A study of femtosecond laser in glaucoma treatment : energy deposition and thermal increase

Abstract

The generation of femtosecond pulsed laser offers completely new possibilities for multiple technical applications. Due to its non-contact processing, extremely high intensity and ultra short pulse duration, it provides precise control of material removal with negligible thermal damage. In ophthalmology, the use of femtosecond lasers is receiving more attention than ever. It opens the highly beneficial possibilities for minimized side effects during the surgery process, and one of the specific areas is laser surgery in glaucoma treatment. Much work has been done for femtosecond laser application in ophthalmology. Some prospective results have been achieved. Meanwhile, the sophisticated interaction mechanism hampers femtosecond lasers' clinical application, and its potential in glaucoma treatment is still at the early stage. In this research, it was the first time that a modified moving breakdown theory was applied to study laser-induced optical breakdown in ocular tissue. It aimed to apply femtosecond laser in iridotomy surgery. Based on this theory, optical breakdown and the corresponding thermal increase were studied. The femtosecond laserinduced moving breakdown model was introduced to simulate the optical breakdown threshold; the Heat Affected Zone model was used to analyze temperature increases in water and ocular tissues. Cyclophotocoagulation is another main method to treat glaucoma. To improve the efficiency of cyclophotocoagulation procedure, a Monte Carlo program was developed and light propagation in multilayered ocular tissue was studied. The i