We conducted this retrospective observational case series with the approval of the Institutional Review Board of the Asan Medical Center and the University of Ulsan College of Medicine (Seoul, South Korea). The study adhered to the tenets of the Declaration of Helsinki and followed good clinical practice guidelines. All patients provided written informed consent to allow their medical information to be included for analysis and publication.
This retrospective study included 18 patients who underwent cataract surgery with bilateral mix-and-match implantation of a TECNIS® +2.75 D multifocal IOL (ZKB00, Johnson & Johnson Vision, Santa Ana, CA, USA) into the dominant eye and a TECNIS® +4.00 D multifocal IOL (ZMB00, Johnson & Johnson Vision) into the nondominant eye by one surgeon (HT) at the Cataract and Refractive Surgery Clinic of Asan Medical Center from March 2015 to February 2016. Patients who met the following inclusion criteria were included: (1) older than 18 years, (2) preexisting corneal astigmatism less than +1.00 D, and (3) visual acuity greater than 0.1 logMAR as measured with a potential acuity meter. Patients were excluded from the analyses if they had (1) optical opacities or pathology on slit-lamp examination, (2) previous corneal surgeries, (3) ocular trauma, (4) intraocular surgery, (5) severe dry eyes, (6) corneal disease, (7) ocular infection, or (8) collagen vascular disease or other autoimmune diseases.
Measurements
All subjects underwent comprehensive ophthalmological examinations preoperatively, including logMAR visual acuity measurements of monocular and binocular uncorrected distance visual acuity (UDVA), UIVA, UNVA, corrected distance visual acuity (CDVA), corrected intermediate visual acuity (CIVA), and corrected near visual acuity (CNVA). Preoperative assessments also included autorefraction and keratometry (Canon R-50, Canon USA Inc., Huntington, NY, USA), slit-lamp examinations (Haag-Streit, Gartenstadtstrasse, Köniz, Switzerland), biometry (IOL Master 500, Carl Zeiss Meditec, Jena, Germany), and corneal topography (Orbscan, Bausch & Lomb, Rochester, NY, USA). Each patient’s dominant eye was determined prior to surgery using the hole-in-the-card test wherein the patient looks at a target through a 1 inch hole in the center of a card held at one arm’s length, with only one eye open at a time, to determine which eye saw the target.
The ophthalmic examinations conducted at 1 and 3-month after surgery included logMAR measurements of monocular and binocular UDVA, UIVA, UNVA, and CDVA. Autorefraction and keratometry were also performed. Intermediate visual acuity was measured at 60 cm. Near visual acuity was measured at 33, 40, and 50 cm, with near visual acuity expressed as the average of visual acuity at these distances. In addition, monocular and binocular defocus curves were obtained at 3-month postoperatively by measuring monocular or binocular visual acuity at 4 m starting from distance correction and then defocusing with added lenses in half-diopter steps from -4.50 D to 0.00 D.
Contrast sensitivity was measured at 3-month postoperatively, using the Functional Acuity Contrast Test of the Ophtec 6500 view-in test system (Stereo Optical Co, Inc., Chicago, IL, USA) with stimulus spatial frequencies between 1.5 and 18 cycles per degree under photopic (target luminance = 85 candelas per square meter [cd/m2]) and mesopic (target luminance = 3 cd/m2) conditions.
Finally, patients were asked to complete a questionnaire regarding their overall satisfaction, the occurrence of visual symptoms, and their dependence on spectacles for near and far vision. Overall satisfaction was assessed using a 5-point Likert scale: 1 = very dissatisfied, 2 = dissatisfied, 3 = neither satisfied nor dissatisfied, 4 = satisfied, and 5 = very satisfied. Visual symptoms (glare, halo, and visual disturbances at night or in the dark) were scored on a 5-point scale from 1 (absent symptoms) to 5 (severe symptoms). Patients were also asked if they would recommend bilateral mix-and-match implantation of multifocal IOLs to their friends or relatives, with allowed responses being yes or no.
Surgical technique
After instillation of topical anesthesia (0.5% proparacaine hydrochloride), the phacoemulsification surgery was performed. A continuous curvilinear capsulorrhexis marker with a 6.0-mm diameter was used to reference the corneal plane. The main clear corneal incision was made using a 2.2-mm keratome, followed by capsulorrhexis using a capsulorrhexis needle. Phacoemulsification was performed using either the Infiniti® or Centurion® phacoemulsifier (Alcon Laboratories, Inc., Fort Worth, TX, USA). Using an injector, a +2.75 D multifocal IOL was implanted into the capsular bag of the dominant eye, and a +4.00 D multifocal IOL was implanted into the capsular bag of the nondominant eye. The target postoperative refraction was emmetropia in both eyes. All patients were administered 0.5% gatifloxacin ophthalmic solution (Gatiflo®, HANDOK, Seoul, South Korea) and prednisolone eye drops (Pred-Forte®, Allergan, Dublin, Ireland) for 1-month postoperatively.
Statistical analysis
Results are expressed as the mean ± standard deviation. Differences between preoperative and postoperative data were assessed using the Wilcoxon signed-rank test. Values for the defocus curves for both eyes, the dominant eye, and the nondominant eye were analyzed by the Kruskal-Wallis test with the Bonferroni correction. All statistical analyses were performed using SPSS® version 21 software (IBM, SPSS Inc., Chicago, IL, USA). Differences were considered statistically significant for P values of less than 0.05.