Contact lenses are thin, curved plastic disks designed to cover the cornea; the clear front covering of the eye. Contact lenses provide a safe and effective way to correct vision when used with care and proper supervision. They can offer a good alternative to eyeglasses depending on your eyes and lifestyle.
HISTORY OF THE CONTACT LENS
Leonardo da Vinci had proposed the idea of applying a corrective lens directly to the surface of the eye as early as 1508 and similar concepts surfaced from Rene Descartes in 1636 but it was not until 1887 that the German physiologist Adolph Eugene Fick constructed the first successful contact lens.
If you are considering corneal refractive surgery, you must :
- Contact lenses typically provide better vision than spectacles for some visual conditions such as severe short-sightedness [myopia], long-sightedness [hyperopia], astigmatism, corneal distortion, or after cataract removal [aphakia].
- Some people like the wider field of vision provided by contact lenses as side vision [peripheral vision] is often blocked, obscured or limited by spectacle frames.
- Contact lenses do not fog up with changes in temperature or from perspiration and they are unaffected by water or rain.
- Many people choose contact lenses for personal or cosmetic reasons because they think glasses make them look less attractive or they find the weight of spectacles on their face annoying.
- Sports players and people involved in vigorous activities often find contact lenses more convenient than spectacles, especially for water sports and contact sports.
- Priests, psychologists and many others also find that contact lenses avoid the barrier effect that spectacles may cause, thus leading to more direct eye-contact.
TYPES OF CONTACT LENSES:
1. Daily-wear soft lenses:
Daily-wear soft lenses are the most comfortable and your eyes will adjust to wearing them in less time than hard contact lenses. These soft lenses may be worn during vigorous physical activity and playing any sport with less likelihood that the lenses will slip out of place. Daily-wear lenses must be removed, cleaned and stored every day.
2. Disposable Contact Lenses :
Disposable Contact Lenses are lenses designed to be replaced on a regular basis usually daily, bi-weekly or monthly. The more often a lens is replaced the less likely the lens will become deposited with proteins and oils. Many problems that contact lens wearers experienced in the past when lenses were replaced on an annual or two yearly bases are seldom seen nowadays. Disposable contact lenses are therefore a healthier alternative. Daily disposable contact lenses are a great option for people who only want to wear their contact lenses a few times a week for example for sport or for going out at night. They also remove the need for cleaning, since they are inserted in the morning (before the start of your day / play sport / work) and then thrown away at the end of the day offering exceptional convenience and good value for money. Lenses, which are replaced on a two-weekly or monthly basis, are good value if you want to wear lenses every day.
3. Leave-in (extended wear) contact lenses:
Leave-in (extended wear) contact lenses are designed to be worn continuously for 30 days and nights and then replaced with a new contact lens. They offer the ultimate in convenience since they usually don’t need removing or manual cleaning. Other advantages include being able to see without struggling to find your glasses if you get up in the night, or not having to worry about removing lenses with dirty hands. If you go camping or for any outdoor sport or short holiday you won’t need to remember to carry bottles of solution around with you.
4. Toric Contact Lenses:
Toric Contact Lenses are made from the same material as regular (spherical) contact lenses. Toric lenses have two powers in them created with curvatures at different angles (one for astigmatism the other for either myopia or Hyperopia. Have you been told you can’t wear soft contact lenses because you have astigmatism? You now have an option!Here’s a mechanism to keep the contact lens relatively stable in the eye when you blink or look around. Toric contact lenses cannot rotate in your eye and keep your vision crisp.
5. Rigid gas Permeable contact lenses:
Rigid gas Permeable contact lenses are usually used for correction of moderate levels of astigmatism. They provide excellent clarity of vision especially in cases where the astigmatism is irregular (such as with keratoconus). Rigid Gas permeable contact lenses offer excellent long-term corneal health since they allow almost as much oxygen to pass through to the cornea as without a lens on the eye. They require a longer period of adaptation than soft lenses. Many of the problems associated with reduced oxygen flow through old-style “hard lenses” are seldom seen nowadays due to the development in these various modern gas permeable lenses.
6. Bifocal & Multifocal Contact Lenses:
Bifocal contact lenses are designed to provide good vision to people who have a condition called presbyopia The main sign that you’re developing presbyopia is that you need to hold menus, newspapers and other reading material farther from your eyes in order to see it clearly. Bifocal contact lenses come in both soft materials and rigid gas permeable (GP) materials. Some can be worn on a disposable basis. That means you have the convenience of throwing the lenses out at specified intervals (even daily, in some cases) and replacing them with fresh, new lenses. One lens manufacturer offers a soft multifocal contact lens made of silicone hydrogel material. This lens is FDA-approved for up to 30 days of continuous wear.
7. Color Contact Lenses
Colored contact lenses come in three kinds: visibility tints, enhancement tints and opaque color tints. Many of these colored contact lenses are available in Plano form, as well as in designs for people who have astigmatism, need bifocal contacts or want a disposable contact lens. A visibility tint is usually a light blue or green tint added to a lens, just to help you see it better during insertion and removal, or if you drop it. Since it’s a very light tint, it does not affect your eye color An enhancement tint is a solid but translucent (see-through) tint that is a little darker than a visibility tint. An enhancement tint does change your eye color. As the name implies, it’s meant to enhance the existing color of your eyes. These types of tints are usually best for people who have light colored eyes and want to make their eye color more intense. Color tints are deeper, opaque tints that can change your eye color completely. Usually they are made of patterns of solid colors. If you have dark eyes, you’ll need this type of color contact lens to change your eye color. Color contacts come in a wide variety of colors, including hazel, green, blue, violet, amethyst and gray. The companies that make colored contact lenses have gone all out to mimic the natural look of the colored portion of the eye, called the iris Since this area is made up of colorful shapes and lines, some color contacts feature a series of tiny colored dots on the lens to make them look more natural on the eye. But the center of the lens, the part that lies over your pupil is clear so you can see.
8. Prosthetic Contact Lenses:
Prosthetic Contact Lenses are used in patients with corneal disfigurations, corneal scarring and de-centered pupils.
9. Specialty Contact Lenses:
Rose K Lens:
Heralded as “a quantum leap forward in the evolution of lens design for the condition” of keratoconus the Rose K lens has become the world’s most frequently prescribed gas permeable contact lens for keratoconus. Unlike traditional contact lenses, the complex geometry built into every Rose K contact lens closely mimics the cone like shape of the cornea, for every stage of the condition. The result, a more comfortable fitting lens for patients and better sight (visual acuity). The Rose K lenses complex geometry has only become possible since computer controlled contact lens lathes were developed to cut sophisticated oxygen permeable polymers to the right shape.
SCLERAL CONTACT LENSES:
A Scleral lens is a large type of contact lens that rests on the sclera and creates a tear-filled vault over the cornea. Scleral lenses are designed to treat a variety of eye conditions which do not respond to other forms of treatment.
- A Scleral lens is a large type of contact lens that rests on the sclera and creates a tear-filled vault over the cornea. Scleral lenses are designed to treat a variety of eye conditions which do not respond to other forms of treatment.
- Modern Scleral lenses are made of a highly oxygen permeable polymer. They are also unique in their design in that they fit onto and are supported by the sclera, the white portion of the eye. The cause of this unique positioning is usually relevant to a specific patient, whose cornea may be too sensitive to support the lens directly. In comparison to regular contact lenses, Scleral lenses bulge outward considerably more. The space between the cornea and the lens is filled with artificial tears. The liquid, which is contained in a thin elastic reservoir, conforms to the irregularities of the deformed cornea, allowing vision to be restored comfortably.
- Scleral lenses may be used to correct any one of a growing number of disorders or injuries to the eye, such as Microphthalmia, keratoconus, corneal ectasia, Stevens-Johnson syndrome, Sjögren’s syndrome, aniridia, neurotrophic keratitis (anaesthetic corneas) and pellucid degeneration. Injuries to the eye such as surgical complications, distorted corneal implants, as well as chemical and burn injuries also may be treated by the use of Scleral lenses.
SOME HANDY TIPS FOR SAFE AND COMFORTABLE CONTACT LENS USE:
- Never wear lenses longer than prescribed.
- Do not wear daily lenses while sleeping.
- Do not wear your lenses overnight unless recommended by your contact lens practitioner. Overnight wear of contact lenses increases the risk of complications.
- Always wash, rinse, and dry your hands before handling lenses. Avoid pump and moisturizing soap and use lint free cotton towels and tissues.
- Do not use saliva to wet your lenses. Do not put lenses in your mouth.
- Use only approved contact lens solutions for lubricating or wetting your lenses.
- Always use fresh solution in your lens case when disinfecting your lenses.
- Ask your contact lens practitioner about wearing lenses during water activities and other sports. In some cases alternative lenses may be prescribed for sport, other hobbies and specific work related activities.
- Schedule and keep follow-up appointments with your contact lens practitioner.
- Never use non-sterile home-prepared saline. The use of home-prepared saline with contact lenses has been associated with serious infections.
- Contact lens storage cases can be a source of bacteria and other microbial growth. Lens cases should be cleaned, rinsed and allowed to air dry each time the lenses are removed. Replace the lens case frequently.
- If your eyes become red, irritated, painful, abnormally light sensitive or if your vision worsens while wearing lenses immediately remove the lens and consult a contact lens practitioner.
- Do not get lotions, creams, sprays or chemicals in your eyes or on your lenses. It is best to insert lenses before applying make-up and remove them before removing make-up. Water- based and gel-based cosmetics are less likely to damage lenses than oil-based products. Do not apply eyeliner on the inside rim of the eyelids.
- You should have eye examinations every 6 x to 12 months or as recommended by your contact lens practitioner.
- Contact lenses wear out with time and should be replaced regularly.
- Disposable lenses should be thrown away after the recommended wearing period prescribed by your contact lens practitioner.
- Daily disposable lenses should not be re-used.