A simple objective pupillometer

This device uses counter-rotating Perspex blocks to measure the diameter of the pupil of the human eye. The instrument is accurate to +or-5%, gives direct readings on a linear scale and is suitable for use in drug studies.

[1]  I. E. Loewenfeld,et al.  Electronic pupillography; a new instrument and some clinical applications. , 1958, A.M.A. archives of ophthalmology.

[2]  D. G. Green,et al.  Closed-circuit television pupillometer. , 1967, Journal of the Optical Society of America.