Abstract
Purpose: :
To compare the different aberrometrical patterns and contrast sensitivity test in myopic patients before LASIK
Methods: :
Prospective, transversal, descriptive, comparative design. We included patients undergoing LASIK. We classified the patients into 3 groups depending on the degree of myopia. Group 1: 0 to < -3.00 Diopters (D) (58 eyes), group 2: -3.00 to -6.00 D (65 eyes) and group 3: > -6.00 D (11 eyes). Lower and higher order aberrations were measured using a Shack-Hartmann wavefront sensor with the CustomVue II Visx, and contrast sensitivity test with the Sine Wave Contrast Test. The Root-mean-square (RMS) values were calculated for low and high order aberrations in the 3 groups. Data was analyzed with the statistical program SPSS 16.0, using the ANOVA test for variance analysis and correlating the data using Pearson's test
Results: :
One hundred thirty-four eyes (70 patients) were included. Fifty eight eyes in group 1, 65 eyes in group 2 and 11 eyes in group 3. There was a statistically significant difference between groups in the total percentage of high-order aberrations (HOA) and the RMS (P<0.0005), not found in the RMS HOA. As expected, defocus presented a statistically significant difference in the 3 groups: P < 0.05. Astigmatism was found with a statistically significant difference between groups 1 and 2 (P < 0.05). The high order aberrations were not significantly different in the three groups, predominating coma. In the contrast sensitivity test there was no statistically significant difference found between the values of frequencies in the 3 different groups
Conclusions: :
Contrast sensitivity test is not influenced by the myopic refractive error. Mean percentage of high-order aberrations is less than 10% in patients with myopia. Coma was most frequent in all groups
Keywords: contrast sensitivity • myopia • refractive surgery: LASIK