What question did this study set out to answer?

This research aims to explore the causes of corneal swelling during sleep in wearers of extended contact lenses, focusing on osmotic factors and oxygen availability.

March 21, 2026

The Osmotic Component of Swelling under Extended Wear Soft Contact Lenses

Key Points

This research aims to explore the causes of corneal swelling during sleep in wearers of extended contact lenses, focusing on osmotic factors and oxygen availability.
Measured corneal swelling in human subjects wearing extended wear contact lenses during sleep.
Compared swelling levels to normal corneal swelling experienced with regular lens wear and no lenses.
Analyzed the effects of oxygen tension on corneal health under contact lens wear.
Normal corneal swelling during sleep is approximately 3%.
Extended wear contact lenses contribute an additional 6-8% swelling due to low oxygen levels.
Total swelling upon waking in contact lens wearers is 8-12%.

Abstract

Abstract Swelling of the cornea during sleep when wearing an extended wear contact lens has an osmotic and hypoxic component. The normal swelling of the cornea during sleep, caused by the change from hypertonic tears of the open eye to the isotonic tears of the closed eye, is about 3%. Under an extended‐wear contact lens, there is an additional 6 to 8% swelling of the cornea in the closed eye because the cornea under the contact lens is at an oxygen tension substantially below that present in the palpebral conjunctiva. Data on human subjects wearing extended wear contact lenses are consistent with this allocation of the 8 to 12% total corneal swelling observed upon awakening.

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