Impact of Cone Position on Prognostic Outcomes of Deep Anterior Lamellar Keratoplasty (DALK) in Advanced Keratoconus

PURPOSE: To evaluate the impact of cone position on prognostic outcomes of deep anterior lamellar keratoplasty (DALK) in advanced keratoconus. METHODS: This retrospective study analyzed 49 eyes (48 patients) with advanced keratoconus undergoing DALK between 2015 and 2023. Cases were categorized as central (n = 26) or paracentral (n = 23) based on the position of the cone. Primary outcomes included uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), manifest refraction, keratometric characteristics, corneal thickness, and quality of life assessments. RESULTS: The results showed that the postoperative UCVA and BCVA in the central group were significantly better than those in the paracentral group (UCVA: 0.492 ± 0.192 vs. 0.617 ± 0.241, P = 0.049; BCVA: 0.192 ± 0.102 vs. 0.396 ± 0.199, P < 0.001). Although the paracentral group exhibited a more significant recovery in central corneal thickness (CCT) (CCT: 528.654 ± 30.900 vs. 549.696 ± 36.394, P = 0.034; postop CCT-preop CCT: 127.615 ± 55.697 vs. 155.565 ± 37.490, P = 0.048), no significant difference was found in postoperative keratometric characteristics between the 2 groups (P > 0.05). Quality-of-life assessments revealed that the central group achieved significantly higher postoperative scores in the far vision and driving subscales compared with the paracentral group (both P < 0.05). In contrast, the paracentral group demonstrated significantly better postoperative scores in the color vision and peripheral vision subscales (P = 0.017 and P = 0.038, respectively). Cone position exhibited a positive correlation with UCVA, BCVA, and CCT (P < 0.001). CONCLUSIONS: The corneal cone position significantly affects DALK prognosis, influencing postoperative quality of life. Central group shows better visual acuity, whereas paracentral group demonstrates significant CCT recovery. Tailoring surgical strategies based on cone position may mitigate prognostic disparities and optimize visual rehabilitation.