Researchers suggest lens warmers may be able to reduce lens fogging from mask wear during slit lamp exams. Photo: Ani Kolleshi on Unsplash

Since the onset of the pandemic, many health care settings have required mask wear during visits; for optometry specifically, this has led to increased lens fogging at the slit lamp during retinal exams, as room-temperature lenses frequently accumulate condensation in mask-wearing patients. To combat this issue, a recent study published in Optometry and Vision Science suggests lens warmers may reduce lens fogging and, in turn, eliminate potential disruptions during the exam.

Lens warming to decrease fogging is not a new idea; in fact, professional photographers have been using this technology for decades, says lead researcher Marta C. Fabrykowski, OD, of the Manhattan Eye, Ear and Throat Hospital ophthalmology department. Additionally, professional photography lens warmers are inexpensive and can be easily purchased through various online purveyors for less than $20, she adds.

“Keeping the lenses warm between patients decreases the time needed to warm up lenses for patients who may be heavier breathers. In fact, you can examine all patients with warmed lenses,” Dr. Fabrykowski explains.

Dr. Fabrykowski and her team evaluated the degree of lens fogging in mask-wearing patients using ImageJ to measure lens surface areas fogged in slit lamp photos of 90D lenses before and after the use of a lens warmer. Additionally, they queried eye care providers by survey, asking them to rate their experience with diagnostic lens fogging during retinal exams in mask-wearing patients with and without lens warmers.

Based on the results, the lens warmers were highly effective. For mask-wearing subjects, the percent of the fogged lens area in the 90D lens was roughly 33% with unheated lenses compared with about 1% when a heated lens was used.

The doctors who responded to the survey noted significant less fogging of the 78D and 90D lenses when using the lens warmer and noted this addition helped facilitate the retinal exam.

Practitioners have suggested other methods to reduce lens fogging, such as requesting patients tape the top of their face mask to the bridge of their nose to prevent exhaled breath from traveling upward, pinching the face mask to the top of the patient’s nose and applying anti-fog solution to the lenses, the authors noted. However, these suggestions are difficult to implement since patients may resist having tape applied to their face, complain of difficulty breathing from a tight tape seal or skin sensitivities to adhesives or simply not want their face touched, the investigators explained. Additionally, using anti-fogging solution could decrease the integrity of the lens coating, complicate lens cleaning and require time to reapply throughout the day.

Despite the promising study results, lens warmer designs could be improved in terms of functionality, the researchers noted. For example, a few survey respondents commented that, while heating the lens improved their retinal exam, the heating platform could be more user-friendly.

One potential improvement the investigators suggested is to develop a lens case with a built-in warmer and temperature gauge.