convert_logmar_to_etdrs: LogMAR -> ETDRS conversion

In admiralophtha: ADaM in R Asset Library - Ophthalmology

LogMAR –> ETDRS conversion

Description

Convert LogMAR score to ETDRS units

Usage

convert_logmar_to_etdrs(value)

Arguments

value

object containing logMAR score to convert to ETDRS. Permitted values a numeric value, e.g. 2, -5, 1.4 Default value none

Details

logMAR value converted to ETDRS as:

ETDRS = -(logMAR - 1.7) / 0.02

Source for conversion formula: Beck, R.W., et al. A computerized method of visual acuity testing. American Journal of Ophthalmology, 135(2), pp.194-205. doi:https://doi.org/10.1016/s0002-9394(02)01825-1.

Value

The input value converted to ETDRS units.

Author(s)

Nandini R Thampi

Examples

library(tibble)
library(dplyr)
library(admiral)

oe <- tribble(
  ~STUDYID, ~USUBJID, ~OETESTCD, ~OEMETHOD, ~OESTRESN,
  "XXX001", "P01", "VACSCORE", "logMAR EYE CHART", 1.08,
  "XXX001", "P02", "VACSCORE", "logMAR EYE CHART", 1.66,
  "XXX001", "P03", "VACSCORE", "logMAR EYE CHART", 1.60,
  "XXX001", "P04", "VACSCORE", "ETDRS EYE CHART", 57,
  "XXX001", "P05", "VACSCORE", "ETDRS EYE CHART", 1
)

adbcva <- oe %>%
  filter(OETESTCD == "VACSCORE" & toupper(OEMETHOD) == "LOGMAR EYE CHART") %>%
  mutate(OESTRESN = convert_logmar_to_etdrs(OESTRESN))

admiralophtha documentation built on Jan. 18, 2026, 9:07 a.m.