Mayuri Bhargava

How does hypertension affect your eyes

Hypertension has profound effects on various parts of the eye. Classically, elevated blood pressure results in a series of retinal microvascular changes called hypertensive retinopathy, comprising of generalized and focal retinal arteriolar narrowing, arteriovenous nicking, retinal hemorrhages, microaneurysms and, in severe cases, optic disc and macular edema. Studies have shown that mild hypertensive retinopathy signs are common and seen in nearly 10% of the general adult non-diabetic population. Hypertensive retinopathy signs are associated with other indicators of end-organ damage (for example, left ventricular hypertrophy, renal impairment) and may be a risk marker of future clinical events, such as stroke, congestive heart failure and cardiovascular mortality. Furthermore, hypertension is one of the major risk factors for development and progression of diabetic retinopathy, and control of blood pressure has been shown in large clinical trials to prevent visual loss from diabetic retinopathy. In addition, several retinal diseases such as retinal vascular occlusion (artery and vein occlusion), retinal arteriolar emboli, macroaneurysm, ischemic optic neuropathy and age-related macular degeneration may also be related to hypertension; however, there is as yet no evidence that treatment of hypertension prevents vision loss from these conditions. In management of patients with hypertension, physicians should be aware of the full spectrum of the relationship of blood pressure and the eye.

Choroidal thickness and high myopia: a case-control study of young Chinese men in Singapore.

To determine the distribution of choroidal thickness (CT) and ocular factors associated with CT in high myopic eyes in comparison with emmetropic eyes of young healthy adults.

Peripapillary choroidal thickness in young Asians with high myopia.

PURPOSE To describe the topography and predictors of peripapillary choroidal thickness (PPCT) in highly myopic eyes of young, healthy, Asian subjects. METHODS A total of 870 young male subjects aged 21.63 ± 1.15 years were recruited from the Singapore military. Choroidal imaging was performed using enhanced depth imaging (EDI) spectral-domain optical coherence tomography (SD-OCT). Peripapillary choroidal thickness was manually measured at eight locations around the optic disc. RESULTS We analyzed 448 subjects with high myopia (defined as spherical equivalent [SE] worse than -6.0 diopters [D]) and 116 with emmetropia (SE > -0.5 and < 0.5 D). The mean SE was -8.52 ± 1.20 D for the high-myopic group, and 0.11 ± 0.24 D for the emmetropic group. The mean peripapillary choroid was significantly thinner (142.62 ± 43.84 μm) in high myopes compared with emmetropes (181.90 ± 46.43 μm, P < 0.001). Likewise, PPCT showed further decrease with increase in degree of myopic refractive error. Distribution of PPCT showed a markedly different pattern in high-myopic eyes (thickest superiorly) and emmetropic eyes (thickest temporally). However, peripapillary choroid in both the groups was thinnest at the inferior location. Among the ocular factors studied, axial length, IOP, presence of posterior staphyloma, and chorioretinal atrophy were the factors significantly associated with PPCT. CONCLUSIONS Highly myopic eyes have significantly thinner peripapillary choroid and showed different distribution of thickness, compared with emmetropes. Axial length, IOP, and presence of posterior staphyloma and chorioretinal atrophy significantly influence PPCT and should be taken into consideration during clinical interpretation of PPCT measurement.

Asian age‐related macular degeneration phenotyping study: rationale, design and protocol of a prospective cohort study

Background:  Current knowledge of the phenotypic characteristics (e.g. clinical features, risk factors, natural history and treatment response) of age‐related macular degeneration (AMD) in Asians remains limited. This report summarizes the rationale and study design of a prospective observational study of Asian neovascular AMD, including polypoidal choroidovasculopathy variant.

Early age-related macular degeneration detection by focal biologically inspired feature

Age-related macular degeneration (AMD) is a leading cause of vision loss. The presence of drusen are often associated to AMD. Drusen are tiny yellowish-white extracellular buildup present around the macular region of the retina. Clinically, ophthalmologists examine the area around the macula to determine the presence and severity of drusen. However, manual identification and recognition of drusen is subjective, time consuming and expensive. To reduce manual workload and facilitate large-scale early AMD screening, it is essential to detect drusen automatically. In this paper, we propose to use biologically inspired features (BIF) for the purpose of AMD detection. The optic disc and macula are detected to determine a focal region around macula for feature extraction. The extracted features are then classified using support vector machines (SVM). Our experimental results, tested on 350 images, demonstrate that the biologically inspired features from the focal region is effective for drusen detection with a sensitivity of 86.3% and specificity of 91.9%. The results of our proposed approach can be used to reduce workload of ophthalmologists and diagnosis cost.

THALIA - An automatic hierarchical analysis system to detect drusen lesion images for amd assessment

Age-related macular degeneration (AMD) is a leading cause of permanent blindness. In its early stage AMD is characterized by drusen which are extracellelur deposits in the retina. In this paper, we present THALIA, an automatic system for the detection of drusen images for AMD assessment. First, the macular region of interest is detected using a seeded mode tracking approach. The macular region of interest is then mapped into a new representation using a hierarchicial word transform (HWI). In HWI, dense sampling is first carried out to generate structured pixels which embed local context. These structured pixels are then clustered using hierarchical k-means. The HWI image is subsequently classified using a SVM-based classifier. We have tested THALIA on a dataset of 350 images and obtained an accuracy of 95.46%. Results are promising for further validation of the THALIA system.

Prevalence and risk factors for retinopathy in persons without diabetes: the Singapore Indian Eye Study

To describe prevalence and risk factors for retinopathy in an Asian Indian population without diabetes.

Automatic fovea detection in retinal fundus images

The fovea (centre of the retinal macula region) is responsible for central vision. Conditions which can affect the macula region in particular include AMD and macular oedema, which lead to a direct loss in visual acuity due to the effect on central vision. The detection of the fovea is an important step in the assessment of retinal images for pathologies relating to these visual conditions. In this paper, we propose a method to automatically detect the fovea in retinal fundus images. The method makes use of optic disc detection as a starting point. Using information from an extensive database, typical locations of the fovea are used to define search regions for subsequent analysis. We make use of a combination of the image characteristics of the macular region with noise and vessel removal for fovea detection. The proposed method is tested on a large database of 750 retinal fundus images, achieving an accuracy of 86.53%.

Peripheral retinal changes in highly myopic young Asian eyes

To determine the type and prevalence of peripheral retinal changes and its relationship with axial length (AL) in a population of young Asian adult males.

Ranibizumab And Aflibercept For The Treatment Of Pigment Epithelial Detachment In Neovascular Age-related Macular Degeneration: Data from an Observational Study

Purpose: To assess the effect of intravitreal ranibizumab and aflibercept on retinal pigment epithelial detachment (RPED) in patients with neovascular age-related macular degeneration. Methods: This was a retrospective analysis of data from a prospectively designed and implemented clinical audit. Analysis included change in RPED dimensions and visual acuity in 92/233 treatment-naive eyes with neovascular age-related macular degeneration and RPED 6 months after treatment with either aflibercept or ranibizumab. Results: There was no significant between-group difference in the adjusted mean change for maximum RPED height (P = 0.195), diameter (P = 0.522) or visual acuity (P = 0.836) at 6 months. Injection frequency was the only clinical variable that affected RPED height (P = 0.050) and visual acuity change for both treatment groups (P = 0.004). Around 30% of eyes in each group had complete resolution of RPED at 6 months. Conclusion: Eyes with neovascular age-related macular degeneration and RPED showed significant functional and anatomical responses after 6 months of intravitreal anti–vascular endothelial growth factor injections. However, we found no significant difference in anatomical response or change in visual acuity between eyes treated with ranibizumab compared with aflibercept. Larger, prospectively designed, randomized studies with longer term follow-up may identify a difference between the two drugs that we did not detect.