ERG b/a ratio and retinal circulation time of CRVO

Fourteen cases of central retinal vein occlusion (CRVO) were studied with electroretinogram (ERG) and fluorescein angiogram. The cases were divided into a venous stasis retinopathy group (VSR,9 cases) and a hemorrhagic retinopathy group(HR, 5 cases). The b/a ratio and retinal circualtion time (RCT) were measured and compared with the control group. The mean b/a ratio of the HR group (0.86) was decreased as compared with the VSR group (1.18) and the control group (1.23). The RCT of the HR group was markedly delayed to 13.68 seconds as compared with the VSR group (11.09 sec) and the control group (6.4 sec). These facts suggest that both the b/a ratio and the RCT are possible parameters for estimating retinal ischemia and that the ERG is a reliable examination method for classification of CRVO.

Effect of Method of Illumination on the Visual Contrast Sensitivity Funetion

To find out the good visual environment for reading, the methods of illumination were studied using Arden Contrast Sensitivity System. Among various factors for comfortable reading condition such as air condition, temperature, humidity, noise and light, the intensity and characters of illumination were the most important factors for eye health. If the character of illuminations are fairly good, to make the brighter condition is better for eye hdalth. But in artificial illumination, there are so many limitations for supplying light of good characters. So we set the luminosity on the desk to 500 lx in which tbe best visual acuity presented, and checked the contrast sensitivity by changing the luminosity of the room. The results suggested that the condition in which luminosity on the desk was higher twice than the room was favorable for reading.