Contact lens damage and consequences

 
Contact lens help
Lens fitting and care
Lens insertion and removal
Contact lens disinfection
Contact lens protein removal
Lens solution incompatibility
Contact lens history
Contact lens future
Contact lens glossary
 
Types of contact lens
Soft contact lenses
Hard contact lenses
Disposable contact lenses
Extended wear contact lenses
Bifocal contact lenses
Contact lenses for astigmatism
Therapeutic contact lenses
 
Contact lens problems
Contact lens dry eyes
Damage to lenses
Contact lens infections
Eyelid inflammation
Corneal complications
Contact lens conjunctivitis
Giant papillary conjunctivitis
Peripheral corneal infiltrates
 
Damage to Lenses

There are eye complications, which result from deteriorated contact lens quality. One reason for deterioration of lens quality is careless handling of lenses causing spoilage and damages. Quality deterioration could also result from natural wear and tear or natural ageing of contact lenses. The factors that affect lens quality are spoilage, deposits on the lens, warpage and damages.

Spoilage

Spoilage in contacts is due to factors such as tear chemistry, cleaning and disinfecting techniques, the contact lens material and contaminates in the environment. Spoilage is more common in soft contacts and therapeutic lenses than in RGP lenses.

Spoilage is of many kinds. These are organic, inorganic, mixed deposits, microbial contamination, contact lens defects and ageing of contact lenses.

Spoilage results in problems such as poor visual clarity due to loss of transparency, uneven surface and poor wetting of lenses leading to increased discomfort. Some other complications are poor fitting resulting from altered lens dimensions, eye problems due to lens deposit and reduced oxygen flow through the lens to the cornea. Serious situations arise when sometimes lens spoilage leads to eye inflammation and severe allergic reactions like the giant papillary conjunctivitis.

Lens deposits

The main constituents of lens deposits are proteins and lipids. These are natural and unavoidable deposits, which are formed on the lenses by the interaction of the tear proteins and the contact lens. The denatured protein, which constitutes most of the total protein deposits, clouds the lenses. Lipids are gland secretions which rub off on the contacts giving them a greasy appearance.

These deposits, rub against the eye causing eye complications. Deposits also change the fit, oxygen permeability, surface and edge quality of the contacts. They also make the lens tighter and interfere with tear flow. Furthermore, they reduce comfort, visual acuity and wearing time besides causing burning and irritation.

An interesting observation has been the incidence of less protein deposits and more lipid deposits in silicon-hydrogel lenses compared to disposable hydrogel lenses. The significance of this difference has eluded clinicians.

Environmental contaminants like dirt, dust, smoke, oils and make-ups can also coat the lenses.

Deposits can form within hours or can occur after months and have been seen to be more common in those having dry eyes, blepharitis, poor tear quality and abnormal blinking.

A good cleaning regimen should be able to remove the deposits. Wearing daily wear disposable contacts may be tried out since the incidence of deposits with these lenses is significantly lower as compared to soft contact lenses. In case of persistent deposits the RGP lenses may be worn.

Warpage

In contact lens warpage, the curvature of the lens is changed from its original parameter. Such alterations of the curvature are often caused by exposing the lens to excessive heat such as rinsing them in hot water or placing them near a source of heat. The RGP lenses change their curvature when they are squeezed too hard by the fingers during cleaning. Changed curvature leads to poor fitting and causes several eye problems.

One of the more serious fallout of lens warpage is corneal warpage. The warped lens, as it were, molds the cornea to its own distorted shape giving rise to what is known as induced irregular astigmatism. The complication results in, poor vision with contact lens which worsens with time, frequent changes in lenses, and sometimes an irritated red eye. The corneal warpage should be evaluated with a keratometer or a corneal topographer. Corneal warpage is more common with hard PMMA lenses than with RGP or soft contact lenses.

The only treatment is discontinuation of contact lenses but it may take weeks or even months for the cornea to regain a regular and stable shape. Meanwhile during the interim period the patient may wear RGP lenses. Contacts may be worn again if the cornea has a stable shape. In case corneal warpage persists then wearing of glasses or refractive surgery may be needed.

Damages

Contact lenses are sometimes damaged during manufacture or due to careless handling. Damages produce tears, cracks and chips on the lenses which can cause eye irritations. Depending on where the damage is, patients may or may not have symptoms. Some of the symptoms are ocular injection, foreign body sensation, tearing and blurred vision. Additionally bacterial organisms may enter the cracks caused by damages and intensify any existing complication.

Treatment includes removal of the affected lens and instructing the patient on proper lens handling. Lubricant treatment may be done if the corneal epithelium is affected. Antibiotic use should be rare.