Contact Lens Overwear Syndrome (also known as contact lens-induced acute red eye, CLARE, or tight lens syndrome) is the result of patients over-extending their contact lens wearing time or by wearing their contact lenses in a closed eye environment (during sleep.) It is most common in people that wear non-gas permeable contact lenses, but can occur with any lens type.
When contact lenses are worn for an extended time they can significantly reduce the amount of oxygen reaching the eye. The amount of reduction is based on a combination of how much the lens can move, how thick it is, how oxygen permeable it is, and how they are worn.
Some symptoms of lens overwear are ocular pain and redness, tearing, decreased vision, and photophobia (light sensitivity). If the contact lens is still being worn or cannot be removed by the individual during an exam, it will show that the lens is “stuck” and unable to rotate normally. Often people will find it difficult to realize that they have worn their contact lenses too long since the corneal abrasions are masked by the decreased sensitivity brought on by oxygen deprivation.
Additionally, poor hygiene can cause lens overwear. Sleeping in daily wear only lenses or wearing lenses all night can lead to complications that are often ignored until there is an infection or signs of hypoxia (decreased oxygen). Some people wear their lenses for too long to avoid buying news ones and end up with significantly blurred vision or red, irritated eyes. When contact lenses are worn too long or not cleaned well deposits can reduce the oxygen permeability of the lenses and lead to overwear syndrome.
To resolve this issue, the patient should discontinue contact lens wear temporarily, and the doctor should determine the degree of inflammation. Sodium fluorescein staining is used to reveal areas where the epithelium has been compromised and to rule out ulceration. Topical antibiotics or steroids may be prescribed to help alleviate symptoms.
After the eye heals, contact lens use can begin again although there should be a refitting for daily lenses and reeducation of lens care guidelines. Studies do show that long-term contact lens wear as well as a previous case of CLARE increases the risk for contact lens overwear syndrome.
Long-term changes due to oxygen deprivation can include abnormal blood vessel growing in the cornea, abnormalities of endothelial cell size and shape, microcysts, corneal thinning, and reduced corneal sensitivity. This may lead to corneal exhaustion syndrome and contact lens intolerance.
To prevent contact lens overwear and the secondary complications, contact lens use should begin gradually, even if your lenses are comfortable the first day. Even the most advanced silicone hydrogel lenses cannot prevent contact lens overwear syndrome if they are not used in the proper way.