According to a recent study led by Turkish investigator Serap Yurttaser Ocak, MD, and her colleagues, the pupillary diameter has shown significant differences between when the COVID-19 virus was active and 3 months post-infection.
The researchers are from the Department of Ophthalmology, Prof. Dr. Cemil Tascioglu Education and Research Hospital, University of Health Sciences, Istanbul, Turkey.
The study included 58 COVID-19 cases (mean age 47.23 ± 1.1 years). The scotopic, mesopic and photopic diameters were noted. Pupil diameters were noted at the 0, 1st, 2nd, 4th, 6th, 8th, and 10th seconds in reflex pupil dilation after the termination of a light.
The average dilation speed was calculated at the 1st, 2nd, 4th, 6th, 8th, and 10th seconds. Pupil responses measured during COVID-19 infection and 3 months later were compared.
The study found that mean scotopic and mesopic pupil diameter value of during COVID-19 infection was lower than the 3rd month post-infection. (p = 0.001 and p = 0.023, respectively).
There were no significant differences in the mean photopic pupillary diameter and the mean pupillary diameter at 0 seconds between measurements (p > 0.05, p = 0.734; respectively).
During active infection, the mean pupillary diameters were significantly lower at 1, 2, 4, 6, 8, and 10 seconds (p 0.01, for all comparisons), and the average speeds at which the pupils dilated at each time point were significantly lower during active infection compared to measurements taken at 3 months (p = 0.001; p 0.01 for each).
Researchers believe that these findings lay down the foundation of further studies regarding the impact of COVID-19 on the autonomous nervous system.
“Since pupil functions are managed by the autonomic nervous system, the assessment of pupil function might be a useful test for determining autonomic dysfunction,” the authors concluded.
Details of the study can be found here: https://link.springer.com/article/10.1007%2Fs10792-021-02053-z