Eye Care Centre
Contact Lenses
CONTACT LENSES AND CONTACT LENS PROBLEMS
Professor Trevor R Carmichael
Head: Department of Ophthalmology
University of the Witwatersrand
It is estimated that nearly 10% of people in North America (24 million people) wear contact lenses. In South Africa it is likely to be less common than this since short sightedness (myopia) is commonest in Caucasians (whites) and least common in Negroid (African) races. Contact lenses are mostly worn for myopia although hyperopia (far-sightedness) and astigmatism (abnormal curve of the cornea) can also be helped.
Many patients benefit from this remarkable development but about one in 20 may develop a problem with their contact lenses which may be mild or very severe and sight-threatening.
Signs of a problem with contact lenses may include redness of the eye, pain, watering of the eye and excessive sensitivity to sunlight. Vision might become cloudy or a sticky discharge develop. If these suddenly occur the patient should be seen by their ophthalmologist. Itching or occasional slight redness or irritation are of less concern but persistent problems, even of a minor nature, should not be ignored. If an acute problem develops the lesnes must be removed and advice sought.
Conjunctivitis ('pink eye') will cause a sticky discharge from a red eye and usually will indicate a bacterial infection. This will require antibiotic eye drops and removal of the contact lenses.
Giant papillary conjunctivitis (GPC) is an allergic type of conjunctivitis usually occurring with soft contact lens wear. Treatment is difficult and usually requires a reduction in the wearing time of the lens or a change to a different type of lens such as a hard contact lens. Steroid eye drops improve the condition but are not safe for long-term use and should only be prescribed by an ophthalmologist for use in contact lens patients. Avoidance of heat and chemical disinfection can also improve the condition so the use of disposable contact lenses can be helpful in GPC.
Another type of allergy is that related to the cleaning and soaking solutions. Thimerosal, one of the preservatives in the contact lens solutions, caused allergic reactions in as many as 10% of patients. It has been eliminated from most contact lens solutions because of this. Usually with allergy induced by the soaking solutions, the symptoms will be worst in the morning when the lenses are first inserted, with burning, discomfort and redness and the symptoms get somewhat better during the day.
Abrasions (scrapes) of the cornea can occur during contact lens insertion or removal and can be very painful. They will heal with antibiotic oitment and an eyepatch to keep the lid from scratching on the cornea while it is healing.
More ominous is corneal ulceration (keratitis) due to bacterial, fungal or amoebic infection.
Bacterial keratitis may be very rapidly progressive and cause loss of vision. Fungal keratitis is rare in South Africa except in the hot humid conditions found in Kwazulu-Natal.
Keratitis generally has been shown to occur more commonly with extended wear of contact lenses and an poses an even greater risk if people sleep with the lenses in. Patients with keratitis typically present with an acute onset of pain, watering of the eye, sensitivity to sunlight and a sticky discharge. Pain is most severe in patients with keratitis caused by Acanthamoeba which is a free-living amoeba found in tap water. For this reason only sterile saline (salt water solution specially made for the purpose) should be used to wash contact lenses and never tap water.
Contact lenses have radically changed the lives of millions of people for the better but it is wise to be aware of the potential problems that might arise. Seek help from your ophthalmologist should any acute problem develop.
