Quantitative analysis of light sensitivities in central 30-degree visual field of normal Chinese and glaucoma...

To examine the difference in the light sensitivity in the central visual field between the normal subjects and patients with or without the early visual field damages and propose the criteria to identify the possible early disturbances in the visual field.

Light sensitivities at the 76 locations in the central field were measured in 108 normal eyes of 75 normal volunteers aged from 20 to 78 years, and 82 eyes of 53 patients with early open-angle or closure-angle glaucoma on the Humphrey Field Analyzer (Model 610), using the Central-30-2 program.

No sex and eye differences were found. The significant differences in the light sensitivities existed between the age of 20-45 years and the age of 46-78 years in the normal subjects. The lower limit of 80% normal range for each location in the central field of the two age groups was calculated. The light sensitivity decreased by 2-3 dB at every 10 degree from the eccentricity. The light sensitivity in the inferior field was 1-2 dB higher than that in the superior field. There was no statistical difference between the nasal and the temporal field. For the patients with the field defects, the light sensitivity of many locations decreased by 4-8 dB, and by 1-2 dB in the patients without the field defects as compared with the normal controls.

Based on comparisons with the normal controls and the lower limit of 80% normal range, we proposed the following criteria for classification of the damages in the glaucoma visual field. Grade I: light sensitivity reduces by 1-3 dB at a cluster of locations in the field; Grade II: light sensitivity reduces by 4-6 dB at a cluster of locations in the field; Grade II: light sensitivity reduces by more than 6 dB at a cluster of locations in the field.