Abstract
Purpose: :
To test the hypothesis that visual symptoms after LASIK treatment can be predicted by postoperative wavefront measurements.
Methods: :
Fifty-four eyes of 28 myopic patients underwent LASIK treatment. Mean age was 36.6 ± 7.5 years (range 24-55 years); mean preoperative SE was -4.55 ± 1.58 D (range -1.63 - -7.13 D)One month postoperatively wavefront sensing was performed (Zywave, Bausch & Lomb). Wavefront errors were described using Zernike polynomials (6 mm pupil diameter). All patients completed a questionnaire that differentiated between right and left eye and between three lighting conditions (photopic, high-mesopic and low-mesopic). Intensities of the symptoms "glare", "halos", "starbursts", "blurred vision" and "ghosting" were marked by the patients on a visual analogue scale (0-100). The influence of wavefront aberrations on a particular symptom was assessed by means of a multiple backwards regression model. Thus, the point value of the specific symptom was the dependent in each model, while the magnitude of homologous Zernike coefficients (e.g. C22 by C22 and C2-2) represented the predictors.
Results: :
Under photopic conditions coefficients of determination (R2) ranged from 0.10 (glare; C42) to 0.32 (halos; C20, C33, C44, C55). Under high-mesopic conditions, R2 ranged from 0.16 (glare; C31, C44) to 0.44 (halos; C20, C42, C55), whereas under low-mesopic conditions R2 varied between 0 (ghosting) and 0.23 (halos; C20). In all groups, defocus (C20) influenced the intensity of halos and blurred vision significantly, while among other aberrations, primary coma (C31) predicted glare and starbursts in 2 out of 3 regression models.
Conclusions: :
Visual symptoms after LASIK can be partially predicted by wavefront aberration measurements. Since the coefficients of determination are relatively low, it must be assumed that the perception of visual symptoms is multifactorial.
Keywords: cornea: clinical science • refractive surgery: LASIK • quality of life