***TASK***
the task is to simplify the input abstract of a biomedical literature

***INPUT***
the input is the abstract of a biomedical literature

***OUTPUT***
the output is the simplified abstract for the input abstract of a biomedical literature

***DOCUMENTATION***

***EXAMPLES***

Input: We identified 20 studies that had analyzed a total of 1947 eyes of 1866 participants (individual studies ranged from 8 to 346 participants who were randomized). The studies were conducted in eight different countries: one in Brazil, three in China, three in Cuba, one in Egypt, two in Iran, two in Thailand, seven in Turkey, and one in Venezuela. Overall risk of bias was unclear, as many studies did not provide information on randomization methods or masking to prevent performance and detection bias. The risk ratio for recurrence of pterygium using conjunctival autograft versus amniotic membrane transplant was 0.87 (95% confidence interval (CI) 0.43 to 1.77) and 0.53 (95% CI 0.33 to 0.85) at 3 months and 6 months, respectively. These estimates include participants with primary and recurrent pterygia. We performed a subgroup analysis to compare participants with primary pterygia with participants with recurrent pterygia. For participants with primary pterygia, the risk ratio was 0.92 (95% CI 0.37 to 2.30) and 0.58 (95% CI 0.27 to 1.27) at 3 months and 6 months, respectively. We were only able to estimate the recurrence of pterygia at 6 months for participants with recurrent pterygia, and the risk ratio comparing conjunctival autograft with amniotic membrane transplant was 0.45 (95% CI 0.21 to 0.99). One included study was a doctoral thesis and did not use allocation concealment. When this study was excluded in a sensitivity analysis, the risk ratio for pterygium recurrence at 6 months' follow-up was 0.43 (95% CI 0.30 to 0.62) for participants with primary and recurrent pterygium. One of the secondary outcomes, the proportion of participants with clinical improvement, was analyzed in only one study. This study reported clinical outcome as the risk of non-recurrence, which was seen in 93.8% of participants in the conjunctival limbal autograft group and 93.3% in the amniotic membrane transplant group at 3 months after surgery. We did not analyze data on the need for repeat surgery, vision-related quality of life, and direct and indirect costs of surgery due to an insufficient number of studies reporting these outcomes. Thirteen studies reported adverse events associated with conjunctival autograft surgery and amniotic membrane transplant surgery. Adverse events that occurred in more than one study were granuloma and pyogenic granuloma and increased intraocular pressure. None of the included studies reported that participants had developed induced astigmatism. In association with pterygium excision, conjunctival autograft is associated with a lower risk of recurrence at six months' after surgery than amniotic membrane transplant. Participants with recurrent pterygia in particular have a lower risk of recurrence when they receive conjunctival autograft surgery compared with amniotic membrane transplant. There are few studies comparing the two techniques with respect to visual acuity outcomes, and we identified no studies that reported on vision-related quality of life or direct or indirect costs. Comparison of these two procedures in such outcome measures bears further investigation. There were an insufficient number of studies that used adjunctive mitomycin C to estimate the effects on pterygium recurrence following conjunctival autograft or amniotic membrane transplant.
Output:

We considered the type of pterygium surgery to be better if it the pterygium returned in a smaller proportion of people at three and six months after the surgery. We searched online databases of published medical articles to find studies that had assigned participants to one of the two surgeries. We included in our review only the studies in which the participants were assigned randomly to their surgery, so that they had an equal chance of being assigned to either one. Study participants could have this growth for the first time (primary pterygium) or could need another surgery because their growth had returned previous surgery. The evidence is current to November 2015. We found 20 studies that compared the two surgeries in a total of 1947 eyes. We combined information from the studies to determine which surgery was better. Six months after surgery, the pterygium returned only one third to over half as often in people who had CAG surgery than in people who had AMT surgery. This difference could not be explained by chance alone. The studies we found did not answer all of our questions. We still want to know the effects of the surgeries on clarity of vision, quality of vision, quality of life and costs. More research studies are needed that answer these questions. The overall quality of the evidence in favor of CAG is low to moderate because of issues in the conduct of the studies and results were sometimes not similar across studies. Future published research may have an impact on the conclusions provided in this review.