Clinical Trial: Structure Function Correlation in Primary Open Angle Glaucoma
Study Status: Completed
Recruit Status: Completed
Study Type: Observational
Official Title: A Cross Sectional Study of Correlation Between Retinal Nerve Fibre Thickness Measured by Optical Coherence Tomography and Humphrey Visual Fields in Early and Moderate Open Angle
Brief Summary:
Glaucoma is an optic neuropathy characterised by progressive degeneration of retinal ganglion cells and axons that leads to nerve fibre loss, optic disc cupping, and consecutive glaucomatous visual field defects. It is considered to be one of the major causes of blindness worldwide.
It is a well accepted fact least 25 - 40% of retinal ganglion cells need to be lost before statistically detectable visual field defects appear on automated visual field testing, which is also consistent with post-mortem histologic findings in glaucomatous eyes. Since the damage associated with glaucoma is irreversible, and retinal nerve fibre layer loss is considered as an early sign of glaucomatous damage, its early detection and prevention is warranted. Retinal nerve fibre layer studies can be undertaken through non - invasive, reproducible technologies such as optical coherence tomography, scanning laser polarimetry etc.
The purpose of the study is to evaluate the relationship between visual fields and retinal nerve fibre layer thickness as measured by Cirrus spectral domain optical coherence tomography with visual fields by Humphrey Field Analyser (HFA) in early and moderate primary open - angle glaucoma.
Detailed Summary:
It is often said that the structural damage due to glaucoma precedes functional loss, it is not always clear in its interpretation. To define, which test shows up the earliest sign of glaucomatous damage would be difficult to predict, since the outcome can be influenced by many factors, such as the sensitivity of the test, inter - individual difference or the stage of the disease process itself. Studies on post-mortem retinal ganglion cells counts and SAP field loss in humans and monkeys lead to an observation that, on an average about 25% retinal ganglion cells loss leads to development of an afferent pupillary defect, 35% loss for visual field defects and 40% loss leads to worsening of visual acuity. It would be safe to state that a) the most important clinical challenge is early detection of glaucomatous damage and progression over a period of time; b) Both structural and functional tests are important in assessing early damage and progression; c) significant damage to the retinal ganglion cells can occur before standard tests detect a functional loss in vision. These have paved the way to the development of many studies on the structure - function correlation and stating linear models for the same. However these studies present a dilemma; is the structure - function relation on glaucoma, a statistical statement (a structural measure will reach significance before a functional test) or relational statement (statistical correlation between the structural and functional tests).
We propose to evaluate the structure - function correlation in early and moderate open - angle glaucoma by assessing the retinal nerve fibre layer thickness by Spectral Domain Optical Coherence Tomography and areas of decreased visual field sensitivity given by Humphrey 24 - 2 Swedish Interactive Threshold Algorithm Standard protocol of automated perimetry and determine any representational or sta
Sponsor: Vasan Eye Care Hospital
Current Primary Outcome: Correlation between retinal nerve fibre layer thickness measured by optical coherence tomography and mean sensitivity, mean deviation as reported by visual fields. [ Time Frame: The subjects shall be studied over an avergae period of 4 weeks from the presentation for the purpose of optical coherence tomography and visual field studies. ]
Original Primary Outcome: Same as current
Current Secondary Outcome: Correlation between retinal nerve fibre layer thinning and scotomatous defects in visual fields in primary open angle glaucoma. [ Time Frame: The subjects shall be reviewed over an average period of 4 weeks to obtain the optical coherence tomography and visual field studies. ]
Original Secondary Outcome: Same as current
Information By: Vasan Eye Care Hospital
Dates:
Date Received: December 5, 2013
Date Started: February 2013
Date Completion:
Last Updated: December 28, 2014
Last Verified: December 2014
