The eyes are body's most highly developed sensory organs. In fact, a far larger part of the brain is dedicated to vision than to hearing, taste, touch, or smell combined! Genetic factors play a role in many kinds of eye disease, including those diseases that are the leading cause of blindness among infants, children and adults.
More than sixty percent of cases of blindness among infants are caused by inherited eye diseases such as congenital (present at birth) cataracts, congenital glaucoma, retinal degeneration, optic atrophy (condition that affects the optic nerve) and eye malformations. Up to forty percent of patients with certain types of strabismus (ocular misalignment) have a family history of the disease.
The most common forms of vision impairment are errors of refraction - the way light rays are focused inside the eye so images can be transmitted to the brain. Nearsightedness (myopia), farsightedness (hyperopia), presbyopia and astigmatism are examples of refractive disorders and often occur when the eyes are otherwise healthy. Refractive errors are correctable usually with glasses, contact lenses, or refractive surgery, such as LASIK (Laser-Assisted inSItu Keratomileusis).
Nearsightedness is a refractive error that makes far-away objects look blurry. It happens when the shape of the eye makes light focus in front of the retina instead of on it. The most common symptoms of nearsightedness are:
Presbyopia makes it hard for middle-aged and older adults to see things up close. As people age, the lens in the eye gets harder and less flexible and stops focusing light correctly on the retina. Everyone gets presbyopia as they get older, usually after age 45. Many people have another refractive error in addition to presbyopia.
Astigmatism can make far-away and nearby objects look blurry or distorted. It happens when the cornea or lens has a different shape than normal, which makes light bend differently as it enters the eye. People with astigmatism often have another refractive error, like nearsightedness or farsightedness.
A healthy lens is clear like a camera's. Light passes through it to the retina, where images are processed. A cataract is a clouding of the eye’s lens. Cataracts often form slowly. They don't cause symptoms like pain, redness, or tearing in the eye. As we age, the proteins that help make up the lens can start to clump together, which causes the clouding. Cataracts can make your vision appear blurry, cloudy, hazy or dim.Additionally, symptoms of cataracts can include:
Increasing difficulty seeing at night or in low light
Visual halos around bright lights
Glaucoma is a disease that damages the optic nerve, which connects eye to the brain. The condition usually is due to too much pressure in the eye. There is a fluid that normally circulates around the front of the eye. With many kinds of glaucoma, that fluid doesn't drain as well as it should. As a result, pressure builds up inside the eye. Over time, it starts to harm the optic nerve.
The retina is a thin lining on the back of the eye that is made up of cells that collect images and pass them on to brain. Retinal disorders block this transfer. There are different types:
The term "corneal disease" refers to a variety of conditions that affect mainly the cornea. These include infections, degeneration, and many other disorders that may arise mostly as a result of heredity. Diseases affecting the cornea are a major cause of blindness worldwide, second only to cataract in overall importance. The epidemiology of corneal blindness is complicated and encompasses a wide variety of infectious and inflammatory eye diseases that cause corneal scarring, which ultimately leads to functional blindness.
Some of the general eye related ailments are eye strain, red eyes, lazy eye, colour blindness, cross eyes (strabismus), Uvetis (group of diseases that cause inflammation of uvea - middle layer of the eye that contain most of the blood vessels),dry eyes, excess tearing, floaters, conjunctivitis and eye lid / sac problems.
Some of the general eye related problems particular to children are -