A Decade of Strabismus Surgery Outcomes at Kilimanjaro Christian Medical Centre, Tanzania

Abstract

Background: Strabismus, a condition characterised by eye misalignment, affects 2-5% of the global population, leading to vision problems, psychological distress, and social challenges. Despite surgical interventions aiming to realign the eyes, predicting outcomes remains difficult, and there's a lack of data on strabismus surgery outcomes in Tanzania, hindering effective service planning and resource allocation. Aim: The study aimed to evaluate the outcomes of strabismus surgery and its associated prognostic factors among strabismus patients attending KCMC Hospital in Northern Tanzania over ten years. Participants and Methods: A hospital-based analytical cross-sectional study was conducted at the ophthalmology department of KCMC in Tanzania. Medical records of 115 patients undergoing first-time strabismus surgery from January 2011 to December 2020 were analysed. A successful outcome was defined as a postoperative deviation angle within 10 prism diopters of exotropia or 5 prism diopters of esotropia of orthophoria at 1 week postoperatively. Factors associated with surgery outcomes were assessed using a generalised linear model, considering variables with P < 0.05 as statistically significant. Results: Over the study period, 115 patients underwent first-time strabismus surgery, with the majority presenting at or before age 9 and a significant proportion undergoing surgery at this age. Most cases had preoperative angles exceeding 45 degrees, following surgery, 71.3% achieved orthophoria, while complications were noted in 34.8% of cases, which were mainly under-corrected due to large angles. Analytically, associations between demographic and clinical factors and surgical outcomes were explored. Participants with acquired strabismus exhibited a significantly higher proportion of good outcomes compared to congenital cases (p = 0.015). Larger pre-operative angles (> 45 degrees) were associated with poorer outcomes (p = 0.001), while smaller angles (≤ 20 degrees) showed a trend towards better outcomes (p = 0.083). Furthermore, age at presentation, laterality, and angle before surgery significantly influenced surgical outcomes. Participants aged 10-19 years were 1.4 times more likely to have a good outcome compared to those aged ≤ 9 years (CPR = 1.4, 95% CI: 1.12-1.70). Conclusion: Three-quarters of patients achieved orthophoria post-surgery. While factors like type of strabismus, preoperative angle, and type of horizontal strabismus showed clinical association with successful outcomes in crude analysis, they did not remain significant when adjusted. This study, like others, suggests that prognostic factors remain unpredictable for successful strabismus surgery outcomes.