Complications of contact lens wear
A contact lens is a foreign object inserted into the eye; this alters the natural environment of the eye. The amount of bacteria on the surface of the eye is then increased due to contaminated hands, lenses, and lens care systems. Putting a contact lens on the eye causes attraction of pathogens and increases antibiotic resistance. This enables bacteria to adhere to the contact lens.
Materials on the lens or in the contact lens solution can cause a mild allergic reaction. This initiates a disturbance in the tear film which causes an irritation, which may lead to
Giant Papillary Conjunctivitis (GPC)
GPC is also known as contact lens-induced papillary conjunctivitis.
GPC refers to large lumps that form under the palpebral conjunctiva which is found under the eyelid, mainly on the upper tarsal plate.
It is often caused by an allergic reaction to lens deposits, lens materials or contact lens solutions.
GPC causes great discomfort by being very itchy, producing a discharge, increasing movement of the lens and reducing visual acuity.
To treat GPC, the contact lens wearer must stop wearing lenses completely for a while.
When their optometrist or ophthalmologist lets them know that they have recovered and can now continue lens wear, they are advised to replace lenses more frequently, wear lenses for fewer hours and pay close attention to lens care and wear procedures.
GPC is not a sight threatening condition
corneal abrasion
A tiny particle may attach itself on the lens and end up under the lens, scratching the eye. This may result in a corneal abrasion.
A corneal abrasion also occurs when the edge of a soft contact lens has a tear or defect.
This may cause some degree of pain and discomfort.
It normally does not require medical attention since it normally only affects the superficial layers of the cornea
corneal ulcer
A corneal ulcer can be caused by bacteria, fungi or parasitic amoeba.
Improper lens care, a small break in the cornea or a corneal abrasion can result in microorganisms having an opportunity to invade the cornea.
Signs and symptoms include a painful red eye, photophobia, tearing and foreign body sensation.
Wearers are advised to seek medical attention immediately if that happens.
A corneal ulcer leads to permanent decrease in vision due to corneal scarring and or corneal perforation and should be treated as quickly as possible.
corneal infiltrates
Sleeping in contact lenses leads to a times eight incidence of corneal infiltrates, and a times four incidence of microbial keratitis.
Acute hypoxia may lead to contact lens over wear syndrome (CLARE) and chronic hypoxia can lead to the commencement of corneal neovascularisation which may affect the visual acuity.
Corneal neovascularisation is the growth of new blood vessels from the limbus to the cornea. Under normal conditions the cornea does not have blood vessels.
If however the contact lens is worn for extended periods of time, or does not allow oxygen delivery for extended periods, the cornea responds to the hypoxia by growing abnormal blood vessels.
Further hypoxia leads to larger vessels and growth of connective tissue.
Superior Limbic Keratoconjunctivitis
Superior Limbic Keratoconjunctivitis is an infection that is caused by an immunological response to the spoilage of a soft contact lens or by exposure to thimesoral-preservative solutions.
This response can occur even after many years of successfully wearing contact lenses.
Signs and symptoms include hyperemia of the bulbar and palpebral conjuctiva, superior arcuate staining of the cornea, superior limbic proliferation,pain, foreign body sensation photophobia, burning and itching.
The symtoms continue to increase in intensity as time progresses and may last for years.
Soft contact lens wear should be stopped completely for as long as ten months in severe cases.
Bacteria from the hands, contact lens care system and storage system, now reach the surface of the eye with the aid of the contact lens.
Contact lenses reduce the ocular defence, change the quantity and types of bacteria and interfere with the natural barrier.
Any compromise in the cornea allows bacteria to adhere to the cell membrane. Pseudomonas aeruginosa is a sight threatening infection that is caused by the bacterium pseudomonas.
Acanthamoeba is a rare microbial keratitis that is caused by a pathogen that is found in soil and air. It is mainly contracted from contaminated water.
Blepharitis
Blepharitis is an inflammation of the eyelids.
It is likely to occur in individuals who wear contact lenses for extended periods.
Signs and symptoms of blepharitis include dryness, burning, itching, photophobia and an irritated eye.
Blepharitis can be classified as either seborrheic or staphylococcal. Both types occur in contact lens wearers.
The material in the soft contact lenses may evoke an allergic reaction or hypersensitivity in the eye.
Over extended periods of wearing the soft contact lenses, this can lead to inflammation of the eyelid.
This leads to seborrheic blepharitis. It is characterized by crusty lid margins, lid inflammation and greasy lashes.
Staphylococcal blepharitis is an infection of an inflamed eyelid by bacteria for example staphylococcal aureus.
It can lead to loss of eye lashes. Blepharitis needs treatment with lid scrubs, antibiotics and topical steroids
OPTOMETRY-SHARP VISION
Optometrist