Prevalence of and risk factors for age-related macular degeneration in Nepal: the Bhaktapur Retina Study

Stages, pathogenesis, clinical management and advancements in therapies of age-related macular degeneration

Age-related macular degeneration (AMD) is a retinal degenerative disorder prevalent in the elderly population, which leads to the loss of central vision. The disease progression can be managed, if not prevented, either by blocking neovascularization ("wet" form of AMD) or by preserving retinal pigment epithelium and photoreceptor cells ("dry" form of AMD). Although current therapeutic modalities are moderately successful in delaying the progression and management of the disease, advances over the past years in regenerative medicine using iPSC, embryonic stem cells, advanced materials (including nanomaterials) and organ bio-printing show great prospects in restoring vision and efficient management of either forms of AMD. This review focuses on the molecular mechanism of the disease, model systems (both cellular and animal) used in studying AMD, the list of various regenerative therapies and the current treatments available. The article also highlights on the recent clinical trials using regenerative therapies and management of the disease.

Does outer retinal layer thickness correlate with the central visual field indices in early dry age-related macular degeneration?

PURPOSE

Age-related macular degeneration (ARMD) is the leading cause of irreversible blindness worldwide and Nepal is one among them. We aimed to determine the relationship between outer retinal layer thickness parameters with central visual field indices in early dry ARMD cases among Nepalese population.

MATERIALS AND METHODS

The subjects for this descriptive, cross-sectional study comprised 40 patients with early dry ARMD from the ophthalmology department of a tertiary level hospital of Nepal. The retinal layer thickness was measured with spectral-domain optical coherence tomography (SD-OCT), and the visual field indices were assessed using the 10-2 protocol of Humphrey visual field analyzer (HFA). Thus, the retinal layer structures correlated with visual field indices among our population.

RESULTS

Among our early dry ARMD population, the foveal threshold (FT) was found to be significantly correlated with retinal pigment epithelium (RPE) elevation (P < 0.01, r = -0.541), outer segment (OS) length (P = 0.02, r = 0.465), and inner segment ellipsoid (ISe) band disruption (P = 0.01, r = -0.499), but not with presence of hyperreflective foci (P = 0.464), RPE thickness (P = 0.612), and central macular thickness (P = 0.214). However, no significant correlation between mean deviation and pattern standard deviation of visual field with retinal layer thickness parameters was identified.

CONCLUSION

In early dry ARMD, a reduced FT is significantly correlated with the integrity of the ISe band, thinning of OS length, and drusen-associated RPE elevation. The results highlight the utility of both SD-OCT retinal layer measurement and central visual field testing by HFA in ARMD to monitor the progression of the disease.

Roles of IL-8 -251A/T and +781C/T polymorphisms, IL-8 level, and the risk of age-related macular degeneration

OBJECTIVE

To clarify the association between IL-8 gene polymorphisms, IL-8 level, towards the risk of age-related macular degeneration (AMD).

METHODS

Meta-analysis was performed from available studies that investigated IL-8 -251A/T (rs4073) and +781C/T (rs2227306) polymorphisms and IL-8 levels in patients with AMD and controls.

RESULTS

Overall, the pooled result showed a significant association between AMD with allelic (T vs. C; OR 1.53; p = 0.005), dominant (TT + CT vs. CC; OR 1.95; p = 0.017), homozygous (TT vs. CC; OR 2.03; p = 0.039) and heterozygous (CT vs. CC; OR 1.92; p = 0.032) models of rs2227306; while subgroup analysis revealed a significant association between rs2227306 with wet AMD in allelic (T vs. C; OR 1.69; p = 0.016), recessive (TT vs. CT + CC; OR 1.81; p = 0.00007), and homozygous (TT vs. CC; OR 2.64; p = 0.003) models. No significant association was observed between rs4073 with AMD in all inheritance models. In parallel, patients with AMD, particularly wet AMD had an elevated level of IL-8 compared to control.

CONCLUSION

This meta-analysis suggests that patients with AMD or wet AMD have higher IL-8 levels compared to control, which is also supported by the evidence that carrier T allele of rs2227306 exhibited an increase in the risk of AMD or wet AMD. Thus, IL-8 +781C/T (rs2227306) polymorphism and the level of intraocular IL-8 may be useful as a biomarker for early detection and a therapeutic target of AMD.

Treatment Landscape of Macular Disorders in Indian Patients with the Advent of Razumab™ (World's First Biosimilar Ranibizumab): A Comprehensive Review

Ranibizumab is approved for the treatment of several macular disorders, including wet age-related macular degeneration (wet AMD), diabetic macular edema (DME), retinal vein occlusion (RVO) and myopic choroidal neovascularization (mCNV), among others. The unaffordability of the innovator ranibizumab among patients from developing countries such as India led to the development of the world’s first biosimilar ranibizumab, which is a cost-effective alternative that does not compromise efficacy and safety. Razumab™, developed and produced by Intas Pharmaceuticals Ltd., India, is the world’s first biosimilar of ranibizumab, and is approved in India for the treatment of various macular disorders, including wet AMD, DME, RVO and mCNV. The efficacy and safety of Razumab for the treatment of these macular disorders have been evaluated in both prospective and real-world retrospective studies. Razumab has shown an efficacy similar to that of the innovator ranibizumab, achieving improved visual acuity, as measured by the best corrected visual acuity, and reduction in the central macular thickness, leading to improved patient outcomes. The safety profile of Razumab is comparable to that of the innovator ranibizumab and is well tolerated without any new safety concerns. Here, we review the clinical and real-world data of Razumab in the treatment of macular disorders.

Cluster-randomised trial of community-based screening for eye disease in adults in Nepal: the Village-Integrated Eye Worker Trial II (VIEW II) trial protocol

INTRODUCTION

The majority of blindness worldwide could be prevented or reversed with early diagnosis and treatment, yet identifying at-risk and prevalent cases of eye disease and linking them with care remain important obstacles to addressing this burden. Leading causes of blindness like glaucoma, diabetic retinopathy and age-related macular degeneration have detectable early asymptomatic phases and can cause irreversible vision loss. Mass screening for such diseases could reduce visual impairment at the population level.

METHODS AND ANALYSIS

This protocol describes a parallel-group cluster-randomised trial designed to determine whether community-based screening for glaucoma, diabetic retinopathy and age-related macular degeneration reduces population-level visual impairment in Nepal. A door-to-door population census is conducted in all study communities. All adults aged ≥60 years have visual acuity tested at the census visit, and those meeting referral criteria are referred to a local eye care facility for further diagnosis and management. Communities are subsequently randomised to a community-based screening programme or to no additional intervention. The intervention consists of a single round of screening including intraocular pressure and optical coherence tomography assessment of all adults ≥60 years old with enhanced linkage to care for participants meeting referral criteria. Four years after implementation of the intervention, masked outcome assessors conduct a repeat census to collect data on the primary outcome, visual acuity. Individuals with incident visual impairment receive a comprehensive ophthalmological examination to determine the cause of visual impairment. Outcomes are compared by treatment arm according to the originally assigned intervention.

ETHICS AND DISSEMINATION

The trial has received ethical approval from the University of California San Francisco Institutional Review Board, Nepal Netra Jyoti Sangh and the Nepal Health Research Council. Results of this trial will be disseminated through publication in peer-reviewed journals and presentation at local and international meetings.

TRIAL REGISTRATION NUMBER

NCT03752840.

Prevalence, Pattern and Risk Factors of Retinal Diseases Among an Elderly Population in Nepal: The Bhaktapur Retina Study

Introduction

Retinal diseases are an emerging cause of visual impairment in the developing world. The aim of this study was to explore the prevalence, pattern, and risk factors of retinal diseases in Nepal.

Methods

This is a population-based, cross-sectional study conducted from 2013 to 2015. The sample size was 2100 subjects age 60 years and above from 30 clusters of Bhaktapur district, Nepal. Detailed history, visual acuity, and anterior and posterior segment examinations were performed. Blood sugar and blood pressure were measured.

Results

Complete information was available for 1860 (88.57%) subjects. Mean age was 69.64±7.31 years, ranging from 60 to 95 years. The prevalence of any retinal disorder was 52.37% (95% confidence interval (CI): 50.07–54.66%). The prevalence of retinal disorders increased with ageing: 51.26% between 60 and 69 years and 53.05% among those age 80 years and above. Age-related macular degeneration (AMD) was the most common retinal disease (35.43%), followed by hypertensive retinopathy (4.35%), epiretinal membrane (ERM) (3.66%), branch retinal vein occlusion (BRVO) (2.90%), and diabetic retinopathy (DR) (2.15%). Other rare retinal disorders included myopic fundus (0.86%), chorioretinal scar (0.54%), retinal holes (0.32%), retinitis pigmentosa (0.32%), retinal detachment (0.16%), and coloboma (0.11%). In multivariate logistic regression analysis, those with prior cataract surgery (odds ratio (OR), 1.71; 95% CI: 1.32–2.22, p < 0.001) and systemic hypertension (OR, 1.21; 95% CI: 1.001–1.47, p = 0.049) had significantly increased retinal disorders.

Conclusion

Prevalence of retinal disorder was 52.37% at age 60 years and above. AMD, hypertensive retinopathy, ERM, BRVO, and DR were the most common retinal disorders. Retinal disorders increased with ageing. Retinal disorders were found associated with hypertension and prior cataract surgery. Timely screening, control of blood sugar and high blood pressure, and regular eye check-ups could help to save vision from retinal diseases.

Autophagy: A new insight into pathogenesis and treatment possibilities in age-related macular degeneration

Age-related macular degeneration (AMD) is a significant problem in healthcare, because it is a leading cause of central vision loss in individuals over 50 years old in well-developed countries. Pathogenesis of AMD is multifactorial and still not completely understood. Proven risk factors include the following: natural senescence of retina, oxidative stress, complement activation, chronic subretinal inflammatory reaction, genetic and environmental factors. Data on links between autophagy and AMD development are being raised. Autophagy is a cellular process involving the degradation of long-lived proteins and damaged fragments and components of cells; it is responsible for the maintenance of dynamic intracellular homeostasis and it enables cell survival under stress conditions. Disturbances of autophagy mechanisms, i.e. its activation or inhibition, may lead to the development of many various pathologies. Thus, autophagy plays a dual role, as a mechanism responsible for protecting or killing cells. The paper describes autophagy mechanisms and their role in the natural process of retinal cells senescence and presents the autophagy impairment as a crucial cause of AMD development. We also describe the impact of intravitreal anti-VEGF therapy on retinal autophagy mechanisms and potential new therapeutic modalities for AMD based on autophagy modulation.

Clinical outcomes of 1 + PRN and 3 + Q3M regimens of intravitreal conbercept injection for exudative age-related macular degeneration

This retrospective study aimed to analyze the clinical outcomes of two regimens of intravitreal injections of conbercept [1+pro re nata (PRN) and 3 + Q3M] for the therapy of exudative age-related macular degeneration (AMD). In total, 105 eyes diagnosed with exudative AMD were enrolled. The eyes in the 1+PRN group (n = 51) received intravitreal injection of conbercept one time, followed by PRN retreatment. The eyes in the 3 + Q3M group (n = 54) received intravitreal injection of conbercept on three consecutive monthly, subsequently, once every three months for three times. After treatment, patients were followed up for 12 months. The best-corrected visual acuity (BCVA), central retinal thickness (CRT), and choroidal neovascularization (CNV) leakage area were compared before and after treatment. Moreover, the number of injections and adverse reactions were recorded. Compared with the 1+PRN group, BCVA was significantly improved and CRT was remarkably decreased in the 3 + Q3M group at 3, 6 and 12 months after operation. The disappeared or reduced CNV leakage area (93%) of the 3 + Q3M group was higher than that of the 1 + PRN group at the last follow-up. Moreover, the mean numbers of conbercept injections of the 1 + PRN group were less than the 3 + Q3M group. During the follow-up, there were no serious adverse reactions or ocular complications. This study reveals that intravitreal injection of conbercept using 3 + Q3M regimen has certain advantages than 1 + PRN regimen in extending drug delivery interval, improving patient’s vision, and reducing CRT.

Light-Emitting Diodes (LEDS): Implications for Safety

Since the original ICNIRP Statement was published in 2000, there have been significant improvements in the efficiency and radiance (i.e., optical radiation emission) of LEDs. The most important improvement is the development of 'white' LEDs that can be used as general lighting sources, which are more efficient than traditional lighting sources. LEDs emitting in the ultraviolet wavelength region have also become available and have made their way into consumer products. All these changes have led to a rise in concern for the safety of the optical radiation emissions from LEDs. Several in vitro and animal studies have been conducted, which indicate that blue and white LEDs can potentially cause retinal cell damage under high irradiance and lengthy exposure conditions. However, these studies cannot be directly extrapolated to normal exposure conditions for humans, and equivalent effects can also be caused by the optical radiation from other light sources under extreme exposure conditions. Acute damage to the human retina from typical exposure to blue or white LEDs has not been demonstrated. Concern for potential long-term effects, e.g. age-related macular degeneration (AMD), remains based on epidemiological studies indicating a link between high levels of exposure to sunlight and AMD. When evaluating the optical radiation safety of LEDs, it has now been established that published safety standards for lamps, not lasers, should be applied. Thus far, the only clear, acute adverse health effects from LEDs are those due to temporal light modulation (including flicker). Glare can also create visual disturbances when LED light fixtures are not properly designed. Further research is needed on potential health effects from short- and long-term exposure to new and emerging lighting technologies.

A Multicenter, Retrospective Study (RE-ENACT 2) on the Use of Razumab™ (World's First Biosimilar Ranibizumab) in Wet Age-Related Macular Degeneration

INTRODUCTION

The REal life assessmENt of safety And effeCTiveness of Razumab (RE-ENACT) and long-term RE-ENACT 2 retrospective studies have evaluated the use of Razumab™ (world's first biosimilar ranibizumab) in retinal disorders in Indian patients. This report presents the subgroup analysis from the RE-ENACT 2 study in patients with wet age-related macular degeneration (wet AMD).

METHODS

Medical charts of patients administered biosimilar ranibizumab injections as PRN treatment regimen between September 2015 and June 2018, at 17 centers across India, were reviewed. Changes from baseline in best-corrected visual acuity (BCVA, based on Snellen's or logMAR chart), central subfield thickness (CSFT), intraocular pressure (IOP), and proportions of patients having intraretinal fluid (IRF) and subretinal fluid (SRF) at weeks 4, 8, 12, 16, 20, 24, 30, 36, and 48 were evaluated.

RESULTS

Of 103 patients with wet AMD, 62.1% were men and the majority (74.8%) were treatment naïve. The majority (57.9%) of the patients had received 3 (range 1-5) injections. Significant improvements were observed from baseline to all timepoints for BCVA (baseline, 0.92 ± 0.6 [n = 94]; week 48, 0.51 ± 0.4 [n = 14]; P = 0.0014) and CSFT (baseline, 430.83 ± 14.4 [n = 85]; week 48, 301.26 ± 11.6 [n = 15]; P < 0.0001). Changes in IOP from baseline to 48 weeks were minimal and not significant (14.92 ± 3.2 [n = 94] vs. 14.50 ± 2.1 [n = 18]; P = 0.9068). A decrease in proportions of patients having IRF (baseline, 63.6% [n = 99] vs. week 48, 15% [n = 20]) and SRF (baseline, 82.3% [n = 96] vs. week 48, 5% [n = 20]) were also observed. Similar results were observed for occult and classic subgroups. There were no new safety concerns.

CONCLUSION

Razumab (biosimilar ranibizumab) demonstrated improvements in visual acuity and disease outcomes in patients with wet age-related macular degeneration without new safety issues.

Prevalence and causes of low vision and blindness in an elderly population in Nepal: the Bhaktapur retina study

BACKGROUND

This study aims to explore the prevalence and causes of low vision and blindness focused on retinal disease in a population above 60 years in Nepal.

METHODS

Two thousand one hundred subjects were enrolled in a population-based cross-sectional study. History, presenting and best corrected visual acuity after subjective refraction, anterior and posterior segment examinations was obtained in detail.

RESULTS

Among the total subjects, 1860 (88.57%) had complete information. Age varies from 60 to 95 (mean age: 69.64 ± 7.31) years. Low vision and blindness in both eyes at presentation was found in 984 (52.90%, 95% confidence interval (CI): 50.60-55.19) and 36 (1.94%, 95% CI: 1.35-2.66) subjects respectively. After best correction, bilateral low vision and blindness was found in 426 (22.92%, 95% CI: 21.01-24.88), and 30 (1.61%, 95% CI: 0.10-2.30) subjects respectively. As compared to 60-69 years old, risk of visual impairment was four times higher (95% CI:3.26-5.58) in the 70-79 year olds and 14 times higher (95% CI: 9.72-19.73) in the age group 80 years and above. Major causes of bilateral low vision were cataract (68.07%), followed by retinal disorders (28.64%), and for blindness; retinal disorders (46.66%), followed by cataract (43.33%). Illiteracy was significantly associated with visual impairment.

CONCLUSION

Among the elderly population, prevalence of visual impairment was high. Refractive error, cataract and retinal disorders were the major cause of low vision. Screening the population at the age 60 years and above, focused on cataract and posterior segment diseases, providing glasses and timely referral can help reduce visual impairment.