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Temperature, humidity affect tear film with CL wear
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Environmental conditions affected some parameters of the tear film in soft contact lens wearers, researchers in Japan found in a study.
Changes in air temperature and relative humidity had no effect on the tear volume in patients wearing two types of soft contact lenses, according to the study authors. However, as the temperature and humidity were decreased, the tear film on the lenses became thinner, the tear breakup time became shorter and ocular dryness increased, the study authors found.
Kunio Maruyama and colleagues at Kyoto Prefectural University of Medicine enrolled 11 men who wore soft contact lenses daily in the study, in which they were exposed in different sessions to four sets of conditions in an environmental chamber. In the sessions the air temperature and humidity were set to 5· C and 10%; 15· C and 20%; 25· C and 40%; and 35· C and 50%. The men wore two types of lenses, one with a water content of 72% and one with a water content of 37.5%.
No significant differences were found in the tear meniscus radius with or without the soft contact lenses, regardless of type. As temperature and humidity decreased, tear interference patterns increased, noninvasive tear breakup time became shorter and ocular dryness increased.
Dryness scores were higher with the lenses that had higher water content.
The study is published in the August issue of Investigative Ophthalmology & Visual Science.