Application of Thermovision In the Assessment of Thermal Properthies Ophthalmic Viscoelastic Substances

Ophthalmic viscoelastic devices play a crucial role in cataract surgery today by protecting corneal endothelium, structures of anterior chamber and maintaining space inside the eye for safe manipulation during surgical treatment. Many factors likely affect the corneal endothelium during phacoemulsification procedure. These can be divided into 3 groups: 1) direct mechanical trauma including inadvertent touch of the endothelium by ophthalmic instruments, nuclear fragments, intraocular implant; 2) chemical adverse effects of irrigating solution; 3) influence of ultrasound energy affecting endothelium directly or increased, indirectly by temperature, acoustic contraction or via the generation of free radicals. Among various intraoperative complications that lead to endothelial cell loss thermal injury is potentially relevant. The main source of increased temperature is ultrasound energy delivered into the eye and partially converted into thermal energy. Different viscoelastic substances currently used during cataract surgery have various physical properties, e.g. rheology, osmotic strength, viscosity, cohesion that provide different levels of endothelium protection from mechanical, irrigating and ultrasound insult and corneal deturgescence due to osmotic and thermal factors. However thermal factor is thought to be potentially devastating on corneal endothelium. However little is known how different viscoelastic regiments can protect cornea against this kind of injury during cataract surgery