Contact lenses (CLs) are used by millions of people and can result in problems with the corneas and also exacerbate previous problems. They alter the delivery of oxygen to the cornea, disturb the tear film and cause a degree of mechanical trauma. The associated problems may be related to the type of lens used, be they soft, rigid or gas permeable, and may vary from a reduction in vision from oxygen deprivation through to visual loss from infection problems.
If your eye becomes red, feels uncomfortable or the eyesight deteriorates, remove the contact lens and do not re-insert it until the problems have settled. If the problems do not resolve quickly seek professional attention promptly – some CL related problems can have a serious impact on the eyesight.
Patient related factors which predispose to CL problems include;
- Dry eyes
- Blepharitis
- Allergic conjunctivitis
- Smoking
- Immunosuppression
Issues related to the use and handling of CLs include;
- Failing to clean non-disposable lenses properly
- Failing to use fresh storage solution
- Overlong use of a lens – for example wearing lenses overnight
Lens related problems include;
- Poor fitting lenses – overly tightly applied to the cornea or excessively mobile
- The use of damaged lenses or those with protein and lipid deposits on their surface
- The use of a cleaning or storage solution to which a person has developed allegy – particularly applies to Thiomersal
Contact Lens related problems include;
- Conjunctival problems
- Allergy to CL solutions – particularly thiomersal
- Giant Papillary Conjunctivitis – this is a chronic inflammation of the conjunctival lining of the upper eyelid resulting in fleshy masses beneath the lid contributed to by;
- An immune response to altered proteins on the CLs
- Mechanical trauma to the tissue by the edges of the lenses
- Toxic Conjunctivitis
- A response to cleaning solutions or other chemicals which get into the tear film with CL handling – e.g. hand cream or perfume
- Corneal Problems
- Superficial Punctate Keratitis (SPK) – in this condition the eyes become irritable and there are tiny areas of disturbance of the lining of the corneas , particularly in the lower half of the cornea. This problem can be contributed to by multiple factors including;
- Dryness of the eyes
- Environmental irritants – smoke, dust
- Oral medications which disturb the tear film such as antihistamines and diuretics
- Mechanical Injury
- When inserting and removing lenses
- From damaged lenses
- From accumulated debris on the lens surfaces
- Overly tight lenses
- Corneal Oxygen Deprivation – this can cause swelling of the cornea and result in blurring of the vision and a breakdown of the lining of the cornea which can cause ulceration. If it is a chronic problem, blood vessels may grow into the cornea and the cornea may become scarred.
- Contact Lens Associated Immune Keratitis or CL-induced red eye (CLARE) – is a condition in which the body becomes sensitised to endotoxins from bacteria resulting in an immune mediated inflammation of the cornea which can disturb the corneal lining and also result in inflammatory infitrates forming. In severe cases swelling and ulceration of the cornea may occur.
- Microbial Keratitis – this is the most serious problem associated with CL use and may result in impaired vision.
- Micro-trauma from the CLs breach the natural protection of the cornea and allows organisms to enter the tissue.
- Many different organisms can cause microbial keratitis including;
- Bacteria
- Acanthomoeba (a soil organism which typically enters the eye when swimming at natural hot pools)
- Although viral infections such as Herpes Simplex may occur in CL wearers these are not a direct consequence of CL use
- Superficial Punctate Keratitis (SPK) – in this condition the eyes become irritable and there are tiny areas of disturbance of the lining of the corneas , particularly in the lower half of the cornea. This problem can be contributed to by multiple factors including;