Ciliary muscle may play role in presbyopia

Dallas-The mechanism of accommodation remains a controversial subject. One preeminent explanation of presbyopia is that it is caused by an age-related decline in the magnitude of force that can be exerted by the ciliary muscle because of the normal equatorial lens growth. Ronald Schachar, MD, PhD, demonstrated why this is the case.

"The eye is small, so there has to be minimal displacement and minimal force that causes accommodation. The anterior lens surface steepens in the center, the peripheral surface flattens, and the central thickness increases with a large change in optical power," said Dr. Schachar, adjunct professor, Department of Physics, University of Texas, Arlington, and chief executive officer of Velatec.

He demonstrated with several examples how objects that have a profile similar to that of the human lens change in response to an application of an equatorial force.1

Central steepening