Using the Lotmar moiré fringe interferometer and the potential acuity meter, I predicted the postoperative Snellen visual acuities in 30 implanted eyes that required secondary capsulotomies. The Lotmar interferometer was within one line of the postoperative visual acuity in 29 eyes (96.6%); the potential acuity meter prediction was within one line in 10 eyes (33.3%). An earlier study defined seven clinical conditions that produced false positive results with the laser interferometer. The same results occurred with the Lotmar interferometer. When the potential acuity meter was used, six of the seven conditions produced false positive results.