When light rays enter the eye, they are absorbed and converted into electrical signals by retinal nerves. These signals are subsequently sent to the brain where they are interpreted as visual images. In a normal eye, light rays enter the eye through the cornea (window of the eye) and are focused with the help of a crystalline lens behind the pupil at a point directly on the retina (the light sensitive nervous tissue at the back of the eyeball). However, only about four in ten people have normal visual acuity. For the rest, clear vision may be achieved by refocusing light rays with the use of corrective lenses.
How does a contact lens work?
Contact lenses are delicately crafted, very thin optical discs generally worn directly on the eye. They are comfortably held in place by a natural layer of tears present between the contact lens and the cornea. Contact lenses eliminate the barriers encountered with spectacles that interfere with the line of sight above, below and to the sides of the eye. They offer outstanding peripheral vision. In addition, contacts can reduce or eliminate the image distortion sometimes caused by eyeglasses.
What are the different types?
There are several types of contact lenses designed to fit the most common vision conditions:
Daily-wear soft lenses
These are made of soft, flexible plastics that allow oxygen to pass through to the eyes.
Benefits:
· very short adaptation period
· more comfortable and more difficult to dislodge
· available in tints and bifocals too
· great for active lifestyles
· while careful cleaning is required, lens care maintenance products are simple and effective
Daliy-wear disposable soft lenses
Single-use, daily wear lens that are designed to be worn for a single day, discarded at night, and replaced with a brand new pair.
Benefits:
· typically no lens care is required
· assures fresh and clean lenses when replaced
· great for active lifestyles
Extended-wear soft lenses
· Available for overnight wear. Made of soft, flexible plastics that allow oxygen to pass through to the eyes.
· can usually be prescribed for up to seven days of wear without removal
Extended-wear disposable soft lenses
· Soft lenses worn continuously from one to six nights, and then discarded.
· require little or no cleaning
· available in tints and bifocals too
· spare lenses conveniently on hand
Frequent and planned replacement soft lenses
· Soft daily or extended wear lenses that are replaced on a planned schedule, most often every two weeks, monthly or quarterly.
· assures fresh and clean lenses when replaced
· available in most prescriptions
· spare lenses conveniently on hand
Rigid Gas Permeable (RGP)
· Made of slightly flexible plastics that allow oxygen to pass through to the eyes
· vision may be sharper than with soft contact lenses
· easy to put on and to care for
· durable with a relatively long life (1-2) years
· available in tints (for handling purposes) and bifocals
· daily-wear and extended-wear designs available
· planned replacement schedule also available
How to insert contact lenses properly?
Wash, rinse and dry your hands before touching the contacts. A wet finger could cause a soft lens to flatten. Do not use fingernails when handling your lenses. If you are near a sink, close the drain to avoid any mishaps. Always insert your contacts in the same order to eliminate mix-ups. Pour the lens and storage fluid from the case into your palm. Examine your lens for particles, deposits or tears. Place the lens, cup side up, on your forefinger. Be sure the lens is right side out—the lens' edge will appear almost straight up. If the lens is inside out, the edges will bow out slightly. If the lens is inside out, reverse it before proceeding.
Insertion:
· Hold your upper eyelid or lashes to hinder blinking.
· Pull your bottom eyelid down using your middle finger
· Look up at the ceiling so that the white part of your eye shows and position the lens onto the white part
· Or, you can look forward at the lens and gently situate it in the centre of your eye
· Remove your finger and let the bottom eyelid go before the top
· Look down to position the lens
· Close your eye for a moment.
· Apply one to two eye drops (lens lubricant) if your lenses feel dry or vision blurs.
· Repeat the same steps for inserting the lens for the left (or second) eye.
· Be sure to have your eye doctor demonstrate these steps prior to your first attempt at inserting your lenses
Removal:
Bend over so that your head is parallel to the floor, cup your left hand under your right eye. Place your thumb, index or forefinger of your right hand at the outer corner of your eyelids. Look straight down and open both eyes wide. Pull your finger in an upward and downward direction and remove the lens.
Cleanse, rinse and disinfect your lenses after removal and before wearing them again as contact lens cases can be a source of bacterial growth. Enzyme cleaners and cleaning solutions alone cannot substitute for disinfecting, although there are multipurpose products that can perform many of these functions if used as directed. Never use non-sterile homemade saline, distilled water or tap water for any part of your lens care regimen. Use products recommended by your eye care professional. Not all solutions can be used for all contact lenses. Solutions can become contaminated during use. Do not let the bottle tip touch any surface including your contact lenses.
Normal wearing schedules:
You should not wear lenses during the first 2 days, but frequently practice insertion and removal until proficient.
It is essential to build up tolerance gradually
You should wear lenses 2 hours a day for 2 days, increase the wearing time to 3 hours for 2 days and then add one hour every third day until all day tolerance is achieved.
What are the benefits?
For those who lead an active lifestyle, contacts can provide close to natural vision, with no side effects if worn and fitted correctly. Excellent peripheral vision for sports, for driving, for safety etc.
For those who prefer the way they look without glasses or find glasses to be cumbersome and awkward, contacts can provide ease, convenience and comfort.
For those who have always wanted to change their eye colour.
For those who work or play in an environment in which spectacles are not an option, contacts allow for comfortable wear.
For those who think laser surgery and its risks are frightening and prohibitively expensive, contacts can provide a safe, comfortable and time-tested alternative.
Safety tips for contact lens wearers:
· Visit a reputable eyecare professional for a complete eye examination every 12 months or more frequently if directed by your doctor
· Use only contact lenses if they are medically approved and only if prescribed by a licensed eye care practitioner
· Never swap contact lens with another person
· Do not wear lenses longer than prescribed, nor when sleeping unless otherwise directed
· If eyes become red or irritated, remove the lenses immediately and consult your doctor
· Replace contacts as recommended by your doctor because they wear out over time. Throw away disposable lenses after recommended wearing period
Courtesy : NDTV.com
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