Contact Lenses

These are small polymer covers, which are placed directly over the cornea. They are of two main types: soft and semi soft.

Soft contact lenses are pliable and therefore very comfortable, but require utmost care and maintenance. Infections and allergy are the likely complications. 
Semi-soft lenses (or rigid gas permeable lenses) are rigid and thus, initially, slightly uncomfortable to wear, but do not require too much care. Complications like infection and allergy are uncommon with these lenses.

Advantages: They provide reversible alternatives for vision correction especially in circumstances where other modalities are either not advisable (young individuals with unstable error) or not possible (scarred or irregular cornea).

Cannot be used by: Patients with a high degree of astigmatism.

Complications: In the Indian context infection, allergy, mishandling, dust and pollution associated conjunctivitis continue to be major causes of contact lens intolerance. This is more s since wearers do not comply with he regulatory practices relating to the lens care and maintenance schedules.

Extended wear lenses are not as suitable for Indian conditions as in the west. 
Hard lenses are obsolete and should never be used as they prevent oxygen supply to the cornea.