Igor A. Dovish, assistant professor at the University of Texas Southwestern Medical Center in Dallas, says research shows cold temperatures cause the medium -- the oily substance that helps form the outermost layer of the tear film -- to become too thick and stiff to spread onto the eye surface.
"In outdoor conditions, the wind accelerates the drop in temperature of the ocular surface and the eyelids, thus the effect is even more pronounced," Dovish said in a statement.
"This mechanism seems to be one of the major factors that cause dry eye to worsen in cold, windy weather such that it can affect even healthy people."
The research team said they expected to see measurable effects of temperature on medium, but they were surprised the bulk of medium abruptly melted in a very narrow range of temperatures, right around the eye surface and eyelid temperature of 32 to 34 degrees Celsius (89.6 F to 93.2 F), and worsening at 30 degrees C (86 F).
The study is published in Investigative Ophthalmology & Visual Science.