Background
The aim of this study was to design a self-retaining rat contact lens to simplify intravitreous injection in rats.
Material and Methods
A self-retaining, plane-concave prism contact lens customized for rats was designed. Forty diabetic rats were randomly divided into 2 groups and received the intravitreous injection of 10 μl of a cell suspension containing bone marrow-derived stroma cell (BMSC). Group A: used a microsyringe and a rat contact lens (n=20). Group B: used the same microsyringe and a traditional cover-slip (n=20).The duration of the intravitreous injection course and the success rate of intravitreous injection were observed.
Results
With the use of a self-retaining rat contact lens, a clear and stable view of the rat fundus was provided and the intravitreous injection course of rats quickly achieved, averaging 4.65±0.53 min in Group A and 12.33±2.79 min in Group B. The difference was statistically significant, and the time saved averaged 7.68 min. None of the Group A rats had retinal bleeding or lens injury; whereas 2 of 20 Group B rats had bleeding and 1 of 20 had lens injury. There was no significant difference between the rats in Group A and Group B.
Conclusions
A self-retaining rat contact lens is a potentially powerful instrument that allows high-quality observation of the rat fundus and simplifies the course of intravitreal injection.

Keywords: Contact Lenses, Cornea - physiology, Elasticity, Equipment Design, Fundus Oculi, Hemorrhage, Intravitreal Injections - methods, Syringes, Viscosity