Aspheric IOLs perform better than spherical IOLs

Aspheric intraocular lenses (IOLs) induce less wavefront aberrations and perform better in photopic and mesopic conditions than spherical IOLs, according to a report published in the September issue of Journal of Refractive Surgery.

Aldo Caporossi and co-workers from the University of Siena, Italy conducted a prospective, comparative, randomized study of 250 eyes of 125 subjects with bilateral cataracts. Patients were randomly assigned to receive either a spherical biconvex optic (AcrySof SN60AT [Alcon] or Sensar AR40e [AMO]) or an aspheric optic (AcrySof IQ SN60WF [Alcon], Tecnis Z9000 [AMO] or SofPort L161AO [Bausch & Lomb]).

Aspheric IOLs demonstrated better contract sensitivity compared with spherical IOLs at spatial frequencies of six, 12 and 18 cycles per degree under photopic conditions and at all spatial frequencies under mesopic conditions. There were no significant differences between the aspheric IOLs at all spatial frequencies under either photopic or mesopic conditions. Mean total spherical aberration was statistically lower in dominant eyes with aspheric IOLs compared with eyes with spherical IOLs for a 5 mm pupil diameter.

The results of this comparative study confirm that it is possible to improve the optical performance of IOLs by modifying the surfaces.