Surgical approach for the implantation of a capsular ring electrode into the posterior chamber

Abstract

Purpose : We evaluated the feasibility of the implantation of a bipolar capsular ring electrode into the sulcus of the anterior chamber of a phakic non-human primate. The sensor is supposed to measure electric potentials of the ciliary muscle. The measurements of these potentials during the accommodation process might ultimately lead to the development of biomimetic artificial intraocular lenses for presbyopia correction.

Methods : The implant consists of a microcontroller, a biopotential amplifier, and a Bluetooth transmitter on a flexible circuit board (12x18 mm), a button-cell battery, and the capsular ring electrode (Ø 10 mm). After a 180-degree limbal conjunctival peritomy in the superior half circumference, mobilization and placement of traction sutures under the rectus superior, lateral and medial rectus muscles, the chip was positioned under the superior rectus muscle. The attached battery was pushed posteriorly behind the globe in the superior temporal quadrant. After installation of viscoelastic agent (OVD) the circular sensor probe was pushed into the anterior chamber via a clear cornea tunnel incision of approx. 3 mm in the upper temporal quadrant. The electrode was carefully advanced under the dilated iris with two forceps to prevent tilting and damaging the anterior capsule. The ring sensor was placed underneath the iris above the anterior capsule and the ciliary muscle. The anterior chamber was stabilized with a corneal tunnel suture allowing the adjacent cable to exit the chamber towards the chip. Before the surgery was performed on a live animal, it was tested in 4 eyes of two deceased phakic primates.

Results : During the implantation tests, in two eyes the ring electrode broke during the advancement into the posterior chamber underneath the iris. After optimizing the process, the device was successfully implanted in one eye of the living phakic primate and electrical potentials were successfully recorded after the animal woke up from anesthesia. A mild inflammatory response was visible during the follow up-period. Radiography showed a correct positioning of electrode, chip and battery.

Conclusions : The primate model demonstrates the feasibility of the surgical implantation of a circular electrode into the posterior chamber. With regard to future developments of biomimetic accommodative IOLs a concomitant improvement of surgical techniques is crucial to ensure treatment success.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.