Purpose: In 1995, the Act on Welfare of Physically Disabled Persons was revised and the visual impairment grading methods were modified. In this revision, the target size for peripheral visual field measurements was changed from V/4 to I/4. We compared the area of I/4 and V4 visual fields in normal eyes and evaluated its influence on the decision of the visual impairment grade 5.
Subjects and methods: Goldmann kinetic perimetry results obtained from 137 eyes of 137 subjects (age 10-79, average ± SD: 47.0 ± 17.5) at Kinki University Hospital were retrospectively evaluated. The V/4 and I/4 isopter areas were calculated using Image J and compared with the normal visual field range in the visual impairment criteria.
Results: The V/4 isopter area decreased from age 70 and the I/4 isopter area decreased significantly from age 50. The aging slope of the isopter areas were significantly larger in I/4 than in V/4. In age 60 to 69, 19% showed a smaller I/4 isopter area than that of the grade 5 criteria. In age 70 to 79, 75% showed a smaller I/4 isopter area than that of the grade 5 criteria.
Conclusion: In some elderly people, the binocular I/4 isopter area is smaller than the visual impairment grade 5 criteria.