Development of a rabbit model of tear film instability and evaluation of viscosity of artificial tear preparations.

OBJECTIVE

The purposes of this study were to establish a quantitative method for evaluating rabbit tear film status and investigate the efficacy of artificial tear preparations through ocular surface bathing or eye drop application.

METHODS

The rabbit tear film was evaluated using a noninvasive specular reflection video recording system. The appearance of a tear break area (TBA) on the tear film images (7.4 mm2/mm) after 30 seconds of eye opening was quantified by image analysis. To induce disruption of the rabbit tear film, the ocular surface was challenged for 60 minutes with 1 ppm hypochloric acid (HOCl). Immediately after irrigation, artificial tear preparations composed of viscosity agents sodium hyaluronate (SH), hydroxypropylmethycellulose (HPMC), hydroxyethylcellulose (HEC), or chondroitin sulfate (CS) were applied to the rabbit eye through ocular surface bathing or eye drop application, and the recovery of the disrupted tear film was compared for each preparation.

RESULTS

A dramatic increase in TBA was observed immediately after the ocular surface was challenged with HOCl, and it returned to the initial level after 6 hours. Immediately after ocular surface bathing and eye drop application, a dramatic recovery of TBA was observed in all the test solution-treated eyes. One hour after treatments, prolonged amelioration of the tear film instability was observed after ocular surface bathing, but not by eye drop application, with the artificial tear preparations composed of HPMC or SH.

CONCLUSION

Ocular surface bathing with artificial tear preparations composed of a suitable viscosity agents could be useful in managing tear film instability.