Here at the retina, the light rays are converted to electrical impulses which are then transmitted through the optic nerve, to the brain, where the image is translated and perceived in an upright position!
Think of the eye as a camera.
A camera needs a lens and a film to produce an image.
In the same way, the eyeball needs a lens (cornea, crystalline lens, vitreous) to refract, or focus the light and a film (retina) on which to focus the rays.
The use of the Excimer Laser in corneal refractive surgery has greatly increased the safety of the procedure as the refractive correction is achieved by the removal of as little as 10%-20% of the total corneal thickness.
Excimer Photorefractive Keratectomy (PRK) is now a procedure used all over the world and has helped thousands of patients say goodbye to glasses.
A recent advance in the treatment of high refractive errors is a procedure termed Laser In-situ Keratomileusis (LASIK) which is often an adjunct to PRK.
Eye defects, which do not require surgery, like eye strains, watering of the eyes, itching in the eye region, eye pain, diminishing visionary power, redness, blurring vision, near and far sightedness can be cured through yogic treatment.
On the other hand organic defects like Cataract, Glaucoma etc requiring surgery need eye specialists.
Patients having any eye disorder can cure the problem by having a proper diet, doing yogasanas followed by some eye exercises.
Do not work in hot sun, as bright light destroys Vitamin A.
Practice Pran mudra
In the mornings after cleaning mouth, fill it with water so that the cheeks get puffed up and then splash water on the eyes several times. Then throw out water from the mouth. Keep eyes closed for some time. This will make eyes feel cool and fresh.
The distance while watching T.V. should be at least 3 meters (10 feet) and while reading or writing, the book should be at a distance of 30 cm (12 inches).
General considerations : Some eye problems such as nearsightedness or farsightedness do not limit the trainee in the selection of practices. On the other hand acute eye problems and glaucoma should be taken into account.
Contraindications : Inverted asanas (including Padahastasana) are strictly contraindicated in glaucoma. No inverted asanas are recommended, if the eye vessels are weak, and in conjunctivitis.
Recommendations : Trataka also helps according to Yoga tradition. Glaucoma is a stress related disease, patients with this problem may benefit from relaxation and calming pranayama, and they should be properly medically treated.