Kumari Neelam

Choroidal neovascularization in pathological myopia

Myopic choroidal neovascularization (CNV) is one of the leading causes of visual impairment worldwide. The clinical and socioeconomic impact of myopic CNV in Asian countries is particularly significant due to rising trend in the prevalence and severity of pathological myopia. The exact pathogenesis of myopic CNV remains unclear and there is paucity of information with respect to incidence and risk factors for myopic CNV from prospective studies. Furthermore, there are no recognized measures that may prevent or delay the development of CNV in eyes with pathological myopia. Advances have been made in the diagnosis and characterization of myopic CNV over the years. Until recently, treatment modalities for myopic CNV were limited to thermal laser photocoagulation and photodynamic therapy with verteporfin, both these modalities primarily aim at prevention of further visual loss. In the last 5 years, inhibitors of vascular endothelial growth factor (VEGF) have been used successfully and may improve vision to some extent. Nevertheless, the long-term safety and efficacy of anti-VEGF agents remains unknown. Furthermore, the risk of developing chorioretinal atrophy remains the key factor in determining the final visual outcome. This review article summarizes the current literature on myopic CNV, highlighting new evolving diagnostic and treatment modalities, prognostic factors influencing visual outcome, and areas of future research.

Psychophysical function in age-related maculopathy.

Age-related macular degeneration (AMD), the late stage of age-related maculopathy (ARM), is the leading cause of blind registration in developed countries. The visual loss in AMD occurs due to dysfunction and death of photoreceptors (rods and cones) secondary to an atrophic or a neovascular event. The psychophysical tests of vision, which depend on the functional status of the photoreceptors, may detect subtle alterations in the macula before morphological fundus changes are apparent ophthalmoscopically, and before traditional measures of visual acuity exhibit deterioration, and may be a useful tool for assessing and monitoring patients with ARM. Furthermore, worsening of these visual functions over time may reflect disease progression, and some of these, alone or in combination with other parameters, may act as a prognostic indicator for identifying eyes at risk for developing neovascular AMD. Lastly, psychophysical tests often correlate with subjective and relatively undefined symptoms in patients with early ARM, and may reflect limitation of daily activities for ARM patients. However, clinical studies investigating psychophysical function have largely been cross-sectional in nature, with small sample sizes, and lack consistency in terms of the grading and classification of ARM. This article aims to comprehensively review the literature germane to psychophysical tests in ARM, and to furnish the reader with an insight into this complex area of research.

Monthly Consistency of Macular Pigment Optical Density and Serum Concentrations of Lutein and Zeaxanthin

Purpose: This study was undertaken to assess serial month-to-month consistency of macular pigment (MP) optical density and serum concentrations of lutein (L) and zeaxanthin (Z). Four healthy subjects aged between 23 and 51 years volunteered to participate in this study. Methods: MP optical density (measured psychophysically using heterochromatic flicker photometry [HFP]), and serum concentrations of L and Z (quantified using high-performance liquid chromatography [HPLC]), were recorded every month for 24 consecutive months. Results: Mean MP optical density (±SD) was 0.361 (0.086) and 0.369 (0.074) for right and left eyes, respectively. There was no statistically significant seasonal variation in MP optical density for the group (two-way ANOVA: p > 0.05). Serum concentrations of L and Z demonstrated a statistically significant subject-season interaction effect (two-way ANOVA: p < 0.01). Serial serum concentrations of L and Z were positively correlated within all four subjects (r = 0.370 to 0.786), and significantly so for three subjects (p < 0.05). There was no obvious relationship, synchronous or lagged, between serum concentrations of L (or Z) and MP optical density (r = −0.036 to 0.368). Conclusions: MP optical density was relatively stable for all subjects over the 24-month period. Fluctuations in serum concentrations of L and Z, in the absence of dietary modification or supplementation, are associated with stable MP optical density.

Risk Factors for Age-Related Maculopathy

Age-related maculopathy (ARM) is the leading cause of blindness in the elderly. Although beneficial therapeutic strategies have recently begun to emerge, much remains unclear regarding the etiopathogenesis of this disorder. Epidemiologic studies have enhanced our understanding of ARM, but the data, often conflicting, has led to difficulties with drawing firm conclusions with respect to risk for this condition. As a consequence, we saw a need to assimilate the published findings with respect to risk factors for ARM, through a review of the literature appraising results from published cross-sectional studies, prospective cohort studies, case series, and case control studies investigating risk for this condition. Our review shows that, to date, and across a spectrum of epidemiologic study designs, only age, cigarette smoking, and family history of ARM have been consistently demonstrated to represent risk for this condition. In addition, genetic studies have recently implicated many genes in the pathogenesis of age-related maculopathy, including Complement Factor H, PLEKHA 1, and LOC387715/HTRA1, demonstrating that environmental and genetic factors are important for the development of ARM suggesting that gene-environment interaction plays an important role in the pathogenesis of this condition.

Carotenoids and Co-Antioxidants in Age-Related Maculopathy: Design and Methods

Age-related macular degeneration (AMD), is the leading cause of blind registration in the Western World among individuals 65 years or older. Early AMD, a clinical state without overt functional loss, is said to be present clinically when yellowish deposits known as drusen and/or alterations of fundus pigmentation are seen in the macular retina. Although the etiopathogenesis of AMD remains uncertain, there is a growing body of evidence in support of the view that cumulative oxidative damage plays a causal role. Appropriate dietary antioxidant supplementation is likely to be beneficial in maintaining visual function in patients with AMD, and preventing or delaying the progression of early AMD to late AMD. The Carotenoids in Age-Related Maculopathy (CARMA) Study is a randomized and double-masked clinical trial of antioxidant supplementation versus placebo in 433 participants with either early AMD features of sufficient severity in at least one eye or any level of AMD in one eye with late AMD (neovascular AMD or central geographic atrophy) in the fellow eye. The aim of the CARMA Study is to investigate whether lutein and zeaxanthin, in combination with co-antioxidants (vitamin C, E, and zinc), has a beneficial effect on visual function and/or prevention of progression from early to late stages of disease. The primary outcome is improved or preserved distance visual acuity at 12 months. Secondary outcomes include improved or preserved interferometric acuity, contrast sensitivity, shape discrimination ability, and change in AMD severity as monitored by fundus photography. This article outlines the CARMA Study design and methodology, including its rationale.

Macular pigment and ocular biometry

This study is designed to investigate the relationship between macular pigment optical density (MPOD) and ocular biometric parameters. The following details were recorded for 180 healthy subjects: demographic profile; best-corrected visual acuity; refractive status; ocular biometric parameters [axial length (AL), anterior chamber depth (ACD), lens thickness (LT) and vitreous chamber depth (VCD)]; ocular dominance; MPOD; serum lutein (L) and zeaxanthin (Z). The mean MPOD (+/-SD) was 0.307 (0.155) and 0.305 (0.149) in the right and left eyes, respectively. No demonstrable relationship was observed between MPOD and AL, ACD or VCD [AL: r=0.091, p=0.225; ACD: r=0.091, p=0.227; VCD: r=0.146, p=0.051]. There was a significant and inverse relationship between LT and MPOD (r=-0.204; p=0.008), which was attenuated to non-significance after correction for age and height (r=-0.058; p=0.466). This study fails to identify an association between MPOD and ocular biometric parameters. This is an important negative finding, which allows investigators to study MP, and its relationship with potentially important variables, without the need to correct for ocular biometric parameters.

Macular pigment levels following successful macular hole surgery.

Aim: Macular pigment (MP) is composed of two hydroxycarotenoids contained within the photoreceptors and the axons of the central neurosensory retina, with peak concentrations in the Henle layer. A full thickness macular hole (FTMH) is characterised by absence of all retinal layers in an area centred at the former centre of the fovea. The authors report the results of a study designed to investigate MP levels in patients following successful FTMH surgery, using Raman spectroscopy, and to correlate these findings with functional and topographic outcomes. Methods: The following details were recorded for 12 eyes of 12 patients following successful closure of a FTMH: best corrected visual acuity; macula threshold test, fixation, fundus photography, and macular pigment levels using Raman spectroscopy. High resolution imaging of the retina using optical coherence tomography (OCT) was performed in nine of the 12 study eyes. Results: Mean (SD) best corrected visual acuity was 0.6 (0.4) and improved significantly from preoperative levels. On macula threshold testing of the operated eye, a central scotoma was detectable in one eye only (8.3%). MP levels were demonstrable in 10 of the 12 study eyes following successful FTMH surgery. MP levels were higher in three study eyes, and lower in seven study eyes, when compared with the fellow eye. Of the three pairs of eyes where MP levels were greater in the study eye, macular pathology was present in two fellow eyes. Conclusions: The presence of MP was confirmed in the neurosensory retina of an anatomically closed FTMH in 10 of 12 study eyes, although the levels were lower than the fellow normal macula in nine of 10 cases. This suggests a good degree of physiological recovery of photoreceptors and their axons following successful FTMH surgery.

Putative protective role of lutein and zeaxanthin in diabetic retinopathy

Diabetic retinopathy (DR) is one of the most important microvascular complications of diabetes and remains the leading cause of blindness in the working-age individuals. The exact aetiopathogenesis of DR remains elusive despite major advances in basic science and clinical research. Oxidative damage as one of the underlying causes for DR is increasingly being recognised. In humans, three hydroxycarotenoids, lutein (L), zeaxanthin (Z) and meso-zeaxanthin (MZ), accumulate at the central retina (to the exclusion of all other dietary carotenoids), where they are collectively known as macular pigment. These hydroxycarotenoids by nature of their biochemical structure and function help neutralise reactive oxygen species, and thereby, prevent oxidative damage to the retina (biological antioxidants). Apart from their key antioxidant function, evidence is emerging that these carotenoids may also exhibit neuroprotective and anti-inflammatory function in the retina. Since the preliminary identification of hydroxycarotenoid in the human macula by Wald in the 1940s, there has been astounding progress in our knowledge of the role of these carotenoids in promoting ocular health. While the Age-Related Eye Disease Study 2 has established a clinical benefit for L and Z supplements in patients with age-related macular degeneration, the role of these carotenoids in other retinal diseases potentially linked to oxidative damage remains unclear. In this article, we comprehensively review the literature germane to the putative protective role of two hydroxycarotenoids, L and Z, in the pathogenesis of DR.

Six-Year Incidence of Age-Related Macular Degeneration in Asian Malays: The Singapore Malay Eye Study

PURPOSE To determine the 6-year incidence of early and late age-related macular degeneration (AMD) in a Singaporean Malay population and to validate the Age-Related Eye Disease Study (AREDS) simplified severity scale in Asians. DESIGN Prospective, population cohort study. PARTICIPANTS The Singapore Malay Eye Study baseline participants (age, ≥40 years; 2006-2008) were followed up in 2011 through 2013, and 1901 of 3280 of eligible participants (72.1%) took part. METHODS Fundus photographs were graded using the Wisconsin AMD grading system. MAIN OUTCOME MEASURES Incidence of early and late AMD. RESULTS Gradable fundus photographs were available for 1809 participants who attended both baseline and 6-year follow-up examinations. The age-standardized incidences of early and late AMD were 5.89% (95% confidence interval [CI], 4.81-7.16) and 0.76% (95% CI, 0.42-1.29), respectively. The 5-year age-standardized incidence of early AMD (calculated based on the 6-year incidence) was lower in our population (5.58%; 95% CI, 4.43-7.01) compared with the Beaver Dam Eye Study population (8.19%). The incidence of late AMD in our population was similar to that of the Beaver Dam Eye Study population (0.98% [95% CI, 0.49-1.86] vs. 0.91%), the Blue Mountains Eye Study population (1.10% [95% CI, 0.52-9.56] vs. 1.10%), and the Hisayama Study population (1.09% [95% CI, 0.54-4.25] vs. 0.84%). The incidence of late AMD increased markedly with increasing baseline AREDS score (step 0, 0.23%; step 4, 9.09%). CONCLUSIONS This study documented the incidence of early and late AMD in a Malay population. The AREDS simplified severity scale is useful in predicting the risk of late AMD development in Asians.

The Spatial Profile of Macular Pigment in Subjects From a Singapore Chinese Population

PURPOSE To examine the spatial profile of macular pigment (MP) and its relationship with serum concentrations of lutein (L) and zeaxanthin (Z) in subjects from a Singapore Chinese population. METHODS In this cross-sectional study, the following details were recorded in 95 healthy subjects: sociodemographic, lifestyle information, body mass index (BMI), visual acuity, MP spatial profile using a macular densitometer, and serum L and Z. RESULTS The mean (SD) age of the population was 42.40 (± 13) years, ranging from 21 to 68 years. Females demonstrated significantly lower MP optical density (MPOD) than males (MPOD: females = 0.52 ± 0.17; males = 0.61 ± 0.21, P = 0.03). MP spatial profile was typical and atypical with central dip in 68 (85%) and 12 (15%) subjects, respectively. Age and BMI were found to be significant predictors for atypical MP spatial profile (age: odds ratio, OR = 1.06, 95% confidence interval, CI = 1.01-1.13, P = 0.04; BMI: OR = 1.17, 95% CI = 1.01-1.34, P = 0.03). A positive relationship was observed between MPOD and serum concentrations of L and Z, but only the latter relationship reached statistical significance (serum L: r = 0.12, P = 0.30; serum Z: r = 0.26, P = 0.02). CONCLUSIONS A central dip in MP spatial profile was observed with older age and higher BMI, the two known risk factors for AMD, suggesting that atypical MP spatial profile may be associated with an increased risk of AMD. Further studies with larger sample sizes are required to confirm these observations.