Pentacam tomograms: a novel method for quantification of posterior capsule opacification.

PURPOSE: To develop and validate a method to quantify posterior capsule opacification (PCO) in eyes after cataract surgery and intraocular lens implantation using Scheimpflug Pentacam tomograms and compare its validity with slit lamp retroillumination image analysis.

METHODS

One hundred twenty-four pseudophakic eyes of 124 patients were divided into two groups. Group 1 consisted of 40 eyes with visually significant PCO, and group 2 consisted of 84 eyes without visually significant PCO. Pentacam Imaging was performed after full mydriasis using the 50-scan acquisition protocol, and high-resolution tomograms were reconstructed and analyzed using ImageJ freeware. Retroillumination photographs were captured for group 1 eyes using the Topcon digital slit lamp, and these were analyzed using POCOman software to calculate an aggregate severity grade and percentage PCO value. Correlation coefficients were calculated for PCO values obtained using POCOman and ImageJ.

RESULTS

Mean PCO percentage value obtained using POCOman software was 23.34 +/- 6.25 U, mean aggregate PCO severity grade was 0.46 +/- 0.28 U, and mean pixel-intensity value using ImageJ was 31.071 +/- 8.26 U. There was a significant positive correlation between the percentage PCO (P = 0.000; r = 0.864) and PCO severity grade (P = 0.001; r = 0.490) obtained for group 1 eyes using slit lamp retroillumination images and PCO pixel intensity obtained using Pentacam tomograms.

CONCLUSIONS

Retroillumination photographs are the standard for quantifying PCO. Pentacam tomograms are easier to obtain and are free of flash reflections, and they allow for a more objective analysis. The correlation between the two methods demonstrates that ImageJ analysis of Pentacam tomograms is a viable tool for PCO analysis.