of geographic atrophy and impact of fundus autofluorescence patterns in age-related macular degeneration

Modeling Visual Acuity in Geographic Atrophy Secondary to Age-Related Macular Degeneration

Purpose: To analyze and model visual acuity (VA) in geographic atrophy (GA) secondary to age-related macular degeneration (AMD). Methods: The course of VA was analyzed using Turnbull's estimator in 226 eyes with uni- or bilateral GA due to AMD (151 patients; mean age 74.0 ± 7.6 years; mean follow-up time 33.4 ± 23.4 months) from the natural history FAM (Fundus-Autofluorescence Imaging in AMD) study. The variables ‘age at baseline', ‘gender', ‘lesion size', ‘diagnosis of the fellow eye', ‘status of the fovea', ‘focality of the lesion' and ‘pattern' were evaluated for effects on predicting VA using linear mixed-effects models. Results: Mean VA at baseline was 0.6 (Snellen 20/80) ± 0.4 logMAR [range -0.1 to 1.8 (20/17 to hand motions)], showing an estimated mean increase of 0.181 (95% CI 0.152-0.210) and 0.256 (0.214-0.300) after 2 and 4 years of follow-up, respectively. The percentage of eyes with a loss of ≥3 lines was 34% by 2 years and 47% by 4 years. Linear mixed model analysis suggested that 65% of VA variability could be explained by the assessed predictor variables. The strongest effect was found for the ‘status of the fovea' (0.69 logMAR units between ‘definitively spared fovea' and ‘definitive foveal involvement', p < 0.001). The second strongest effect was identified for ‘total lesion size' (effects between 0.02 and 0.09 logMAR units for each mm depending on foveal involvement, p < 0.001, square root transformed values). Conclusions: These findings underscore the importance of GA lesion characteristics as these have the strongest impact on VA. Natural history data and modeling VA to other variables will be helpful for refining outcome parameters and estimating possible benefits of therapeutic interventions.

Clinical applications of fundus autofluorescence in retinal disease

Fundus autofluorescence (FAF) is a non-invasive retinal imaging modality used in clinical practice to provide a density map of lipofuscin, the predominant ocular fluorophore, in the retinal pigment epithelium. Multiple commercially available imaging systems, including the fundus camera, the confocal scanning laser ophthalmoscope, and the ultra-widefield imaging device, are available to the clinician. Each offers unique advantages for evaluating various retinal diseases. The clinical applications of FAF continue to expand. It is now an essential tool for evaluating age related macular degeneration, macular dystrophies, retinitis pigmentosa, white dot syndromes, retinal drug toxicities, and various other retinal disorders. FAF may detect abnormalities beyond those detected on funduscopic exam, fluorescein angiography, or optical coherence tomography, and can be used to elucidate disease pathogenesis, form genotype-phenotype correlations, diagnose and monitor disease, and evaluate novel therapies. Given its ease of use, non-invasive nature, and value in characterizing retinal disease, FAF enjoys increasing clinical relevance. This review summarizes common ocular fluorophores, imaging modalities, and FAF findings for a wide spectrum of retinal disorders.

Impact of Wet Macular Degeneration on the Execution of Natural Actions

PURPOSE

To use eye movements to investigate how people with a central scotoma might be impaired in the execution of natural actions and whether task familiarity affects performance.

METHODS

Sixteen participants with AMD and 16 age-matched controls performed two natural actions: (1) a familiar sandwich-making task and (2) a less familiar model-building task. In each action, task-relevant and task-irrelevant objects were placed on a table, covering 90°. The participants were asked to execute the actions without a time constraint. Eye movements were recorded.

RESULTS

The people with AMD were significantly slower than the controls, both in the exploration phase (before the first reaching movement) and in the working phase (execution of action), especially in the unfamiliar task. Gaze duration was longer on relevant than irrelevant objects in both groups and tasks, as might be expected. However, for the participants with AMD, gaze durations were longer on all of the objects, whether relevant or irrelevant, except in the more familiar task. This suggests that participants with AMD take longer to extract the information they need but that this can be counteracted when the task items are familiar. The number of saccades/min of the task was significantly greater for the people with AMD than for the controls.

CONCLUSIONS

The present results show that people with AMD can accomplish natural actions efficiently, but need longer gaze durations and more eye movements than normally sighted people. This effect can be reduced when executing a familiar task.

Automated geographic atrophy segmentation for SD-OCT images using region-based C-V model via local similarity factor

Age-related macular degeneration (AMD) is the leading cause of blindness among elderly individuals. Geographic atrophy (GA) is a phenotypic manifestation of the advanced stages of non-exudative AMD. Determination of GA extent in SD-OCT scans allows the quantification of GA-related features, such as radius or area, which could be of important value to monitor AMD progression and possibly identify regions of future GA involvement. The purpose of this work is to develop an automated algorithm to segment GA regions in SD-OCT images. An en face GA fundus image is generated by averaging the axial intensity within an automatically detected sub-volume of the three dimensional SD-OCT data, where an initial coarse GA region is estimated by an iterative threshold segmentation method and an intensity profile set, and subsequently refined by a region-based Chan-Vese model with a local similarity factor. 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 quantitatively evaluate the automated segmentation algorithm. We compared results obtained by the proposed algorithm, manual segmentation by graders, a previously proposed method, and experimental commercial software. When compared to a manually determined gold standard, our algorithm presented a mean overlap ratio (OR) of 81.86% and 70% for the first and second data sets, respectively, while the previously proposed method OR was 72.60% and 65.88% for the first and second data sets, respectively, and the experimental commercial software OR was 62.40% for the second data set.

Randomized Trial to Evaluate Tandospirone in Geographic Atrophy Secondary to Age-Related Macular Degeneration: The GATE Study

PURPOSE

To determine the safety and efficacy of AL-8309B (tandospirone) in the management of patients with geographic atrophy (GA) secondary to age-related macular degeneration (AMD) and obtain standardized data on GA lesion growth progression.

DESIGN

Prospective, controlled, double-masked, randomized, multicenter phase 3 clinical trial.

METHODS

setting: Forty-eight clinical sites.

PATIENTS

Patients with GA associated with AMD were enrolled. All patients were followed for a minimum of 30 months, and up to 36 months. intervention procedures: Patients were randomized (1:1:1) to receive AL-8309B ophthalmic solution 1.0%, 1.75%, or vehicle, administered as a twice-daily topical ocular drop.

MAIN OUTCOME MEASURES

The primary efficacy endpoint was mean annualized lesion enlargement from baseline as assessed with fundus autofluorescence (FAF) imaging.

RESULTS

A total of 768 eyes of 768 patients were enrolled and treated with AL-8309B 1.0% (n = 250), AL-8309B 1.75% (n = 258), or vehicle (n = 260). An increase in mean lesion size was observed in both the AL-8309B and vehicle treatment groups, and growth rates were similar in all treatment groups. Annualized lesion growth rates were 1.73, 1.76, and 1.71 mm(2) for AL-8309B 1.0%, AL-8309B 1.75%, and vehicle, respectively.

CONCLUSIONS

AL-8309B 1.0% and 1.75% did not affect lesion growth in eyes with GA secondary to AMD. There were no clinically relevant safety issues identified for AL-8309B. The large natural history dataset from this study is a valuable repository for future comparisons.

Geographic atrophy in patients with advanced dry age-related macular degeneration: current challenges and future prospects

Geographic atrophy (GA) of the retinal pigment epithelium (RPE) is a devastating complication of age-related macular degeneration (AMD). GA may be classified as drusen-related (drusen-associated GA) or neovascularization-related (neovascular-associated GA). Drusen-related GA remains a large public health concern due to the burden of blindness it produces, but pathophysiology of the condition is obscure and there are no proven treatment options. Genotyping, cell biology, and clinical imaging point to upregulation of parainflammatory pathways, oxidative stress, and choroidal sclerosis as contributors, among other factors. Onset and monitoring of progression is accomplished through clinical imaging instrumentation such as optical coherence tomography, photography, and autofluorescence, which are the tools most helpful in determining end points for clinical trials at present. A number of treatment approaches with diverse targets are in development at this time, some of which are in human clinical trials. Neovascular-associated GA is a consequence of RPE loss after development of neovascular AMD. The neovascular process leads to a plethora of cellular stresses such as ischemia, inflammation, and dramatic changes in cell environment that further taxes RPE cells already dysfunctional from drusen-associated changes. GA may therefore develop secondary to the neovascular process de novo or preexisting drusen-associated GA may continue to worsen with the development of neovascular AMD. Neovascular-associated GA is a prominent cause of continued vision loss in patients with otherwise successfully treated neovascular AMD. Clearly, treatment with vascular endothelial growth factor (VEGF) inhibitors early in the course of the neovascular disease is of great clinical benefit. However, there is a rationale and some suggestive evidence that anti-VEGF agents themselves could be toxic to RPE and enhance neovascular-associated GA. The increasing prevalence of legal blindness from this condition due to the aging of the general population lends urgency to the search for a therapy to ameliorate GA.

Phase ii, randomized, placebo-controlled, 90-day study of emixustat hydrochloride in geographic atrophy associated with dry age-related macular degeneration

PURPOSE

This study assessed the safety, tolerability, and pharmacodynamics of emixustat hydrochloride (ACU-4429), a novel visual cycle modulator, in subjects with geographic atrophy associated with dry age-related macular degeneration.

METHODS

Subjects were randomly assigned to oral emixustat (2, 5, 7, or 10 mg once daily) or placebo (3:1 ratio) for 90 days. Recovery of rod photoreceptor sensitivity after a photobleach was measured by electroretinography. Safety evaluations included analysis of adverse events and ophthalmic examinations.

RESULTS

Seventy-two subjects (54 emixustat and 18 placebo) were evaluated. Emixustat suppressed rod photoreceptor sensitivity in a dose-dependent manner. Suppression plateaued by Day 14 and was reversible within 7 days to 14 days after drug cessation. Most systemic adverse events were not considered treatment related. Dose-related ocular adverse events (chromatopsia, 57% emixustat vs. 17% placebo and delayed dark adaptation, 48% emixustat vs. 6% placebo) were mild to moderate in severity, and the majority resolved on study or within 7 days to 14 days after study drug cessation. Reversibility of these adverse events with long-term administration, however, is undetermined.

CONCLUSION

In this Phase II study, emixustat produced a dose-dependent reversible effect on rod function that is consistent with the proposed mechanism of action. These results support further testing of emixustat for the treatment of geographic atrophy associated with dry age-related macular degeneration.

Natural History of Geographic Atrophy Progression Secondary to Age-Related Macular Degeneration (Geographic Atrophy Progression Study)

PURPOSE

The Geographic Atrophy Progression (GAP) study was designed to assess the rate of geographic atrophy (GA) progression and to identify prognostic factors by measuring the enlargement of the atrophic lesions using fundus autofluorescence (FAF) and color fundus photography (CFP).

DESIGN

Prospective, multicenter, noninterventional natural history study.

PARTICIPANTS

A total of 603 participants were enrolled in the study; 413 of those had gradable lesion data from FAF or CFP, and 321 had gradable lesion data from both FAF and CFP.

METHODS

Atrophic lesion areas were measured by FAF and CFP to assess lesion progression over time. Lesion size assessments and best-corrected visual acuity (BCVA) were conducted at screening/baseline (day 0) and at 3 follow-up visits: month 6, month 12, and month 18 (or early exit).

MAIN OUTCOME MEASURES

The GA lesion progression rate in disease subgroups and mean change from baseline visual acuity.

RESULTS

Mean (standard error) lesion size changes from baseline, determined by FAF and CFP, respectively, were 0.88 (0.1) and 0.78 (0.1) mm(2) at 6 months, 1.85 (0.1) and 1.57 (0.1) mm(2) at 12 months, and 3.14 (0.4) and 3.17 (0.5) mm(2) at 18 months. The mean change in lesion size from baseline to month 12 was significantly greater in participants who had eyes with multifocal atrophic spots compared with those with unifocal spots (P < 0.001) and those with extrafoveal lesions compared with those with foveal lesions (P = 0.001). The mean (standard deviation) decrease in visual acuity was 6.2 ± 15.6 letters for patients with image data available. Atrophic lesions with a diffuse (mean 0.95 mm(2)) or banded (mean 1.01 mm(2)) FAF pattern grew more rapidly by month 6 compared with those with the "none" (mean, 0.13 mm(2)) and focal (mean, 0.36 mm(2)) FAF patterns.

CONCLUSIONS

Although differences were observed in mean lesion size measurements using FAF imaging compared with CFP, the measurements were highly correlated with one another. Significant differences were found in lesion progression rates in participants stratified by hyperfluorescence pattern subtype. This large GA natural history study provides a strong foundation for future clinical trials.

Correlation between neovascular lesion type and clinical characteristics of nonneovascular fellow eyes in patients with unilateral, neovascular age-related macular degeneration

PURPOSE

To investigate the association between the type of neovascularization (NV) and the clinical characteristics of nonneovascular fellow eyes in patients with unilateral, neovascular age-related macular degeneration.

METHODS

Eighty-three patients with treatment-naive, unilateral, neovascular age-related macular degeneration were retrospectively analyzed. Neovascular lesions were classified using both fluorescein angiography and optical coherence tomography as Type 1 (subretinal pigment epithelium), 2 (subretinal), 3 (intraretinal), or mixed NV. The associations between NV lesion type and baseline clinical and imaging characteristics of the fellow eye, including central geographic atrophy, noncentral geographic atrophy, pigmentary changes, soft drusen, cuticular drusen, reticular pseudodrusen, and subfoveal choroidal thickness, were examined. Subfoveal choroidal thickness was defined as thin if thickness was <120 μm.

RESULTS

In the fellow eyes of patients with treatment-naive, unilateral, neovascular age-related macular degeneration, Type 3 NV had an increased adjusted odds ratio of reticular pseudodrusen (15.361, P < 0.001) and thin subfoveal choroidal thickness (21.537, P < 0.001) as well as a tendency toward an increased adjusted odds ratio of central geographic atrophy (4.775, P = 0.028). Fellow eyes of patients with Type 1 NV showed a decreased adjusted odds ratio of reticular pseudodrusen (0.233, P = 0.007) and thin subfoveal choroidal thickness (0.080, P = 0.005).

CONCLUSION

In patients with unilateral, neovascular age-related macular degeneration, certain nonneovascular features of the fellow eye correlate with the NV lesion composition based on type, as anatomically classified utilizing both fluorescein angiography and optical coherence tomography. Patients with Type 3 NV were more likely to have reticular pseudodrusen and/or thin subfoveal choroidal thickness in the fellow eye compared with those with Type 1 NV. Patients with Type 3 NV also showed a trend toward increased central geographic atrophy in the fellow eye.

Investigating the choriocapillaris and choroidal vasculature with new optical coherence tomography technologies

The body of knowledge of in vivo investigation of the choroid has been markedly enhanced by recent technological advances in optical coherence tomography (OCT). New insights elucidating the morphological features of the choriocapillaris and choroidal vasculature, in both physiological and pathological conditions, indicate that the choroid plays a pivotal role in many posterior segment diseases. In this article, a review of the histological characteristics of the choroid, which must be considered for the proper interpretation of in vivo imaging, is followed by a comprehensive discussion of fundamental principles of the current state-of-the-art in OCT, including cross-sectional OCT, en face OCT, and OCT angiography using both spectral domain OCT and swept source OCT technologies. A detailed review of the tomographic features of the choroid in the normal eye is followed by relevant findings in prevalent chorioretinal diseases, focusing on major causes of vision loss such as typical early and advanced age-related macular degeneration, polypoidal choroidal vasculopathy, central serous chorioretinopathy, pachychoroid spectrum disorders, diabetic choroidopathy, and myopia.

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.

The Project MACULA Retinal Pigment Epithelium Grading System for Histology and Optical Coherence Tomography in Age-Related Macular Degeneration

PURPOSE

To seek pathways of retinal pigment epithelium (RPE) fate in age-related macular degeneration via a morphology grading system; provide nomenclature, visualization targets, and metrics for clinical imaging and model systems.

METHODS

Donor eyes with geographic atrophy (GA) or choroidal neovascularization (CNV) and one GA eye with previous clinical spectral-domain optical coherence tomography (SDOCT) imaging were processed for histology, photodocumented, and annotated at predefined locations. Retinal pigment epithelial cells contained spindle-shaped melanosomes, apposed a basal lamina or basal laminar deposit (BLamD), and exhibited recognizable morphologies. Thicknesses and unbiased estimates of frequencies were obtained.

RESULTS

In 13 GA eyes (449 locations), 'Shedding,' 'Sloughed,' and 'Dissociated' morphologies were abundant; 22.2% of atrophic locations had 'Dissociated' RPE. In 39 CNV eyes (1363 locations), 37.3% of locations with fibrovascular/fibrocellular scar had 'Entombed' RPE; 'Sloughed,' 'Dissociated,' and 'Bilaminar' morphologies were abundant. Of abnormal RPE, CNV and GA both had ~35% 'Sloughed'/'Intraretinal,' with more Intraretinal in CNV (9.5% vs. 1.8%). 'Shedding' cells associated with granule aggregations in BLamD. The RPE layer did not thin, and BLamD remained thick, with progression. Granule-containing material consistent with three morphologies correlated to SDOCT hyperreflective foci in the previously examined GA patient.

CONCLUSIONS

Retinal pigment epithelium morphology indicates multiple pathways in GA and CNV. Atrophic/scarred areas have numerous cells capable of transcribing genes and generating imaging signals. Shed granule aggregates, possibly apoptotic, are visible in SDOCT, as are 'Dissociated' and 'Sloughed' cells. The significance of RPE phenotypes is addressable in longitudinal, high-resolution imaging in clinic populations. Data can motivate future molecular phenotyping studies.

Choroidal maps in non-exudative age-related macular degeneration

PURPOSE

To compare choroidal thickness maps (CMs) in patients with non-exudative age-related macular degeneration (AMD) and control subjects using swept source optical coherence tomography (Swept-OCT).

METHODS

CMs were automatically measured in the different Early Treatment of Diabetic Retinopathy Study (ETDRS) sectors in eyes with early non-exudative AMD (early AMD) (large soft drusen: group 1; reticular pseudodrusen: group 2 and variable combination of large soft drusen and reticular pseudodrusen: group 3), late non-exudative AMD/geographic atrophy (GA) (late AMD) (group 4) and control subjects (group 5). Fundus autofluorescence (FAF) images were overlaid to sectorial CMs in late-AMD group (group 4).

RESULTS

A total of 90 eyes (90 patients, 79.7±8.34 years old) were included. CMs were significantly reduced in early-AMD group 2 and 3 and late-AMD group 4 compared with control subjects in group 5 and early-AMD group 1 (large soft drusen alone) for each ETDRS sectors (p<0.05). No difference in CMs was found by comparing group 2 with 3 and group 2 and 3 with group 4. No statistical differences in CMs were found among ETDRS sectors with >50% absence of FAF ('Hypo FAF' sectors) resulting from retinal atrophy versus ≤50% absence of FAF ('hyper/iso FAF' sectors owing to >50% preserved retina) in late-AMD group (group 4) (p=0.328).

CONCLUSIONS

CMs appeared thinner in early non-exudative AMD with intermediate distribution of reticular pseudodrusen versus control subjects and early non-exudative AMD with drusen alone. Same results were found in the group with variable combination of large soft drusen and reticular pseudodrusen. In GA eyes, a choroidal thinning could be detected independently of the retinal pigmented epithelium status.

Bicyclic [3.3.0]-Octahydrocyclopenta[c]pyrrolo Antagonists of Retinol Binding Protein 4: Potential Treatment of Atrophic Age-Related Macular Degeneration and Stargardt Disease

Antagonists of retinol-binding protein 4 (RBP4) impede ocular uptake of serum all-trans retinol (1) and have been shown to reduce cytotoxic bisretinoid formation in the retinal pigment epithelium (RPE), which is associated with the pathogenesis of both dry age-related macular degeneration (AMD) and Stargardt disease. Thus, these agents show promise as a potential pharmacotherapy by which to stem further neurodegeneration and concomitant vision loss associated with geographic atrophy of the macula. We previously disclosed the discovery of a novel series of nonretinoid RBP4 antagonists, represented by bicyclic [3.3.0]-octahydrocyclopenta[c]pyrrolo analogue 4. We describe herein the utilization of a pyrimidine-4-carboxylic acid fragment as a suitable isostere for the anthranilic acid appendage of 4, which led to the discovery of standout antagonist 33. Analogue 33 possesses exquisite in vitro RBP4 binding affinity and favorable drug-like characteristics and was found to reduce circulating plasma RBP4 levels in vivo in a robust manner (>90%).

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.

Increased Fundus Autofluorescence and Progression of Geographic Atrophy Secondary to Age-Related Macular Degeneration: The GAIN Study

PURPOSE

To define the role of increased fundus autofluorescence (FAF), a surrogate for lipofuscin content, as a risk factor for progression of geographic atrophy (GA).

DESIGN

Prospective natural history cohort study, the GAIN (Characterization of geographic atrophy progression in patients with age-related macular degeneration).

METHODS

setting: Single-center study conducted in Barcelona, Spain.

PATIENTS

After screening of 211 patients, 109 eyes of 82 patients with GA secondary to age-related macular degeneration and a minimum follow-up of 6 months were included.

OBSERVATION PROCEDURES

Lipofuscin content was classified independently by 2 masked observers according to FAF patterns described previously. Bivariate, stratified, and multivariable analyses were used to explore the associations between GA growth and independent variables. Mediation analysis was used to evaluate the contribution of FAF patterns to GA progression.

MAIN OUTCOME

Progression of GA in mm(2)/year as measured with FAF.

RESULTS

Median follow-up was 18 months (range, 6-42). Median GA growth was 1.61 mm(2)/year. FAF, baseline area of atrophy, and time of follow-up were independently associated with GA progression (P < .004). FAF patterns and baseline area of atrophy were strongly associated (P < .0001), suggesting potential confounding. Mediation analysis suggested that most of the effect of FAF patterns on GA growth was actually caused by baseline area of atrophy.

CONCLUSIONS

FAF patterns, baseline area of atrophy, and time of follow-up were associated with GA progression. However, FAF patterns seem to be a consequence (not a cause) of enlarging atrophy and their effect on GA progression seems mostly driven by baseline area of atrophy.

Modeling Photo-Bleaching Kinetics to Create High Resolution Maps of Rod Rhodopsin in the Human Retina

We introduce and describe a novel non-invasive in-vivo method for mapping local rod rhodopsin distribution in the human retina over a 30-degree field. Our approach is based on analyzing the brightening of detected lipofuscin autofluorescence within small pixel clusters in registered imaging sequences taken with a commercial 488nm confocal scanning laser ophthalmoscope (cSLO) over a 1 minute period. We modeled the kinetics of rhodopsin bleaching by applying variational optimization techniques from applied mathematics. The physical model and the numerical analysis with its implementation are outlined in detail. This new technique enables the creation of spatial maps of the retinal rhodopsin and retinal pigment epithelium (RPE) bisretinoid distribution with an ≈ 50μm resolution.

Serum levels of lipid metabolites in age-related macular degeneration

Age-related macular degeneration (AMD) is a neurodegenerative disease that causes adult-onset blindness. There are 2 forms of this progressive disease: wet and dry. Currently there is no cure for AMD, but several treatment options have started to emerge making early detection critical for therapeutic success. Analysis of the eyes of Abca4(-/-)Rdh8(-/-) mice that display light-induced retinal degeneration indicates that 11-cis-retinal and docosahexaenoic acid (DHA) levels were significantly decreased as compared with the eyes of control dark-adapted C57BL/6J mice. In addition, exposure to intense light correlated with higher levels of prostaglandin G2 in the eyes of Abca4(-/-)Rdh8(-/-) mice. Intense light exposure also lowered DHA levels in the eyes of wild-type C57BL/6J mice without discernible retinal degeneration. Analysis of human serum from patients with AMD recapitulated these dysregulated DHA levels and revealed dysregulation of arachidonic acid (AA) levels as well (∼32% increase in patients with AMD compared with average levels in healthy individuals). From these observations, we then built a statistical model that included levels of DHA and AA from human serum. This model had a 74% probability of correctly identifying patients with AMD from controls. Addition of a genetic analysis for one of the most prevalent amino acid substitutions in the age-related maculopathy susceptibility 2 gene linked to AMD, Ala(69)→Ser, did not improve the statistical model. Thus, we have characterized a reliable method with the potential to detect AMD without a genetic component, paving the way for a larger-scale clinical evaluation. Our studies on mouse models along with the analysis of human serum suggest that our small molecule-based model may serve as an effective tool to estimate the risk of developing AMD.

Geographic atrophy in patients receiving anti-vascular endothelial growth factor for neovascular age-related macular degeneration

PURPOSE

To examine factors associated with the apparent growth of geographic atrophy (GA) in a consecutive series of eyes with treatment-naive neovascular age-related macular degeneration receiving intravitreal anti-vascular endothelial growth factor therapy on a treat-and-extend regimen.

METHODS

This was a retrospective cohort study. Two independent graders identified areas of GA using near-infrared reflectance imaging and spectral domain optical coherence tomography (SD-OCT). Neovascular lesion subtypes were classified based on fluorescein angiography (FA) as occult choroidal neovascularization, classic choroidal neovascularization, retinal angiomatous proliferation, or mixed choroidal neovascularization, and by the anatomical classification system which utilizes FA and SD-OCT as Types 1 (sub-retinal pigment epithelium), 2 (subretinal), 3 (intraretinal), or mixed neovascularization.

RESULTS

Ninety-one patients (94 eyes) fit the inclusion criteria, of which 52 eyes (55.3%) experienced apparent GA growth. The odds of developing apparent GA were significantly lower in Type 1 neovascularization compared to the other lesion types (P < 0.001). Using both FA and SD-OCT to classify neovascular age-related macular degeneration significantly improves the goodness of fit in the correlation between apparent GA growth and baseline neovascular lesion type (P < 0.001).

CONCLUSION

Treatment-naive neovascular age-related macular degeneration eyes with Type 1 neovascularization at baseline were less likely to develop GA than eyes with other types. The correlation between apparent GA growth and subtype of neovascularization is stronger when lesions are classified with an anatomic grading that utilizes both FA and SD-OCT.

The value of multifocal electroretinography to predict progressive visual acuity loss in early AMD

BACKGROUND

To investigate, in a prospective study, the role of multifocal electroretinography (mfERG) for predicting visual acuity decline in early age-related macular degeneration (AMD) with time.

METHODS

Twenty-six early AMD patients (12 males and 14 females, mean age 66.9 ± 9.8; range 46-82 years) were included in the study. A complete ophthalmic examination and mfERG (Retiscan, Roland Germany, ISCEV standard protocol) were performed at the study entry (baseline), after 20 and 24 months. The first-order kernel mfERG responses were analyzed by ring analysis. The amplitude density (AD) of the first positive peak (P1, nV/deg(2)), the P1 amplitude (µV) and P1 implicit time (ms) for Rings 1 (central) to 6 (most peripheral) were evaluated. Data were statistically analyzed by analysis of variance and receiver operating characteristic (ROC) curves.

RESULTS

The loss in the mfERG Ring 1 AD from normal control values, recorded at baseline, was correlated with the decrease in ETDRS visual acuity with time (P = 0.004). ROC analysis showed that, after 24 months, the average decline in visual acuity was greater (3 letters vs 0.4 letters, P = 0.0021) in patients whose Ring 1 P1 AD at baseline was equal to or less than 65.9 nV/deg(2), compared to those with higher AD values. Both P1 amplitude and AD of Ring 1 had an area under the curve of 0.702 (95% confidence interval 0.50-0.92) with a sensitivity of 64.3% (35.14-87.24%) and a specificity of 91.7% (61.52-99.79%).

CONCLUSIONS

The present results indicate that mfERG P1 amplitude and AD of Ring 1 may be highly specific to predict visual acuity decline in early AMD.

Pathogenic mechanisms and the prospect of gene therapy for choroideremia

INTRODUCTION

Choroideremia is a rare, X-linked disorder recognized by its specific ocular phenotype as a progressive degenerative retinopathy resulting in blindness. New therapeutic approaches, primarily based on genetic mechanisms, have emerged that aim to prevent the progressive vision loss.

AREAS COVERED

This article will review the research that has progressed incrementally over the past two decades from mapping to gene discovery, uncovering the presumed mechanisms triggering the retinopathy to preclinical testing of potential therapies.

EXPERT OPINION

While still in an evaluative phase, the introduction of gene replacement as a potential therapy has been greeted with great enthusiasm by patients, advocacy groups and the medical community.

Clinical and genetic factors associated with progression of geographic atrophy lesions in age-related macular degeneration

Worldwide, age-related macular degeneration (AMD) is a serious threat to vision loss in individuals over 50 years of age with a pooled prevalence of approximately 9%. For 2020, the number of people afflicted with this condition is estimated to reach 200 million. While AMD lesions presenting as geographic atrophy (GA) show high inter-individual variability, only little is known about prognostic factors. Here, we aimed to elucidate the contribution of clinical, demographic and genetic factors on GA progression. Analyzing the currently largest dataset on GA lesion growth (N = 388), our findings suggest a significant and independent contribution of three factors on GA lesion growth including at least two genetic factors (ARMS2_rs10490924 [P < 0.00088] and C3_rs2230199 [P < 0.00015]) as well as one clinical component (presence of GA in the fellow eye [P < 0.00023]). These correlations jointly explain up to 7.2% of the observed inter-individual variance in GA lesion progression and should be considered in strategy planning of interventional clinical trials aimed at evaluating novel treatment options in advanced GA due to AMD.

Directional Kinetics of Geographic Atrophy Progression in Age-Related Macular Degeneration with Foveal Sparing

PURPOSE

To describe the directional kinetics of the spread of geographic atrophy (GA) spread in eyes with age-related macular degeneration and foveal sparing.

DESIGN

Prospective, noninterventional natural history study: Fundus Autofluorescence Imaging in Age-Related Macular Degeneration (FAM; clinicaltrials.gov identifier, NCT00393692).

SUBJECTS

Participants of the FAM study exhibiting foveal sparing of GA.

METHODS

Eyes were examined longitudinally with fundus autofluorescence (FAF; excitation wavelength, 488 nm; emission wavelength, >500 nm) and near infrared (NIR) reflectance imaging (Spectralis HRA+OCT or HRA2; Heidelberg Engineering, Heidelberg, Germany). Areas of foveal sparing and GA were measured by 2 independent readers using a semiautomated software tool that allows for combined NIR reflectance and FAF image grading (RegionFinder; Heidelberg Engineering). A linear mixed effect model was used to model GA kinetics over time.

MAIN OUTCOME MEASURE

Change of GA lesion size over time (central vs. peripheral progression).

RESULTS

A total of 47 eyes of 36 patients (mean age, 73.8±7.5 years) met the inclusion criteria. Mean follow-up time was 25.2±16.9 months (range, 5.9-74.6 months). Interreader agreement for measurements of GA and foveal-sparing size were 0.995 and 0.946, respectively. Mean area progression of GA toward the periphery was 2.27±0.22 mm(2)/year and 0.25±0.03 mm(2)/year toward the center. Analysis of square root-transformed data revealed a 2.8-fold faster atrophy progression toward the periphery than toward the fovea. Faster atrophy progression toward the fovea correlated with faster progression toward the periphery in presence of marked interindividual differences.

CONCLUSIONS

The results demonstrate a significantly faster centrifugal than centripetal GA spread in eyes with GA and foveal sparing. Although the underlying pathomechanisms for differential GA progression remain unknown, local factors may be operative that protect the foveal retina-retinal pigment epithelial complex. Quantification of directional spread characteristics and modeling may be useful in the design of interventional clinical trials aiming to prolong foveal survival in eyes with GA.

[Forms of age-related macular degeneration]

Age-related macular degeneration (AMD) is the major reason for blindness affecting about 50 % of blind people in Germany. Early forms of AMD with drusen and pigment epithelium changes can be detected in 20 % of patients over 65 years old. The dry form of AMD causes slow deterioration of visual acuity, which cannot currently be adequately treated. In contrast development of a choroidal neovascularization (CNV) membrane results in rapid visual loss which will become permanent if treatment is not started immediately. Using anti-vascular endothelial growth factor (VEGF) agents stabilization and improvement of visual acuity is possible. Special types of AMD, such as retinal angiomatous proliferation and polypoidal choroidal vasculopathy are much less common. The natural course of the diseases can be very different, end stages often result in scarring and anti-VEGF agents are only weakly effective.

Significance of the hyperautofluorescent ring associated with choroidal neovascularisation in eyes undergoing anti-VEGF therapy for wet age-related macular degeneration

AIM

To characterise the presence of a hyperautofluorescent (HAF) ring associated with choroidal neovascularisation (CNV) complex in patients with wet age-related macular degeneration (AMD).

METHODS

Fundus autofluorescence images and spectral-domain optical coherence tomography (OCT) scans from 362 eyes with wet AMD were reviewed. The presence and size of an HAF ring associated with the CNV complex was evaluated. A subgroup of 64 treatment-naive eyes with new-onset CNV was studied to analyse the relationship between pretreatment OCT characteristics and the presence of the HAF ring.

RESULTS

An HAF ring was present in 38% of the entire cohort of eyes and in 39% of treatment-naive eyes. The presence of the HAF ring was significantly correlated with the extent of baseline subretinal fluid (SRF) on OCT (p=0.0113), the number of antivascular endothelial growth factor (VEGF) injections (p=0.0439) and the number of treatment cycles (p=0.0154). Eyes with an HAF ring were more likely to have disruption of the ellipsoid zone line once the SRF was resolved compared with eyes without an HAF ring (p=0.0002). In multivariate analysis, the best predictors for HAF ring were the baseline area of SRF (p=0.0449) and the number of anti-VEGF treatments received (p=0.0568).

CONCLUSIONS

Nearly 40% of wet AMD eyes had an HAF ring. In treatment-naive eyes, the HAF ring had a significant association with SRF and was found as early as the baseline measurement and as long as 18 months after beginning treatment, persisting for up to 6 years after the initial diagnosis. Its association with baseline SRF and disruption of the ellipsoid zone line of the photoreceptors on OCT could indicate continuous stress on the outer retinal structures after exposure to prolonged SRF and/or transmitted autofluorescence from loss of the photoreceptors overlying the retinal pigment epithelium.

Spectral-domain optical coherence tomography and fundus autofluorescence evaluation of torpedo maculopathy

The authors describe the spectral-domain optical coherence tomography and fundus autofluorescence findings in a case of torpedo maculopathy. Spectral-domain optical coherence tomography revealed loss or disruption of the retinal pigment epithelium and overlying disruption of the outer neurosensory retina. Fundus autofluorescence revealed reduced fundus autofluorescence of the lesion surrounded by a rim of increased fundus autofluorescence.

Progressing geographic atrophy: choroidal thickness and retinal sensitivity identify two clinical phenotypes

PURPOSE

To analyse changes in choroidal thickness and retinal sensitivity (Se) in patients with geographic atrophy (GA) with or without choroidal neovascularisation (CNV) in the fellow eye.

PARTICIPANTS

Patients with bilateral GA (B-GA group) and patients with unilateral GA and CNV in the fellow eye (U-GA group) were followed every 6 months, and enhanced depth imaging optical coherence tomography (OCT), blue and near infrared-wavelength fundus autofluorescence (B- and NIR-FAF), and microperimetry were evaluated.

METHODS

GA area, choroidal thickness, and Se were measured in the eye with GA at baseline and every 6 months up to the last follow-up visit.

RESULTS

19 patients (8 in the B-GA group (16 eyes) and 11 in the U-GA group (11 eyes)) were studied. The mean±SD follow-up was 1.66±0.71 years (range 0.74-2.60 years) in the U-GA group, and 1.51±0.86 years (range 0.58-2.95 years) in the B-GA group (p=0.6766). Mean GA area was not significantly different between groups at baseline (p=0.4118 in the B-FA and p=0.6806 in the NIR-FAF) or at follow-up (p=0.5734 in the B-FAF and p=0.8945 in the NIR-FAF). Mean GA area significantly increased in both groups during follow-up (p=0.0050 for B-FAF and p=0.0052 for NIR-FAF in the U-GA group; p=0.0049 for B-FAF and p=0.0072 for NIR-FAF in the B-GA group). Choroidal thickness was significantly greater in the B-GA group compared with the U-GA group both at baseline (mean choroidal thickness 170.5±78.5 μm vs 129.1±36.1 μm; p=0.0371) and at last follow-up (173.2±86.1 μm vs 123±32.1 μm; p=0.0340). During follow-up mean choroidal thickness significantly decreased only in the U-GA group (p=0.0276); conversely mean Se significantly decreased only in B-GA group (p=0.0405).

CONCLUSIONS

During follow-up, changes in Se and choroidal thickness differed in patients with GA with or without CNV in the fellow eye. These results identify at least two GA phenotypes, in which the development and progression of GA may be primarily due to different pathophysiologic mechanisms.

Fundus autofluorescence characteristics of nascent geographic atrophy in age-related macular degeneration

PURPOSE

We examined the fundus autofluorescence (FAF) characteristics of nascent geographic atrophy (nGA), pathological features preceding the development of drusen-associated atrophy in eyes with age-related macular degeneration (AMD) that can be visualized using high-resolution optical coherence tomography (OCT).

METHODS

Spectral-domain OCT (SD-OCT) and FAF imaging were performed longitudinally in 221 eyes with intermediate AMD (having at least drusen >125 μm), and seven areas that developed drusen-associated atrophy in five eyes were examined and categorized with respect to FAF characteristics. These categories then were used to characterize 49 areas of nGA or drusen-associated atrophy on SD-OCT identified in a cross-sectional study with 230 participants with bilateral intermediate AMD.

RESULTS

Sequential imaging revealed that FAF characteristics in the atrophic areas could be grouped into three categories: predominantly hyperautofluorescent (hyperAF), presence of both hyper- and hypoautofluorescence (mixed AF), or predominantly hypoautofluorescent (hypoAF). In the cross-sectional study, the FAF characteristics were significantly dependent on the type of atrophic area (P = 0.002), where areas of nGA appeared most commonly as being mixed AF (63%), while areas of drusen-associated atrophy most commonly as hypoAF (86%).

CONCLUSIONS

Fundus autofluorescence imaging revealed that areas of nGA were most commonly characterized by both hyper- and hypoautofluorescent changes, which differs from areas of drusen-associated atrophy that most often appeared hypoautofluorescent. These findings provide important insights into the FAF characteristics of areas undergoing atrophic changes in eyes still considered to be in the early stages of AMD by current methods, and thus assist in the characterization of disease severity in these early stages.

Widespread choroidal thickening and abnormal midperipheral fundus autofluorescence characterize exudative age-related macular degeneration with choroidal vascular hyperpermeability

Purpose

To investigate the clinical findings that characterize exudative age-related macular degeneration (AMD) with choroidal vascular hyperpermeability (CVH).

Design

Retrospective comparative study.

Participants

Forty-eight consecutive patients attending the outpatient clinic of Tokyo University Hospital between May 2013 and July 2013.

Methods

The presence or absence of CVH was determined with indocyanine green angiography performed at the latest visit. When CVH was observed, the eye was categorized as CVH(+) AMD, otherwise it was categorized as CVH(-) AMD. Using high-penetration optical coherence tomography, we measured choroidal thickness at the fovea and at four midperipheral areas (mean choroidal thickness at points on 6- and 9-papilla diameter circles superior, inferior, temporal, and nasal to the fovea). Ultrawide field retinal imaging was used to investigate abnormalities in midperipheral fundus autofluorescence (FAF). Choroidal thickness and the proportion of FAF abnormalities were compared between the CVH(+) AMD and CVH(−) AMD eyes and between eyes with polypoidal choroidal vasculopathy and typical AMD. Multiple regression analysis was used to control for treatment history and other characteristics.

Results

CVH was observed in 17 cases. Choroidal thickness was higher in the CVH(+) AMD eyes than in the CVH(−) AMD eyes at the fovea (325 μm versus 229 μm, respectively; P=0.0010, t-test), superior point (277 μm versus 215 μm, respectively; P=0.0021, t-test), inferior point (225 μm versus 161 μm, respectively; P=0.0002, t-test), and nasal point (202 μm versus 165 μm, respectively; P=0.042, t-test). The significance was maintained after controlling for possible confounders. The choroid was thicker at the fovea and at the inferior point in polypoidal choroidal vasculopathy than in typical AMD. The rate of midperipheral FAF abnormality was significantly higher in the CVH(+) AMD eyes than in the CVH(−) AMD eyes (82% versus 48%, respectively; P=0.031).

Conclusion

AMD with CVH is associated with widespread choroidal thickening and peripheral FAF abnormalities.

Subretinal injection of amyloid-β peptide accelerates RPE cell senescence and retinal degeneration

Drusen are considered a hallmark characteristic of age-related macular degeneration (AMD). In our previous study, we found that amyloid-β (Aβ) peptide, a component of drusen, induced the cells of the retinal pigment epithelium (RPE; RPE cells) to enter senescence; however, its effects in vivo remain unknown. Thus, the present study was carried out to explore the in vivo effects of Aβ peptide on RPE cell senescence and senescence-associated inflammation in C57BL/6 mice. C57BL/6 mice received a subretinal injection of Aβ(1-42) peptide; on day 7 post-injection, the mice were anesthetized and subjected to whole-body perfusion with 4% paraformaldehyde (PFA) in PBS and the whole eyes were then enucleated. Retinal function was assessed by electroretinography (ERG), and the morphological characteristics of the retina were examined by light and electron microscopy. Fundus autofluorescence (FAF) was examined by confocal scanning laser ophthalmoscopy (cSLO). The expression of p16INK4a, a marker of cellular senescence, was examined by immunofluorescence staining and western blot analysis. The RPE-choroid was analyzed for cytokine expression by RT-PCR. In Aβ(1-42)-injected mice, scotopic ERG responses declined. Degenerative alterations, including the disruption of the inner segment (IS)/outer segment (OS) junction and extensive vacuolation and thickness of Bruch's membrane (BrM) were observed under a a light microscope. The accumulation of vacuoles and the loss of basal infoldings in the RPE were identified using an electron microscope. FAF and p16INK4a expression increased in Aβ(1-42)-injected mice. In addition, Aβ(1-42) upregulated interleukin (IL)-6 and IL-8 gene expression in the RPE-choroid. In conclusion, our results confirm the effects of Aβ(1-42) peptide on RPE senescence in vivo. The Aβ-injected mice developed AMD-like ocular pathology. It is thus suggested that RPE cell senescence is a potential mechanistic link between inflammation and retinal degeneration.

Phase 1, dose-ranging study of emixustat hydrochloride (ACU-4429), a novel visual cycle modulator, in healthy volunteers

BACKGROUND

Emixustat hydrochloride (formerly ACU-4429) is a nonretinoid compound with a unique mode of action in the retinal pigment epithelium, where it modulates the biosynthesis of visual chromophore through its effect on retinal pigment epithelium-specific 65 kDa protein isomerase. This study provides clinicians with a background for understanding the pharmacokinetics and safety profile of orally administered emixustat.

METHODS

This randomized, double-masked, placebo-controlled Phase 1b study evaluated the pharmacokinetics, tolerability, and safety of a 14-day course of oral emixustat (5, 10, 20, 30, or 40 mg) or placebo (3:1 ratio) once daily in healthy volunteers.

RESULTS

A total of 40 subjects were enrolled (mean age, 38 years; 75% male). Emixustat (n = 30) was rapidly absorbed (median T(max), 3.0-5 hours) and readily eliminated (mean t(1/2), 4.6-7.9 hours), and mean C(max) and AUC(0-24) generally increased in proportion to dose. No significant accumulation of emixustat was observed with multiple-dose administration. Ocular adverse events occurred in 67% of the subjects who received emixustat; all were considered mild and resolved after study completion. Systemic adverse events were minimal.

CONCLUSION

Oral emixustat was safe and well tolerated when administered once daily for 14 days with minimal systemic adverse events reported. These data support evaluation of emixustat in subjects with geographic atrophy associated with dry age-related macular degeneration.

Multifocal electroretinography in subjects with age-related macular degeneration

PURPOSE

To evaluate retinal function objectively in subjects with different stages of age-related macular degeneration (AMD) using multifocal electroretinography (mfERG) and compare it with age-matched control group.

METHODS

A total of 42 subjects with AMD and 37 age-matched healthy control group aged over 55 years were included in this prospective study. mfERG test was performed to all subjects. Average values in concentric ring analysis in four rings (ring 1, from 0° to 5° of eccentricity relative to fixation; ring 2, from 5° to 10°; ring 3, from 10° to 15°; ring 4, over 15°) and in quadrant analysis (superior nasal quadrant, superior temporal quadrant, inferior nasal quadrant and inferior temporal quadrant) were recorded. Test results were evaluated by one-way ANOVA test and independent samples t test.

RESULTS

In mfERG concentric ring analysis, N1 amplitude, P1 amplitude and N2 amplitude were found to be lower and N1 implicit time, P1 implicit time and N2 implicit time were found to be delayed in subjects with AMD compared to control group. In quadrant analysis, N1, P1 and N2 amplitude was lower in all quadrants, whereas N1 implicit time was normal and P1 and N2 implicit times were prolonged in subjects with AMD.

CONCLUSION

mfERG is a useful test in evaluating retinal function in subjects with AMD. AMD affects both photoreceptors and inner retinal function at late stages.

Space representation in age-related macular degeneration

PURPOSE

To investigate the effect of age-related macular degeneration (AMD) on memory for spatial representations in realistic environments.

METHODS

Participants were 19 patients with AMD and 13 age-matched observers. In a short-term spatial memory task, observers were first presented with one view of a scene (the prime view), and their task was to change the viewpoint forward or backward to match the prime view. Memory performance was measured as the number of snapshots between the selected view and the prime view.

RESULTS

When selecting a match to the prime view, both people with AMD and those in the control group showed systematic biases toward the middle view of the range of snapshots. People with AMD exhibited a stronger middle bias after presentation of close and far prime views while navigating accurately after a middle prime view. No relation was found between visual acuity, visual field defect, or lesion size and the memory performance.

CONCLUSIONS

Memory tasks using indoor scenes can be accomplished when central vision is impoverished, as with AMD. Stronger center bias for a scene location suggests that people with AMD rely more on their memory of a canonical view.

Age-related macular degeneration: linking clinical presentation to pathology

Age-related macular degeneration (AMD) is one of the leading causes of blindness worldwide in the elderly population. Optometrists, as primary eye health care providers, require the skills and knowledge to accurately diagnose and manage AMD patients. There is an overwhelming body of research related to the clinical presentation, etiology, epidemiology, and pathology of this disease. Additionally, the evolution of new imaging modalities creates new opportunities to clinically detect and analyze previously uncharacterized and earlier changes in the retina. The challenge for optometrists is to combine all this information into an applicable knowledge base for use in everyday clinical assessment of AMD so that timely and accurate referrals can be made to retinal specialists. This review attempts to address this issue by linking the clinical presentation of AMD with the underlying disease biology. We emphasize the contribution of recent noninvasive imaging technologies to the clinical assessment of early and more advanced AMD including optical coherence tomography, fundus autofluorescence, and infrared reflectance.

Design, synthesis, and evaluation of nonretinoid retinol binding protein 4 antagonists for the potential treatment of atrophic age-related macular degeneration and Stargardt disease

Accumulation of lipofuscin in the retina is associated with pathogenesis of atrophic age-related macular degeneration and Stargardt disease. Lipofuscin bisretinoids (exemplified by N-retinylidene-N-retinylethanolamine) seem to mediate lipofuscin toxicity. Synthesis of lipofuscin bisretinoids depends on the influx of retinol from serum to the retina. Compounds antagonizing the retinol-dependent interaction of retinol-binding protein 4 (RBP4) with transthyretin in the serum would reduce serum RBP4 and retinol and inhibit bisretinoid formation. We recently showed that A1120 (3), a potent carboxylic acid based RBP4 antagonist, can significantly reduce lipofuscin bisretinoid formation in the retinas of Abca4^–/– mice. As part of the NIH Blueprint Neurotherapeutics Network project we undertook the in vitro exploration to identify novel conformationally flexible and constrained RBP4 antagonists with improved potency and metabolic stability. We also demonstrate that upon acute and chronic dosing in rats, 43, a potent cyclopentyl fused pyrrolidine antagonist, reduced circulating plasma RBP4 protein levels by approximately 60%.

The role of proteases and inflammatory molecules in triggering neovascular age-related macular degeneration: basic science to clinical relevance

Age-related macular degeneration (AMD) causes severe vision impairment in aged individuals. The health impact and cost of the disease will dramatically increase over the years, with the increase in the aging population. Currently, antivascular endothelial growth factor agents are routinely used for managing late-stage AMD, and recent data have shown that up to 15%-33% of patients do not respond to this treatment. Henceforth, there is a need to develop better treatment options. One avenue is to investigate the role proteases and inflammatory molecules might have in regulating and being regulated by vascular endothelial growth factor. Moreover, emerging data indicate that proteases and inflammatory molecules might be critical in the development and progression of AMD. This article reviews recent literature that investigates proteases and inflammatory molecules involved in the development of AMD. Gaining insights into the proteolytic and inflammatory pathways associated with the pathophysiology of AMD could enable the development of additional or alternative drug strategies for the treatment of AMD.

A prospective longitudinal study of retinal structure and function in achromatopsia

PURPOSE

To longitudinally characterize retinal structure and function in achromatopsia (ACHM) in preparation for clinical gene therapy trials.

METHODS

Thirty-eight molecularly confirmed ACHM subjects underwent serial assessments, including spectral domain optical coherence tomography (SD-OCT), microperimetry, and fundus autofluorescence (FAF). Foveal structure on SD-OCT was graded and compared for evidence of progression, along with serial measurements of foveal total retinal thickness (FTRT) and outer nuclear layer (ONL) thickness. Fundus autofluorescence patterns were characterized and compared over time.

RESULTS

Mean follow-up was 19.5 months (age range at baseline, 6-52 years). Only 2 (5%) of 37 subjects demonstrated change in serial foveal SD-OCT scans. There was no statistically significant change over time in FTRT (P = 0.83), ONL thickness (P = 0.27), hyporeflective zone diameter (P = 0.42), visual acuity (P = 0.89), contrast sensitivity (P = 0.22), mean retinal sensitivity (P = 0.84), and fixation stability (P = 0.58). Three distinct FAF patterns were observed (n = 30): central increased FAF (n = 4), normal FAF (n = 11), and well-demarcated reduced FAF (n = 15); with the latter group displaying a slow increase in the area of reduced FAF of 0.03 mm(2) over 19.3 months (P = 0.002).

CONCLUSIONS

Previously published cross-sectional studies have described conflicting findings with respect to the age-dependency of progression. This study, which constitutes the largest and longest prospective longitudinal study of ACHM to date, suggests that although ACHM may be progressive, any such progression is slow and subtle in most patients, and does not correlate with age or genotype. We also describe the first serial assessment of FAF, which is highly variable between individuals, even of similar age and genotype.

Geographic atrophy progression in eyes with age-related macular degeneration: role of fundus autofluorescence patterns, fellow eye and baseline atrophy area

BACKGROUND/OBJECTIVE

To evaluate if fundus autofluorescence (FAF) patterns around geographic atrophy (GA) and the status of the fellow eye have an impact on GA progression.

METHODS

We included 54 eyes of 35 patients with GA. Areas of GA were quantified by RegionFinder software.

RESULTS

GA progression rates in eyes with a diffuse trickling pattern (median 1.42 mm(2)/year) were significantly higher than in normal eyes (median 0.22 mm(2)/year) and eyes with other diffuse FAF patterns (median 0.46 mm(2)/year). Eyes with a banded pattern had a significantly higher progression rate (median 0.81 mm(2)/year) than those without any FAF abnormalities (p = 0.038). The group with baseline total atrophy of the eyes <1 disk area (DA; median 0.42 mm(2)) had an inverse relation with GA progression compared to the groups with baseline atrophy >1 DA (p < 0.05).

CONCLUSION

Diffuse trickling and banded patterns may have an impact on GA progression and may serve as prognostic factors.

Prevalence and risk factors for age-related macular degeneration in the elderly Chinese population in south-western Taiwan: the Puzih eye study

AIM

This study aimed to ascertain the prevalence of and the risk factors associated with early and late age-related macular degeneration (AMD) among Chinese individuals aged ≥65 years residing in Puzih, Taiwan.

METHODS

This population-based cross-sectional study graded digital colour photographs of the ocular fundus of 673 individuals using the Wisconsin Age-Related Maculopathy Grading System. We compared the characteristics of individuals with early and late AMD using χ(2)-analyses and described risk factors for early and late AMD using odds ratios and 95% confidence intervals.

RESULTS

Individuals with late AMD were significantly older and more likely to have hypertension. Further, their sunlight exposure time was longer than that of those with early AMD, only drusen, or no AMD lesions (P<0.01). A history of hyperlipidaemia for >10 years was a significant risk factor for early AMD, while old age, hypertension for >10 years, and exposure to sunlight for >8 h per day were associated with late AMD.

CONCLUSIONS

The prevalence rate of early AMD in the present study was 15.0%, which is similar to that reported for Caucasians and Japanese included in the European Eye Study and the Hisayama Study, respectively. The late AMD prevalence rate of 7.3% found among our study participants was comparable to that reported by the Greenland Inuit Eye Study and Reykjavik Study, but considerably lower than that reported for Caucasians, indicating that late AMD might be less prevalent among Asians than Caucasians.

Two-photon microscopy reveals early rod photoreceptor cell damage in light-exposed mutant mice

Atrophic age-related and juvenile macular degeneration are especially devastating due to lack of an effective cure. Two retinal cell types, photoreceptor cells and the adjacent retinal pigmented epithelium (RPE), reportedly display the earliest pathological changes. Abca4(-/-)Rdh8(-/-) mice, which mimic many features of human retinal degeneration, allowed us to determine the sequence of light-induced events leading to retinal degeneration. Using two-photon microscopy with 3D reconstruction methodology, we observed an initial strong retinoid-derived fluorescence and expansion of Abca4(-/-)Rdh8(-/-) mouse rod cell outer segments accompanied by macrophage infiltration after brief exposure of the retina to bright light. Additionally, light-dependent fluorescent compounds produced in rod outer segments were not transferred to the RPE of mice genetically defective in RPE phagocytosis. Collectively, these findings suggest that for light-induced retinopathies in mice, rod photoreceptors are the primary site of toxic retinoid accumulation and degeneration, followed by secondary changes in the RPE.