Author’s Name(s): Wissam Nassrallah, Asahi Fujita, Andre Pollmann, Alice Lorch, Joan Miller, Tobias Elze, Nazlee Zebardast, Samir Jabbour

Author’s Disclosure Block: Wissam Nassrallah, none; Asahi Fujita, none; Andre Pollmann, none; Alice Lorch, none; Joan Miller, none; Tobias Elze, none; Nazlee Zebardast, none; Samir Jabbour, none

Abstract Body
Purpose: In advanced keratoconus, anterior lamellar keratoplasty (ALK) is perceived as a safer but more technically demanding alternative to penetrating keratoplasty (PKP). However, comparisons regarding pre-operative determinants for procedure selection and long-term outcomes in the US remain limited. Study Design: Retrospective cohort study Methods: We conducted a retrospective cohort analysis using data from the IRIS registry, spanning January 1, 2013, to December 31, 2020. Univariate and multivariable logistic regression identified factors influencing the choice between ALK and PKP. Cumulative incidence of complications was calculated. Kaplan Meier graphs were constructed to look at different subsequent surgeries. Results: A total 1005 ALK eyes and 9400 PKP eyes were included with a mean age of 39.98 (15.47) and 44.30 (16.41) respectively. Younger, non-Hispanics, with commercial insurance, and with better pre-operative vision (OR 0.67; 95% CI 0.60-0.74) and lower intraocular pressure (IOP) (OR 0.96; 95% CI 0.94-0.98) patients were more likely to receive ALK on univariate analysis. After controlling for covariates, only younger age, better pre-operative vision (OR 0.54; 95% CI 0.46-0.63) and lower IOP (OR 0.97; 95% CI 0.94-0.99) persisted as influencing factors. ALK eyes had significantly fewer graft failures and rejections at 90 days (failure: 3.3% in ALK vs. 12.6% in PKP, p<0.001; rejection: 1.9% in ALK vs. 5.8% in PKP, p<0.001) and one-year (failure: 5.4% in ALK vs. 12.3% in PKP, p<0.001; rejection: 6.5% in ALK vs. 11.7% in PKP, p<0.001) post-operatively, but not at 3 and 5 years. Overall, re-grafts rate between both procedures were not statistically different up to 5 years. Subsequent secondary cataract or glaucoma surgeries were also not statistically different up to 5 years of follow-up. Conclusions: In the US, younger patients with better pre-operative vision are more likely to receive ALK. Other socioeconomic factors such as ethnicity and insurance coverage may also play an important role. However, our data suggests that ALK may not results in improved post-operative outcomes compared to PKP over 5 years.