Halo size under distance and near conditions in refractive multifocal intraocular lenses

Aims-To calculate the diameter of halos perceived by patients with multifoc al intraocular lenses (IOLs) and to stimulate halos in patients with refrac tive multifocal IOLs in a clinical experiment. Methods-Calculations were done to show the diameter of halos in the case of the bifocal intraocular lens. 24 patients with a refractive multifocal IOL s and five patients with a monofocal IOL were asked about their subjective observation of halos and were included in a clinical experiment using a com puter program (Glare & Halo, FW Fitzke and C Lohmann, Tomey AG) which simul ates a light source of 0.15 square degrees (sq deg) in order to stimulate a nd measure halos. Halo testing took place monoculary, under mesopic conditi ons through the distance and the near focus of the multifocal lens and thro ugh the focus of the monofocal lens. Results-The halo diameter depends on the pupil diameter, the refractive pow er of the cornea, and distance focus of the multifocal IOL as well as the a dditional lens power for the near focus. 23 out of 24 patients with a refra ctive multifocal IOL described halos at night when looking at a bright ligh t source. Only one patient was disturbed by the appearance of halos. Under test conditions, halos were detected in all patients with a refractive mult ifocal IOL. The halo area testing through the distance focus was 1.05 sq de g +/- 0.41, through the near focus 1.07 sq deg +/- 0.49 and in the monofoca l lens 0.26 sq deg +/- 0.13. Conclusions-Under high contrast conditions halos can be stimulated in all p atients with multifocal intraocular lenses. The halo size using the distanc e or the near focus is identical.