Reading Speed and Visual Acuity in Photopic and Mesopic Conditions After Bilateral Implantation of Diffractive Multifocal Intraocular Lenses.

PURPOSE: To assess functional visual performance - particularly reading speed - under photopic and mesopic conditions in patients bilaterally implanted with either the AT LISA Tri 839MP or Tecnis Synergy DFR00V diffractive multifocal intraocular lenses (IOL).

DESIGN

Prospective randomized controlled trial.

METHODS

This trial included 60 patients that underwent bilateral cataract surgery with implantation of either the AT LISA Tri or Synergy IOLs. At 3 months postoperatively, distance-corrected visual acuity (VA) and distance-corrected reading speed were measured under photopic (85 cd/m²) and mesopic (3 cd/m²) conditions. Photopic defocus curves were also analyzed and compared.

RESULTS

Mesopic VA was significantly worse than photopic VA by ∼1 ETDRS line, without inter-IOL differences. Photopic reading speeds were 143.4 ± 40.0 and 136.4 ± 27.0 wpm for the AT LISA Tri and Synergy, respectively. Mesopic reading speeds declining significantly to 38.2 ± 34.2 and 22.4 ± 29.7 wpm under mesopic conditions, respectively. Mesopic reading speed was significantly lower than in photopic conditions for both groups.

CONCLUSIONS

Standard VA testing may underestimate functional limitations of multifocal IOLs under mesopic conditions. The substantial loss of reading speed suggests that mesopic near vision is impaired. Low luminance reading speed is a practical, patient-relevant endpoint and should be considered in IOL evaluations.