This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. To understand human presbyopia by studying the dynamics of accommodation and presbyopia in nonhuman primates. Nonhuman primates are the preferred model for human presbyopia, the loss of ability to focus with age. We determined real-time dynamics of the intraocular structure involved in accommodation during midbrain stimulation. These studies generated new information about the mechanisms of accommodation. Centrally stimulated maximum accommodative amplitude declined significantly with age, suggesting that such stimulation is valid for studying accommodation and presbyopia. Lens centripetal movement decreased with age, possibly due to a loss of forward CM movement, which was more pronounced than the loss of centripetal CM movement. Following extraction of the lens substance, movement of the ciliary processes (CP) and capsule in response to stimulation increased. The older capsule movement was still sufficient to induce ~6 to 10 diopters of accommodation, assuming a lens of the same characteristics as the normal young or middle-aged crystalline lens. But when the lens capsule was also removed, CP movement amplitude decreased. Older CP can move over and above that necessary to induce maximum accommodation but the lens cannot. Surgical procedures to disturb the lens-zonule complex can be used as probes to determine the normal function and age-related changes of the accommodative apparatus. Whether the older capsule has the ability to mold an accommodating intraocular lens (IOL) would depend on the characteristics of the IOL and how much force the capsule can exert. Accommodating IOLs may be more effective in restoring accommodation in the presbyopic eye if they rely on centripetal CB and thereby centripetal capsular movement rather than forward CB movement. This research used WNPRC Research Services.
Showing the most recent 10 out of 528 publications
