Modeling Corneal Oxygen with Scleral Gas Permeable Lens Wear

Area of Science:

• Ophthalmology
• Biomedical Engineering
• Corneal Physiology

Background:

• Scleral gas permeable (GP) contact lenses are used to correct various refractive errors and ocular surface diseases.
• Ensuring adequate oxygen supply to the anterior cornea is crucial for maintaining ocular health during contact lens wear.

Purpose of the Study:

• To provide theoretical guidelines for clinicians to optimize anterior corneal oxygen supply in patients wearing scleral GP contact lenses.
• To develop an updated computational model for predicting oxygen tension at the anterior corneal surface.

Main Methods:

• A computational model was developed incorporating variable corneal oxygen consumption using Monod equations.
• The model predicts oxygen tension and flux profiles through the lens, tear film, and cornea under various boundary conditions.
• Tear exchange with the scleral lenses was modeled as nonexistent.

Main Results:

• Most current scleral GP lenses may induce corneal hypoxia under open eye conditions.
• Only lenses with very thin tear vaults are predicted to maintain anterior corneal oxygen tension above 100 mmHg.
• Corneal oxygen tension and flux are more sensitive to tear vault thickness than lens oxygen permeability.

Conclusions:

• Clinicians should consider prescribing scleral GP lenses with higher oxygen permeability.
• Fitting scleral GP lenses with minimal corneal clearance is advisable to enhance oxygen supply.