Many individuals especially the aged have suffered different kinds of eye diseases. So to dig up those issues we have to study first ophthalmology. Ophthalmology is the branch of medicine which deals with the diseases and surgery of the visual pathways including the eye and brain. Ophthalmology comes from the Greek root ophthalmos which means eye and logos means word, thought or discourse. Ophthalmology literally means, the science of eyes. In 1600 BC an Egyptian papyrus discloses that ophthalmology, in comparison with other medical specialties was relatively advanced. Many ocular conditions such as blepharitis, chalazion, iritis, cataract, trachoma, ophthalmoplegia were already recognized entities. On the other hand available treatments were far less sophisticated. In the 2nd century A.D, Galen wrote several ophthalmic texts that described the eye as the most divine organ. He theorized that rays proceed from the brain through the optic nerve, retina, lens and cornea, continuing in straight lines toward the object of regard.

These rays would then return exactly the same to the lens, where vision was mysteriously manufactured and retransmitted to the brain. The surgeon Susruta performed cataract surgery in India over 2,000 years ago, it was not until the mid- 19th century in western Europe that a solid scientific and medical advances of the period include the development of the ophthalmoscope an increased understanding of refractive errors and their correction of sophisticated knowledge of visual physiology. The current practice of ophthalmology remains based on a firm foundation of scientific research. A number of medical breakthroughs have been made as a result of research in ophthalmology. For example, the first successful use of antiviral agents was for the treatment of eye disease. In the area of surgery, corneal transplants were the first successful homotransplants. Other surgical innovations include the development of laser photocoagulation, microsurgery, and the development of techniques for micromanipulation and laser photocoagulation from within the vitreous cavity itself. Modern diagnostic advances range from the use of ultrasound and fluorescein angiography to sophisticated electrophysiology and visual function studies. These new advances continue to add challenge and excitement to the field, giving every indication that the future of ophthalmology will be as dynamic as its history. Other medical specialty dealing with the eyes such as Georg Bartisch, a German physician who wrote an eye diseases in the 16th century. He is credited as founder of the medical practice of ophthalmology. Many important eye operations were first developed such as surgical correction of strabismus, first performed in 1738. the first descriptions of visual defects included those of glaucoma in 1750, night blindness in 1767, colour blindness in 1794 and astigmatism in 1801. Frans C. Donders in 1864 advances in optics allowed eyeglasses to be fitted to vision problems. By using the ophthalmoscope it is possible to look inside the eye and relate eye defects to internal condition. Recent advances include eye examinations, early treatment of congenital defects, and eye banks to store corneas for transplants. Ophthalmologist are the one who test visual function and examine the eye for faulty development, disease, injury, degeneration, aging or refractive errors. They prescribe treatment for eye disease and lenses for refraction and perform surgery when needed.