Predicting scleral GP lens entrapped tear layer oxygen tensions

Area of Science:

• Ophthalmology
• Biomedical Engineering
• Corneal Physiology

Background:

• Scleral gas permeable (GP) contact lenses are increasingly used for corneal and tear conditions.
• Oxygen delivery to the cornea under contact lenses is a critical concern.

Purpose of the Study:

• To apply an existing oxygen resistance model to scleral GP lens systems.
• To evaluate oxygen tension in the tear layer beneath scleral lenses.

Main Methods:

• Utilized a computer spreadsheet model simulating oxygen resistance in series.
• Calculated theoretical oxygen tensions for tear layers under scleral lenses.

Main Results:

• Only optimal scleral GP lens parameters (thickness, Dk, tear layer) achieved sufficient tear oxygen tension (>100 mmHg).
• Corneal hypoxia may occur with current scleral GP lens designs and fittings.

Conclusions:

• Clinicians should select scleral GP lenses with the highest available Dk materials.
• Minimizing excessive corneal clearance in scleral lens fitting is crucial to prevent anterior segment hypoxia.