Visual acuity prediction before neodymium-YAG laser posterior capsulotomy.

A laser interferometer (Retinometer) and the Potential Acuity Meter (PAM) was used to assess macular function before neodymium-YAG laser posterior capsulotomy in 40 patients. Although specificity was excellent with the PAM (91%) and Retinometer (93%), sensitivity was limited to 42% and 33%, respectively. Diffuse posterior capsular opacification which precluded the delivery of light through a clear portion of the capsule was the most likely cause of the high false negative rate. A positive result on either test has good predictive value, reducing the changes of the capsulotomy being a failure by fourfold.