Posters

Do small-aperture presbyopic corrections influence the visual field?

Poster Details

First Author: S.Blazaki GREECE

Co Author(s):    D. Atchison   M. Suheimat   S. Plainis   N. Charman     

Abstract Details

Purpose:

To explore the effect of small-aperture optics, designed to aid presbyopes by increasing ocular depth-of-focus, on measurements of the visual field.

Setting:

Institute of Health & Biomedical Innovation and School of Optometry & Vision Science, Queensland University of Technology, Kelvin Grove, Queensland, Australia, Institute of Vision and Optics, University of Crete, Crete, Greece, Faculty of Life Sciences, University of Manchester, Manchester, UK

Methods:

Theoretical and ray-tracing models were used to predict the impact of different designs of small-aperture contact-lenses or inlays on the proportion of light-passing through natural pupils of various diameters as a function of the direction in the visual-field. 5 subjects were tested using 3 afocal, opaque soft contact-lenses. Two were opaque over a 10mm diameter with central clear circular apertures of 1.5 and 3.0mm in diameter. The third had an annular opaque zone with inner and outer diameters of 1.5 and 4.0mm, simulating the KAMRA inlay. A fourth, clear-lens was used for comparison. Visual-fields were evaluated with static automated perimetry.

Results:

According to ray-tracing, the lenses with the circular apertures were expected to reduce the relative transmittance of the pupil to zero at specific field-angles(~60deg). In contrast, the annular-stop had no-effect on the absolute field but relative transmittance was reduced over the central area, the exact effects depending upon the natural pupil diameter. Experimental results broadly agreed. Using 1.5 and 3.0mm pupils, only minor losses in sensitivity(~2dB) occurred across the central(10deg) field. Beyond this angle, sensitivity-losses increased to 7dB at the edge of the measured field. The field-results with the annular-stop showed only a slight loss in sensitivity(≤3dB) across the field.

Conclusions:

The present theoretical and experimental results support earlier clinical findings that KAMRA-type annular stops, unlike circular artificial pupils, have only minor effects on measurements of the visual field. FINANCIAL DISCLOUSRE: NONE