Neelu Hira, OD, FAAO
Minnesota Eye Consultants
What are Contact Lenses, specifically soft Contact Lenses?
Contact Lenses, or “contacts,” are corrective lenses that are worn directly on the eye. Soft contacts are made from a plastic called hydrogel and are about 35% to 80% water. Water makes the lenses flexible, comfortable and allows for oxygen permeability. Contact Lenses rest on the cornea, which is the clear, dome-shaped front surface of the eye. The function of the cornea is to focus light onto the retina. The cornea does not have blood vessels and gets its oxygen directly from the air. Soft Contact Lenses cover the entire cornea, so an adequate amount of oxygen must pass through the contact to maintain the health of the eye.
What do soft Contact Lenses correct?
Soft Contact Lenses are used to correct a variety of visual disorders, including myopia (nearsightedness), hyperopia (farsightedness), astigmatism (uneven curvature of the cornea) and presbyopia (age-related decrease in near vision). Many patients prefer contacts to glasses for cosmetic reasons or for use during exercise. Contacts also have less image distortion and greater field of view than glasses. Specialty soft Contact Lenses can be used to change eye color or to improve the appearance of an abnormal eye. Eye doctors may also use a soft contact lens as a temporary “bandage” (bandage soft contact lens) to relieve eye pain from a corneal injury or surgery.
Although soft Contact Lenses can be successfully worn by most patients, they may not be appropriate for everyone. Patients who have frequent eye infections, dry eye syndrome, ocular allergies or certain other eye conditions may not be able to successfully wear contacts. Contacts are also not appropriate for patients who are exposed to dust and chemicals or who cannot properly handle the lenses.
Soft Contact Lenses should be fitted only by an optometrist or ophthalmologist. To determine if Contact Lenses are an option for a patient, the eye doctor will perform a complete eye exam and measure the curvature of the cornea. The eye doctor may need to use trial lenses of several different brands, materials, powers and sizes before finding the best lens for each patient. An eye care professional will demonstrate proper insertion, removal, disinfection of the Contact Lenses.
Patients who wear Contact Lenses must be monitored at least yearly by an eye doctor. The doctor will monitor the health of the cornea and update the patient’s prescription. The eye doctor will also identify and correct any problems that may be caused by contact lens wear.
What are Disposable Soft Lenses?
Today, most soft Contact Lenses are disposable and must be replaced at certain intervals depending on the manufacturer’s and your eye doctor’s recommendation. The most common replacement schedule is every two weeks, but there are also lenses that are replaced every day, month, or 3 months. Non-disposable or ‘conventional’ lenses are less common and must be replaced every year. Non-disposable lenses may be the only option for very high or unusual prescriptions. Frequent lens replacement helps ensure that contaminants such as bacteria, mold and fungus will not form on the contacts.
Although most lenses need to be removed at night, extended wear silicone-hydrogel lenses were approved for overnight wear by the FDA in 1999. These lenses may be worn continuously for up to 30 days and then replaced. Eye doctors may modify the wearing schedule of extended wear Contact Lenses to the patients’ needs. Even though silicone-hydrogel lenses transmit up to 6 times more oxygen to the eye than traditional contacts, eye infections and inflammation are still possible when wearing these lenses overnight.
How Do I Clean and Disinfect Soft Contact Lenses?
Naturally occurring mucous, protein and lipids can accumulate on the lenses in the form of deposits, which can irritate the eyes and can also act as a depot for bacteria. Proper cleaning and disinfecting keeps the lenses free of deposits and bacteria. There are two main types of soft contact lens care products: multi-purpose solution and hydrogen peroxide solution. These are defined below.
Multi-purpose solutions have a disinfectant and cleaner conveniently combined in one bottle. The solution is strong enough to kill the most common contact lens contaminants, but not so strong that it irritates the eye. Although multi-purpose solutions advertise that they do not require the wearer to rub the contacts, they do recommend rinsing each side of the contact with the solution for 5 seconds before storing the lenses in their case. Many eye doctors recommend rubbing the contacts because it is more effective and wastes less solution than rinsing. The wearer should put an ample amount of solution in the palm of one hand and gently rub the lens for about 10 seconds with the index finger of the other hand.
Hydrogen peroxide solutions work differently than multi-purpose solutions. In this method, the lenses are disinfected and cleaned with 3% hydrogen peroxide. The lenses are stored in a special vial that is designed to neutralize the hydrogen peroxide. It is important to leave the Contact Lenses in the vial until the hydrogen peroxide has been neutralized, which takes six hours. Inserting the Contact Lenses before the solution is neutralized can cause chemical burns to the eye. The lenses should not be rinsed with the hydrogen peroxide solution prior to insertion. The vials become less effective at neutralizing over time and need to be replaced with each purchase of solution. This method is a good alternative for patients who are sensitive to multi-purpose solutions because after the hydrogen peroxide is neutralized, it is free of disinfectants, preservatives and cleaners.
What are Some Guidelines for Safe Contact Lens Wear?
Proper wear, care and handling of Contact Lenses are essential to promoting healthy eyes. Patients who ignore certain precautions are at risk for developing infections, inflammation, corneal scarring and other potentially sight-threatening conditions. Patients who have contact lens-related eye complications may have to discontinue wearing lenses indefinitely. Serious complications may permanently damage the eyes. To reduce the likelihood of contact lens complications, simple precautions must be taken.
- Hands should be properly washed with soap and water and dried before handling the Contact Lenses.
- Moisturizing lotions, creams and fragrant soaps should be not be used until after handling Contact Lenses.
- Aerosol sprays should be avoided while wearing contacts.
- Make-up should be applied only after inserting the contacts.
- Contact lens cleaning solutions should be used only as directed by the manufacturer. When using multi-purpose solution, it is important to replace the solution each day. Never “top off” solution or mix brands.
- Contact lens cases should be rinsed with multi-purpose solution and air dried daily. The case should be replaced every 2-3 months.
- Contact Lenses should never be stored in tap water or saliva for even a short period of time. Contacts should also never be stored in saline solution, even if it labeled as “sterile.”
- It is not recommended that patients swim or use hot tubs while wearing Contact Lenses. Even if treated with chloride, water contains microorganisms that can cause serious eye infections.
- Prescription and over-the-counter eye drops should not be used when wearing Contact Lenses unless they are specifically approved for such use.
- Contact Lenses should be removed at least one hour before sleep
- Patients should immediately remove their soft contact lens and see their eye doctor if the eye becomes red, painful, irritated or if the vision becomes blurry. The lenses should not be re-inserted until the eye doctor has determined that it is safe to do so. It is important that all contact lens wearers have an up-to-date pair of glasses in the event that they will not be able to wear their contacts for a period of time.
Glossary:
Myopia
Hyperopia
Astigmatism
Presbyopia
Eye Doctor
Complete Eye Exam
Silicone Hydrogel
