Contact Lens are a popular visual aid for correction of Refractive Errors. They are second to spectacles in popularity.
What are the different types of Contact Lenses?
(A) Depending on Material
1) Rigid Contact Lenses
They have stable Physical Parameters (Acrylic, PMMA; Silicones, Combination of polymers)
Commonly called Hard Lenses when made out of PMMA and Semi soft or gas permeable when made out of Silicones.
2) Hydrogel Lenses
They do not have stable physical parameters and have high proportions of water as a constituent. They are generally referred to as Soft Lenses. They easily mould to the contour of the front of the eye.
(B) Depending upon type of Correction desired
1) Spherical, for simple spherica power correction
2) Toric, correct cylinderical power, they have a small ballast in the lower segment for stable orientation while in use.
(C) Special Purpose
1) Cosmetic Lenses
To hide blemishes on the cornea (opacities)
To create impression of an eye, iris print lenses
To change colour of the iris, for fashion or to make both the eyes look alike in cases of a difference of shade or colour of iris in the two eyes
2) Bandage Lenses
To cover an abrasion, a small self sealed corneal injury or blistering of cornea due to some reason
3) Special Lenses for Correction of Corneal Irregularities
They are prescribed by specialists in conditions such as keratoconus (cone like corneal surface), Pellucid Degeneration(a degenerative disease that affect the shape in the periphery of cornea. They can be of rigid or hydrogel material.
4) Scleral Lenses
They are special lenses that are designed for corneal irregularities, are larger in diameter, rest on the sclera (white of the eye) and have a fluid layer below them cushioning over the cornea.
Care of Contact Lenses
There are specific care needs of each type of Contact Lens (CL) that are explained by the dispensing practitioner but a few thumb rules are common to all:
1) Wash your hands with soap and water before handling a CL. Keep a mirror and clean towel handy while inserting a CL
2) Keep your kit away from cosmetics and talcum powder
3) In case your CL falls to the ground, do not drag it. Wet your finger and touch the CL and it will adhere to the water film. Dis infect before re insertion with CL solution provided.
4) Daily disposable lenses must be thrown after a single wear. Other disposable lenses should be discarded accordingly after opening and not after number of wears!
5) Daily disposable CL is the safest option amongst the hydrogel CLs.
6) Always keep a pair of prescription glasses with you for safety.
7) Remove CL from both the eyes immediately if you have redness, discharge from eyes, glare, pain, or foreign body sensation.
8) You may use lubricating drops and solutions as directed over the CL, but no suspensions!
9) Regular check up is important as safety of the device in the hands of a patient is responsibility of the dispensing professional