This bar is an assembly of optical filters of progressive densities providing a graduated system of dissociation. This is very useful to reinforce weak fusional status and can be used to measure Afferent Pupillary Defects (APD), also termed ‘diminished pupil reaction to light levels’. The log units quantify how much light is transmitted as: 41%, 22%, 12%, 7%, 5% and 3%.

An overlay filter (catalogue number SGR-952-NO) can be supplied if greater densities are required. This increases the density of all of the above light levels by 1.8 log units. 

Supplied in a neat wallet.