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| CONTACT LENS |
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What is Contact Lens?
It is a device made up of medical grade plastic materials used mainly for correction of refractive error.
What are its advantages?
More active spectacle free life, greater cosmestic acceptability, better & clearer images, lack of misting, good field of view, etc.
Is it preferred over spectacles in all cases?
No.
In what cases spectacles are preferred?
In case of school going children, high cylindrical power, severe allergic disorders, neurotic patients, people with poor manual dexterity, etc.
What are indications of contact lenses apart from refractive errors?
Contact lens can be used in case of keratoconus, to provide support to thin or perforated corneas, to provide regularity to irregular corneas, to hide corneal opacities, etc.
How many types of CL's are available?
Two main types: Rigid Gas Permeable (Semi-soft) and Soft.
What are the criteria for selecting the best one?
Depends on the individual case e.g. in high cylindrical error one need rigid toric lens, etc.
How long can a contact lens be worn?
Wearing duration of a contact lens is decided by its oxygen transmissibility. High the oxygen transmissibility the longer the lens can be worn. Generally lenses can be safely worn during all waking hour of the day. One should not sleep with contact lenses on.
What are the differences between rigid and soft contact lenses?
Rigid lenses as the name suggests are rigid, they are smaller than the diameter of the cornea, in the initial period they feel quite uncomfortable but they are easy to maintain and are relatively safer in terms of complications like allergies and infections. Soft lenses are a lot more comfortable but require greater care and are slightly more likely to cause allergies and infections. Soft lenses are also more costly.
Can one sleep with the contact lenses on?
Not with the (conventional) daily wear contact lens, but you may sleep with the extended wear lenses.
What complications can occur if CL's are worn for long?
Over-wear Syndrome i.e. redness, pain, watering, swelling of lids, spectacle blur, etc may occur due to deprivation of oxygen by the cornea.
What is the risk in sleeping with contact lenses on?
Over-wear syndrome can occur.
What are daily and extended wear lenses?
Daily wear lenses require to be worn for only 10-12 hours a day and to be removed at night. While extended wear lenses can be worn continuously for a week or so.
What are disposable contact lenses?
These contact lenses are worn on a daily wear basis and then regularly replaced by a fresh pair every day (Daily disposable) or fortnightly (Bi-weekly disposable). Replacement with a fresh pair reduces the risk of allergies and infections. There is no rationale in disposing the lenses after a month because monthly replacement does not reduce the risk of allergies or infections.
What is Enzyme treatment of contact lenses?
After some period of use soft contact lenses develop protein deposition on them from eye secretions. These deposits can give rise to allergies in the eye. These can be removed by subjecting the contact lenses to Enzyme Treatment by enzyme tablets every fortnight.
What are multipurpose solutions?
In the past there used to be 2-3 different solutions required to clean, rinse and store the contact lenses. The multipurpose solutions combine all these in one making lens care easy.
What is the life of a contact lens?
(Conventional) Daily wear contact lenses can be used for about one year, after which they should be replaced, whereas Disposable or Frequent Replacement contact lens have different usage period. Life of the lens depends on the care and handling.
What are cosmetic lenses?
Contact lenses of different shades and pattern are available, which impart the eyes of the wearer a look of a different color.
What is GPC? What can be done for it?
Giant Papillary Conjunctivitis is a commonly seen complication of contact lens use. It is caused by two mechanisms: protein deposits on the lens and irritation caused by movement of edge of the lens. It is seen more commonly with soft than with rigid contact lenses. One may have to discontinue contact lenses for a short while and use anti-allergic eye drops. In severe and recurrent cases one may be required to change the type of contact lens or completely abandon their use.
What is a contact lens trial?
Contact lens has to be customized for every patient based on corneal curvature, corneal diameter and refractive error. Such a lens is fit on to the patient's eye and the fit assessed after giving it about 20 minutes to settle in the eye. Perfect fit is important to ensure good eye health and clear vision. |
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