Development and evaluation of a novel porcine desiccation-induced dry eye model for investigation of the aetiology and treatment for dry eye: Implications for the ageing eye

Dry eye syndrome is multi-factorial in origin and has become a worldwide ocular problem, especially affecting the elderly. There have been several investigations into the aetiology and treatment of dry eye. Apart from clinical studies, several animal models of dry eye have been studied. However, due to the species difference and the complexity of dry eye, no single animal model can represent completely the human dry eye condition.;Porcine organs are better substitutes for human organs; however, porcine eyes have never been used to study dry eye. Moreover, among all developed animal models, none can be used to study the effect of blinking in dry eye.;Therefore, the aims of this study were to: (1) Determine the possibility of using porcine eye to establish an animal dry eye model (DEM); (2) Develop a novel porcine dry eye model (pDEM) with adjustable 'lacrimation' and 'blink' rates; (3) Ascertain the reproducibility of the pDEM system. (4) Simulate different severities of desiccation-induced dry eye in the pDEM; (5) Investigate the effect of different 'blink' rates on desiccation-induced dry eye simulated by the pDEM; (6) Investigate the effect of different artificial tears on desiccation-induced dry eye using the pDEM; (7) Investigate the effect of different viscosities of solutions on desiccation induced dry eye using the pDEM.;Baseline data on the number of dead cells on the porcine corneal epithelial surface were obtained using the trypan blue exclusion technique. A pDEM was developed and evaluated so that different severities of desiccation-induced dry eye could be simulated by adjusting the 'lacrimation-blink' intervals. The effect of different 'blink' rates on the desiccation-induced dry eye was studied by keeping the same amount of 'lacrimation' but varying the 'blink' rate. It was found that artificial tears with higher viscosity maybe better for protecting the cornea against desiccation.;In conclusion, we have developed and evaluated a novel porcine desiccation-induced dry eye model, incorporating 'lacrimation' and 'blinking' systems, that is capable of simulating different severities of dry eye and which can be used to study the aetiology and treatment of desiccation-induced dry eye.