Related Experiment Video
Updated: Dec 3, 2025
08:42
Monocular Visual Deprivation and Ocular Dominance Plasticity Measurement in the Mouse Primary Visual Cortex
Published on: February 8, 2020
10.9K
Ocular Surface Potential Difference Measured in Human Subjects to Study Ocular Surface Ion Transport
Neel D Pasricha1, Alex J Smith1,2, Marc H Levin3
1Department of Ophthalmology, University of California San Francisco, San Francisco, CA, USA.
Translational Vision Science & Technology
|October 29, 2020
Summary
Ocular surface potential difference (OSPD) measurement in humans is feasible and safe, revealing significant cystic fibrosis transmembrane conductance regulator (CFTR) activity. This new method can assess ocular surface health and test treatments for eye disorders.
Area of Science:
- Ophthalmology
- Physiology
- Biophysics
Background:
- The ocular surface epithelium, including corneal and conjunctival epithelia, expresses key ion channels: cystic fibrosis transmembrane conductance regulator (CFTR) and epithelial sodium channel (ENaC).
- Understanding ion transport at the ocular surface is crucial for maintaining ocular surface homeostasis and function.
Purpose of the Study:
- To establish a methodology for measuring ocular surface potential difference (OSPD) in human subjects.
- To assess the feasibility, safety, and utility of OSPD measurement for evaluating ocular surface ion transport.
Main Methods:
- OSPD was measured in human subjects using a fluid-filled electrode contacting the ocular surface and a subcutaneous reference electrode.
- A high-impedance voltmeter recorded OSPD continuously during perfusate fluid exchanges, including the application of ENaC inhibitor amiloride and CFTR activator isoproterenol.
Main Results:
- Baseline OSPD in normal subjects was -21.3 ± 3.6 mV.
- Amiloride caused a small depolarization, while zero chloride solution and isoproterenol induced significant hyperpolarization, indicating robust CFTR activity.
- Isoproterenol-induced hyperpolarization was absent in cystic fibrosis subjects, confirming the role of functional CFTR.
Conclusions:
- OSPD measurement is a feasible and safe technique for assessing ocular surface ion transport in humans.
- The study demonstrates significant CFTR activity and minimal ENaC activity at the ocular surface.
- OSPD measurement offers a novel approach for investigating ocular surface fluid transport and evaluating therapeutic interventions for ocular surface diseases.
