The increase in ocular surface temperature due to dilation is lower in patients with diabetic retinopathy than in age matched controls, making it a potential parameter for disease diagnosis, according to findings published in Experimental Eye Research.
Healthy volunteers (n=80), patients with non-proliferative diabetic retinopathy (NPDR; n=50), and proliferative diabetic retinopathy (PDR; n=20) were recruited in India for this study. OST was assessed via thermal imaging at 7 points of interest in a controlled environment before and after dilation.
Among the controls, temperatures ranged from the highest at the inner canthus (mean, 36.08±0.62° C) to the lowest at the corneal center (mean, 34.79±0.68° C). Temperatures for each participant were reliable across differing images and no trends were observed on the basis of gender or between left or right eyes. However, temperature tended to decrease ~1° C in the cornea and 0.8°C in the limbus with increased age.
Stratified by gender, all 7 points of interest differed significantly between the age-matched controls and the NPDR (all P <.001) and PDR (all P <.001) cohorts, in which temperatures were lower among the patients.
Among the controls, OST after dilation increased in all regions among men and women (all P <.001), specifically by an average of 0.82° C in the cornea and 0.75° C in conjunctiva and limbus.
For the patient cohorts, the researchers observed a more subtle, but significant increase in OST after dilation at all points of interest (all P <.001). For NPDR, the mean increase was 0.61° C in the cornea and 0.48° C in conjunctiva and limbus and 0.62°C and 0.47°C for the patients with PDR, respectively.
This study was limited by not attempting to assess best cutoffs which could differentiate between healthy eyes and eyes with diabetic retinopathy, additional study would be needed to determine the utility of OST as a diagnostic tool.
The study authors conclude that patients with NPDR and PDR had significantly lower OST before and after dilation compared with healthy controls.
Chandrasekar B, Rao AP, Murugesan M, et al. Ocular surface temperature measurement in diabetic retinopathy. Exp Eye Res. 2021;211:108749. doi:10.1016/j.exer.2021.108749