All about Contact Lenses
Contact lens invention does not have a single name contributing to its birth, but a number of people who have evolved the concept and each step was important in the development of contact lenses that we wear today. Leonardo Da Vinci was the first person to have conceived the idea of ‘contact lenses’ in the 16th century, but it came to reality in the 19th century by F.E. Muller. In the 20th century, modern day soft lenses were invented by Czech chemists Otto Wichterle and Drahoslav Lim.
What Are Contacts Lenses?
Contact Lenses are thin concaved plastic that is worn directly on the coloured part of eyes, where the lenses ‘stick’ to the eye. Contact lenses are usually worn by people who are near sighted, far sighted, have bifocals but do not want to wear glasses. They can also be worn as a cosmetic, to change or enhance eye colour.
Types of Contact Lenses
There are two major types of contacts- Soft Contacts and Hard Contacts\ Rigid Gas Permeable Contacts.
These are made from plastic materials containing water which makes them soft, and hence also called Hydrogels. Soft contacts can have low or high oxygen permeability. These have a hint of blue in its appearance and usually are slightly bigger than the coloured circle of the eye. Soft lenses are flexible and can be torn easily if not handled well.
Rigid Gas Permeable Contacts (Hard Contacts)
Rigid Gas Permeable Contacts or RPG Contacts are made from hard plastic and have very high oxygen permeability. Healthy eyes need plenty of oxygen. Oxygen can pass through through RPG lenses which make these lenses more comfortable and healthier. The size of these is smaller than the coloured part of the eye, the material is not flexible but it takes the shape of the eye easily. Hard lenses cannot be torn but can be broken if not handles carefully.
Within each of these contact lenses, there different materials and designs available, for example, number of hours they can be worn, changing schedule etc. Soft lenses are extremely comfortable to wear and need very less time to adapt while RGPs require an adaptation period before they can be comfortably worn. But RPGs give better vision.
The more popular Soft lenses come in various kinds –
Daily Disposables – Wear in the morning, throw in the evening. These are for one time use.
Weekly \ Fortnightly \ Monthly Lenses – These can be worn during the day and must be disposed off after the intended period.
Yearly Lenses – These are worn during the day, must be removed at night. These must be changed annually, and cleaned with Cleaning Tablets every few months.
Apart from replacement schedule, there are a number of hours each lens can be worn at a stretch (for example – 8 hours a day \ 12 hours etc). The lenses must be kept in clean solution for atleast 4 hours in between two wearings.
Wearing one pair of lenses for longer than intended periods can lead to unhealthy protein deposits on the cornea. Therefore, daily or monthly lenses are said to be healthier than yearly lenses.
Pros & Cons of Contact lenses –
Advantages of Contact Lenses
Contact lenses give better vision without any hindrances or obstructions.
Can be worn in rains, they do not fog up.
Some people may feel they look better in lenses.
Better for sports activities
Disadvantages of Contact Lenses
Infections & complications are possible
Need more care than glasses
Slightly more expensive