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Hi, need to submit a 1000 words essay on the topic The Ability to Perceive a Minor Change in Luminosity.To perform the CS test (CST), the basic requirements for all four tests were: 1) to have an adeq
Hi, need to submit a 1000 words essay on the topic The Ability to Perceive a Minor Change in Luminosity.
To perform the CS test (CST), the basic requirements for all four tests were: 1) to have an adequate luminance level required for each test. 2) to have precise test distance. and 3) to perform each test approximately at the same eye sight level as that of test charts. The CST luminance requirement for Pelli-Robson charts was 60–120 cd/m2, while for Vistech6000 and Cambridge plates the adequate luminance levels were 103–240 cd/m2 and 100 cd/m2 respectively. The Lux value required for Cardiff cards CST was equal to that of the gray background cards. For each test the required Lux level was verified by using a Lux meter. The value of precise test distance varies from test to test. For Pelli-Robson CST the required separation was 1 m. For Vistech and Cambridge plates CSTs, the required separation was 3.048 m and 6 m respectively, and within the acuity limit for Cardiff cards CST (Wood and Wood 1995). After having all basic requirements for each test, the test charts/cards were hung vertically on a wall one after the other. To determine CS values, corresponding observations were made: first with the right eye (without any correction), starting horizontally on each line of charts/cards and moving from the left hand side to the right hand side, and then from top to bottom for each letter/symbol on the chart /card. The tests were repeated for a plastic in front of an eye pretended to be a cataract. The tests were concluded when two or three letters/symbols were named incorrectly. The corresponding observations for CS were recorded. The CS function (CSF) value obtained for monocular right eye (RE) testing without cataract through Pelli-Robson CST is 1.95 while with cataract it is 1.65 – a quite lower value (fig. 4 and 5) . From Cardiff CST the evaluated contrast (%) values for monocular.
