Eye Terminology
Astigmatism – the surface of the eye is not round, but is more like the surface of an egg or a football. Part of the cornea has a flat curvature and part has a steeper curvature. This causes two focal points and makes vision at distance and near blurry
Cataract – an opacity or cloudiness of the crystalline lens that prevents a clear image from forming on the retina. The opaque or cloudy lens may require surgical removal if visual loss becomes significant, with the lost optical power being replaced with an implanted intraocular lens. Cataracts may be caused by trauma, disease or age.
Cornea – the clear covering on the surface of the eye.
(see picture)
Farsightedness – see hyperopia
Glaucoma – a group of diseases characterized by increased intraocular pressure resulting in damage to the optic nerve and retinal nerve fibers. Glaucoma is evidenced by typical visual field defects and increased size of the optic cup. While irreversible, further damage from glaucoma can be prevented with either medication of surgery. Glaucoma is a major cause of preventable vision loss.
 |
| An intraocular lens (IOL) |
IOL (intra-ocular lens) – this is a specialized piece of plastic that is placed in the eye during cataract surgery. This replaces the natural lens of the eye that over time has become a cloudy cataract.
Iris – the colored part of the eye.
(see picture)
 |
| Hyperoptic refraction |
Hyperopia (farsightedness) – the surface of the eye is flatter than normal or the eye is shorter than average. This causes the eye to focus images behind the retina. Near vision is very poor and distance vision may or may not be affected.
LASIK – a refractive laser procedure that is used to change the shape of the cornea to better focus light on the retina. This can treat myopia, hyperopia and astigmatism. A flap is made and the laser is used underneath the flap. This procedure, when successful, allows patients to be less dependent on glasses. (click here for more information)
Macular degeneration – one of the most common causes of decreased vision after age 60, macular degeneration is the breakdown and damage of the central retina, or macula. The most common form is called “dry” macular degeneration, which is caused by aging and thinning of the tissues of the macula. Vision loss under the “dry” form is gradual. The other less frequent form is referred to as “wet” macular degeneration where abnormal blood vessels may grow under the retina and leak fluid and blood. These changes can cause rapid and severe vision loss.
 |
| Myopic refraction |
Myopia (nearsightedness) – the surface of the eye is steeper than normal or the eye is longer than average. This causes the eye to focus images in front of the retina. Distance vision is poor and some degree of near vision is good.
Nearsightedness – see myopia
Ophthalmologist (Eye MD) - a doctor who has received graduate training in a medical school and then sub-specialized in eye care. They can do routine eye exams, prescribe glasses and contacts, diagnose eye diseases, prescribe all types of medications, and do eye surgery.
Optician – a person trained to fit, adjust and dispense glasses and contact lenses. Some opticians may be involved in the manufacturing of the lens material for glasses.
Optometrist - a doctor who has received graduate training in an optometry school. They can do routine eye exams, prescribe glasses and contacts, diagnose eye diseases and prescribe some types of medications. They cannot do surgery. However, they are not medical doctors.
Optic nerve – the connection between the eye and the brain. This sends the information received by the retina to be interpreted by the brain. (see picture)
Presbyopia – the natural aging and loss of flexibility of the lens in the eye. This is a normal age-related issue that affects most people beginning around age 40 to 45. This is usually treated with glasses or contact lenses. Refractive laser surgery can provide a temporary benefit for this.
PRK – a refractive laser procedure that is used to change the shape of the cornea to better focus light on the retina. This can treat myopia, hyperopia and astigmatism. In this surgery, a flap is not made, instead there is a large abrasion on the surface of the eye for 2 to 5 days. This procedure, when successful, allows patients to be less dependent on glasses.
Pupil – the black circle in the eye. Its’ size is controlled by the iris. This regulates how much light enters the eye. It also affects the depth of field that a person sees. This is not a structure, it is only an empty space.
Retina – the back layer of the eye that senses light and sends impulses that travel through the optic nerve to the brain. This is the part of the eye that actually does the “seeing”. The central part of the retina is called the macula and is responsible for our fine detail vision.
|
