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

Objective: To objectively measure and compare halo, flicker, and glare disa bility in pseudophakic eyes with monofocal (MONO) and multifocal (MULTI) in traocular lenses (IOLs) with respect to the influence of corneal surface qu ality, astigmatism, and age. Design: Prospective case series. Participants: This clinical trial involved 28 eyes of 28 patients after sma ll-incision cataract surgery with a MONO silicone IOL and 28 eyes of 28 pat ients with zonal-progressive silicone IOL. Intervention: A computer program objectively determined halo, glare, and fl icker. Corneal surface quality and astigmatism were measured using computer ized videokeratography. Ray-tracing analysis was performed based on the vid eokeratography data to calculate retinal peak distance and distortion index . A questionnaire was sent to all patients to evaluate the incidence of sub jective 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 stat istically significant difference between MONO and MULTI. Flicker (in % cont rast to add) was -0.7 (+/-2.9) in the MONO group and -1.0 (+/-4.2) in the M ULTI group with no statistical differences. Glare (in % contrast to add) wa s 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 (pea k distance > 6.0 mu m) or astigmatism (>1 diopter) had statistically signif icant greater halos than did patients with regular corneal shape (peak dist ance 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 patient s noticed light sensations (mainly halos) after surgery that were not prese nt before surgery, with the majority not being bothered by these at all. Conclusion: in monofocal as well as in multifocal eyes, halo and glare disa bility occurred. Patient age, corneal surface quality, and IOL design playe d an important role in these photic phenomena. Because these photic phenome na may be more prevalent in night driving conditions, the authors' study su ggests that night driving ability, especially in the elderly patient with p seudophakia, should be examined carefully.