PREOPERATIVE ULTRASOUND BIOMICROSCOPY TO ASSESS EASE OF HAPTIC REMOVAL BEFORE PENETRATING KERATOPLASTY COMBINED WITH LENS EXCHANGE

Purpose: To evaluate a method of assessing anterior chamber intraocula r lens (IOL) haptics before combined penetrating keratoplasty and IOL exchange in eyes with poor corneal clarity resulting from pseudophakic bullous keratopathy (PBK). Setting: Department of Ophthalmology, Toro nto Hospital, Ontario, Canada. Methods: Twelve eyes (25 haptics) with PBK were studied using ultrasound biomicroscopy (UBM). The degree of h aptic encasement was graded. The result was compared with the degree o f difficulty and the complications encountered in removing the IOL at the time of surgery. The surgeons were masked as to the UBM results, R esults: All haptics were easily visualized with UBM, with 23 in the an gle and 2 passing through a peripheral iridectomy. On UBM, 9 haptics w ere noted to lie free in the angle, and 16 were encased by fibrotic ti ssue. Eight were covered by less than 100 mu m and 8 by more than 100 mu m of tissue. Calculations using Kappa statistics found a strong pre dictive value for the UBM in identifying the presence or absence of fi brotic encasement and degree of difficulty in removing the anterior ch amber IOL haptics. Ultrasound biomicroscopy also allowed assessment of the adjacent angle for synechias. Conclusion: Ultrasound biomicroscop y provides an alternative method for evaluating anterior chamber IOL h aptics when gonioscopy is not possible because of corneal opacity. Thi s method allows the surgeon to predict preoperatively the degree of di fficulty that will be encountered in explanting the IOL.