Handheld chromatic pupillometry may determine functional loss in patients with glaucoma
Click Here to Manage Email Alerts
A newly developed handheld chromatic pupillometer has shown accuracy in revealing pupillometric dysfunctions in patients with varying severity of glaucoma, according to data published in British Journal of Ophthalmology.
“The detection of glaucoma is challenging, in part because no stand-alone, affordable and accurate tool allows for it in an opportunistic or community setting,” Raymond P. Najjar, PhD, of Singapore Eye Research Institute and Duke-NUS Medical School, and colleagues wrote. “Using a custom-built handheld pupillometer, in this study, we evaluated the pupillary responses to exponentially increasing blue and red light stimulations in patients with different severities of glaucoma. Furthermore, we compared the performance of our handheld chromatic pupillometer for glaucoma classification with established structural and functional investigation tools.”
The clinic-based, prospective study included 322 subjects, of which 149 had confirmed glaucoma and 173 were healthy controls. Using the handheld chromatic pupillometer, researchers monocularly assessed changes in pupil size in response to 9 seconds of increasing blue and red light stimuli. Pupillometric features were compared between the groups, and the features with the highest classification potential were then incorporated into a generalized linear model for glaucoma classification. The performance of the handheld pupillometer, OCT and Humphrey visual field (HVF) was compared using receiver operating characteristic curve analyses.
In patients with glaucoma vs. control subjects, pupillary light responses were altered.
“Principally, phasic constriction to blue (P < .001) and red (P < .001) lights, as well as maximum constriction to blue (P < .001) and red (P < .001) lights were reduced in patients with glaucoma,” the researchers wrote.
In terms of glaucoma classification, the handheld chromatic pupillometer yielded a sensitivity of 87.9%, specificity of 88.4% and an area under the ROC curve (AUC) of 0.94.
In early to moderate glaucoma, the handheld pupillometer (AUC = 0.91) was found to be similar to HVF (AUC = 0.91) in classification performance but reduced compared with OCT (AUC = 0.97). However, in severe glaucoma, the handheld pupillometer (AUC = 0.98) was similar to both HVF and OCT in classification performance.
“Our proof-of-concept study highlights the feasibility and high accuracy of chromatic pupillometry delivered using a handheld device for the objective detection of functional loss in glaucoma in a clinical setting,” the researchers wrote. “Further community-based or opportunistic screening studies, as well as cost-effectiveness analyses, are necessary to confirm whether [handheld chromatic pupillometry] is a useful tool for glaucoma screening.”
Perspective
Back to Top
I remember reading an article on pupil perimetry for glaucoma detection when I was in school. The idea to create a more objective functional glaucoma test was sound, but it never gained widespread use. When I saw Najjar’s paper, my first reaction was, “Haven’t we already tried this?” Well, the authors have a new twist. They examined the pupil’s light response to different wavelengths and compared glaucoma patients to controls. Interestingly, their instrument was able to classify glaucoma with about 88% sensitivity and specificity. In moderate glaucoma it works as well as HVF, and in severe glaucoma it was on par with OCT and HVF. It’s unlikely that chromatic pupillometry will help with early glaucoma diagnosis.
So, do you need to run out and buy a handheld chromatic pupillometer? Absolutely not. While this test may be helpful in community screenings you can probably do as good a job screening for glaucoma with your handheld ophthalmoscope. Still, a simple-to-use instrument that can get high-risk patients in for a professional evaluation could be a valuable weapon in the battle with glaucoma.
Collapse
Read more about
Click Here to Manage Email Alerts