[Discussion on logarithmic visual acuity chart and five grade notation].
To explore the scientific aspect of logarithmic visual acuity chart and five grade notation, a visual test-type ten times large as the test-type of 4.0 grade was put 0.5 m before the eye, if the eye saw it, then the visual acuity was 2.0 grade (visual angle 1000' = 16.67 degrees). If moving this test-type to 0.05 m before the eye, 1.0 grade (visual angle 10 000' = 166.7 degrees) was obtained. They are more scientific than original records: hand movement for 2.0 grade and light perception for 1.0 grade. These test-type theoretically satisfy the demand of 5 grade notation. Logarithmic visual acuity chart and 5 grade notation is more superior subject created in China.
Luo
Wen-bin
WB
Department of Ophthalmology, Sichuan Provincial People's Hospital, Chengdu 610072, China. Luojian@sobey.com
Luo
You-rong
YR
D008433:Mathematics; D009907:Optometry / Q000379:methods*