In myopic eyes with moderate to large pupillary offset, CV-centered treatments performed better in terms of induced ocular aberrations and asphericity, but both centrations were identical in photopic visual acuity.

Background:The aim of this study is to evaluate the safety and effectiveness of riboflavin-ultraviolet type A (UV-A) light rays induced cross-linking of corneal collagen in improving visual acuity and in stabilizing the progression of keratoconic eyes. The method of corneal cross-linking using riboflavin and UV-A light is technically simple and less invasive than all other therapies proposed for keratoconus. It is the only treatment that treats not only the refractive effects of the condition but the underlying pathophysiology.Materials and Methods:In this prospective, nonrandomized clinical study, 20 eyes of 19 patients with keratoconus were treated by combined riboflavin UV-A collagen cross linking. The eyes were saturated with riboflavin solution and were subjected for 30 min under UV-A light with a dose parameter of 3 mW/cm2. Safety and effectiveness of the treatment was assessed by measuring the uncorrected visual acuity, best corrected visual acuity, manifest cylinder/sphere, keratometry, pachymetry, posterior and anterior elevations from Pentacam and corneal aberrations at 6 months and 1 year post-treatment.Results:Comparative analysis of the pre-operative and 1 year post-operative evaluation showed a mean gain of 4.15 lines of UCVA (P= 0.001) and 1.65 lines of BCVA (P= 0.002). The reduction in the average keratometry reading was 1.36 D (P= 0.0004) and 1.4 D (P= 0.001) at the apex. Manifest refraction sphere showed a mean reduction of 1.26 D (P= 0.033) and 1.25 D (0.0003) for manifest cylinder. Topo-aberrometric analysis showed improvement in corneal symmetry.Conclusion:Cross-linking was safe and an effective therapeutical option for progressive keratoconus.

Excimer laser LASIK using a non-wavefront-guided aberration-free ablation profile yielded excellent visual outcomes. The preoperative astigmatism was reduced to subclinical values with no clinically relevant induction of HOA.

Our results show that non-customized "aberration neutral" ablation profiles derived from wavefront analysis are able to minimize the amount of induced aberrations of both the cornea and the eye.

Differential pachymetry is a metric useful for describing intended central ablation depth but not for achieved refractive correction. The rotating Scheimpflug technique offers the best estimation (closest slope to 1) and OCP offers the best correlation (closest r2 to 1) for describing intended central ablation depth achieved. The three techniques give different measurements for ablation depth, with OCP being substantially different from ultrasound and Scheimpflug. Only borderline correlations were obtained for achieved refractive correction with ultrasound and OCP.