What is Contact Lens?

These are the lenses which are produced to correct the refraction defects of the eye and as an alternative to the glasses and which are placed on the front side of the cornea. Along with their medical usage to correct the refraction defects, the contact lenses can also be used for cosmetics and curative purposes.

The principles of refraction and related to optics are similarly applied to contact lenses. This contains the correction of current defect by replacing the contact lens surface with corneal curvature which accured in accordance with the degree of myopia and hypermetropia. Since the major part of astigmatic defects develop due to the distortion of frontal layer of cornea, either hard or special soft lenses produced only for astigmatism shall be used. 

While the sphere number of glasses and contact lenses are equivalent for lower numbers, as the sphere number augments, the myopes shall use lesser and hypermetropes shall use higher numbered contact lenses with regards to the glasses. 

Types of Contact Lenses

Today, mainly, there are two types of contact lenses. These are: the gas permeable hard lenses and the soft lenses.

1. The Gas permeable hard lenses:

Their name refers to their ability to allow oxygene transfer to the eye and because of this ability they cause less damage in the cornea epithel metabolism regarding the hard lenses which are not used any more. They are especially preffered in events like high astigmatism and keratoconus since they do not take the form of cornea.

2. Soft Lenses:

There are various types under this cathegry. Among these types, 1 day duration lenses of daily use, 1 month long duration lenses of daily use, 3 months long duration lenses of daily use, 1 year long duration daily lenses, 1 week long duration lenses to be weared all week, 1 month long duration lenses to be weared all month, the therapeutic lenses to be used for treatment of certain diseases, bifocal lenses and colored lenses can be listed.

The use of this type of lenses is very comfortable. Most of the lenses to be used for the treatment of eye defect are colourless and does not change the appearence when weared. They correct the defect as they are weared and they provide a bright vision. 

Advantages of contact lenses

- Lenses show the objects in their actual size.

- Lenses provide a wider visual area. Side vision is weak in glasses.

- Lenses do not present irritating obstacles. In glasses the frame and lens edges are always felt.

- Lenses do not  mist up when transmitted to warmer environment. But glasses may mist up and dependently may cause blurred vision. 

- Lenses do not irritate you in course of sportive activities, dancing, etc while glasses always fall during activities.

- You can wear sun glasses while wearing lenses however, glasses obstacle wearing sun glasses.

- Lenses do not weight down in the face while glasses are irritating.