Abstract
Purpose: :
Characterize the ocular toxicity, surface tension (ST), mucoadhesion, and tear stabilizing properties of novel, bio-engineered polymers (HydraTears).
Methods: :
Ocular toxicity was assessed in vitro using the EpiOcularTM Tissue Model (MatTak Corporation). ST was calculated using a capillary Surface Tension Apparatus. Mucoadhesion was determined by collecting steady state controlled rate flow curves of equi-viscous polymer solutions, dispersions of 5% mucin, and mixtures of polymers and mucin. Tear stabilization was assessed via tear break up time (TBUT). A masked examiner tested 10 rabbits for each polymer. Balanced salt solution (BSS) containing fluorescein was administered to an eye and the lids manually closed twice. Then the lids were held open, a timer started, and the tear film scanned with a broad beam slit lamp (Kowa SL-15) in a darkened room using a cobalt blue filter. The timer was stopped when tear film disruption first occurred and the TBUT recorded. The ocular surface was flushed with BSS. The polymer solution was then tested in an identical manner. The mean TBUT (BSS) was subtracted from the mean TBUT (polymer) to control for inter-individual differences. The TBUT results were compared utilizing a one-way ANOVA (p<0.05) with a post-hoc Tukey HSD test (p<0.05).
Results: :
The polymers are denoted by alphanumeric code. All polymers demonstrated 80% viability or greater on the EpiOcular assay corresponding to a Draize eye score of 0-15 (non-irritating). The rank order ST were DHSP2<DHSA2<100DHS<20DHS<DHSA1=DHSP1<60DHS<buffer. The rank order mucoadhesion was 10% DHSP1>10% DHSA1>10% 100DHS>8.5% 60DHS>10%DHSA2=10%DHSP2. The ranked TBUT were 11.5%DHSA1*>12% DHSA2=11.5%DHSP1*>8.5% 60DHS*>12% DHSP2*>1% hydroxypropylmethylcellulose. *= significant difference
Conclusions: :
The HydraTears polymers demonstrated excellent potential for use as artificial tears based on their mucoadhesion and tear stabilizing properties. Further investigation is warranted.
Keywords: cornea: tears/tear film/dry eye