In laser iridectomy an argon laser is focused on a small area of the iris in the human eye, leading to tissue removal that can help to equalize pressures in the anterior and posterior chambers of the eye. FIDAP studies [1] of the conduction and convection heat transfer to the eye tissues during the iridectomy process have helped to explain possible causes of corneal burns and lens opacities and their relationship to laser operational parameters.

The FIDAP predictions helped to explain reported postoperative problems.

Figure 1. Computational mesh used to discretize the human eye.

The FIDAP analysis involved a 3D discretization of the eye, with the transient absorption of a laser heat source defined in a small region of the iris. The resulting temperature and velocity distribution predictions indicated that natural convection has a large impact on the thermal history and that excessive temperature rises and longer durations of high temperature can be expected for some laser operating parameters. This overheating may help to explain some of the postoperative problems reported by ophthalmologists.

[1] A Powerful Finite Element Analysis of Argon Laser Iridectomy: Influence of Natural Convection on the Human Eye, G. (Sbirlea) Apiou and J.P. L'Huillier, Fourth International Conference on Simulations in Biomedicine, 1997.

Figure 2. Temperature and natural convection currents in the eye following laser heating.

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