Objective and subjective evaluation of photic phenomena after monofocal and multifocal intraocular lens implantation

Objective: To objectively measure and compare halo, flicker, and glare disability in pseudophakic eyes with monofocal (MONO) and multifocal (MULTI) intraocular lenses (IOLs) with respect to the influence of corneal surface quality, astigmatism, and age. Design: Prospective case series. Participants: This clinical trial involved 28 eyes of 28 patients after small-incision cataract surgery with a MONO silicone IOL and 28 eyes of 28 patients with zonal-progressive silicone IOL. Intervention: A computer program objectively determined halo, glare, and flicker. Corneal surface quality and astigmatism were measured using computerized videokeratography. Ray-tracing analysis was performed based on the videokeratography data to calculate retinal peak distance and distortion index. A questionnaire was sent to all patients to evaluate the incidence of subjective photic phenomena. Results: Mean halo size (square degrees +/- standard deviation) valued 6.1 (+/-1.3) in the MONO group and 7.2 (+/-2.3) in the MULTI group with no statistically significant difference between MONO and MULTI. Flicker (in % contrast to add) was -0.7 (+/-2.9) in the MONO group and -1.0 (+/-4.2) in the MULTI group with no statistical differences. Glare (in % contrast to add) was 5.5 (+/-16.5) in the MONO group and 6.5 (+/-18.0) in the MULTI group with no statistical differences. Patients in the MONO group older than 70 years of age had significantly more glare than those younger than 70 years (P = 0.017). In the MULTI group, patients with corneal shape irregularities (peak distance > 6.0 mu m) or astigmatism (>1 diopter) had statistically significant greater halos than did patients with regular corneal shape (peak distance less than or equal to 6.0 mu m) or astigmatism (less than or equal to 1 diopter) (P < 0.005). Three of 27 MONO patients and 9 of 28 MULTI patients noticed light sensations (mainly halos) after surgery that were not present before surgery, with the majority not being bothered by these at all. Conclusion: in monofocal as well as in multifocal eyes, halo and glare disability occurred. Patient age, corneal surface quality, and IOL design played an important role in these photic phenomena. Because these photic phenomena may be more prevalent in night driving conditions, the authors' study suggests that night driving ability, especially in the elderly patient with pseudophakia, should be examined carefully.