Computerized Scoring of the Functional Field Preliminary Report

Abstract

The new computerized Autoperimeter has now been programmed to include the Functional Relative-Value Scale. This combination simultaneously performs automated perimetry and ergoperimetry: it plots the field, either monocular or binocular, and instantly prints the Functional score. The score is called ‘functional’ because it measures more than merely area; it assesses the total field’s usefulness and expresses it in percent or simple fraction — as does the Snellen Scale for central acuity. Thus, consultants for industry or government now have a standard scale to help determine job fitness, driver safety, social security disability, worker’s compensation, etc and to do this automatically, quickly, impersonally and as accurately as subjective testing will permit.

This year, the American Medical Association has adopted the Scale as standard for the U.S. with its publication of the 1984 edition of the official ‘A.M.A. Guides to Impairment — The Visual System.’

As part of more extensive trials performed at the suggestion of the President of the International Ophthalmological Council, preliminary tests have already calibrated the combined Autoperimeter and Relative-Value Scales so that scores match those of the standard Goldmann. Certain problems arose. Their solution yielded some interesting fundamental biological observations; also ideas for monitoring (by the I.P.S.) of the Scales’ manufacture and, if necessary, their future modification.

The method for determining the usefulness of a patient’s visual field by means of relative value scales has been describe elsewhere (1–3). More recently, during the past year, there have been two new developments: (1) these scales have been adopted by the American Medical Association; and (2) they have been computerized.

Last month (April 1984) the Scales became standard for the United States by their publication in the latest edition of the official ‘A.M.A. Guides to Impairment — The Visual System’ (4).

In America, the Scales are already available as software on the Cooper Vision/Dicon Automated Perimeter (as you have seen in today’s commercial exhibit). And from Switzerland, Prof. Frankhauser has written me that he intends to incorporate them into his Octopus perimeter.

The newly devised combination of automated testing and automated scoring has produced certain advantages: It has made assessment of the functional field less tedious, faster, more repeatable, more objective, more accurate and less dependent on highly trained personnel. At the same time it raised an immediate question of validity, the answer to which revealed a new concept of perception.

The immediate question was: Do the automated scores match those heretofore obtained conventionally on the standard Goldmann perimeter? The answer is: They do now. They did not, at first — not until adjustments were made in the light intensities of the automated test-objects. This led to some interesting revelations.