Intraocular lens eases visual field testing

Bangkok, Thailand-Presbyopic spectacle correction is not necessary when performing visual field testing using automated perimetry (Humphrey Field Analyzer, Carl Zeiss Meditec) in pseudophakic patients with a diffractive aspheric multifocal IOL (ZM900; Tecnis multifocal IOL, Abbott Medical Optics) implanted, according to Naris Kitnarong, MD, MBA.

His conclusion was based on the results of a study showing no differences in a variety of test parameters in which visual field evaluation (30-2 SITA standard algorithm) was performed with and without +3 D of spectacle add. The study included 43 eyes of 31 patients, including 20 eyes with glaucoma (mild to moderate) and 20 nonglaucomatous eyes. All had undergone uncomplicated phacoemulsification with implantation of the multifocal IOL at the Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand, where Dr. Kitnarong is associate professor, Department of Ophthalmology.

"In general, presbyopic correction is needed during visual field evaluation in presbyopic eyes with a monofocal IOL," Dr. Kitnarong said. "The results from our study showed no statistically significant differences [among eyes] in the . . . visual field results with the [lens] whether or not the testing was done with or without additional presbyopic correction. However, the results may be different in eyes with multifocal IOLs of a different design [implanted].

The 25-item NEI Visual Function Questionnaire (version 2000) was used for the quality-of-life evaluation. Mean score was 89.4 with a range from 75.4 to 99.2.

Study candidates

Patients were eligible for the study if they had no other ocular conditions that could affect visual fields except cataract and glaucoma, and they had to have postoperative uncorrected visual acuity of 20/40 or better at distance and J3 or better at near. Patients were excluded if they were unable to perform the visual field testing or had unreliable visual field results or advanced visual field defects.

"Patients with advanced glaucoma are not good candidates for a multifocal IOL because they have disease-related loss of contrast sensitivity that can be exacerbated by the multifocal IOL," Dr. Kitnarong said.

The patients were randomly assigned to visual field testing with or without +3 D add first. Comparisons of results from testing with and without presbyopic correction were done for reliability parameters (percent fixation loss, percent false positives, percent false negatives), mean deviation, and mean pattern standard deviation and showed no statistically significant differences. There also were no differences found when comparing the mean difference in results from testing with and without presbyopic correction between the glaucomatous and nonglaucomatous eyes.

Dr. Kitnarong noted that the study had some limitations. The analyses were based on visual field testing done only once on each eye and did not include the point-to-point analysis.

FYI

Naris Kitnarong, MD, MBAE-mail: tenkn@mahidol.ac.th

Dr. Kitnarong did not indicate any financial interest in the subject matter.