Abstract
Purpose:
Tear film hyperosmolarity is a recognised hallmark of dry eye disease. Lubricating eye drops have been shown to improve signs and symptoms of dry eye disease. However, their effect upon tear osmolarity has not been established. This study aimed to evaluate tear osmolarity after using lubricating eye drops 4 times daily for 3 weeks.
Methods:
Thirty participants with dry eye disease (OSDI score ≥20 and tear osmolarity ≥300 mOsm/L) were enrolled in this prospective, dispensing, non-randomized study involving a baseline visit and 3-week follow-up. The following ocular surface parameters were determined at baseline: osmolarity; non-invasive tear break up time (NITBUT); conjunctival hyperemia; corneal and conjunctival staining. Participants were instructed to instil one drop of a hydroxypropyl guar-based drop (Systane Ultra; Alcon, Fort Worth, TX) 4 times daily in each eye for 3 weeks and completed a symptom questionnaire between visits. At the follow-up visit, the OSDI questionnaire and ocular surface parameters were reassessed. At the end of these assessments, one drop of Systane Ultra was instilled into each eye and osmolarity was measured after 15 minutes to examine short-term changes in osmolarity.
Results:
Twenty eight participants completed the study (5M; 23F: median age 54 yrs, range 25-83 yrs). At baseline, mean OSDI score was 44.94±15.23 and mean osmolarity were 312.5±10.6 / 308.8±12.6 mOsm/L (OD/OS). After 3 weeks, mean osmolarity reduced to 306.4±16.8 / 305.1±9.9 mOsm/L (OD/OS; p<0.05 and p=0.07, respectively). Statistically significant improvements in conjunctival hyperemia, central corneal staining (p<0.05 OU) and NITBUT (p<0.01 OD only) were observed. Mean OSDI scores reduced to 28.27±17.0 (p<0.01). A significant reduction in osmolarity was observed 15 minutes after instilling the lubricating drop (p<0.05 OU). There were no changes in acuity (all p>0.05).
Conclusions:
A significant, measurable reduction in osmolarity in addition to improvements in dry eye symptoms and some tear film parameters were observed after 3 weeks of daily use of a hydroxypropyl guar-based lubricant drop. A decrease in osmolarity was also demonstrated 15 minutes after drop instillation.