ACCOMMODATION OF AN ENDOCAPSULAR SILICONE LENS (PHACO-ERSATZ) IN THE AGING RHESUS-MONKEY

BACKGROUND: After accommodative changes of endocapsular silicone lense s in presenile nonhuman primates had been confirmed by several authors , this pilot study was designed to evaluate the ability of an artifici al lens to restore accommodation in the senile eye of a rhesus monkey that had previously lost most of its accommodative capability. METHODS : An injectable silicone lens was implanted in one eye of six rhesus m onkeys who were older than 17 years. Accommodation was documented as t he amount of decrease of anterior chamber depth after pilocarpine stim ulation. RESULTS: Four months after surgery, the decrease of anterior chamber depth was higher in the operated eye with the silicone intraoc ular lens in the two monkeys who had marked presbyopic changes in the natural lens. One monkey was kept for more than 4 years, retaining a d ecrease of at least 0.5 mm with the silicone lens, whereas the natural lens failed to show any accommodative change. CONCLUSIONS: These find ings support recent reports that presbyopia is primarily a consequence of lenticular aging rather than ciliary muscle factors. A pliable inj ected lens may therefore have the potential to restore accommodation i n the senile primate eye.