Contact lenses: microbial keratitis
They are more flattering than glasses in the aesthetic aspect, but far from being harmless to the health of the eyes. Wearing contact lenses requires some hygiene precautions. What are the most common risks and infections in the event of negligence?
When you wear contact lenses, you are placing a foreign object directly on your cornea. This, a true window to the eye, is made up of transparent cells: as they do not contain vessels, they extract much of the oxygen necessary for their metabolism from the ambient air.
Soft contact lenses, for daily use or frequently renewed, have significantly increased their level of oxygen permeability thanks to a new material, silicone hydrogel. They are now used as a first-line treatment and are better tolerated for dry eyes.
However, even the best performing lenses do not prevent deposits that slow the flow of oxygen and reduce your wearing comfort.
These deposits come mainly from tears that contain water, fats and proteins, and from outside with dust and makeup. Ultimately, the lack of oxygenation of corneal cells leads to their degradation, or even their destruction.
This loss can be irreversible for some cells that do not renew. Its function is to protect the cornea from germs that are naturally found in the eye. Most of its germs are harmless and adhere to lenses without consequences. Others, on the other hand, can enter through damaged cells and cause infections.
Risk of microbial keratitis
Wearing contact lenses in the shower can, according to a recent study, increase the risk of developing a painful infection by seven. To achieve this finding, British researchers studied the habits of 78 contact lens wearers to determine risk factors for developing microbial keratitis, an inflammation of the cornea. Among the participants, 37 had already developed this pathology. "Contact lenses for vision correction offer many benefits. However, microbial keratitis associated with contact lenses is a common cause of permanent visual impairment and some cases may even require a corneal transplant or result in loss of vision. of the eye ", alerted the ophthalmologist Parwez Hossain of the University of Southampton to the Telegraph.
Bath waters can contain germs or parasites.
For the same reason, it is strongly recommended that you remove your contact lenses when swimming in the sea, in a river, or in a pool. Because you are exposing your cornea to parasites and other germs present in dirty river water, pool water, and sea water. If you really ca not do without your swimming glasses, wear well-sealed swimming goggles with disposable contact lenses.
During sleep, the cornea is deprived of oxygen and therefore more vulnerable.
Leaving your lenses on to sleep is also not a good idea. The risk of microbial keratitis can triple, according to the British scientific team. The reason ? When you close your eyes while wearing glasses, even for a short nap, the cornea (front surface of the eye) can no longer receive the oxygen it needs. Thus deprived of oxygen, it becomes vulnerable to infections.
"Poor contact lens hygiene is a known contributor to infection, with 66% of complications attributed to poor hygiene practices and large variations in hygiene awareness and risk recognition among wearers.", the researcher summarized.
What to do if you suspect an infection?
"If you have redness or pain, you should remove your lenses. If this persists, see an ophthalmologist as soon as possible. This is the golden rule!" Explains Dr. Evelyne Le Blond.
The most common infections are:
keratitis (Acanthamoeba keratitis),
and contamination by fungi (due to a fungus) or linked to amoebae.
These complications can, without prompt treatment, cause the loss of some or all of your vision and ultimately lead to a corneal transplant.
How to limit the risk of infections?
"Poor handling and maintenance of lenses is responsible for 90% of infections," says Dr. Evelyne Le Blond, ophthalmologist.
Handle the lenses with clean, dry hands.
If you wear disposable lenses, the risk is lower because a new, sterile lens is placed in your eyes every day. However, if your hands are not clean and dry when handling them, the risk of infection is the same as with lenses that are changed frequently.
Wash and change the lens case regularly.
The lens case should be washed regularly with the cleaning solution and changed as often as possible.
The use of tap water is prohibited due to the presence of parasites such as amoebae that can adhere to the lens, become resistant cysts and cause severe keratitis.
Therefore, the cleaning solution allows the contact lenses to be decontaminated, avoiding the formation of protein or fat deposits that reduce vision and comfort with the lenses.
Wearing your contact lenses in the shower, when sleeping or bathing is not recommended
Keeping your contact lenses in while you shower and sleeping in them can increase your risk of developing an eye-damaging infection by a factor of seven.
In all cases, only strict compliance with hygiene and use conditions can limit the risk of contagion and enjoy all the benefits of contact lenses safely.