A clinical evaluation of the potential acuity meter in 210 cases.

The potential acuity meter (PAM) has been reported to be a useful instrument for predicting postoperative visual acuity after cataract extraction surgery. In this study, 210 eyes were tested with the PAM before surgery, and the best postoperative visual acuity was obtained. The PAM accurately predicted the postoperative visual acuity to within three lines in 85.2% of the cases. Further, the PAM was able to predict whether or not an operation would be successful (success defined as a final visual acuity of 20/40 or better) in 91.6% of the cases. It was found that senile macular degeneration may cause false-positive tests (predicted acuity better than final acuity), and this should be watched for when the test is used. When the test is in error, the tendency is for the PAM to underestimate the final acuity rather than to overestimate.