Factors Influencing the Acquisition and Quality of HRT Images in the Long-term Follow up of Patients Post-trabeculectomy

Abstract

Abstract: : Purpose:To identify those factors affecting the acquisition and quality of HRT images in the long-term follow-up of patients post-trabeculectomy. Methods:The quality of HRT images, acquired in 145 consecutive patients (mean age 67.6±9.2 years) recruited into a randomised controlled trial of primary trabeculectomy, was analysed. Imaging had been performed within 90 days prior to surgery and at all annual post-operative visits. Each aligned series was inspected for eye movements that could not be corrected by the software. The quality of the obtained topographic image profile and clarity was graded as "good" or "poor" by subjective analysis. "Unobtainable" images were also documented. A series was classified as "perfect" if it contained no eye movements and was of good quality. Where possible, information regarding factors affecting image quality and acquisition was recorded. Results:Patients were followed up for an average 4.8±0.7years. Images were obtained in all patients at baseline and in an average of 78.7±4.4% of patients at the follow-up visits. Of these, 49.6±5.2% had 3 or more "perfect" images. The percentage of poor quality images increased post-operatively reaching a peak of 29.9% at 3 years with cataract accounting for 38.9% of these. In 37.9±5.0% of all patients, images were either unobtainable or of poor quality. Cataract alone was responsible for 28.9±4.6% of these, increasing to 50.3±6.3% when pupil size was also considered. IOL deposits and capsular fibrosis had a small but increasing effect from 2 years onwards. Other factors affecting image quality and acquisition included corneal epitheliopathy and vitreous floaters. Conclusions: The development of cataract following trabeculectomy combined with a poorly dilating pupil and other media opacities are the main factors preventing the acquisition of good quality HRT images. This has clinical implications regarding the use of HRT imaging in the long-term follow-up of patients post-trabeculectomy.

Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, S • imaging/image analysis: clinical