Multifocal intraocular lens implantation in prepresbyopic patients with unilateral cataract. 
To evaluate the benefits of implantation of a zonal-progressive multifocal intraocular lens (IOL) in prepresbyopic patients with unilateral cataract.  Prospective, nonrandomized, comparative trial.  Ninety-five eyes of 95 prepresbyopic patients aged between 14 and 40 years with either multifocal or monofocal IOL implantation at two institutions and with more than 6 months follow-up.  Temporal clear corneal phacoemulsification and foldable IOL implantation was performed in all eyes.  In 54 patients, a zonal-progressive optic multifocal IOL (Array SA40-N, Allergan, Irvine, CA) was implanted, whereas 41 patients received a monofocal IOL and served as controls.  Preoperative patient demographics, mean postoperative spherical equivalent, astigmatism, and uncorrected and best-corrected distance visual acuities were similar in the two groups.  Patients with a multifocal IOL achieved a significantly better uncorrected near visual acuity than patients with monofocal IOL (0.18 versus 0.37; P = 0.0001).  With distance correction only, mean near visual acuity was 0.17 versus 0.43 (P = 0.0001).  Best-corrected near visual acuity was 0.11 for both groups (P = 0.91), with +1.43 diopters (D) for the multifocal group and +2.35 D for the monofocal group (P = 0.0001).  Spectacle dependency differed significantly between the two groups, with 21 patients (51%) of the monofocal group commonly requiring an additional plus add for near tasks compared with 5 patients (9%) in the multifocal group (P = 0.001).  Stereopsis was superior in the multifocal group (P < 0.001), with 42 (77%) and 33 (61%) patients with a multifocal IOL responding positively to the Lang and Titmus tests, respectively.  In the monofocal group; only 20 (48%) and 9 (22%) patients gave correct answers.  Multifocal IOL implantation is a viable alternative to monofocal pseudophakia in prepresbyopic patients with unilateral cataract.