Characteristics of the normal central visual field measured with resolution perimetry

The ring perimeter is an innovative device that measures the resolution threshold at 50 locations in the central visual field in approximately 6 min. This study was undertaken to define the characteristics of the resolution visual field in normal eyes using this instrument and to check the repeatability of the measurement. A total of 114 perimetrically naive, normal subjects aged from 20 to 79 years were prospectively enrolled; 55 randomly chosen subjects were tested twice, with a rest period of less than or equal to 60 s elapsing between examinations. The resolution threshold increased towards the periphery in all subjects. A small but significant decline in sensitivity occurred with age; this loss was greatest in the inner part of the field. Variability in threshold between subjects was not found to increase towards the periphery or in the upper field as compared with the lower. The field was highly repeatable when reexamined in the same subject. This study defines the resolution visual field in normal subjects, along with its inter- and intra-observer variability, and gives age-corrected predictive confidence intervals for each location of the field using the ring perimeter.