Abstract
Purpose: :
Cataract surgery is the most common ocular surgical procedure worldwide, and the quality of the implants has utmost importance for the outcome of the surgery. Over time, posterior capsule opacification (PCO) can occur, creating a secondary cataract. Approximately 30% of patients develop PCO within 1-5 years following surgery. In this study, we perform a posterior view (Miyake) macroscopic analysis to grade PCO and the location of the IOL.
Methods: :
Ninety-four formalin-fixed eyes were received from the Eye Bank of Ontario (50 phakic and 44 pseudophakic eyes). The globes were sectioned along the coronal axis and the anterior half was placed under a microscope with the cornea facing down. The location of the haptics was noted as bag-bag (B-B), bag-sulcus (B-S), sulcus-sulcus (S-S). The ciliary ring was measured in its longitudinal (L) and transverse (T) axis. The decentration index was obtained with the formula y - x/2; where y and x are the largest and the smallest distance between the IOL optic edge and the margin of the ciliary ring, respectively. The density of the central PCO was graded from 1 to 4. The Soemmering’s ring was graded (1 to 4) for extent (SRA, quadrants involved) and intensity (SRI, loss of transparency). The eyes were classified in the following groups: Crystalline lens, Acrysof Natural, Acrysof, and Other IOLs. Images were analyzed using the IMAGEJ software. Statistical comparisons were made using the Student T-test and a p<0.05 was considered significant.
Results: :
The overall ciliary ring diameter was 10.1 + 0.67 mm (L) x 10 + 0.67 mm (T). The average difference between (L) and (T) was 0.43 + 0.36 mm; this difference was statistically significant only within the "Other IOL" group (p=0.0002). The location of the haptics were: 38 B-B; 4 B-S and 2 S-S. The overall decentration index was 1.5 + 0.37, Central PCO was 0.75 + 0.9, SRA was 3.75 + 1.49, and SRI was 2.5 + 1.29. There were no significant differences between Acrysof and Acrysof Natural lenses. The "Other IOL" group showed significantly more decentration (1.51 + 0.4) and significantly higher Central PCO (1.51 + 0.4), SRA (3.52 + 1.16), and SRI (2.88 + 1.17) scores, compared to the other groups (p<0.05).
Conclusions: :
This study showed that the ciliary ring was distorted along the axis of the IOL in the "Other IOL" group. The possible reason for this distortion is that larger lenses and harder haptics deformed the ciliary ring. The results indicate that Acrysof and Acrysof Natural lenses deform the ciliary ring less than "Other IOLs" when used in cataract surgery. The "Other IOL" group also displayed greater decentration, PCO, and Soemmering’s ring formation, when compared with Acrysof lenses. The lower incidence of PCO with Acrysof lenses is likely attributable to the design of the lens edge and the material itself.
Keywords: posterior capsular opacification (PCO) • cataract • intraocular lens