Correlation of pupil size with visual acuity and contrast sensitivity after implantation of an apodized diffractive intraocular lens.

Purpose: To determine whether pupil size is correlated with visual acuity and contrast sensitivity at all distances in eyes with an apodized diffractive intraocular lens (IOL).

Setting: Private Clinic, Oviedo, Spain.

Methods: Six months after surgery, the best corrected distance visual acuity, best distance-corrected near visual acuity, intermediate visual acuity, and distance contrast sensitivity under photopic (85 cd/m2) and mesopic (5 cd/m2) conditions were measured in 670 eyes of 335 consecutive patients who had implantation of the AcrySof ReSTOR Natural IOL (SN60D3, Alcon). Pupil diameters in distance vision were measured using a pupillometer.

Results: The logMAR best corrected distance acuity was significantly better with larger pupils (r = 0.297; P = 1.36 x 10(-8)), whereas logMAR best distance-corrected near acuity was significantly worse with larger pupils (r = 0.276, P = 1.02 x 10(-7)). For all pupil diameters, intermediate visual acuity worsened significantly as the distance of the test increased (P<.01). Statistically significant differences in photopic and mesopic contrast sensitivity at all spatial frequencies were found between the small-pupil and large-pupil groups (P<.01). Distance photopic contrast sensitivity and mesopic contrast sensitivity were better in patients with large pupils than in patients with small pupils.

Conclusions: A larger pupil was correlated significantly with better distance visual acuity and with worse near visual acuity. For all pupil diameters, intermediate visual acuity worsened significantly as the distance of the test increased. Distance contrast sensitivity was better with larger pupils at all spatial frequencies in bright-light and dim-light conditions.