[Risk factors for secondary cataract: a case-control study with multivariate analysis].

Abstract

AIM: A retrospective case-control study was initiated to determine the risk factors for the development of posterior capsule opacification. SUBJECTS AND METHODS: 100 cases of patients with secondary cataract treated by YAG laser capsulotomy were compared with 100 controls (patients who had cataract surgery not complicated with a secondary cataract). The posterior capsule was examined by the biomicroscope. A 1-to-1 matched case-control study was designed by stratifying inclusions on the basis of age, sex, and delay. We studied the risk factors related to the patient, the primary cataract, the surgical technique, the surgeon's skill, and intraoperative and postoperative complications. All the lenses were biconvex and all-PMMA with the same design. Statistical analysis was done in 3 steps: a univariate analysis, then a bivariate analysis using chi-square and the Student tests and finally, we performed a multivariate analysis with a logistic regression. The significance level for type I error rate was fixed at 5%. RESULTS: The average age was 61.6 years. The mean delay was 32.7 months for cases and 34.5 months for controls. The bivariate analysis identified nine risk factors: corneal opacities (p=0.031), absence of a posterior chamber lens p=10(- 4)), the can opener anterior capsulotomy (p=0.003), ciliary sulcus fixation of the lens p=0.030), a large optic diameter of 7mm p=10(- 5)) and (t=0.002), poor intraoperative pupillary dilatation (p=0.003), a less experienced surgeon (p=3.10(- 4)), postoperative inflammation (p=0.021), and persistence of residual cortical material (p=0.002). The multivariate analysis selected five principal factors: absence of a posterior chamber lens, an optic diameter of 7mm, poor intraoperative pupillary dilatation, a less skilled surgeon, and persistence of cortical material. CONCLUSION: This case-control study reveals some of the risk factors previously identified and may contribute to the determination of methods for prevention of secondary cataract. The new intraocular lenses and pharmacological agents would lead to better results.