EyeKinetix® (Coming Soon)
Checking pupils for RAPDs is an important part of the comprehensive eye exam and is recommended in the AAO’s Preferred Practice Patterns® for POAG suspects and patients however the swinging flashlight test is difficult for humans to do well, and even more difficult and time consuming to accurately quantify.
Importantly, there is evidence that very small RAPDs may be clinically significant.
Historical Methods: The “Swinging Flashlight Test”
With origins stemming from the 19th century, this manual and subjective method of detecting an RAPD is commonly known to be difficult to perform well, under the best of circumstances. Although known to be an important physical sign, many well-intentioned doctors report little incidence – not because the sign is not present, but because it is difficult or impossible to detect and it is rarely quantified.
A Perfect Storm
Confounding issues such as minimum contrast (dark iris + black pupil + dark room), anisocoria, misshapen pupils and the lack of standardized light intensity conspire to make the swinging flashlight test even more challenging.
RAPDx utilizes a high-definition, machine-vision system under controlled infrared conditions to present monocular visual stimuli while recording binocular pupil responses. Unlike human observers that only see one eye response at a time, RAPDx simultaneous images both direct and consensual light responses. The power of the system is to collect a series of responses and average them into a consolidated response curve. Pupil testing is notoriously non-standardized, variable, and noisy. Response averaging significantly helps filter the noise inherent in the biological responses.
Easy, objective, quantitative, delegated, detailed … perhaps better than the finest human observer. RAPDx may be the most significant advancement in pupil testing in decades.
RAPDx is designed to allow minimally trained technical staff to collect objective data on PLR (pupil light reflex) responses.
RAPDx pupillography provides 6 key measurements that make up the fundamentals of the pupil response “Signature”.
- Resting pupil diameter
- Latency, onset of constriction
- Velocity of constriction
- Amplitude of constriction
- Latency, maximum constriction
- Velocity of recovery
This is important new information that clinicians rarely collect reliably or at all.
A differential assessment of the mean of the right eye stimulated constrictions versus the mean of the left eye stimulated constrictions are compiled as “RAPDx Score”.
- The RAPDx score here indicates that the right eye sees less light and the averaged score is recorded as 0.71 (constriction amplitude differential).
- Assessed independently as being comparable to the swinging flashlight test when quantified using neutral density filters.