Outcomes of surgery for primary congenital glaucoma in Kenya: a multicentre retrospective case series

Abstract

Introduction: Primary congenital glaucoma (PCG) is a childhood developmental eye disorder associated with elevated IOP. It is the leading cause of childhood glaucoma and an important cause of childhood blindness worldwide. The condition is difficult to manage and ultimately requires surgical intervention. In Kenya, there are several surgical options available for PCG, but no published studies evaluating the effectiveness of such procedures. This study aimed to assess the outcomes of these procedures, thus facilitating evidence-based practice in the management of PCG. Methods: This was a retrospective case series conducted in 4 tertiary hospitals in Kenya (Kenyatta National Hospital, PCEA Kikuyu Hospital, Tenwek Mission Hospital and Sabatia Eye Hospital). Eyes of children <16 years of age who were operated for PCG from 2005 to 2014, were followed up to a maximum of 2 years. Post-operative IOP was the primary outcome measure. Surgical success and complication rates were calculated for each type of surgery. Kaplan Meier (KM) survivor curves were used to assess the cumulative probability of surgical success. Results: The number of primary surgeries performed was 213 in 131 patients. Repeat surgeries were done in 33 eyes of 26 patients. Most patients were males and were diagnosed before 1 year of age. 52.6% of surgeries were conducted at the Kikuyu Eye Unit (KEU). Majority of primary surgeries were trabeculectomies (TET- 40.8%) and combined trabeculectomy-trabeculotomies (CTT- 38%). Qualified success was obtained in 73.3% of eyes and complete success in 23% of eyes. KM probability of success at 1 month, 3 months, 6 months, 1 year and 2 years were 95%, 86%, 81%, 76% and 71% respectively. Ahmed Glaucoma Valve (AGV) and CTT had the highest success rates, at 83.3% and 81.8% respectively, whilst TET had the lowest (59.7%). The only significant predictor of surgical failure was a large pre-operative cup disc ratio (CDR). There was no change in the mean number of glaucoma drugs used between pre- and post-operative period. Serious complications were endophthalmitis (1), suprachoroidal haemorrhage (2) and retinal detachment (2). The most common repeat procedure xiv was AGV. Repeat surgeries achieved a percentage reduction in median IOP of only 21.9% from baseline at final follow-up visit. Conclusion: The most frequently-performed surgical procedures for PCG are TET and CTT. Surgical intervention was successful up to a period of 2 years post-operatively. CTT and AGV achieved the highest rates of surgical success as primary procedures. A large pre-operative CDR was a risk factor for surgical failure.