[Proposed scoring system for assessment of functional impairment due to visual field defects]

The purpose of the study is the development of a scoring system for the assessment of functional impairment due to visual field defects, based on the Esterman grid, but adapted to the existing system in the Federal Republic of Germany.

The score areas and the evaluation rules were altered iteratively, until the functional score by the new system matched as much as possible the score obtained from the existing system of geometrical defect patterns.

The visual field is divided into 100 score areas, which are smaller in the visual field center and in its lower region, respectively. The areas inside the reference isopter are counted and taken as total function in percent. Areas with monocular perception are rated with 3/4 points. Functional impairment is defined as the difference of total function to 100%. For 9 of 20 defect patterns, the functional scores are equal. Another six patterns differ by 1-4%. The remaining 5 of 20 patterns differ by 6-8% in either direction.

The new system is easier to apply, more consistent, and covers irregular defect patterns. The level of functional impairment is nearly identical with both systems. A transition to the scoring system would considerably increase the certitude and the quality of assessment especially in difficult cases.