Background: The aim of this study was to determine the prognosis of visual acuity and contrast sensitivity in keratoconus patients according to the correlation between aberrations changes before and after RGP lenses.

Materials and Methods: A total of 40 eyes of twenty patients 20 to 40 years with mild, moderate keratoconus were participated in this study. Ocular examinations were included VA with standard Snellen chart, CS with CSV 1000 chart and HOAs with technolas aberrometer objective (Bush & Luamb). All these tests were performed before and after RGP lenses. Refraction and corneal radius of curvature were measured using Autokeratometr. Data were then analyzed with Spss softwair version 11.5.

Results: Mean contrast sensitivity at each spatial frequency with RGP lenses was higher than the best correction in both male and female. Compairing with best correction mean high order aberration of the 5 and 6 mm pupil was reduced with RGP lenses but the effect was not statistically significant different. Mean high order aberration with pupil 6 mm was more than pupil 5 mm. Using Pearson correlation test, there was no significant correlation between visual change and Contrast sensitivity changes with high order aberrations.

Conclusion: Visual performances and visual acuity were improved with RGP lens than best correction by reduction of high-order aberrations. However, there was no correlation or relationship between high order aberrations and visual performance. This indicates that Aberrometery condition was unrelated with Prediction of visual acuity changes in this patients.