Tomographic And Biomechanical Remodeling After Doughnut Refractive Lenticule Transplantation In Advanced Keratoconus

To evaluate the clinical efficacy, safety, and tomographic–biomechanical effects of Doughnut Refractive Lenticule Transplantation (DRLT) in eyes with advanced keratoconus over a 16-month follow-up period.

Health Net Hospital, Peshawar, Pakistan.

This prospective interventional study included 41 eyes of 40 patients (age 11–32 years) with advanced
keratoconus with or without VKC, after ethical approval (IRB No: HNH/IRB/2024/07). Allogeneic stromal lenticules from
SMILE donors (–6.00 to –10.00 D) were fashioned into a doughnut configuration and implanted into femtosecond laser
created intrastromal pockets, centered on the ectatic region while preserving the central optical zone. Patients were
followed for 16 months with assessment of distance corrected visual acuity, Scheimpflug tomography, anterior segment
OCT, keratometric indices, pachymetry,PPI, and Ambrosio relational thickness (ARTmax). Paired t-tests or Wilcoxon
signed-rank tests were used, with p < 0.05 considered significant.

Mean DCVA improved significantly from logMAR 1.00 ± 0.20 preoperatively to 0.30 ± 0.15 at 16 months (mean gain 0.70 logMAR; p < 0.001), with 30% of eyes achieving logMAR 0.18 or better. Mean K2 decreased from 60.46 ± 6.27 D to 55.29 ± 6.19 D (p = 0.002), and Kmax from 70.07 ± 9.72 D to 62.90 ± 7.76 D (p < 0.001). Topographic astigmatism reduced from 8.27 ± 3.50 D to 4.81 ± 2.55 D (p < 0.001). Thinnest corneal thickness increased by 33 µm. Posterior corneal curvature parameters showed significant flattening. Final D value improved from 31.00 ± 4.51 to 14.52 ± 2.05 (p < 0.0001). PPI values increased significantly, while ARTmax decreased, reflecting redistribution of corneal thickness and biomechanical reinforcement in the paracentral cornea.

DRLT resulted in significant improvements in visual acuity, corneal regularity, and tomographic–biomechanical parameters in advanced keratoconus over 16 months. As a minimally invasive, sutureless, and endothelial-sparing procedure, DRLT may represent a viable alternative for selected patients unsuitable for conventional surgical options. Larger controlled studies with longer follow-up are warranted to confirm long-term stability and progression control.