Simple clinical techniques to evaluate visual function in patients with early cataract.

Among the 80 subjects who were recruited with normal retinal and neural function, 54 had cataract and a visual acuity (VA) better than 6/24. The 26 age-matched subjects had clear media. Contrast sensitivity (CS) at low and intermediate spatial frequencies was measured using the Pelli-Robson letter chart. Two measures of glare disability (GD) were obtained using the Mentor Brightness Acuity Tester (BAT) in conjunction with a logMAR VA chart and the Pelli-Robson chart. Although CS is predominantly affected at high spatial frequencies in early cataract, we found that some subjects had reduced scores on the Pelli-Robson chart. This CS loss could not be predicted from VA measurements and was particularly found in subjects with posterior subcapsular cataract. High GD scores were found in a number of subjects with relatively good VA and could not be predicted from results of VA or CS. We suggest that CS and GD measurements using the Pelli-Robson chart and the BAT provide valuable information regarding the management of patients with early cataract.