Nonproliferative diabetic retinopathy associated with lower ocular surface temperature

Eur J Ophthalmol. 2009;1004-1008.

Lower ocular surface temperature was associated with diminished blood flow in eyes with nonproliferative diabetic retinopathy, a study showed.

"Ocular surface temperature is a parameter determined by external and body temperature, tear film features and ocular blood flow," the study authors said. "It can be considered an indirect marker of ocular blood flow, which is measurable by infrared thermography."

The prospective study included 51 patients with nonproliferative diabetic retinopathy and 53 healthy, age- and gender-matched controls. One eye of each participant was studied. Investigators assessed best corrected visual acuity, IOP, anterior and posterior segment anatomy, and tear film breakup time. They used stereoscopic color fundus photographs and fluorescein angiography to gauge the severity of diabetic retinopathy. A thermo camera and burst recording unit were used to measure and record ocular surface temperature.

Study data showed that diabetic retinopathy eyes had lower ocular surface temperature than control eyes at all follow-up points. The difference was statistically significant at the first four follow-up points (P < .001) and at the fifth point (P = .003).

All eyes had a higher temperature at the extremities at the first and fifth points, and a lower temperature at the center of the cornea, the study authors said.

"Of special interest is the significance for corneal temperature, which is the most reliable value of [ocular surface temperature], because the avascularity of the cornea should minimize the influence of the conjunctival vascular network on thermographic analysis," they said.

Further study is needed to gauge difference between groups and determine the utility of thermographic evaluation in diabetic patients, the authors said.