# A Novel Technique for Corneal Transepithelial Electrical Resistance Measurement in Mice

## TL;DR

This paper introduces a new method to measure corneal electrical resistance in mice, which helps assess the toxicity of eye drops.

## Contribution

The study presents a novel technique for measuring corneal transepithelial electrical resistance in mice.

## Key findings

- Exposure to 0.5% BAC significantly reduced corneal TER within 1 minute.
- TEM and IHC showed disrupted tight junctions and reduced ZO-1 staining in higher BAC concentrations.
- The developed technique enables precise evaluation of corneal toxicity in mice.

## Abstract

We developed a technique that can measure corneal transepithelial electrical resistance (TER) in mice, which was used for evaluating corneal toxicity induced by ophthalmic drugs. We used a tissue culture well and its insert to mount the mouse globe and separated the cornea from the rest of the globe to enable corneal TER measurements to be taken. The explanted mouse eyes were divided into groups, and the corneal epithelia were exposed to different concentrations of BAC. Half of these eyes were fixed for transmission electron microscopy (TEM) examination and the other for ZO-1 immunohistochemical (IHC) evaluation. After exposure to control, 0.1%, 0.2%, and 0.5% BAC, the TER was 100 ± 0%, 91 ± 14%, 83 ± 13%, and 34 ± 12% of the pre-exposure TER at 1 min, respectively, with a statistically significant decrease in the 0.5% group. After 3 min, the TER showed a statistically significant decrease in the 0.2% and 0.5% groups. The TEM examinations showed a loss of epithelial tight junctions between superficial cells in the 0.2% and 0.5% groups. The IHC examination showed decreased ZO-1 staining of the corneal epithelium of the same groups as compared to the control. To the best of our knowledge, we succeeded in developing an innovative technique for corneal TER measurement in mice.