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Abstract: Tear film osmolarity in patients taking IOP lowering meds

To evaluate tear film osmolarity in patients treated with intraocular pressure-lowering medications.
Forty patients treated for glaucoma or ocular hypertension (OHT) were consecutively recruited for the study. Each patient was asked to complete an evaluation of ocular surface disease symptoms, the Ocular Surface Disease Index, and underwent a complete evaluation of the ocular surface including measurement of tear film osmolarity, Schirmer test, tear breakup time (TBUT), and corneal and conjunctival staining.
Twenty-four patients (60%) reported ocular surface disease symptoms. Nineteen patients (47.5%) had a tear osmolarity ≤308 mOsms/L, 11 (27.5%) between 309 and 328 mOsms/L, and 10 (25%) >328 mOsms/L. A tear deficiency was observed in 20 patients (50%). Twenty-seven patients (67.5%) had an abnormal tear quality analyzed with TBUT, and 16 patients (40%) showed positive staining using the Oxford schema. Tear osmolarity was significantly correlated to Ocular Surface Disease Index (r = 0.486; P = 0.002) and TBUT (r = -0.49; P = 0.009). There was a statistically significant correlation between tear osmolarity and the number of drugs (r = 0.409; P = 0.009), the number of instillations (r = 0.405; P = 0.01), and the number of instillations of preserved eye drops (r = 0.629; P < 0.0001). Using the multiple regression method, tear osmolarity remained significantly correlated to the number of instillations of preserved eye drops (P = 0.004).
Tear osmolarity was increased in patients treated for glaucoma or OHT, particularly in those using multiple preserved eye drops. The evaluation of the ocular surface of patients treated for glaucoma or OHT may benefit from such analysis, and future trials for new intraocular pressure-lowering eye drops should thus evaluate tear osmolarity.

Cornea. 2012 Sep;31(9):994-9. doi: 10.1097/ICO.0b013e31823f8cb6.
Labbé A, Terry O, Brasnu E, Van Went C, Baudouin C.
Department of Ophthalmology III, Quinze-Vingts National Ophthalmology Hospital, Paris, France.