Recognition vs resolution charts for defocus curve determination in trifocal intraocular lenses.

Purpose: To determine the impact of optotype choice on the determination of defocus curve in patients with cataract implanted with presbyopia-correcting intraocular lens (IOL).

Setting: Oftalvist Alicante, Alicante, Spain.

Design: Observational case-control study.

Methods: Patients implanted with Asqelio Trifocal IOL participated in this study. Uncorrected and corrected distance visual acuity (VA) and subjective refraction were determined. Monocular defocus curves were obtained 6 months postoperatively with the Clinical Trial Suite system using either Early Treatment Diabetic Retinopathy Study (ETDRS) or Landolt C charts under photopic conditions (85 cd/m 2 ), and range of vergence from +2.00 to -5.00 diopters (D) in 0.50 D steps.

Results: A total of 49 patients were enrolled in the study, 24 in the ETDRS group (7 male, 17 female) and 25 in the Landolt C group (5 male, 20 female). Nonsignificant differences were found between patients conforming both groups, except for preoperative intraocular pressure and white-to-white distance. All patients were within ±1.00 D from intended refraction after surgery. 75% of patients in the ETDRS group and 84% in the Landolt C group were within ±0.50 D. Average difference between the groups across vergences provided by the defocus curve was 0.12 ± 0.05 logMAR units, significant for all vergences ( P < .05). Differences in VA were significant for distance, intermediate, and near between both groups, except for uncorrected distance VA.

Conclusions: Defocus curves created using Landolt C charts yield significantly lower through-focus outcomes than those created with standard ETDRS charts. This should be taken into account when comparing the performance of presbyopia-correcting systems across studies where recognition charts might have been used because of patient characteristics.