Contact Lenses

Contact lenses are made up of plastic material (flexible or rigid plastic material) which is placed in front of the eyeball. Contact lenses are the replacement for vision correction and who do not want to wear glasses and undergo LASIK surgery.

Contact lens material
• Soft Contact Lenses
Soft contact lenses are made up of soft and flexible plastics material which allows oxygen to pass through to the cornea. Soft contact lenses are easier to adjust and more comfortable for long time usage.
→ Hydrogel: Old generation contact lenses are made-up of hydrogel material. Hydrogel material provides lesser oxygen to the eye and users can wear this lens for lesser hours. Still these lenses are available in the market.
→ Silicon-hydrogel: Newer soft lens materials available in the market which includes silicone material in hydrogels contact lens to provide 5 times more oxygen to the eye while you wear your lenses for a very long time.
→ Hypergel: Latest generation soft contact lens with silicon-hydrogel material which improves eye comfort and can be worn longer hours than other lenses.

Different modality of soft contact lenses - Soft lenses have general classifications, based on frequency of replacement:
• Daily disposable Contact Lens - Discard after a single day of wear.
• Bi-weekly disposable Contact Lens - Discard every two weeks, or sooner.
• Monthly disposable Contact Lens - Discard every month.
• Conventional Soft Contact Lens - Discard every six months or longer
• Extended wear or Continuous wear Contact Lens - "Continuous wear" is a term used to describe extended wear lenses that are worn 24 hours per day for up to 7 to 30 consecutive days (for a limited number of days).

Soft contact lenses are available in different design, depending on their intended purpose:
• Spherical soft contact lens - having same power throughout the entire optical area of Contact Lens.
• Toric Soft contact lens - having different power in different meridian of the contact lens to correct astigmatism.
• Multifocal soft contact lens - having different power zones to correct distance and near vision
• Cosmetic (color) soft contact lens - having pattern colors in a contact lens to change or intensify eye color. These lenses are available in a limited power range.
• Prosthetic soft contact lens - having opaque CL with color, used medically to hide any opacity of the cornea.

• Rigid Gas Permeable (RGP) Contact Lenses
Rigid gas-permeable (RGPs) contact lenses, are made from fluorosilicone acrylate material which is a more durable plastic that transmits oxygen to the eye and resistant to deposit buildup over CL. This type of lens generally gives a clearer and crisper vision. RGP CLs are less expensive, don't dehydrate, easier while handling, cleaning and disinfecting, and last longer than soft contact lenses. RGP contact lenses are custom made for each individual. The contact lens practitioner measures the exact shape of the cornea and prescribes lenses with the curvature, size, and corrective power that are suitable to particular eyes. However, RGPs are not much comfortable initially as soft contacts and this may take a few weeks to get adapted to them.
Contact lens practitioners are using topography to enabling the back surface of the lens to better align with the cornea. Topographic guided contact lens result in well centered on the eye, providing good comfort and crisp vision.

• Hybrid Contact lens
Hybrid contact lenses are having rigid gas permeable material in the center of CL and periphery is ‘skirt’ of hydrogel or silicone-hydrogel soft lens material. These lenses are designed to provide comfort and clarity that rivals soft material combined with crystal-clear optics with RGP material.

• Scleral contact lens
Scleral contact lenses are large size rigid gas permeable lenses with customized design. This lens covers total cornea placed directly over the sclera. There is no touch with central to mid-peripheral cornea but may have bit touch at the peripheral cornea.

• Orthokeratology (Ortho-K)
Orthokeratology or Ortho-k is used to correct myopia temporarily with overnight usage. It’s specially designed rigid gas permeable (RGP) contact lenses to change the corneal curvature temporarily. Curvature change of cornea improves the eye’s ability to focus on objects without glasses. Mostly Ortho-K lenses are worn while sleeping at night for at least eight hours each night. Some Ortho-K lenses are prescribed only for daytime wear. Ortho-K lenses are removed upon awakening and not worn during the day and people can be without their glasses or contact lenses approximately 10-12 hours. If Ortho-K is not used regularly than the corneas will return to their original curvature and again person may need to wear eyeglasses. Ortho-K lenses must be continued to wear every day. Ortho-K practitioner will help with care and maintenance schedule for lenses.