Effect of Laser in situ Keratomileusis on LogMAR Visual Acuity and Contrast Sensitivity

Overview

Purpose:
to determine effect of laser in situ keratomileusis (LASIK) on visual functions: visual acuity (VA) and contrast sensitivity (CS).

Patients and methods:
Prospective study includes results of VA and CS preoperatively and 1, 3 and 6 months postoperatively in patients with middle and high myopia. 36 eyes of 18 patients (3 men and 15 women) were divided according to spherical equivalent into 2 groups: group A (> -5.0 D, 18 eyes) and group B (< –5.0 D, 18 eyes). Mean patient’s 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 both groups, results of preoperative best corrected visual acuity (BCVA) were compared to uncorrected visual acuity (UCVA) after surgery.

Results:
Visual acuity preoperatively was significantly decreased in comparison to controls in both groups, considerable decrease can be detected at 1 month postoperatively and it returns to preoperative values during 6 months after surgery. Postoperatively, a significant decrease of CS can be detected, above all at intermediate spatial frequencies. During first 6 months, values of CS slowly increase in both groups. However, only in group B (< –5D) the preoperative values have been reached.

Conclusions:
Our study suggests that both used methods are very sensitive for evaluation of visual functions after refractive surgery. Changes of contrast sensitivity reveal even slightly changed optic factors of cornea that can cause subjective complaints of patients.

Key words:
LASIK, logMAR charts, contrast sensitivity