Recurrence After Conjunctival Autograft versus Amniotic Membrane Transplantation for Primary Pterygium: A Retrospective Kaplan-Meier Cohort Study

Purpose: To compare recurrence after conjunctival autograft (CAG) and amniotic membrane transplantation (AMT) for primary pterygium and to identify unadjusted predictors of recurrence, with an exploratory analysis by age group. Patients and Methods: This retrospective cohort study included 402 patients who underwent primary pterygium excision by a single surgeon over 10 years (CAG, n=193; AMT, n=209). Patients chose their surgical technique after counselling, and all were followed for 12 months. The primary outcome was recurrence, defined as fibrovascular tissue extending ≥ 1.5 mm onto the cornea. Associations were assessed with chi-square or Fisher’s exact tests. All analyses were unadjusted; multivariable regression was not performed because of the limited number of recurrence events. Recurrence-free probability was estimated with the Kaplan–Meier method and compared with the log-rank test. Effect sizes were reported as odds ratio (OR), absolute risk reduction (ARR), relative risk reduction (RRR), and number needed to treat (NNT). Age-stratified analyses were exploratory. Results: The overall recurrence rate was 11.7% (47/402) at 12 months, and all recurrences occurred within 9 months. Recurrence was lower with CAG than AMT (8.3% vs 14.8%; Fisher’s exact p=0.044), with an unadjusted OR for AMT of 1.93 (95% CI: 1.02– 3.65), ARR of 6.5% points, RRR of 44.1%, and NNT of 15.3. Recurrence-free probability at 12 months was 91.7% with CAG and 85.2% with AMT (log-rank p=0.041). In exploratory age-stratified analyses, recurrence was 0% (0/54) with CAG vs 21.1% (15/71) with AMT in patients aged 20– 40 years, with no difference in patients aged 41– 60 years (11.1% vs 11.5%); the group aged > 60 years (n=12) was too small to interpret. No other variable was associated with recurrence in unadjusted analyses. Conclusion: In this non-randomized cohort, in which patients chose their technique, CAG was associated with lower recurrence than AMT. The apparent difference in younger patients is hypothesis-generating only and requires prospective confirmation, and residual confounding, including by pterygium grade, cannot be excluded.