gms | German Medical Science

The effect of laser in situ keratomileusis on visual functions: visual acuity (VA) and contrast sensitivity (CS) was determined in patients with middle and high myopia.

Prospective study includes results of VA and CS preoperatively and 1, 3 and 6 months postoperatively. 42 eyes of 21 patients (5 men and 16 women) were divided according to spherical equivalent into 2 groups: group A (more than 5D, 20 eyes) and group B (less than 5D, 22 eyes). Mean patient age was 27 years (range 19-46 years). Visual acuity was measured on logMAR charts, contrast sensitivity at 3,6,12 and 18 c/deg was tested using CSV-1000 Contrast sensitivity unit. In boths groups, results of preoperative best corrected visual acuity (BCVA) were compared to uncorrected visual acuity (UCVA) after surgery.

Visual acuity preoperatively was insignificantly decreased in comparison to controls in both groups, considerable decrease can be detected at 1 month postoperatively and it returns to preopeative values during 6 months after surgery. Also, contrast sensitivity measured before surgery reaches only lower level of contrast sensitivity in control group. Postoperatively, a significant decrease can be detected, above all at intermediate spatial frequencies. During first 6 months, values of contrast sensitivity slowly increase in both groups. However, in group A (with more than 5D) values do not reach preoperative values. The differences between the two groups are statistically significant at 3 and 6 months after surgery.

Our study suggests that contrast sensitivity is a more sensitive method for evaluation of visual functions after refractive surgery. Changes of contrast sensitivity reveal even slightly changed optic factor of cornea.