Effect of Glaucoma Medication in Tear Film Osmolarity of Patients Without Symptoms of Ocular Discomfort

Purpose: To evaluate tear film osmolarity in patients with no symptoms of ocular discomfort treated with intraocular pressure (IOP)-lowering medication and compare it with tear film osmolarity of controls. Methods: This was a cross-sectional study of 61 patients with glaucoma or ocular hypertension (study group) and 32 age-matched normals (control group). Neither group of patients reported ocular discomfort. Tear film osmolarity was measured with the TearLab Osmolarity System (TearLab Corp, San Diego, CA), and results were compared between groups. Correlation of osmolarity with parameters associated with medication use (time, number of medications, and number of instillations) was assessed. Results: Mean age of the patients in the medication group was 7110.18 years and in the control group was 69 +/- 10.23 years (P=0.247). In the medication group, the tear film osmolarity was 295.56 +/- 12.54 mOsms/L and in the control group, it was 294.84 +/- 14.73 mOsms/L (P=0.807). Regarding the percentage of patients with tear film hyperosmolarity (osmolarity316 mOsms/L), in the group of normal patients, 3 had osmolarity more than or equal to the selected cutoff value (9.3%) and in the medication group, 7 patients (8.2%). Difference of the percentage between groups was not statistically significant (P=0.999, chi-square test). Tear film osmolarity in the medication group was not correlated to any of the parameters related to treatment. Conclusions: Patients treated with IOP-lowering medication do not exhibit tear film hyperosmolarity as long as they do not report symptoms of ocular discomfort.