When analyzing data from blindness surveys, one needs to map out visual acuity against the Visual impairment categorized in ICD. There are some nuances, especially w.r.t Moderate visual impairment (MVI) based on the charts used as some VA charts yield 6/18 vision while others yield 6/19.
ICD11 Categories
Based on the above, we can arrive at the following
Conversion of Vision Readings to ICD-11 Vision categories
SNELLENS 6 metre
ICD 11
Worse than
Up to
No VI
6/12
Mild VI / EVI
6/12
6/18
Moderate VI
6/18
6/60
Severe VI
6/60
3/60
Blind
3/60
LogMAR
ICD 11
Worse than
Up to
No VI
0.3
Mild VI / EVI
0.3
0.5 / 0.47 used by RAAB Scripts
Moderate VI
0.5/ 0.47 used by RAAB Scripts
1.0
Severe VI
1.0
1.3
Blind
1.3
Logmar Values used in RAAB analysis: RAAB6_reporter.Rmd Lines 1482-1496
0.3: Can see 6/12
0.47 = Cannot see 6/12, Can see 6/18
1.0= Cannot see 6/18, Can see 6/60
1.3= Cannot see 6/60, Can see 3/60
1.8 = Cannot see 3/60, but can see 1/60
3.0 = Light Perception (PL+)
4.0 = No light perception (NPL/PL-)
Decimals
ICD 11
Worse than
Up to
No VI
0.5
Mild VI / EVI
0.5
0.3
Moderate VI
0.3
0.1
Severe VI
0.1
0.05
Blind
0.05
LogMAR / ETDRS 6metre
ICD 11
Worse than
Up to
No VI
6/12
Mild VI / EVI
6/12
6/19
Moderate VI
6/19
6/60
Severe VI
6/60
3/60
Blind
3/60
ETDRS 20 feet
ICD 11
Worse than
Up to
No VI
20/40
Mild VI / EVI
20/40
20/70
Moderate VI
20/70
20/200
Severe VI
20/200
20/400
Blind
20/400
ETDRS 4 metres
ICD 11
Worse than
Up to
No VI
4/8
Mild VI / EVI
4/8
4/12
Moderate VI
4/12
4/40
Severe VI
4/40
4/80
Blind
4/80
LogMAR 13 Feet
ICD 11
Worse than
Up to
No VI
13/26
Mild VI / EVI
13/26
13/42
Moderate VI
13/42
13/131
Severe VI
13/131
13/260
Blind
13/260
All these are based on the VA conversions using standard formulae.
