Artificial Orbit System for Experimental Surgery With Enucleated Globes

Abstract

A portable system for holding, accurately positioning, and restoring the physiologic integrity of enucleated globes during experimental anterior segment procedures and pars plana vitrectomy is described. A 0 to 500-mm Hg vacuum fixation ring and positioning apparatus mechanically locks globes into known spatial position while they are supported in a 2 to 6-mm Hg pressurized, pliable socket designed to match the size and pressure of a natural orbit. A gravity infusion system and an implantable piezoelectric pressure sensor in conjunction with a syringe and stopcock assembly allow for controlled inflation of globes to intraocular pressure OOP) levels from 0 to 70 mm Hg, and to over 300 mm Hg. The fixation vacuum level, and intraocular and extraocular pressures are simultaneously monitored on 3-digit LED displays, and permanent records of each can be generated by routing data to storage devices. The anterior segment remains accessible at all times for surgical procedures and diagnostic measurements. The entire system is portable, allowing globes to be transported to multiple experimental stations, while all pressure settings and the position of the globe are maintained. To demonstrate applications of the artificial orbit system, we describe experiments using it to calibrate applanation tonometers, and to study the relationship between IOP and corneal curvature as well as the effect of trephination procedures and limbal vacuum fixation on IOP.