PURPOSE: To identify the diurnal variations of tear osmolarity (TO) and its relationship with central corneal thickness (CCT) and corneal deswelling over a 14-hour period. METHODS: TO and CCT were measured using the TearLab Osmometer and Bioptigen spectral domain optical coherence tomography, respectively, on 38 healthy neophytes (mean age, 21.5 ± 2.2 years). TO and CCT were measured at bedtime (baseline), upon awakening, 20 minutes, 40 minutes, 1 hour, 2 hours, 4 hours, and 8 hours after awakening. Deswelling rate was estimated and expressed as percent recovery per hour (PRPH). Mixed-effect linear regression models describe the relationships among TO, CCT, and PRPH. RESULTS: The tear film upon wakening (264 ± 14 mOsm/L) was hypoosmotic compared with baseline (297 ± 15 mOsm/L, P < 0.001). TO (in mOsm/L) at 20 minutes, 40 minutes, 1 hour, 2 hours, 4 hours, and 8 hours were 287 ± 10, 292 ± 16, 293 ± 12, 292 ± 10, 289 ± 10, and 286 ± 10, respectively. CCT (mean ± SD) at baseline was 552.2 ± 35.9 µm and increased to 572.0 ± 38.7 µm after sleep. CCT returned to baseline thickness 4 hours after awakening (P < 0.000) and remained stable throughout the day. A small but statistically significant association was found between higher TO and lower CCT (P < 0.0001) and between lower baseline TO and higher PRPH (faster deswelling; P < 0.0001). CONCLUSIONS: The diurnal pattern of TO has been established. The association of TO with corneal thickness and deswelling suggests that the tear film tonicity may be partly responsible for corneal hydration control; however, the effect may not be of clinical significance in a normal study cohort.
PURPOSE: To identify the diurnal variations of tear osmolarity (TO) and its relationship with central corneal thickness (CCT) and corneal deswelling over a 14-hour period. METHODS: TO and CCT were measured using the TearLab Osmometer and Bioptigen spectral domain optical coherence tomography, respectively, on 38 healthy neophytes (mean age, 21.5 ± 2.2 years). TO and CCT were measured at bedtime (baseline), upon awakening, 20 minutes, 40 minutes, 1 hour, 2 hours, 4 hours, and 8 hours after awakening. Deswelling rate was estimated and expressed as percent recovery per hour (PRPH). Mixed-effect linear regression models describe the relationships among TO, CCT, and PRPH. RESULTS: The tear film upon wakening (264 ± 14 mOsm/L) was hypoosmotic compared with baseline (297 ± 15 mOsm/L, P < 0.001). TO (in mOsm/L) at 20 minutes, 40 minutes, 1 hour, 2 hours, 4 hours, and 8 hours were 287 ± 10, 292 ± 16, 293 ± 12, 292 ± 10, 289 ± 10, and 286 ± 10, respectively. CCT (mean ± SD) at baseline was 552.2 ± 35.9 µm and increased to 572.0 ± 38.7 µm after sleep. CCT returned to baseline thickness 4 hours after awakening (P < 0.000) and remained stable throughout the day. A small but statistically significant association was found between higher TO and lower CCT (P < 0.0001) and between lower baseline TO and higher PRPH (faster deswelling; P < 0.0001). CONCLUSIONS: The diurnal pattern of TO has been established. The association of TO with corneal thickness and deswelling suggests that the tear film tonicity may be partly responsible for corneal hydration control; however, the effect may not be of clinical significance in a normal study cohort.
Authors: Mark D P Willcox; Pablo Argüeso; Georgi A Georgiev; Juha M Holopainen; Gordon W Laurie; Tom J Millar; Eric B Papas; Jannick P Rolland; Tannin A Schmidt; Ulrike Stahl; Tatiana Suarez; Lakshman N Subbaraman; Omür Ö Uçakhan; Lyndon Jones Journal: Ocul Surf Date: 2017-07-20 Impact factor: 5.033
Authors: Laura Adelaide Deinema; Algis Jonas Vingrys; Holly Rose Chinnery; Laura Elizabeth Downie Journal: Transl Vis Sci Technol Date: 2017-05-22 Impact factor: 3.283
Authors: Ali A Abusharha; Tariq M AlShehri; Abdullah Y Hakami; Ali M Alsaqr; Raied A Fagehi; Saud A Alanazi; Ali M Masmali Journal: Ther Adv Ophthalmol Date: 2018-08-21