Different Impacts of Luminosity on Contrast Vision in Eyes with Transparent Optic Media and with Cataract Simulation
Objective: To evaluate the effect of luminous intensity on contrast vision under different ocular conditions. Materials and Methods: Ninety eyes of 45 persons were included in this study as follows: 30 healthy eyes, 30 eyes with cataract simulation (using translucent glasses), and 30 myopic eyes. Contrast sensitivity was examined using 5 spatial frequencies (1.5, 3.0, 6.0, 12.0, and 18.0 cycles per degree) of sine wave contrast test optotypes for 4 light intensities (34, 68, 154, and 240 cd/m2). Results: The mean linear contrast sensitivities averaged over the frequencies for each of the 4 light intensities were: healthy eyes: 59 ± 11, 72 ± 16, 79 ± 23, and 80 ± 19; myopic eyes: 52 ± 13, 67 ± 15, 73 ± 21, and 75 ± 18, and cataract simulation eyes: 15 ± 7, 21 ± 8.6, 28.7 ± 13, and 28.6 ± 13, respectively. The linear contrast sensitivities averaged over the light intensities for each of the 5 spatial frequencies were: healthy eyes: 78, 87, 117, 59, and 21; myopic eyes: 65, 84, 109, 54, and 29, and cataract simulation eyes: 37, 41, 28, 8, and 2. Conclusions: The light intensity level had a positive effect on the contrast sensitivity of the examined eyes, except for eyes with cataract simulation, where even the maximum light intensity did not improve the contrast vision. This indicates that patients with cataracts require increased contrast of text rather than brighter illumination to improve the quality of their vision.