visual_demand: visual_demand
In maqui7295/OptomConvertR:

Description Usage Arguments Details Value Author(s) Examples

Calculates visual demand or threshold for a letter

1 2	visual_demand(letter_height, distance, meter = FALSE, feet = FALSE, all = FALSE)

`letter_height`	height or size of the letter. This should be in the same unit as the distance
`distance`	distance from the viewer to the letter, should be in the same unit as the letter.
`meter`	if TRUE, return the visual demand (as a string) in snellen meters
`feet`	if TRUE, return the visual demand (as a string) in snellen feet

visual_demand calculates the minimum va required to view a letter of a given size at a given distance

visual acuity in log MAR or snellen or both

Mark Edosa

visual_demand(1.5, 110) # visual demand in log MAR for a letter size of 1.5 inches at a distance of 110 inches
visual_demand(0.005, 6, all = TRUE) # visual demand (in logMAR and snellen) for a 5mm letter viewed at 6 meters
visual_demand(0.005, 6, meter = TRUE) # visual demand (in snellen meters) for a 5mm letter viewed at 6 meters
visual_demand(0.005, 6, feet = TRUE) # visual demand (in snellen feet) for a 5mm letter viewed at 6 meters
visual_demand(0.005, 6, meter= TRUE, feet = TRUE) # visual demand (in both snellen meter and feet) for a 5mm letter viewed at 6 meters