Is contact lens "T" still important?

Area of Science:

• Ophthalmology
• Biomaterials Science
• Optometry

Background:

• Contact lenses can alter oxygen supply to the cornea.
• Understanding oxygen diffusion through contact lenses is crucial for ocular health.
• Silicone hydrogel lenses are designed for improved oxygen permeability compared to traditional hydrogels.

Purpose of the Study:

• To investigate the impact of variable contact lens thickness on oxygen supply to the cornea.
• To calculate oxygen tension and flux through different silicone hydrogel and hydrogel contact lenses.
• To assess the influence of lens design and material on corneal oxygenation under open- and closed-eye conditions.

Main Methods:

• Complex calculation methods were employed to model oxygen supply.
• Lens thicknesses were measured centrally and peripherally for various optical powers.
• Oxygen tension and flux were calculated using measured thicknesses and material oxygen permeabilities.
• Simulations were performed for both open- and closed-eye conditions.

Main Results:

• Variable thicknesses of silicone hydrogel contact lenses did not significantly affect oxygen tension in the tear layer under open-eye conditions.
• The high oxygen diffusion coefficients of silicone hydrogel lenses are the primary factor in maintaining oxygen levels.
• Minimal impact on oxygen tension was observed even under closed-eye conditions with varying thicknesses.

Conclusions:

• Silicone hydrogel contact lenses maintain adequate oxygen supply to the cornea, largely independent of thickness variations.
• The inherent high oxygen permeability of silicone hydrogel materials is key to their effectiveness.
• These findings support the suitability of silicone hydrogel contact lenses for maintaining corneal health.