Visual outcome of day-case versus inpatient cataract surgery : a randomized clinical trial
Date of Award
Master of Science in Epidemiology & Biostatistics (MSc Epidemiology & Biostats)
Community Health Sciences
Age-related cataract is the major cause of worldwide blindness and severe visual impairment. An estimated 45 million people worldwide are blind, 19.34 million of them due to cataract. Nine of ten cataract-blind people in the world live in developing countries. Like other developing countries, Pakistan has a huge backlog of cataract blindness; it has an estimated 1.5 million and.2.5 million people who are blind, mostly due to cataract, in both eyes and in one eye, respectively. However, the number of cataract surgeries performed each year is only around 140,000. Thus, a dramatic increase in cataract surgical rate is required to reduce such a backlog, and to address the incidence of cataract blindness--300, 000 cases per year. One of the ways in which the burden of cataract blindness could be reduced is to increase the proportion of day-case cataract surgeries. However, there is a lack of data in Pakistan and other developing countries that could provide justification for large-scale conversion from the conventional inpatient cataract surgery to the day-case cataract surgery. we hypothesized that three months postoperatively, the difference in the risk of poor vision (best-corrected visual acuity <6/60 in the operated eye) between patients undergoing day-case extracapsular cataract extraction (ECCE) with posterior chamber (PC) intraocular lens (IOL) and patients undergoing inpatient ECCE with PC IOL is not greater than 5o/o. To test this hypothesis, we conducted a randomised clinical trial in the Iayton Rehmatullah Benevolent Trust Free Base Eye Hospital Karachi, which is the leading cataract operator in Pakistan. Between January 2002 and October 2002, 493 subjects with cataract were enrolled and randomised. Further enrolment was stopped on October 24 2002 because of financial and logistic constraints. We used simple randomisation to assign subjects either to the day-case ECCE with PC IOL, or the inpatient ECCE with pc IOL. The day-cases rested for l-2 hours postoperatively, and were then discharged. The inpatients were retained for 24 hours and then discharged. Subjects were examined before surgery, and at 24 hours, 3 days, l-month and 3 months postoperatively. The outcome measure was poor vision at 3 months. Poor vision was defined as the best-corrected visual acuity of less than 6/60 in the operated eye. The analysis was on an intention-to-treat basis. Most baseline characteristics of 249 day-cases and 244 inpatients were comparable. The mean (+ SD) age of day-cases and inpatients was 59.6±9.9 and 59.7±10.4 years, respectively. Preoperatively, 63.9 %( 159/249) eyes in day-cases and 69.3 % (169/244) eyes among inpatients were blind. At three months, 222(89.2%) day-cases and 219(89.8 %) inpatients could be examined. Multiple logistic regression analysis indicated that there was no statistically significant difference in the risk of poor vision between patients undergoing day-case and the conventional inpatient cataract surgery at three months, adjusting for the effect of age and sex (adjusted RR=0.88; 95% CI: 0.36-2.11). We conclude that three months postoperatively, the difference in the risk of poor vision between patients undergoing day-case ECCE with PC IOL and patients undergoing inpatient ECCE with PC IOL is 0.5%. Our study provides more justification for adopting day-case cataract surgery as the preferred form of cataract surgery.
Ahmad, K. (2003). Visual outcome of day-case versus inpatient cataract surgery : a randomized clinical trial (Unpublished doctoral thesis). Aga Khan University, Karachi, Pakistan.