Glare and Ocular Diseases

Glare is the result of veiling luminance from the different light sources we are exposed to in our everyday lives. The luminance from glare can cause problems ranging from the discomfort of our eyes to vision loss. All individuals are affected by glare issues but those problems are intensified in patients living with ocular diseases. Therefore, understanding the effects of glare is applicable to elucidating visual function and pathology. This makes glare testing highly necessary in both clinic and research. However, there are many components involved in glare testing that makes attaining valid results difficult. This is evident in the flaws of current glare devices and the lack of a standardization of measuring glare. Despite the insufficiency of most glare devices, evaluating those weaknesses can potentially lead to a better understanding of glare and glare testing

Comparison of retinal nerve fiber layer and macular thickness for discriminating primary open-angle glaucoma and normal-tension glaucoma using optical coherence tomography

Purpose The aim of this study was to evaluate the discrimination capabilities of macular and peripapillary retinal nerve fiber layer (pRNFL) thickness parameters as measured using spectral domain optical coherence tomography (SD-OCT) between primary open-angle glaucoma (POAG) and normal-tension glaucoma (NTG). Methods A total of 90 subjects were enrolled: 30 healthy subjects, 30 subjects with POAG and 30 subjects with NTG, consecutively. Retinal nerve fiber layer thickness, macular thickness and volume measurements were obtained with circular and radial SD-OCT scans. All parameters were compared between groups using an analysis of variance test. Areas under receiver-operating characteristic (AROC) curves with sensitivities at specificities greater than or equal to 90 per cent were generated to compare discrimination capabilities of various parameters between POAG and NTG. Results Macular thickness and volume measurements were the highest in normal subjects, followed by NTG and POAG (p < 0.05). Average retinal nerve fiber layer thickness had perfect discrimination for normal-POAG (AROC: 1.000; sensitivity: 100 per cent) and near perfect discrimination for normal-NTG (AROC: 0.979; sensitivity: 93 per cent) as well as NTG-POAG pairs (AROC: 0.900; sensitivity: 60 per cent). Inferior outer macular thickness (IOMT) and total volume were the best macular thickness and volume parameters having similar AROCs and sensitivities between normal and POAG (IOMT, AROC: 0.987; sensitivity: 92 per cent and total volume, AROC: 0.997; sensitivity: 97 per cent), normal and NTG (IOMT, AROC: 0.862, sensitivity: 47 per cent and total volume, AROC: 0.898, sensitivity: 67 per cent) and also between NTG and POAG (IOMT, AROC: 0.910, sensitivity: 53 per cent and total volume, AROC: 0.922, sensitivity: 77 per cent). In each comparison group, there was no statistically significant difference in AROCs between average retinal nerve fiber layer and inferior outer macular thickness, as well as total volume. Conclusions The macular parameters offer comparable performance to pRNFL parameters for the discrimination of NTG and POAG. Average retinal nerve fiber layer thickness, total macular volume and inferior outer macular thickness were the best SD-OCT parameters with superior discriminating capabilities

Predicting individual contrast sensitivity functions from acuity and letter contrast sensitivity measurements.

Contrast sensitivity (CS) is widely used as a measure of visual function in both basic research and clinical evaluation. There is conflicting evidence on the extent to which measuring the full contrast sensitivity function (CSF) offers more functionally relevant information than a single measurement from an optotype CS test, such as the Pelli-Robson chart. Here we examine the relationship between functional CSF parameters and other measures of visual function, and establish a framework for predicting individual CSFs with effectively a zero-parameter model that shifts a standard-shaped template CSF horizontally and vertically according to independent measurements of high contrast acuity and letter CS, respectively. This method was evaluated for three different CSF tests: a chart test (CSV-1000), a computerized sine-wave test (M&amp;S Sine Test), and a recently developed adaptive test (quick CSF). Subjects were 43 individuals with healthy vision or impairment too mild to be considered low vision (acuity range of -0.3 to 0.34 logMAR). While each test demands a slightly different normative template, results show that individual subject CSFs can be predicted with roughly the same precision as test-retest repeatability, confirming that individuals predominantly differ in terms of peak CS and peak spatial frequency. In fact, these parameters were sufficiently related to empirical measurements of acuity and letter CS to permit accurate estimation of the entire CSF of any individual with a deterministic model (zero free parameters). These results demonstrate that in many cases, measuring the full CSF may provide little additional information beyond letter acuity and contrast sensitivity

Management of Diabetic Eye Disease Using Carotenoids and Nutrients

Diabetic retinopathy is the leading cause of blindness and visual disability globally among working-age adults. Until recently, diabetic eye disease is primarily regarded by its microvasculature complications largely characterized by progressive retinopathy and macular edema. However, a growing body of evidence suggests that hyperglycemia-induced oxidative stress and inflammation play an integral role in the early pathogenesis of diabetic retinopathy by potentiating retinal neurodegeneration. The onset of type 2 diabetes mellitus starts with insulin resistance leading to insulin deficiency, hyperglycemia, and dyslipidemia. Which in turn enhances the pro-oxidant and pro-inflammatory pathways. Additionally, various poor dietary behaviors along with obesity worsen physiological state in diabetics. However, decreased levels and depletion of the endogenous antioxidant defense system in the retina can be sufficiently augmented via carotenoid vitamin therapy. Therefore, dietary supplementation of antioxidant micronutrients particularly macular carotenoids lutein, zeaxanthin and meso-zeaxanthin that promote retinal health and optimal visual performance, may serve as an adjunctive therapy in the management of diabetic eye disease

Molecular Genomics of Glaucoma: An Update

Glaucoma is in the top five age-related eye disorders with increasing prevalence globally. Past research has led to the understanding of glaucoma as a neurodegenerative disease. Glaucoma phenomics could be syndromic or non-syndromic. Globally primary open angle, primary angle closure and primary pseudoexfoliation glaucomas are widely present. The genetics and genomics of glaucoma are heterogeneous, both clinically and genetically. Glaucoma has heritability associations, particularly with central corneal thickness, retinal nerve fibre layer and peripapillary atrophy. Ocular embryogenesis genes when mutated could cause either local (in situ), pan-ocular or systemic syndromic glaucoma phenomics. In glaucoma, except for a few single gene causes, most of the associations have been shown with innumerable gene single-nucleotide polymorphisms and epigenetic factors. The biological mechanisms in glaucoma are mechanical strain, inflammation, oxidative stress, vascular dysregulation, and immune imbalance, which independently or collectively contribute to the neurodegeneration and visual morbidity. Biomarkers in glaucoma have experimental study biases and therefore today we cannot apply them effectively in clinical practice and henceforth that demands further research to understand the fundamental basis of the disease. However, the knowledge gained in research will translate into early detection and biomolecular interventional strategies, having traction toward personalised medicine

Health Promotion for AMD and the Role of Nutrition

There is an increase in demand for health promotion and preventative medicine playing a vital role in managing chronic illnesses. Many of these conditions stem from a poor diet, sedentary lifestyle and smoking, all of which are risk factors for age-related macular degeneration (AMD). To combat chronic diseases, the root of the conditions may be addressed through the concept of health promotion. Health promotion thoroughly assesses how a population’s environmental, political, socioeconomic, behavioral, and cultural practices influence its health. This concept can be applied in a primary care setting which takes on a broader approach in treating and managing patients. Primary care providers need to be aware of the connections between common chronic illnesses and AMD. All primary care providers and eyecare specialists must be patients’ advocate and help improve their systemic and ocular prognosis