LASIK increases night-time halos

Patients undergoing LASIK procedures experience an increase in halos around lights in night vision conditions, according to a study published in the April issue of the British Journal of Ophthalmology.

Cesar Villa Collar from the Clinica Oftalmologica Novovision, Spain and colleagues conducted a prospective, observational, analytical study to evaluate the changes in correlations of higher order aberrations (HOAs) of the first corneal surface with halo phenomena under night vision conditions. A total of 11 eyes that had undergone successful LASIK for myopia and astigmatism were examined. Preoperative sphere was -3.48±1.70 D and preoperative cylinder was -0.86±0.87 D. Visual disturbances and pupil size were measured after adaptation to a dark environment.

The halo disturbance index increased by a factor of 2.15 after successful LASIK surgery and total RMS for monochromatic HOA displayed a significant correlation with the halo disturbance index (r=0.36; p<0.01). However, only secondary astigmatism (r=0.36; p<0.01), coma (r=0.25; p=0.02) and spherical aberration (r=0.40; p<0.01) were responsible for this behaviour, with the remaining corneal aberrations until the 6th order not displaying any significant correlation.

It was concluded that LASIK can cause an increase in halos even when the results of the surgery are considered entirely satisfactory according to current international standards of predictability, efficacy and safety.