admiralophtha (version 1.3.0)

convert_logmar_to_etdrs: LogMAR --> ETDRS conversion

Description

Convert LogMAR score to ETDRS units

Usage

convert_logmar_to_etdrs(value)

Value

The input value converted to ETDRS units

Arguments

value

object containing logMAR score to convert to ETDRS

Author

Nandini R Thampi

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.

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))