OBJECTIVE EVALUATION OF DISCOMFORT GLARE IN PATIENTS WITH IRREGULAR CORNEA: AN ELECTROMYOGRAPHIC STUDY

Institute of Vision and Optics, University of Crete

Fifty-five eyes of 31 patients and 24 controls were enrolled in this prospective, non-randomized study. The electrical activity of the mimic muscles was recorded at three different luminances (500, 3000, and 6000 lx) using a portable electromyographic (EMG) system. A discomfort glare value was obtained as the signal/noise ratio for each recording.  All the patients were asked to grade their discomfort after exposure to each luminance using the subjective de Boer scale. Corneal topography-based wavefront analysis, pupil size, and angle kappa were calculated to identify possible significant correlations.

Mean values of discomfort glare for the patients’ group were 1.7±1.5 at 500 lx, 2.7±1.7 at 3000 lx, and 3.2±1.9 at 6000 lx; for the control group 1.4±0.4 at 500 lux, 1.9± 0.9 at 3000 lux and 2.1±0.9 at 6000 lx. There was a statistically significant difference at the level of 0,05 between the two groups at the 6000 lux illuminance level. There was a significant Spearman’s correlation at all luminances between the objective electromyographic recording and the subjective grading of the discomfort feeling. There were no statistically significant correlations between electromyographic responses and keratometric values, pupil size, or kappa angle. Trefoil and coma were significantly correlated with discomfort glare-estimated electromyographic values.