Quantification of posterior capsular opacification in digital images aftercataract surgery

PURPOSE. To describe a software program developed to provide an objective a ssessment of the amount of posterior capsular opacification (PCO) in high-r esolution digital images of the posterior capsule after cataract surgery. METHODS. Images are analyzed by a set protocol of defining the area of the posterior capsule, removing the Purkinje light reflexes by intensity segmen tation, contrast enhancement, filtering to enhance low-density PCO, and var iance analysis using a co-occurrence matrix to assess texture. The accuracy of the system was tested for validity and repeatability. RESULTS. The software developed has been demonstrated to be an objective me thod of quantifying PCO. In validation tests, the image analysis-derived me asure of PCO showed good agreement with clinically derived measures of PCO. Clinicians assessed PCO on a computer screen image and also under slit lam p examination (Pearson correlation coefficient for both methods >0.92). The entire acquisition and analysis system was demonstrated to have a confiden ce limit for 2 SDs of 9.8% for group data. CONCLUSIONS. This system is capable of producing an accurate and reproducib le measure of PCO that is relevant to assessing techniques of PCO preventio n.