Contact Lens Wearers Prefer Warm Tears

Contact Lens Wearers Prefer Warm Artificial Tears


JUNE 1997

Dry eye syndrome is a common condition, and may be described as a decrease in production or flow of the aqueous, lipid or mucin layers of the tear film or as abnormalities of the epithelium, the lid or the blink mechanism. Patients use artificial tear preparations frequently to relieve dry eye symptoms.

This study compares the comfort of the Tears Naturale II (Alcon) artificial tear preparation instilled at room temperature to the same product instilled at body temperature. We hypothesized that the average person could increase comfort level of an artificial tear preparation by warming it to body temperature.


Twenty-three men and 27 women, ages 21 to 41, completed the experiment. Half the participants were contact lens wearers, and all were members of the entering optometry class at Pacific University.

The participants completed a medical questionnaire noting allergies, history of artificial tear use, medications taken, medical conditions and contact lens wear. They also rated the frequency and severity of dry eye symptoms in four categories: burning, soreness, dryness and grittiness.

To determine the baseline health and integrity of the lids, lashes, conjunctiva, cornea and tear film, we performed a slit lamp exam with fluorescein and a Tear Break Up Time test (TBUT). We graded corneal staining on a scale from zero to four, with zero indicating no staining and four indicating coalesced patches. Contact lens wearers removed their lenses 15 to 30 minutes prior to the experiment to ensure an accurate examination and to avoid permanent fluorescein staining of soft lenses.

We grouped the participants into subcategories based on the following criteria: dry eye versus non-dry eye condition; gender; oral contraceptive use; and contact lens wearers versus non-contact lens wearers.

We acclimated the bottles of Tears Naturale II (0.1 fluid oz. each) to an average room temperature of 76 degrees Fahrenheit (SD=2.57) for not less than three hours before instillation. We placed the body temperature Tears Naturale II containers in our pockets, where the average temperature was 89 degrees Fahrenheit (SD= 3.80), for not less than three hours prior to instillation.

We randomly instilled the first drop of Tears Naturale II at either room or body temperature in one eye, and the participants recorded the sensations they experienced. We then instilled a drop of Tears Naturale II at the alternate temperature in the contralateral eye, and participants chose which preparation they preferred (right or left eye).


Twenty-six of the 50 participants preferred body temperature tears, but these results were not statistically significant. We also found no statistical significance for: eye condition (dry eye vs. non-dry eye), p=0.4828; gender, p=0.4184; and oral contraceptive use, p=0.2556.

However, we did achieve statistical significance for the variable of contact lens wear, p=0.0091 (Fig. 1). We might have expected a connection between contact lens wear and a concomitant dry eye condition, but that was not the case; therefore, it is not clear why the contact lens wearers preferred the body temperature solution.

Based on the results of this study, we accept our hypothesis as valid with regard to the subcategory of contact lens wear only. CLS

References are available from the editors at Contact Lens Spectrum, or to receive them via fax, call (800) 239-4684 and request Document #25.

Dr. Mulier practices at Hopkins Eye Clinic, Hopkins, Minn. Dr. Milano is a staff optometrist at an ophthalmological practice in Denver, Colo., specializing in refractive surgery, ocular disease and contact lenses. Dr. Remington is an associate professor of optometry at Pacific University College of Optometry.