Comparison of the Early Visual Performance after Bilateral Implantation of Trifocal and Bifocal Intraocular Lenses

Objective: To compare visual performance after bilateral implantation of a bifocal (ReSTOR +3.0 D) or trifocal (AT Lisa tri. 839MP) intraocular lens (IOL). Methods: This prospective clinical study involved patients who had cataract surgery that included the bilateral implantation of a bifocal or trifocal IOL from April 2017 to May 2018 at Wuhan Aier Eye Hospital. Fifty-two eyes (26 patients) were implanted with a trifocal IOL (AT Lisa tri. 839MP) as trifocal group and fifty-two eyes (26 patients) with a bifocal IOL (ReSTOR +3.0 D) as bifocal IOL group. The follow-up was 3 months. Near, intermediate, and distance visual acuities, defocus curve, optical quality, including modulation transfer functions and intraocular aberrations, ocular aberrations with 3 mm and 5 mm pupil diameters, National Eye Institute Visual Functioning Questionnaire-14 for Chinese people (VF-14-CN), spectacle independence and patient satisfaction were assessed in all patients. Data were assessed with a Student's t test, Mann-Whitney U test, and Chi-square test. Results: No statistically significant difference was found in distance, near, best corrected distance, distance-corrected intermediate, or distance-corrected near visual acuity between the two groups. Uncorrected intermediate visual acuity was significantly better in the trifocal IOL group (Z=-2.347, P=0.019). In the binocular defocus curve, visual acuity was also significantly better for defocus at -1.0, -3.0, 3.5 and 4.0 diopters (Z=-2.619, -2.452, -2.452, -2.147; P=0.009, 0.014, 0.014, 0.032). No significant difference was found between the two groups for mean postoperative contrast sensitivity function under photopic conditions with or without glare. With a 3 mm or 5 mm pupil diameter, intraocular higher-order aberrations, coma, trefoil and total higher-order aberrations, and trefoil aberrations were significantly lower in the trifocal IOL group (P<0.05). With a 5 mm pupil diameter, intraocular spherical aberrations were significantly lower in the trifocal IOL group (Z=-3.053, P=0.002), but no statistically significant difference was found in modulation transfer function at 3 mm and 5 mm pupil diameters between the two groups. The level of overall satisfaction was similarly high for both groups. Conclusions: Trifocal IOLs can provide significantly better intermediate vision and equivalent distance and near visual performance compared to bifocal IOLs and have the same level of overall satisfaction. Key words: trifocal intraocular lens; defocus curve; contrast sensitivity; aberration; visual quality; optical quality