Disorders from contact len wear
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It is estimated, that in the U.S. 6% of the 33 million contact lens wearers experience contact lens related eye disorders. They are a major challenge since these disorders can affect the eye and/or aggravate pre-existing eye disorders.

Causes

Problems that arise from using contact lenses can be caused by, the lens care system used, contact lens material, lens damage, the durability and spoilage characteristics of the lenses, and patient related factors.

Another category of causes of contact lens related eye disorders involves exacerbation of pre-existing eye conditions. Conditions including allergies, dry eyes, blepharitis and eyelid abnormalities can be made worse by contact lens wear. These disorders should be distinguished from disorders directly caused by contact lens wear.

Contact related disorders

Spoilage: Spoilage affects mostly soft and therapeutic contacts. The causes are tear chemistry, inappropriate lens cleaning methods, lens material and environmental contaminates. Spoilage causes poor visual quality, poor wetting of lenses, poor fit due to changed eye parameters, irritation, deposits, and reduced oxygen permeability through the lenses to the eye. The more severe disorders include eye inflammation and allergy.

Deposits: Deposits on contact lenses are formed from tears. Rubbing of these deposits against the eye surface causes inflammation and allergies. Environmental contaminates like oils, dust and smoke can also form deposits. The deposits form a filmy coating. Proper cleaning regimen is needed to remove deposits. Wearing daily wear 2-week disposables may reduce deposits. In severe cases, change over to RGP lenses is recommended.

Warpage: Warpage refers to basic changes in the original fitting parameters. Warpage is commonly caused by excessive squeezing by the fingers while cleaning, and exposure to excessive heat. Warped lens can cause warped cornea, inducing irregular astigmatism. Warpage can also lead to poor vision and spectacle blur. Corneal warpage occurs more with PMMA lenses. It takes days to months to resolve the corneal warpage.

Damage: Damages, like tears, cracks and chips in the lenses are caused during manufacture or handling by the wearer. Damages cause causing eye irritation. Depending on the location of the damage, the patient may or may not have symptoms. The common symptoms are foreign body sensation, tearing and blurred vision. On examination conjunctival injection, superficial punctuate keratitis and corneal defects are usually seen. Sometimes bacteria enter the cracks on the lens, causing infection. Treatment includes discarding the old lens and improved lens handling. Lubrication is advised if the corneal epithelium has been damaged.

Pre-existing conditions

Allergic conjunctivitis is the most common pre-existing factor causing eye disorders. Both seasonal and perennial allergens are the causes. Symptoms include itching, tearing, burning, swollen lids and pressure around the eyes. Wearing of contacts may increase contact lens intolerance. Lens wear therefore should be restricted. Treatment includes, firstly, removal of the offending agent. Artificial tear preparations, vasoconstrictors or antihistamines may be used to reduce the symptoms. Combination antihistamines – mast cell stabilizers are very effective and additionally allow continuous use of the contacts. In severe cases, lens wear should be discontinued totally, until the symptoms subside.

Vernal keratoconjunctivitis is a recurrent condition occurring in young people between 5 to 20 years of age. It may be seasonal or perennial. Symptoms include itching, irritation, redness, light sensitivity and blurred vision. Some affected people have limbal thickening and giant papillae. The cornea can show epithelial damage or a shield ulcer among other possible problems. Treatment includes use of topical antihistamines, vasoconstrictors and mast cell stabilizers. In severe cases, topical steroids are used to get a rapid response. Topical mast cell stabilizers with steroids reduce the amount of steroids needed. Since it is a recurrent childhood condition steroid use must be restricted. The condition resolves on reaching adulthood and the patient can resume wearing contacts.

Atopic conjunctivitis is seen with atopic dermatitis. It develops during childhood, in the teens or in the early 20s and peaks between ages of 30 and 50. Symptoms include tearing, itching, light sensitivity and sometimes lid swelling. Cornea shows keratitis, vascularization and opacity. Treatment includes quick tapering doses of oral steroids. It is the most severe form of eye allergy and its cure is uncertain. The patient, therefore, should not be allowed to wear cosmetic contacts.

Blepharitis is a chronic, long lasting eyelid inflammation involving eyelashes and oil glands. It can also lead to contamination of the contact lens surface by pathogens (bacteria). Symptoms include itching, burning and irritation. Treatment includes good eye hygiene, eyelid cleaning and use of antibiotics. Blepharitis affected patients may wear cosmetic contacts but these should be discarded if the symptoms are severe.

Dry eyes are due to reduced tear production which leads to many eye surface problems. Hormonal changes, oral medications and systemic diseases can affect the severity of the condition. Symptoms include burning, tearing (counter intuitive but true), foreign body sensations, and blurred vision. Dry eyes may lead to contact lens intolerance. Patients with severe dry eye should not wear contacts.

 
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