Effect of Multifocal Intraocular Lens on Contrast Sensitivity in Primary Angle-Closure Patients

This prospective non-randomized clinical study was conducted at the Department of Ophthalmology of the Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand during January 2014 to December 2015. The study protocol and informed consent procedures were both approved by our center's institutional review board (IRB) (approval number Si 384/2014). Each patient provided written informed consent prior to participation.

Primary angle closure was defined as an eye with invisible non-pigmented trabecular meshwork greater than 180 degrees and evidence of peripheral anterior synechiae on gonioscopy without glaucomatous optic disc appearance, glaucomatous pattern visual field damage, or history of increased IOP. Primary angle closure glaucoma was defined as an eye with invisible non-pigmented trabecular meshwork greater than 180 degrees on gonioscopy with glaucomatous optic damage (cup-to-disc ratio greater than 0.5 and/or localized neuro-retinal rim defect) and history of increased IOP raising. Patients with PACG must have been under good disease control, which was defined as IOP under 20 mmHg with 1 to 3 topical anti-glaucoma medications without deterioration of visual field, except generalized depression from cataract. Intra-ocular lens calculation was performed at the baseline visit using IOL Master. All patients received information about the advantages and disadvantages of MIOLs (Tecnis ZMB00 or Acrysof IQ Restore SN6AD1) and of mIOLs (Tecnis ZCB00 or Acrysof IQ SN60WF) before choosing the type of IOL that they individually preferred. Cataract surgery was performed by a single surgeon. Topical anesthesia was applied before standard phacoemulsification (2.2 mm temporal clear cornea incision and continuous curvilinear capsulorhexis) and IOL implantation into the capsular bag. Eyes with any intraoperative or postoperative complication were excluded.

Data specific to uncorrected and best-corrected distant visual acuities (UCVA and BCVA) in logMar, auto-refraction, slit-lamp ophthalmoscopic examination, intraocular pressure (IOP) measurement with Goldmann applanation tonometry, contrast sensitivity (CS), anterior chamber depth (ACD), central corneal thickness (CCT), and axial length (AL) were collected on the preoperative screening day, and at the 2 to 6-month postoperative follow-up. CS was measured under normal room light (photopic) conditions to evaluate patient quality of vision during the performance of their daily activities using a Functional Vision Analyzer. This test produces sine-wave gratings of different spatial frequencies. The absolute values of distance CS were obtained at five spatial frequencies (1.5, 3, 6, 12, and 18 cycles per degree; CPD). Visante® AS-OCT was used to determine CCT and ACD. ACD was defined as the distance between the corneal endothelium and the anterior surface of the crystalline lens (preoperative) or iris plane (postoperative). Axial length was obtained using IOL Master.

Comparisons of continuous data with normal distribution were made using Student's t-test for unpaired data, and using Mann-Whitney U test for non-normally distributed data. A p-value of less than 0.05 was defined as denoting statistical significance.