We have all had referrals from A&E telling us that a patient can’t see out of one eye. Sleepily we may ask “Is there an relative afferent pupillary defect (RAPD)?” to evaluate the seriousness of the presentation. The response is often flustered or surprised. “The pupils are fine” or something like that, but it is evident the referrer does not really know what an RAPD is or why it is useful. And lacking the requisite experience, they cannot then be asked to assess it either. All this may now be about to change thanks to Dr Volpe’s group which has developed an automated portable pupilometer to assess for and quantify RAPD. The machine assessed constriction amplitude, velocity and onset latency in 32 patients and 31 normal subjects who were stimulated with maximal light in one eye and reduced light in the other to mimic an afferent defect. The results showed a strong correlation between an expert examiner and the device, and the latter differentiated between patients with significant RAPD and controls with a high degree of accuracy (91%) in terms of both sensitivity and specificity. Amplitude and velocity were found to be more helpful than latency of onset of pupil constriction. The study unfortunately had some easily avoidable confounders: the patients ages ranged from 27-89 whilst the healthy volunteers were aged 21-34. In addition to being able to follow patients up in the long-term to assess for recovery in, for instance, typical optic neuritis, just like an ECG machine can help alert a technician to an abnormality requiring further assessment, likewise this machine may be used by frontline staff to help health care providers detect significant pathologies requiring urgent management.

A novel computerized portable pupillometer detects and quantifies relative afferent pupillary defect.
Cohen LM, Rosenberg MA, Tanna AP, Volpe NJ.
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Jonathan CP Roos

Harvard, Cambridge & Moorfields-trained Consultant Oculoplastic Surgeon and academic based in London at www.FaceRestoration.com. Publishes in the world’s leading medical journals and lectures internationally on aesthetics, eyelid diseases and thyroid eyes.

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