Snellen fraction


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Related to Snellen fraction: Snellen chart

Snellen fraction

A representation of visual acuity in the form of a fraction (e.g. 6/6 (20/20), 6/24 (20/80), etc.) in which the numerator is the testing distance, usually expressed in metres (or in feet), and the denominator is the distance at which the smallest Snellen letter read by the eye has an angular size of 5 minutes. See near visual acuity; visual acuity; decimal visual acuity.
Table S3 Relationship between Snellen fractions in metres and feet, and for two testing distances (4 and 6 metres)
(6 m)(20 ft)(4 m)
6/320/104/2
6/4.820/164/3.2
6/620/204/4
6/7.520/254/5
6/9.520/324/6.3
6/1220/404/8
6/1520/504/10
6/1820/604/12
6/2120/704/14
6/2420/804/16
6/3020/1004/20
6/3820/1254/25
6/4820/1604/32
6/6020/2004/40
6/9020/3004/60
6/12020/4004/80
6/15020/5004/100
6/18020/6004/120
6/24020/8004/160
6/30020/10004/200
References in periodicals archive ?
(19) In the second analysis, we used only ETDRS values, and we removed data for eyes with an initial Snellen fraction of 20/20 or better.
Pooled ETDRS 62(16) 64(18) 0.024 results (Wilcoxon) Legend: Segregated outcomes for the (1.) right and (2.) left eyes were Snellen fraction, Snellen line and Early Treatment Diabetes Retinopathy Study (ETDRS) score.