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A clear fluid that fills the front of the eye and delivers oxygen and nutrients to the anterior ocular structures.


A blood vessel that brings blood (with oxygen and nutrition) to a tissue such as the retina.


A loss of tissue due to degeneration or impaired blood supply.


An opacity or clouding of the natural lens that normally occurs with aging and results in progressive blurred vision.


A layer of blood vessels within the wall of the eye that supplies oxygen and nutrition to the outer layers of the retina.

Choroidal Neovascularization

Abnormal, ‘new’ blood vessels originating from the choroid which grow underneath the retina; often leads to vision loss from bleeding, leakage of fluid, and scarring; most commonly seen with age-related macular degeneration, but also seen associated with other conditions.

Ciliary Body

The pigmented structure in the middle of the eye responsible for the production of aqueous humor (eye fluid)


The clear ‘watchglass’ covering of the front of the eye responsible for focusing approximately 2/3 of the light waves entering the eye


‘Yellowish deposits’ under the retina that may or may not be associated with retinal pathology; hard drusen are commonly found in otherwise normal eyes; soft drusen are associated with macular degeneration and may represent a manifestation of this disease


Inflammation of the anterior and posterior portions of the inner eye, often as a result of serious infection


The center of the macula, responsible for the finest level of vision and strongest color discrimination


The pigmented vascular structure of the eye that acts like a camera aperture, allowing varying amounts of light into the eye under differing lighting conditions; the round center is referred to as the pupil


Decreased blood supply causing damage to vital tissues such as the retina; often seen in diabetic retinopathy and other retinal vascular diseases


A clear structure within the eye responsible for focusing approximately 1/3 of the light waves entering the eye; also necessary for focusing up close for reading and near tasks (an ability that is gradually lost with age); the lens clouds over time resulting in cataract formation.


The central portion of the retina responsible for clear vision (reading/driving) and color perception; subject to certain diseases such as macular degeneration, macular edema, macular pucker, macular hole, etc.


A growth of abnormal, ‘new’ blood vessels in the eye often leading to vision loss from bleeding, leakage of fluid from the bloodstream, or scarring from a healing response.


A blockage in a structure (for example, a retinal vein occlusion represents a blockage of a retinal vein by clotted blood or other products).

Optic Nerve

The nerve that transmits an electrical signal carrying visual information from the retina to the brain for interpretation.


Light sensors in the retina responsible for converting viewed light into an electrical signal to be interpreted by the brain; divided into rods (contrast, brightness, night vision) and cones (color, fine vision).


The sensitive thin nerve tissue lining the back of the eye that receives a light image from the environment and converts it to an electrical signal that is sent to the brain for interpretation and creation of vision.

Retinal Pigment Epithelium

Also known as the RPE; a layer of cells beneath the retina that provides nutrition and metabolic support to the delicate light receptors (photoreceptors) of the retina; frequently affected by diseases such as age-related macular degeneration.


A disorder or disease of the retina; examples include diabetic retinopathy and hypertensive retinopathy.


The ‘white’ of the eye.


Collectively, the pigmented vascular middle layer of the eye wall (the iris anteriorly, ciliary body intermediately, and choroid posteriorly); subject to inflammation in a process termed uveitis.


Inflammation of blood vessels.


A clear collagenous gel that fills approximately 80% of the eye; located behind the natural lens and in front of the retina; has specific areas of attachment with the retina that can lead to tears or traction on the retina as the gel degenerates naturally with age; often removed in a surgery called vitrectomy.


Inflammation of the vitreous.


Inflammation of the uvea (see definition); anterior uveitis involves the iris while posterior uveitis involves the choroid.


A blood vessel that removes blood (with waste products) from a tissue such as the retina