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Purpose: The length of Descemet's membrane and donor graft sizes in deep anterior lamellar keratoplasty do not match in very steep corneas, which can lead to Descemet's membrane folds. The aim of this study is to establish a theoretical model for graft size calculations for deep anterior lamellar keratoplasty and evaluate its efficacy for preventing Descemet's membrane folds., Methods: We calculated the arc diameter of the recipient bed by using the cosine formula and developed a table to aid surgeons in donor punch size selection. To test the usefulness of this formula, we evaluated the development of Descemet's membrane folds in keratoconus patients with very steep corneas (K >60 D). In group 1, deep anterior lamellar keratoplasty surgeries were performed using graft sizes that were determined based on our model (n=31). In group 2, graft sizes were determined based on the empirical judgment of the surgeon without any formal calculation (n=30)., Results: Our theoretical calculations demonstrated that the diameter of donor punch sizes needed to prevent Descemet's membrane fold increases when the cornea is steeper, or the trephine size is larger. We tested the efficacy of this model on the clinical outcome of deep anterior lamellar keratoplasty. The mean age (28.9 ± 10.1 years vs. 32.8 ± 8.3 years, p=0.11) and preoperative K1 (59.2 ± 9.3 D vs. 58.1 ± 9.4 D, p=0.67), K2 (66.2 ± 6.0 D vs. 65.7 ± 7.4 D, p=0.81), and Km values (62.1 ± 7.7 D vs. 61.8 ± 8.1 D, p=0.88) were similar between the two groups. Three patients developed Descemet's membrane folds in group 2, and none of the patients developed Descemet's membrane folds in group 1. These results supported our theo retical calculations., Conclusion: Adjustment of donor graft size based on the calculated arc diameter of the recipient bed reduced the development of Descemet's membrane folds after deep anterior lamellar keratoplasty in steep corneas.

Purpose: To evaluate long-term clinical results of 2 different accelerated corneal crosslinking (CXL) protocols in pediatric patients with keratoconus. Setting: Beyoglu Eye Training and Research Hospital, Istanbul, Turkey. Design: Retrospective case-control study. Methods: Patients who were younger than 18 years were included in the study. Group 1 received 4 minutes of illumination at 30 mW/cm2, and Group 2 received 5 minutes of illumination at 18 mW/cm2. Uncorrected and corrected distance visual acuities, manifest refraction, corneal topographic parameters, and corneal higher-order aberrations (HOAs) were evaluated at baseline and during 1-, 3-, and 5-year follow-up visits. Results: A total of 143 eyes from 86 patients were included in the study. There were 30 eyes in Group 1 and 113 eyes in Group 2. The mean follow-up time was 4.15 +/- 0.99 years. Mean keratometry (K) and/or maximum K progressed >=1.00 diopter (D) in 7 eyes (23.3%) in Group 1 and 19 eyes (16.8%) in Group 2 (P =.411). Mean K and/or maximum K decreased >=2.00 D in 2 eyes (6.7%) in Group 1 and 24 eyes (21.2%) in Group 2 (P =.06). In Group 1, there were no statistically significant differences in topographic parameters during follow-up. In Group 2, there was a statistically significant reduction in total HOA and coma during the 5-year visit when compared with the preoperative visit (P =.005 and P =.045, respectively). Conclusions: Accelerated CXL is beneficial in terms of halting the progression of keratoconus in pediatric patients throughout 5 years of follow-up examinations. An increased irradiance with a reduced application time reduces the topographic effects of CXL. [ABSTRACT FROM AUTHOR]