Contact lenses are used to correct refractive errors. They are also used to correct certain special eye diseases. Normally, the cornea is spherical. If a patient has a conical cornea, the condition is called a conical cornea or keratoconus. In such cases the pressure of the contact lens flattens the cornea. If a patient has a white mark on the cornea, coloured contact lenses can be given for cosmetic reasons. Colour contacts are often used to change the colour of the eyes.

What are the advantages of contact lenses over spectacles?

Contact lenses have cosmetic value; the patient need not wear specs. Further, side vision is better with contact lenses. Contact lenses should be used if the difference in power of the two eyes is more than 5 dioptres since the patient will start seeing double if he uses glasses. This is because the two eyes cannot cope with a difference of more than 5 dioptres with glasses. Contact lenses give a more normal image than spectacles. Contact lenses are also preferred in refractive errors of high degrees.

Lens care requires only few minutes each day, good hygiene and good habits.