Abstract
Abstract: :
Purpose: Measure the effects of eye lubricants on the tear film in patients with unstable tear films and test the following hypotheses: i. 0.1% sodium hyaluronate (Hylocomod) and a lubricant eye drop containing polyethylene glycol (PEG), propylene glycol (PG) and a unique gelling agent, HP–guar (SYSTANETM), modify the tear film beyond an increase in tear volume and; ii. the lubricant eye drop containing PEG/PG and HP–guar has a longer lasting effect. Methods: 15 patients with an unstable tear film (Tear Film Break Up Time [TFBUT]< 10 sec: lowest 33% of the population) measured by a wide field non–invasive technique were enrolled in this randomised, double–masked cross–over study. A single drop was instilled in each eye and the tear film was analysed every 30 min for 120 min with the TearscopeTM non–invasive lighting system and slit lamp biomicroscope observation system. Results: Tear volume, as assessed by measurement of the tear prism height, was similar at all times pre and post–instillation (p>0.05). The TFBUT pre and post–instillation were compared: i. the 0.1% sodium hyaluronate eye drops produced average increases post–instillation between 17% and 43%, the increase was statistically significant at only 120 min (p=0.005); ii. the lubricant eye drop containing PEG/PG and HP–guar produced average increases post–instillation between 37% and 77%, the increases were statistically significant at all times (p=0.024 to <0.001); iii. the tear film was significantly more stable with the lubricant eye drop containing PEG/PG and HP–guar than with sodium hyaluronate at 120 min (Minimum TFBUT 9.2 sec vs 6.8 sec p=0.032; Median TFBUT 14.0 sec vs 10.7 sec p=0.036). The incidence of thick lipid layers was greater with the lubricant eye drop containing PEG/PG and HP–guar than with sodium hyaluronate eye drops and reached significance at 120 min (p=0.035). Conclusions: Lubricant eye drops containing PEG/PG and HP–guar produce significantly greater and longer lasting effects on the tear film than sodium hyaluronate eye drops in patients with unstable tear films. In particular, 120 min post–instillation the lipid layer is significantly thicker and the TFBUT longer for the lubricant eye drops containing PEG/PG and the HP–guar gelling agent.
Keywords: cornea: tears/tear film/dry eye