Essay on Change Of Visual Acuity With Eccentricity

975 Words Jan 27th, 2016 4 Pages
Change in Visual Acuity with Eccentricity
Humans have a large vison field so it is important to not only test the central vison but also at the peripherals of the retina. This is because individuals tend to not notice vison loss at the peripherals compared to central vision as when an individual views an object they move their eyes and fixate on that object by using their central vison and not their peripheral. Visual acuity is highest at the fovea and lowest at the peripheral which ensures high visual acuity at fixation. A way to measure peripheral vision is the Humphrey perimetry test which assesses the vision field. Any reduction in peripheral vision can indicate the development of disease such as glaucoma or detect any blind spots, scotomas that have developed due to eye disease which can impact daily activities such as driving. The aim of the experiment was to investigate the change in visual acuity across the nasal retina to an eccentricity of 45 degrees.
Method
Firstly, the subject was sat down and the Visual acuity was measured using the log mar chart, the decimal V was calculated. A display board was positioned in front of the subject at a distance of one metre ensuring the subject’s eyes were parallel to the board and the Maltese cross was positioned on the extreme left end. This is to ensure the cross was projected on to the nasal retina when the right eye was tested. The left eye was occluded using the occluder in the trial frame. The subject was instructed to…

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