Optometry Terms: D-E
Diabetic retinopathy: A degenerative disease of the eye caused by the damage done to blood vessels in the retina due to complications from diabetes mellitus. Diabetic retinopathy can eventually lead to blindness.
Dilated pupil: Normally the pupil dilates (opens) in low light situations so that more light can reach the retina, allowing vision even when it’s dark. There are some diseases that cause dilated pupils inappropriately, as well as drugs or other trauma.
Diopter: The diopter is a unit of measurement which identifies the light bending ability (refractive capacity) of a lens.
Diplopia/double vision: Seeing to images of one, single object. Diplopia can be caused by poor functioning of the extra-ocular muscles, or
Drusen: Plural of Druse, drusen are blobs of small, white or yellow deposits which build up on the retina or on the head of the optic nerve.
Dry eye syndrome: More common as people age, dry eye syndrome can be caused by the reduction in the production of tears. In more unusual cases it can be connected to rheumatoid arthritis, lupus erythematosus, and other illnesses.
Ectropion: The turning outward of the lower eyelid. In newborns it is an indicator of Harlequin type ichthyosis, but it also can be due to weakening of the tissue of the lower eyelid. Surgery can correct the condition.
Emmetropia: An eye which is in a state of emmetropia (Greek for ‘well-proportioned’ or ‘fitting’) does not need correction. Emmatropia means that when the eye lens is in its relaxed or neutral state an object far away (at infinity) is in sharp, perfect focus.
Entropion: Medical condition which causes the lower eyelid to turn inwards. Entropion can be quite uncomfortable due to the constant rubbing of the eyelashes against the cornea. Several factors can cause entropion including scarring caused by trachoma, or can be inherited.
Esotropia: Esotropia is a type of strabismus which can cause either one or both eyes to turn inward. The person with esotropia has a cross-eyed appearance, which can be present constantly or intermittently. Esotropia is sometimes called lazy-eye, incorrectly.
Excimer laser- actually called an exciplex laser. An ultraviolet laser often used in eye surgery.
Exotropia- when one or both eyes point outward.
Extraocular- located outside the eyeball.
Eyelid- a thin fold of skin that protects and covers the eye.