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Contact Lenses |
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| What are Contact Lenses? |
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Contact lens are small, thin, curved transparent discs that are worn in apposition with the cornea. They may be corrective (in place of glasses), cosmetic, or therapeutic lens.
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| What are the advantages of Contact Lenses? |
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Contacts provide a safe and effective way to correct vision when used with care and proper supervision as only your eye specialist or your optometrist can decide whether you are a suitable candidate for contact lens use.
They can offer a good alternative to eyeglasses. They are optically superior to glasses as they move with the eye and hence do not cause peripheral distortions which are seen commonly in high powered spectacles.
Contacts cause much lesser magnification/minification of the retinal images hence are especially useful in patients having anisometropia (unequal refractory error in the two eyes).
When compared with spectacles, contact lenses are less affected by wet weather, do not steam up, and provide a wider field of vision.
They are more suitable for a number of sporting activities.
Ophthalmological conditions such as keratoconus and aniseikonia are more accurately corrected with contact lenses.
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| Who are not good candidates for Contact Lenses? |
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Eye conditions like frequent infections, allergic conjunctival conditions, dry eyes (severe), work environment which is very dusty or involves working in chemical fumes may keep you from using contact lenses. Also people who cannot take care of their lenses are not suitable candidates for contact lens wear.
Overactive thyroid gland, severe diabetes or extreme arthritis in the hands, dry eyes related to pregnancy, contraceptives, diuretics, antihistamines and decongestants are the other limiting factors for contact lens use. |
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| What are the advantages and disadvantages of different Contact Lenses? |
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'RGP' lenses are made of special plastics, which have good oxygen permeability. These lenses have a long life. They are non-porous in nature hence they do not absorb chemicals or fumes. They provide excellent quality of vision as they can correct astigmatism as well as uneven curvature of the cornea due to the tear lens that is formed between the cornea and the lens. They are more difficult to get use to as they are thicker and more rigid than soft CLs.
Soft lenses are made of hydrophilic polymers (absorb liquid) and must be kept moist for softness and easier moulding to the corneal surface. These are thin flexible lenses that are easy to get use to. They are usually comfortable from the time that they are used. They are less likely to dislodge and can be worn for longer periods they need to be changed more frequently.
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| Which Contact Lenses are best for me? |
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| If you desire to use contact lenses, you should do so only after consultation with an ophthalmologist. He/she will advise whether contact lenses would be suitable for a person to use or which kind of lenses, soft or gas permeable, should be used in a particular case. It is imperative that a yearly examination be done after the initial use of contact lenses. |
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| What are the adverse effects of Contact Lenses? |
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Contact lens wear may give rise to eye infections, allergic reactions to lens care solutions and deposit on lenses, redness of the eyes, scratched corneas, alteration in corneal shape and structure and abnormal blood vessels growing in the apparently clear cornea.
It is mandatory to consult your eye specialist without delay if there is burning, extreme sensitivity or hazy vision or pain.
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| How should I take care of my Contact Lenses? |
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| The health of your eyes is your responsibility. You must follow the instructions given for contact lens cleaning judiciously. |
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| What are the different types of Contact Lenses available? |
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| Corrective Contact Lenses: |
Conditions correctable with contact lenses include Myopia, hypermetropia, astigmatism and presbyopia.
Spherical lenses for correction of spherical power (myopia and hypermetropia). Toric lenses for correction of cylindrical and spherical powers.
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| Cosmetic Contact Lenses: |
Contact lenses can be used change the appearance of the eye. A range of iris colours is available for cosmetic lenses.
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| Therapeutic Contact Lenses: |
| Soft lenses are used to treat non healing epithelial defects and other corneal conditions to protect an injured or diseased cornea from constant rubbing of blinking eyelids, allowing it to heal. |
| By Material: |
Soft Contact Lenses
Rigid Gas Permeable Lenses
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| By Wear Time: |
| A daily wear lens is designed to be removed prior to sleeping.
An extended wear contact lens is designed for continuous overnight wear. These lenses have to be thrown away after a specified period of time. Extended wear contacts are not usually recommended due to the increased risk of corneal infection. |
| By frequency of replacement: |
Daily Disposable Lenses are thinner and lighter and the most comfortable lenses.
Usually two weekly or monthly disposables are prescribed asthey have a good balance of thickness, handling , comfort and cost effectiveness.
Quarterly or annual lenses which were previously commonly used as the disposable lenses are thinner, more comfortable and because of short duration of use have lesser protein deposits.
Rigid gas permeable lenses are very durable and may last for several years without the need for replacement. PMMA hard lenses were very durable, and were commonly worn for 5 to 10 years. |
| By Design: |
| A spherical contact lens used for correction of spherical errors.
A toric lens used for correction of astigmatism. They correct for both spherical and cylindrical aberration. |
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