Snell-Sterling visual efficiency scale

visual efficiency scale, Snell-Sterling 

A representation of visual efficiency as a function of visual acuity, in which are taken into account other factors such as perception, experience, etc. in estimating how much vision a person has for a given visual acuity.
Table V2 Relationship between visual acuity and the Snell-Sterling visual efficiency scale (in percentage round figures)
visual acuityEfficiencyloss of vision
(m)(ft)(in %)(in %)
6/620/201000
6/7.520/25964
6/920/30919
6/1220/408416
6/1520/507723
6/1820/607030
6/2420/805941
6/3020/1004951
6/4820/1602971
6/6020/2002080
6/9020/300892
6/12020/400397
6/15020/5001.598.5
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