1 NEW METHOD FOR QUANTIFYING VISUAL FIELD DEFECTS IN GLAUCOMATOUS PATIENTS

A new scoring system is introduced to obtain a visual field per centual score beginning from a threshold related automatic field chart, by which it is possible to quantify relative scotomata in proportion to their depth and their impact on everyday life. Our interest is focused on the central 30 degrees visual field map of the C / 30- 2 program of the Humphrey Field Analyser (Allergan), which actually is one of the most common perimetric records in clinical practice. The new method is based on the Esterman's standard, which is worked out so as to ascribe a per cent value to each test point of the Central 30- 2 program; this per cent value is differently weighed depending on the quadrant where each test point is inscribed, its eccentricity and its threshold value. The sum of the threshold-related per cent values of all the grid points is equal to the residual visual field functional score. The ratio of the residual visual field functional score to full score (50) rappresents a new perimetric index related to function. In the case of glaucomatous eyes, a visual field efficiency index is calculated, which, together with visual acuity, rappresents the residual optic nerve function and consequently permits to quantify the optic nerve functional damage. This scoring method has been tested on 15 glaucomatous visual fields. Key words: glaucoma; visual field; threshold related perimetry; defect per cent quantification