The Effects of Femtosecond Laser Created Drainage Channels on the Aqueous Humor Outflow Dynamics of the Eye.

Abstract

Various treatments have been introduced to delay or slow the progress of glaucoma, one of the leading causes of blindness, by reducing intraocular pressure (IOP), the unique manageable factor in glaucoma. However, there are limitations to the continuous usage of currently available treatments. A femtosecond laser presents the potential of advanced treatment by significantly reducing damage to tissues. This dissertation will address the compressive aspects of glaucoma and its treatments and the development of a minimally invasive surgical procedure and a supporting tool to improve the efficiency of this procedure. The experimental setup was built to scan the eye with a femtosecond laser in a predetermined pattern with adjustable parameters. The outflow rate was measured before and after the laser treatment to evaluate the effect of the channel. It was demonstrated that the subsurface scleral channel that increases aqueous humor (AH) outflow rate can be created in ex vivo rabbit eyes with a femtosecond laser. Considering that the goal of glaucoma treatment is to reduce IOP into the normal range, a tool is required to predict the channel dimensions to achieve a predetermined IOP reduction. I developed a 3D finite element model and demonstrated its potential as a tool for estimating channel dimensions by fitting the experimental data to the model. The experimental setup was altered to make a scan on an in vivo rabbit. It was demonstrated that the subsurface scleral channel can be created in the eyes of in vivo rabbits and IOP can be reduced with this channel. It was found that IOP can be reduced with a positive relation to the dimensions of the channel, demonstrating the potential for controlled IOP reduction by manipulating channel dimensions. Therefore, it can be concluded that the subsurface scleral AH drainage channel can be created with a femtosecond laser, overcoming the disadvantages of current treatments. The method has the potential of controlling IOP reduction with the channel dimensions. 3D FEM has potential as a tool for predicting the post treatment IOP and calculating channel dimensions for a required IOP reduction.Ph.D.Biomedical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/61628/1/dchai_1.pd