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

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

Oftalvist Alicante, Alicante, Spain.

Observational case-control study.

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.

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.

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.