Comparison of the Visual Outcomes after Cataract Surgery with Implantation of a Bifocal and Trifocal Diffractive Intraocular Lens

ABSTRACT

PURPOSE: To evaluate and compare visual outcomes and optical quality after implantation of a bifocal (Acrysof ReSTOR® SN6AD1) or trifocal (AT LISA® tri 839MP) diffractive intraocular lens (IOL). METHODS: Fifty-one eyes of 43 patients undergoing cataract surgery were enrolled and assigned to one of two groups the trifocal group, comprising 24 eyes implanted with the trifocal diffractive IOL (AT LISA® tri 839MP), and the bifocal group, comprising 27 eyes implanted with the bifocal diffractive IOL (Acrysof ReSTOR® SN6AD1). Visual acuity (distant, intermediate, and near vision) and refractive postoperative outcomes were evaluated at one and three months postoperatively. Measurements of optical quality (using OQAS II®), contrast sensitivity (using CGT-2000®), automated visual field examination, and evaluation of defocus curve were performed three months postoperatively. RESULTS: No statistically significant differences between the two groups were found in three-month postoperative distant and near (40 cm) visual acuities and optical quality. However, intermediate (63 cm, 80 cm, and 100 cm) visual acuities were significantly better in the trifocal group. Distant contrast sensitivity (5 m) under mesopic conditions was significantly better with the bifocal lens, whereas near contrast sensitivity (30 cm) under mesopic and scotopic conditions was significantly better with trifocal lens. There was no statistical difference between the groups under photopic conditions. In the defocus curve, the visual acuity was significantly better at intermediate distance in the trifocal group. CONCLUSIONS: Trifocal diffractive IOLs provide significantly better intermediate vision than bifocal IOLs, with equivalent postoperative levels of distant and near vision and ocular optical quality. Further, they provide better near contrast sensitivity under scotopic condition compared to diffractive bifocal IOLs.