R
- Radiance L
- reading cap
- reading portion
- reduce-aperture trial case lens
- reduced aperture trial frame
- reduced-aperture lens
- Reference distance
- reference IOP
- Reference plane
- reference seeing distance (RSD)
- reference wavelength
- refracting angle
- refracting edge
- refractive index
- Refractor head
- relative distance magnification
- relative visual attenuation coefficient
- resolution
- resolving power of the fundus camera
- retinal hazard limit
- Retinoscope
- reverse polarity system
- round segment
resolution
Smallest separation between two details, expressed as a linear or angular measurement, at which a pair of points may be recognised as being separate under a given set of conditions.