By Michael Hutton
Sleeping in contact lenses is frequently described by optical professionals as being inadvisable or even unsafe but for ortho-k lens wearers this is not the case. Indeed, ortho-k lenses which are a great new way to correct shortsightedness are designed to be worn only while sleeping and the special material used to manufacture the bespoke lenses has very high oxygen permeability. However, recent media coverage has focused on this issue again with The Mail On Sunday reporting the case of Katie Richardson who often forgot to remove her daytime lenses before going to sleep and exacerbated the problem by occasionally cleaning her lenses with tap water. When an initial irritation in her eye got progressively worse, she went to see her GP who immediately diagnosed microbial keratitis , a severe bacterial infection of the cornea.
The eye has natural protection against foreign bodies - through a fluid covering the eye that contains protective enzymes and by blinking which prevents anything sticking to the eye's surface. Yet minute air and waterborne microbes sometimes break through these defences, penetrating the protective layer of cells on the cornea. The bacteria pseudomonas is the most common microbe identified as the cause of keratitis, while the most dangerous is acanthamoeba, a single-cell organism found in tap water, particularly in hard-water areas, which breeds in dirty lens cases. Reusing lens cases for more than a month is dangerous since they are a breeding ground for bacteria. In reality, Katie's poor lens hygiene was the primary reason she developed such a severe eye infection rather than from sleeping in contact lenses alone.
Dr Simon Kilvington, a microbiologist from the University of Leicester told The Mail On Sunday: ‘Pseudomonas and acanthamoeba occur naturally in the environment, but particularly in bathrooms. Water storage tanks in the loft, used for flushing the toilet and sometimes feeding the cold tap in the bathroom, can be crawling with microscopic bugs. Rinsing or storing your lenses in tap water really can get you in a lot of trouble. In fact, bathrooms are not the best places to put in your contact lenses at all. And you should always use sterile lens-cleaning solution.' So poor lens hygiene is a key risk factor in bacterial infections of the eye and sleeping in contact lenses is only acceptable if the lenses - like ortho-k corrective contact lenses for shortsightedness - are designed to be worn this way.
Check if you are suitable for overnight ortho-k corrective contact lenses for shortsightedness.