Contact Lens Complications

Serious Corneal Complications Associated with Contact Lenses

The most serious contact lens complication is a central corneal ulcer.  A corneal ulcer involves a bacterial infection of the eye in which the bacterium penetrates the protective outer layer of the eye (the epithelium).  Few bacteria can penetrate an intact epithelium but when this happens the bacteria can enter the the interior of the cornea (stroma), producing a crater, like a pot hole, in the cornea.  This produces scarring and therefore vision loss.  


corneal-ulcer


This is a stock image and not one of my patients.  It looks fungal to me.

Notice with whips strands emanating from the central lesion. This patient will have permanent vision loss.


Rarely, the bacteria manages to eat all the way through and into the eye; when this happens, it’s usual all over.  You’ve lost an eye.  As of this writing, in all my years as a eye doctor, every corneal ulcer I’ve seen, except for one, (and by the way, a corneal ulcer can’t be missed) occurred with the patients wearing contact lenses.  So this brings up some obvious questions.  What can be done to reduce the risk of getting this severe, vision threatening disease?  And, do some brands of contacts afford increased safety for ulcers?  The most basic answer is to not wear contacts at all, but that’s no fun.  So what else can be done?  Answer:  Don’t sleep in your contacts.  Or if you do, don’t sleep in them often.  Studies show a direct relationship between the number of consecutive days of wearing contacts and the risk of an ulcer.  So removing nightly is best, weekly is a little riskier and monthly is even more risky.  Wearing your contacts non stop for more than a month is quite frankly kinda nutty.  Many people do it and don’t get ulcers, but it’s risky.  Complicating all this is the fact that there are two brands of contact lenses approved by the FDA for 30 day continuous wear.  These are the Ciba Air Optix Night and Day and the Baush and Lomb Purevision.  These are made from a class of contact lens material called a silicone hydrogels.  Silicone hydrogels provide 5 or 6 times the oxygen to the cornea that the older materials do.  Both these contacts are excellent contacts; with the added oxygen, there is less redness of and eye and reduced or no corneal swelling.  They’re great lenses, but: they don’t reduce the risk for corneal ulcers.  And the reason they do not I suppose is that corneal ulcers are not caused by lack of oxygen.  So the main point here is that one should not be lulled into believing that just because the contact lens is FDA approved, that it’s perfectly safe, because it’s not.  Of course many, many of my patients sleep in their contact, and that’s fine.  It’s just safer if they didn’t.  So the answer is regardless of brand of contact lens, to lower risk, don't sleep in your contacts

Another type of ulcer is called a marginal ulcer.  This ulcer is located close to the edge of the cornea and therefore has less risk of permanent vision loss.  The way this works is this:  We all have staph bacteria growing on us, and this “normal flora” secretes toxins.  The toxins get trapped under the contact lens and or gets stuck to the contact lens and are held against the cornea.  This causes an immune response which causes white, inflammatory cells to migrate into the cornea where they coalesce  and produce a white dot.  The white dot represents millions of white cells so many that they can be seen with the naked eye.  The problem is white cells, when angered, secrete digestive enzymes which literally digest the cornea.  So the white inflammatory cells are fighting something which really isn’t there.  Treatment is a combination of antibiotics and topical steroids.  Although usually not vision threatening, the condition is painful and is no fun.  If this happens, you are doing something wrong.  Remove your contacts at night.  Use a disinfectant solution.  Use good hygiene and throw away your contacts according to your doctor’s instructions.

                            <<<<<<<  WASH BY RUBBING YOUR CONTACT LENS CASE ONCE A WEEK >>>>>>>

Why wash your case?  It looks clean?  Well, it turns out that bacteria can produce a “biofilm”.  Essentially, the bacteria produce a shield-like film under which the bacteria live.  The biofilm reduces the amount of disinfectant solution reaching the bacteria underneath.  So even though the case looks clean, it still has bacteria in it.  A study used a blue stain which stains bacteria.   The stain was applied to a new case: case remains white.  Then the stain was applied one month out: it was pale blue.  Then the stain was  applied to a case 3 months out; it was noticably blue.  Then again at 6 months out; the case looked like it was painted with blue.  The images were striking.  This might explain why some of my contact lens patients seem to be prone to infections.  Washing your case by rubbing it will strip off the biofilm, reducing the risk of infection.   


© Richard Randolph 2012