EVALUATION OF THE PINHOLE PUPILLOMETER

Evaluation of pupil diameter is used in many clinical and research fie lds to aid diagnosis of neurological disorders and to monitor pharmaco logical effects upon the eye. Methods used to determine pupillary diam eter have evolved from simple scale measurements to much more complex systems, supposedly improving accuracy and repeatability. However, man y techniques are restricted to the consulting room or research laborat ory due to the size of the equipment, its cost, or the expertise requi red. We have evaluated a portable pupillometer originally developed by Broca, capable of precise measurements on fixed, dilated pupils, that has the potential to be used by unsupervised patients. Luminance leve ls will still need to be controlled because, although luminance does n ot influence the mechanics of the pupillometer itself, it significantl y affects the natural pupil. The pinhole size should ideally be 1.1 mm in diameter, since smaller pinholes underestimate and larger holes ov erestimate pupil size. The pupillometer also exhibited reasonable accu racy in fixed pupils dilated with tropicamide. Pupil measurements were overestimated by 0.5% using the l.-E mm pinholes (insignificant if th e pupil can be measured to the nearest 0.25 mm) and both intra- and in ter-visit repeatabilities were relatively good. The results from this study therefore indicate that the pinhole pupillometer may be of use i n pupil research, since it facilitates more frequent pupillary measure ments over much longer time intervals than are currently achievable. ( C) 1998 The College of Optometrists. Published by Elsevier Science Ltd . All rights reserved.