Purpose: To investigate the correlation between the change in visual acuity and the difference in objective posterior capsule opacification (PCO) scores before and after neodymium:YAG (Nd:YAG) laser capsulotomy.
Setting: Department of Ophthalmology, Medical University of Vienna, Vienna, Austria.
Methods: Forty pseudophakic eyes of 35 patients with PCO of varying intensity were examined before and after Nd:YAG laser capsulotomy. Visual acuity was determined using the Early Treatment Diabetic Retinopathy Study (ETDRS) chart at 4 m and the Holladay reading chart at 40 cm. The pupil diameter under reading conditions was measured each time. Digital retroillumination images of the posterior capsule were taken, and the corresponding area inside the pupil was evaluated using the Automated Quantification of After-Cataract (AQUA) automated PCO analysis program. The change in visual acuity and difference between PCO scores before and after Nd:YAG laser capsulotomy were calculated for all eyes.
Results: The mean AQUA score (scale 0 to 10) was 3.56 before and 0.13 after Nd:YAG laser capsulotomy. The mean ETDRS visual acuity score (logMAR scale) was 0.28 and -0.07, respectively. The correlation coefficient between the differences in PCO score and distance visual acuity was 0.61 and near visual acuity, 0.62.
Conclusions: The objective PCO score obtained by an automated image-analysis program correlates well with the PCO-induced decrease in visual acuity when the central area (inside the pupillary aperture) of the posterior lens capsule was evaluated. Objective PCO assessment by automated image-analysis systems is, therefore, a valuable and clinically relevant method for clinical studies of the development and prevention of PCO.