logmar

Convert visual acuity between logMAR, Snellen, and decimal. Pure arithmetic, zero dependencies.

pip install logmar

import logmar

logmar.snellen_to_logmar("20/40")  # 0.301
logmar.logmar_to_snellen(0.3)      # "20/40"
logmar.snellen_to_logmar("6/12")   # 0.301  (metric Snellen, same acuity)
logmar.decimal_to_logmar(0.5)      # 0.301
logmar.logmar_to_decimal(0.0)      # 1.0  (20/20)

API

• snellen_to_logmar("20/40") / logmar_to_snellen(0.3, base=20)
• decimal_to_logmar(0.5) / logmar_to_decimal(0.3)
• snellen_to_decimal("20/40") / decimal_to_snellen(0.5, base=20)

logMAR = −log₁₀(decimal acuity); Snellen m/x has decimal m/x. 20/20 = 0.0 logMAR = 1.0 decimal; larger logMAR is worse acuity.

Licence

MIT.