Determination of Contrast Sensitivity and Reaction Time in Albinos Using the New Computer-Based Test

Abstract

Albinism encompasses a group of congenital disorders characterized by absent or deficient melanin production and this often affect vision. Contrast sensitivity is gaining increased recognition as a valuable tool for measuring functional vision and from many literatures it has been shown that albinos reached a lower level of contrast sensitivity. The objective of this study was to determine contrast sensitivity and reaction time in human albinos using the new computer based test (Java program suites) and also to see if there is a relationship between age, contrast sensitivity and reaction time in albinos. 49 Albino subjects with ages ranging from 8-69 years were tested with the new computer based contrast sensitivity/reaction time test. Out of the study population of 49 albino subjects (36 males and 13 females), 7 subjects were within the age group of 20 – 29 years (20.34%), 8 subjects were within the age group of 30 – 39 years (22.03% ), 6 subjects were within the age group of 40 – 49 years (15.25%), 9 subjects were within the age group of 50 – 59 years (27.12%), and 6 subjects were within the age group of 60 – 69 (15.25%). The background luminance was set at 88.5cd/m2. Exposure time for each screen was 20 secs. The data was analyzed, using one way ANOVA statistical analysis. The mean reaction time of the sample population was 2.76 ± 2.08. It was observed that there is a relationship between reaction time and age in albinos. The research also revealed that there is no significant difference in the mean reaction time among numbers, blinking and jumping targets as measured in different age group of subjects. The mean contrast threshold was 2.3 logs CS for numbers, blinking and jumping targets in all the different age groups, but the critical contrast or the asymptote is different in all the age groups. This was shown by the increase in the slope of the graph (k) as the age group increases. Targets with high contrast gave faster reaction time than targets with low contrast. The result is similar to our unpublished data for normal humans (in press).
Keywords: Albinos, Contrast sensitivity, Reaction time, Java.