Visual Field Score: Goldmann isopter III–4e or V–4e

Abstract

Abstract: : Purpose: In 2001 the American Medical Association adopted the Functional Vision Score (FVS) in the Guides to the Evaluation of Permanent Impairment. It is build on a Functional Aquity Score (FAS) and a Functional Field Score (FFS). Separate Visual Field Scores (VFS) for both monocular fields and the binocular field are scored to determine the FFS. We investigated if there is a difference, and so how much, in Visual Field Score between Goldmann isopter III–4e and isopter V–4e. Methods: Goldmann visual fields were obtained from 63 patients of the National Rehabilitation Center for the blind and visually impaired people "Visio Het Loo Erf", Apeldoorn, The Netherlands. All patients entered an observational program for rehabilitation. Written informed consent was obtained from all participants. Visual Fields were measured with Goldmann kinetic perimetry. The score of each isopter was determined by using an overlaygrid of 100 test–points according to the methodology proposed in the Guide. Results: The geometric mean of the ratio between isopter V–4e and III–4e was 14.38 (95% Cl 12.53–16.53). This indicates that there is a significant difference in scores between isopter III–4e and V–4e. Conclusions: This study has shown that if one use the V–4e isopter in stead of the III–4e isopter, there will be an overestimate of the visual fields ability of the subject using FFS. According to our results, this overestimation could be one class. Therefore, the use of isopter V should be restricted to patients with moderate or severe vision loss who are unable to use the isopter III and the findings should be converted by 14.4 points.

Keywords: visual fields • perimetry • low vision