(Alphabetic listed - not to be considered as an all inclusive listing)

Albinism- A deficiency of pigment in the retina, iris, and choroid of the eye. This is often associated with reduced visual acuity, nystagmus, and photophobia. There is also a lack of pigment in the hair and skin. This is hereditary.

Amblyopia- A "dimness" or decrease in vision in one or both eyes without any apparent disease, structural flaw, or damage to the eye(s).

Ametropia- Any refractive error of the eye that can be corrected by either glasses or contact lenses.

Aniridia- The absence of the iris in the eye. Aniridia is generally at birth and it typically occurs in both eyes (bilateral).

Anophthalmia- Absence of the eyeball.

Aphakia- This is when the natural lens of the eye is absent. This is usually the result of surgery for cataracts.

Astigmatism- A refractive error in the eye which prevents the light rays of an image from coming to a single point on the retina. This is mostly caused when the surface of the cornea and/or lens is not evenly curved.

Blind Spot- A "blank" area in the visual field. Can be caused by something inside the eye, such as a damaged retina or a dense cataract, or something outside the eye, such as part of a glasses frame. Each eye has a "normal" blind spot which is the optic disc. This is often referred to as the Natural Blind Spot or Physiological Scotoma.

Cataract- Any cloudiness or opacification of the lens and/or its capsule (the membrane which encloses the lens).

Coloboma- A cleft in the eye, that is present from birth, due to the failure of the eye to completely close while being formed. It can affect the iris, choroid, and/or retina.

Congenital- Means present at birth or shortly thereafter.

Conjunctiva- The clear mucous membrane which lines the inside of the eyelids and the front part of the sclera. It provides lubrication and protection for the eyeball.

Conjunctivitis- Any inflammation of the conjunctiva. "Pink Eye is one type of conjunctivitis.

Diplopia- The seeing of one object as two. Can be the result of strabismus.

Emmetropia- The absence of a refractive error in the eye(s).

Enucleation-The removal of an eyeball by surgery.

Esophoria-The tendency of an eye to turn inward.

Esotropia- The actual turning inward of an eye.

Extraocular Muscles- The six muscles that attach the eye to the head and that are responsible for the movement of the eye up, down, left, right, etc.

Exophoria- The tendency of an eye to turn outward.

Exophthalmos-The abnormal protrusion (outward bulging) of an eyeball.

Exotropia- The actual turning outward of an eye.

Fovea- The small depression in the middle of the macula that has the most acute (or sharpest) vision.

Fundus- The inside back of anything, but in this case, the inside back of the eye.

Glaucoma- The increase of pressure inside the eyeball (increased intraocular pressures) that is caused by an accumulation of aqueous humor. This, in turn, puts pressure on the optic disc, destroying vision.

Hemianopsia (aka Hemianopia)- Blindness of one-half of the visual field in one or both eyes. The field loss can be vertical or horizontal, ( top, bottom, ride side or left side).

Hyperopia- Farsightedness. A refractive error that happens when the eyeball is too short and/or the refractive power of the eye is too weak resulting in light rays coming to focus to a point behind the retina. The person is able to see objects clearly at a distance, but needs correction for focusing on objects close up. + lens

Hyperphoria- The tendency for one eye to deviate (or turn) upward.

Hypertropia- The consistent deviation (or turning) of one eye upward.

Iris- The colored, circular part of the eye behind the cornea that forms the pupil. The iris controls the amount of light entering the eye by changing the size of the pupil.

Keratitis- An inflammation of the cornea.

Keratoconus- A cone-shaped deformity of the cornea.

Macrophthalmia- An abnormally large eyeball.

Macula, Macula Lutea- The small area in the middle back of the eye/retina that is responsible for central vision - the vision used for seeing fine detail and colors.

Macular degeneration- A degeneration of the macular area of the retina. This creates loss of central vision, a central blind spot/central scotoma. This is one of the most common causes of vision loss in persons over the age of 60. The cause is not yet fully determined. This can also occur in children and young adults. This tends to be hereditary.

Microphthalmia- An abnormally small eyeball.

Myopia- Nearsightedness. A refractive error that happens when the eyeball is too long and/or the refractive power of the eye is too strong resulting in light rays coming to focus to a point in front of the retina. The person is able to see objects clearly close up, but needs correction for focusing on objects far away. - lens

Nystagmus- Involuntary, rapid, jerky, and repetitive movements of the eyeball.

Optic Nerve Atrophy- The nerve connecting the eyes with the brain. This carries neural impulses from the retina to the brain. Atrophy is the degeneration of the optic nerve.

Photophobia- A sensitivity to and discomfort from light.

Presbyopia- When, due to the normal aging process of the eye, the lens is no longer able to accommodate when focusing on objects at a close focal distance. Near tasks such as reading, are affected. Stronger reading glasses or a bifocal is needed to help the eye accommodate to near tasks.

Ptosis- A drooping of the upper eyelid.

Retinal Detachment- When the retina pulls away from the choroid.

Retinitis Pigmentosa- A degeneration and atrophication of the retina which has a hereditary cause. In most cases, it involves the loss of peripheral vision often — eventually resulting in the loss of all vision.

Scotoma- A gap or a blind spot in the visual field that may be caused by damage to the retina or visual pathways.

Strabismus-Any misalignment of the eyes when both eyes are uncovered. This is due to an imbalance of the eye muscles that control the movement of the eyes.

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