Abstract
Purpose :
To describe and compare the corneal topographic characteristics of eyes with keratoconus diagnosis previous to performance of transepithelial (Epi-on) and Epi-off Cross linking.
Methods :
This comparative,transversal study includes 90 eyes of 51 subjects that had medical indication for cross linking. The subjects were divided in two groups according to cross linking planned.The topographic data were taken from the clinical files.Data from Orbscan II topography (Bausch & Lomb; NY, USA) were analyzed.Subjects with ocular pathologies, previous ocular surgery, abnormal findings not related to the keratoconus were excluded.The evaluated data were demographic characteristics,visual acuity, corrected and non-corrected; subjective refraction, and topographic values like astigmatism,keratometry,pachymetry,anterior and posterior elevation.All quantitative variables were compared between Epi-on and Epi-off groups,using unpaired t test and a p value of less than 0.05 was considered statistically significant.All data was processed and analyzed using SPSS version 22 (IBM Corp., NY).
Results :
We included 90 eyes of 51 subjects 60 eyes in the Epi-off group and 30 eyes in the Epi-on group.The mean age was 21.86±6.72 and 23.46 ± 6.02 years respectively(p= 0.28).The mean BCVA was 0.16 and 0.24 logMAR for each group(p=0.05).The subjective refraction reported as spherical equivalent was non-statistically different(-7.0 D±4.78 vs -8.15±4.6 D; p=.351).The mean Kmin for the Epi-off group was 47.14±3.74 and in Epi-on group 49.0±4.84 D(p=0.047);Kmax values were 53.25±5.13 D for the first group and 55.52±5.29 D for the second group (p=0.054). The Kmean were for each group 50.19±4.24 D and 52.26±4.94 D(p=0.042). The astigmatism found was 6.09 ± 2.96 D and 6.52 ± 2.3 D (p=.485). Central and thinnest pachymetry were statistically different between groups (p=0.00). There was no statistically difference between groups when anterior and posterior elevation were compared (p=0.066; p=0.085).
Conclusions :
In this study we did found a difference between groups in BCVA. Despite what is expected Kmax was not different between groups, but the Kmin and Kmean were statistically different as the pachymetry data, but this most been taken with caution because this is one of the main values in making the Epi-off and Epi-on indication.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.