A Study of the Depth of Hemianopic Field Defects for Optimizing Computerized Perimetry

Abstract

Although the test point pattern of the computerized perimeter ‘Competer’ has been enlarged, focal diagnosis is in many cases difficult since the area outside 35° of eccentricity cannot be examined. Further improvements of the instrument requires knowledge about the depth at various eccentricities of common neurological field defects. This was calculated in bitemporal and suprageniculate homonymous defects. Forty-one eyes with chiasmal defects and 36 eyes with suprageniculate defects were compared with 26 normal fields. Generally, the central area was more or less intact in relative hemianopias, probably because of the large proportion of macular fibres in the visual pathways, and the depth was found to increase towards the mid- periphery. The results indicate that with a simplified test strategy for the mid-peripheral area, few hemianopic defects would be missed by the ‘Competer’. In this way, the examination of the mid-peripheral area could be shortened. Without prolonging the total test session, which is already 15–20 min per eye, focal diagnosis could be facilitated by adding and testing a number of points in the area outside 35° of eccentricity. Such modifications are in progress.

The paper will be published in full in Neuro-Ophthalmology (Amsterdam).