Dr Moïse Tourabaly · Key points

The cornea breathes through the air

The cornea has no blood vessels: it draws much of its oxygen directly from the air, and its tears clean its surface continuously.

eyelid closed air lens tear film cornea: surface layer (barrier), then stroma O₂O₂O₂O₂O₂O₂ O₂O₂O₂ O₂ microbes trapped under the lens, weakened barrier

Eye open, no lens: oxygen from the air reaches the cornea through the tear film, and each blink renews these tears, which carry away debris and microbes.

A lens already reduces the oxygen supply during the day; blinking continues to renew the tears.

Eyelid closed and lens kept in: oxygen runs short (hypoxia) and the surface layer, which acts as a barrier, weakens; tears circulate less and clear debris and microbes less well, in a warm, moist environment. It is this combination that opens the way to infection of the cornea.

After a night in your lenses, take them out and seek care without delay in case of: Do not put a lens back in, and mention that you wear them.

Naps included, lenses come out before sleeping. Extended-wear lenses and orthokeratology require a specific prescription and follow-up, and do not remove this mechanism.

Educational diagram · Dr Moïse Tourabaly, ophthalmologist. It does not replace a consultation.