Intraoperative Endocapsular Hyperthermia to Prevent Lens Epithelium Proliferation

Abstract

Purpose:: To evaluate the feasibility of lens epithelial cells (LEC) kill by hyperthermia using a handheld thermal probe during cataract surgery.

Methods:: The instrument consists of a 1mm diameter (19ga) thermal probe delivering 1.125W of power in the capsule (Orozco, ARVO 2006). 14 pairs of healthy NZW rabbit eyes were treated immediately after euthanasia and enucleation. The procedure consists of the steps normally performed during cataract surgery with the addition of a heat treatment after nucleus and cortex removal. The capsular bag is refilled with a viscoelastic (SHA, Corneal SA, France) to prevent collapse of the capsular walls and the probe and 3 thermocouples (TC) are inserted in the bag to monitor temperature increase at the anterior, equator, and posterior capsule locations. To prevent capsule shrinkage, the maximum temperature was set at 50oC at any locations creating a 41 to 50oC treatment window. 28 lens capsules were treated at different energy levels (47 to 945Joules) and a live/dead assay was used to assess treatment efficacy at day 0, 1, 3, 5, and 7.

Results:: The best response in cell kill (<0.01) was obtained with energies of ~ 0.5 to 1KJ. The difficulty in positioning the thermocouples with precision caused temperature errors leading to variations in cell kill. Improvements in the set-up and additional experiments are underway.

Conclusions:: Hyperthermia of the lens capsule is feasible.

Keywords: cataract • cell survival • posterior capsular opacification (PCO)