Barry A Weissman, O.D., Ph.D., is Professor of Ophthalmology and Chief, Contact Lens Service, Jules Stein Eye Institute, and Department of Ophthalmology, David Geffen School of Medicine at UCLA, and Adjunct Professor of Optometry, Southern California College of Optometry. Fullerton CA.

Though contact lenses have technically been around for over a century, their explosion in popularity really began about 50 years ago. In the 1950s, all contacts were "hard" lenses, and made from an impermeable material called polymethylmethacrylate (PMMA). Contact lens wearers at the time had relatively few associated eye conditions, and these included problems with fit and comfort, conjunctivae ("red" eyes), corneal abrasion and edema (swelling), and serious dry eyes. Infections sometimes occurred, but this was less common. How well a person tolerated the contact lenses was, back then, basically determined by how comfortable the lenses were, rather than by more objective physiological measurements that are possible today.

The eyes tend to change somewhat over time, so it’s a wonder that most contact lens wearers wear their contacts for many years without any issues at all.

Soft contacts became immensely popular when they were introduced around 1970 because they were so much more comfortable and better tolerated than their earlier predecessors. But along with soft contacts came a host of complications, which we’ll discuss below. For example, bacterial infections became a concern when extended wear lenses became popular in the 1980s.

The Contact Lens "System": More than Meets the Eye

If you think about it, the entire contact lens "system" is actually quite complex. It includes not only the lenses themselves, but also the solution in which the contacts are rinsed, soaked, and disinfected. CL solutions vary in enzymes, pH, preservatives, and other additives, which adds more variables to the pot. The larger system also includes the outside environment, which can fluctuate widely in temperature, moisture, allergens, and pollution, and all of this has a big effect on how our contacts function.

Finally, the whole setup wouldn’t exist without the eyes themselves, which also tend to change somewhat over time. Given all these variables, it’s a wonder that most contact lens wearers wear their contacts for many years without any issues at all. There are, however, some problems that affect contact wearers from time to time, some more severe than others. This article will briefly outline those problems as well as their management and prevention.

Present Day Complications for Contact Wearers

Contact lens wearers rarely experience complications that would threaten their vision (an exception would be infection or other rare corneal conditions). But there are a variety of complications associated with wearing contact lenses.

About half of contact lens wearers have had complications that require treatment, according to one study, but only 1.5% of them actually showed symptoms. Most of the problems were due to inflammation and allergies; few were due to hypoxia (lack of oxygen getting to the eye). Another study found that the most common health concerns linked to wearing contact lenses were damaged corneas, eyelid reactions, allergic reactions, conjunctivitis, inflammation, and infection.

Some eye problems associated with contact lenses are simple, some are more complicated, and some are actually secondary to other issues, but still interfere with one’s ability to wear lenses comfortably. In what follows we cover some of the more common eye problems associated with wearing contact lenses are outlined, including what to look out for and how the issues are generally treated.

Complications Involving the Eyelids
Problems involving the eyelid may stem from issues with its follicles and glands, which can lead to painful styes or cysts, allergic responses (including reactions to one’s contact solution), and a condition known as "giant" or contact lens-induced papillary conjunctivitis (GPC). The conjunctiva is the membrane that covers the eyeball. This form of conjunctivitis is thought to be a result of dirt or debris on the contact lens or simply from mechanical irritation from the contact lens itself. Often patients will be unable to wear their contacts for a while and some may have a drooping eyelid; others may also have some mucus and inflammation.

About half of contact lens wearers have had complications that require treatment, according to one study, but only 1.5% of them actually showed symptoms.

Usually one’s doctor will advise his or her patient not to wear their contacts until all symptoms have gone away – and when one does begin to wear their contacts again, additional cleaning methods may be recommended (for instance, a peroxide-based product and/or enzymatic cleaner), as well as more frequent replacement of the lenses. Occasionally, when routine treatment doesn’t work, other methods like non-steroidal anti-inflammatory drugs (NSAIDs), antihistamines, or steroids (in rare instances) may be necessary.

Hypoxia: When the Eye Can’t "Breathe"
Until the introduction of rigid and soft contact lenses, corneal hypoxia (lack of oxygen to the cornea) was the most common problem for contact wearers. Hypoxia can cause a host of issues, most of which are beyond the scope of this article. One reaction, called "corneal exhaustion syndrome" occurs in people who have previously been able to wear contact lenses, but over time, their corneas do not seem to be able to tolerate lens wear anymore. The cause is not completely clear, but it’s thought that over time contacts can lead to damage that prevents the eye from regulating a healthy moisture level. Making changes to the type of lens one wears (i.e., using lenses that allow for more oxygen flow and are changed more frequently) may allow one to tolerate contact lenses again.

Inflammation in the Eye Can Damage the Cornea
As mentioned above, over time the cells of cornea can become damaged with contact lens wear. Doctors can diagnose corneal damage with a special stain called sodium fluoroscein dye, and refer to the condition as superficial punctuate staining (SPS). Causes of SPS include dryness, chemical or allergic reactions, trauma to the eye (for example, damage can occur from wearing cracked or chipped lenses or from tiny particles of dirt being trapped between the lens and the cornea). The most common problems with contact lenses come from toxicity, allergy (including reactions to contact lens solutions), and soilage or dirty lenses.

People suffering from SPS can have a variety of symptoms, but most often complain of irritation, itching, and dryness of the eye, although some people have no symptoms at all. Patients with SPS are generally instructed to stop wearing their lenses for some time, and to use artificial tears to lubricate the eyes, NSAIDs and/or antihistamine drops, and in more severe cases topical steroids are prescribed.

The most common problems with contact lenses come from toxicity, allergy (including reactions to contact lens solutions), and soilage or dirty lenses.

Long-term management of SPS includes rethinking the type of contacts the patient wears (i.e., switching to daily disposables to avoid potential problems with solutions), or cleaning the lenses with peroxide, or, in the case of rigid contact lenses, rinsing the lenses with preservative-free sterile, saline solution before putting them in the eye.

Sometimes contact lens solution reactions can lead to devastating destruction of certain cells in the cornea. Patients may complain of irritation in the eye, and the doctor may actually observe a little flap of tissue (called a pannus) in the cornea. Treatment for this kind of damage generally involves discontinuing use of contact lenses for a period of time, although a stem cell transplantation procedure may also be necessary under special circumstances.

Of course, dirt, debris, and general damage to the lenses (cracks, scratches, and chips) can also result in inflammation. Soft contact lenses are now usually "disposable" (1-day, 2-week, 1-month or 3-month) and are therefore often replaced before they rack up enough damage to cause any real problems. Rigid contact lenses can sometimes be reconditioned by polishing and cleaning but eventually they become warped, scratched or soiled and should be replaced.

A condition known as contact lens acute red eyes (CLARE) generally occurs during extended wear. These reactions are believed to be due to bacterial contamination of the contact lens, or possibly of the contact solution and/or contact lens case, which could introduce bacterial toxins into the eye. The first method of treatment is typically palliative (to reduce a person’s symptoms as much as possible). Generally, better contact lens care and hygiene – and discontinuing extended wear – should take care of CLARE.

When the Cornea Tears: Corneal Abrasion
A corneal tear, known as corneal abrasion, is a painful and unpleasant occurrence. It is important that your doctor makes sure that infection has not, and does not, set in. Of course it is also necessary to manage the symptoms (which is primarily pain). Abrasion can be due to defects in the contact lens (chips and cracks), flat-fitting lenses, tight edges, and foreign bodies being trapped under the lens.

A person with a corneal tear should temporarily discontinue wearing their contacts to help the healing process. Some doctors may prescribe prophylactic antibiotics, while others may hold off on them unless infection becomes apparent. As enticing as they may be, eye patches are typically not used, since they can also enhance certain types of infection. Oftentimes, hydrating the eye with artificial tears and close follow-ups with one’s doctor are necessary. It is also a good idea to figure out why the abrasion occurred in the first place, to prevent it from happening again.

When Microbes Move In; Microbial Corneal Infection

Why Corneal Infections Occur

A condition called microbial keratitis [MK] is a fancy term for corneal infection that can cause eye pain, photophobia (light sensitivity), "red" eye, discharge, and cause one feel as if a foreign body is in the eye. Lesions can occur, and certain types of lesion are more worrisome than others. The MK infection often occurs in one eye only, and is often due to extended wear.

Risk factors for corneal tears include sloppy contact lens care and hygiene (e.g., "topping off" rather than changing solutions in lens case, dirty cases, etc.), travel, smoking, being male (sorry, guys), being a young adult, and having a compromised immune system.

It is thought that about 20 people out of 10,000 who wear soft contacts worn for extended periods of time will develop MK, though this may be lower with daily-wear lenses, and is likely even lower with rigid contact lenses. Other risk factors include sloppy contact lens care and hygiene (e.g., "topping off" rather than changing solutions in lens case, dirty cases, etc.), travel, smoking, being male (sorry, guys), being a young adult, and having a compromised immune system. Swimming in fresh water and wearing lenses overnight also appear to be risk factors for certain types of infection.

Occasionally, overnight orthokeratology – a specialized treatment in which a specially-designed contact lens is used to reshape the surface of the cornea to reduce myopia – may be an additional risk factor for infection.

Treating and Managing Infection
Because MK can threaten one’s vision, doctors tend to treat it aggressively. Whenever any of the signs or symptoms of MK occur, a person should immediately stop wearing his or her contact lenses in both eyes to decrease the potential for the disease spreading from one eye to the other.

Sometimes doctors will use steroids in order to minimize scarring, but steroid use may actually make the infection more difficult to treat.

It is important for doctors to recognize the infection early. Sometimes doctors at larger facilities will obtain a sample of the lesion to culture; while doctors at smaller practices may just treat the suspected infection. Treatment often involves giving a heavy initial dose of antibiotics every fifteen minutes, and then tapering off. Rechecks with one’s doctor should be frequent, often at 24 hour intervals if not sooner.

Sometimes doctors will use steroids in order to minimize scarring, but steroid use may actually make the infection more difficult to treat. Further treatment will be determined depending on how the patient progresses and the specific type of infection, which may be caused by different types of microorganism (e.g., fungus, herpes, bacteria, etc.), each of which may need to be treated differently.

Adenoviruses and herpes can also cause corneal infections. Contact lenses themselves probably do not cause the infection. Patients with viral infections of the cornea should still discontinue wearing their contacts until after it has cleared up.

Contacts that have been used during corneal infections, particularly during the early stages, should probably be discarded, and, if contact use is continued, new contacts should only be worn once the infection is gone.

Although it is rare, the MK infection is still a major concern, and its management can be complex. Particularly bad infections may require aggressive medical treatment, including injections into the eye and/or systemic antibiotic treatment in the hospital. Corneal transplantation may be necessary under certain circumstances. Depending on the severity of the infection, patients may be referred to a corneal and external eye disease specialist.

The Best Bet: Stop Infections before They Start

The most effective way to tackle the (rare) complications of wearing contact lenses is to prevent them from occurring in the first place. Lack of oxygen to the eye, a.k.a. corneal hypoxia, is very rare these days. Restricting contact lens use to daily wear (removing lenses at night) certainly reduces the risk of bacterial infections, which are unpleasant and can be dangerous, and sometimes threaten one’s vision. Many complications can also be avoided by taking good care of one’s lenses and by practicing proper hygiene with them. The following tips may be useful to keep in mind:

  • While it may be tempting to wear lenses longer than is recommended, make sure to replace your contact lenses at the proper intervals.
  • Do not use tap water in any aspect of contact lens care.
  • Make sure to use fresh solution each time you rinse and store your lenses.
  • Clean your contact lens case daily with fresh soft lens preserved saline and let air dry, and discard it if it becomes soiled – or at least every three months – for a new one.
  • Follow both common sense and the manufacturer’s guidelines for proper contact lens care and use.

Finally, it is important to remember that most people rarely experience severe complications from wearing their contact lenses, and many find great optical – and cosmetic – advantages to wearing contacts. Still, it is important to go for regular check-ups so that asymptomatic problems can be diagnosed and treated in a timely manner. For conditions that do have symptoms, it’s equally important to see a doctor- if possible, within 12 hours of onset of the symptoms. Your doctor will not only treat any conditions that may develop along the way, but under normal circumstances he or she can also advise you about the best ways to care for your lenses, so that they will help your eyes stay healthy and happy for a long time to come.