Visual Outcome and Causes of Poor Visual Outcome of Manual Small Incision Cataract Surgery in Adult Patients at Muhimbili National Hospital from May 2017 to January 2018

Abstract

Background: Cataract is the opacification of the crystalline lens of the eye, which causes progressive decrease in visual acuity, eventually leading to blindness. The precise treatment of cataract is surgical extraction of the opacified lens. Cataract extraction is the most common procedure performed worldwide; despite large number of cataract surgeries being performed, poor surgical outcome results in poor vision there by contributing to failure to reduce cataract blindness. In order to achieve better visual outcomes, monitoring systems of cataract surgery is important to be established. Aim: To assess the post-operative visual outcome and causes of poor visual outcome in adult patients operated for manual small incision cataract surgery at Muhimbili National Hospital (MNH). Methodology: This was a hospital based observational descriptive longitudinal study of consecutive patients underwent cataract surgery at Muhimblili National Hospital from May 2017 to January 2018. A total of 190 patients who met the inclusion criteria were recruited to the study. The patients were examined 1st day post-operative, 7th day post-operative and 6th weeks post operatively. Results: The mean age and standard deviation of the study population was 64.2(11.9) years and the mean age of male and female patients were 63.6(10.8) and 65.0(13.3) years respectively. The best corrected visual acuity at 6th week post-operative was 6/6-6/18(good outcome) in 110(65.1%), <6/18-6/60 (borderline) 30(17.8%) and <6/60 (poor outcome) in 29(17.2%). The leading intra-operative complication was posterior capsule tear in 23(52.3%) eyes. The common early post-operative complications were elevated IOP and corneal edema, and the common late complication was posterior capsule opacification. The residual refractive error was astigmatism in 57(35.6%) eyes, myopia 48(30%), and hyperopia 22 (13%) eyes. Intra-operative complications (31%), post-op complications (27.8%), residual refraction (10.4%) and comorbidities (31%) were the cause of poor visual outcome. Conclusion: The cataract surgical outcome at Muhimbili National Hospital was below WHO standards. The commonest intra-operative complications were iris prolapse and posterior capsule tear. Early complications were corneal edema and high intraocular pressure. The commonest late complication was posterior capsule opacification. Astigmatism was the commonest residual refractive error. The factors associated with poor outcome were mainly presence of intraoperative, post-operative complications and ocular comorbidities. Recommendations: Measures to improve post-operative visual outcome include good pre-operative evaluation and proper selection of patients for surgery to minimize poor outcome. There is a need for cataract surgery monitoring tool to be initiated to the hospital so as to assess the outcome and quality of the surgeries that are conducted in the hospital.