When this information is considered clinically, Dr. Ethier said the sclera is an important factor. “The sclera matters a lot: mechanical strains in the ONH are thought to be much higher in eyes with a soft sclera, thus leading to the possibility of altering the course of glaucoma by intervening to stiffen the sclera,” he said.
In an experimental rat study, the sclera was stiffened, ocular hypertension induced, and the optic nerves followed. Importantly, the preliminary results showed the stiffening protected against axonal loss. “This is extremely interesting and provocative,” he commented.
However, in another study performed in mice, the opposite was found. “The scientific questions remain very much open and there is still a lot to be discovered,” Dr. Ethier said.
Lastly, Dr. Ethier commented on an in vivo study that estimated the biomechanics of the ONH by segmenting the tissues and computing the deformations of the ONH in control subjects and in patients who had undergone filtering surgery. The investigators found large reductions in strains in certain patients.
“The ability to interrogate the ONH and the mechanical strains in this tissue is slowly being translated to a clinical environment,” Dr. Ethier. “This will help us understand what is happening biomechanically in glaucoma in the ONH.”