Development of a long-acting artificial tear for veterinary use

Abstract

Ketratoconjunctivitis sicca, also widely known as dry eye diseases (DEDs), is a multifactorial disease of the tears and ocular surface that results in symptoms of discomfort, visual disturbance, and tear film instability with potential damage to ocular surface [1]. Dry eyes are common in both humans and dogs. The prevalence of dry eye diseases in humans ranges from 7.4% to 33.7% depending on the sources cited, while the incident rate in some breeds of dogs can reach up to 20% [2, 3]. Artificial tear is widely used for treating dry eyes. However, frequent instillation is often required due to its rapid precorneal clearance by tear flow and eye blinking motion. A patient needs to apply an artificial tear for more than 6 times per day if the dry eye symptoms are severe. Other forms of vehicles, including ointments and gels, have longer hydration time but the irritating sensation and undesirable cosmetic outlook greatly limits their use in everyday lives. These problems are augmented for dogs as topical administration must be performed by an animal care taker. To circumvent the shortfalls associated with conventional artificial tears, a novel hyaluronic acid (HA) based “supersoft” hydrogel has been developed. The hydrogel is composed of a crosslinked network of polymers which enables the hydrogels to resist both the dilution caused by tear and the tear flow which occur on ocular surface. Dynamic mechanical analysis performed on “supersoft” hydrogels suggest that the hydrogel exerts minimum forces to deformation (G’ = 0.33Pa at ω = 10rad/s). The novel “supersoft” hydrogel is eliminated slowly from the precorneal surface - approximately 40% of the hydrogel was remaining on ocular surface after 5 hours upon instillation of the hydrogel. By visual inspection, the hydrogel did not cause any gross response on cornea and demonstrated good biocompatibility on rodents and rabbits. Also, the results of the pilot clinical study which involved non-dry eye affected dogs revealed that the hydrogel did not induce any side-effects on canine subjects and thus, further clinical assessment is warranted.

Date of Award	2017
Original language	English
Awarding Institution	The Hong Kong University of Science and Technology