Ch. 16- EYE Diseases and Conditions

achromatopsia

Severe congenital deficiency in color perception; also called complete color blindness

ametropia

Failure of light rays to focus sharply on the retina as a result of a defect in the lens, cornea, or shape of the eyeball; also called error of refraction

astigmatism (Ast)

Distorted vision resulting from a defective curvature of the cornea or lens causing light rays to diffuse over a large area of the retina rather than being sharply focused (correction for ____ requires the use of lenses that alter the way light enters the eyes)

hyperopia

Visual defect in which the eyeball is too short, and the image falls behind the retina; also called farsightedness (unable to see near) (correction requires the use of biconvex lenses)

myopia

Visual defect in which the eyeball is too long, and the image falls in front of the retina; also called nearsightedness (unable to see far) (requires the use of biconvex lenses)

cataract

Opacity that forms on the lens and impairs vision, caused by proteins that slowly build up over time (most are age related. surgical treatment to remove the clouded lens and replace it with an artificial intraocular lens (IOL) is one of the safest and most effective surgeries performed in medicine)

chalazion

Small, hard tumor developing on the eyelid, somewhat similar to a sebaceous cyst; also called meibomian cyst

conjunctivitis

Inflammation of the conjunctiva and inner eyelids with vascular congestion; also called pinkeye (causes include irritants, allergy, and viral, bacterial, or fungal infections. The viral form of _____ is highly contagious)

drusen

Small yellowish deposits composed of retinal pigment cells that develop under the retina and are associated with an increased risk of developing age-related macular degeneration

ectropion

Eversion, or outward turning, of the edge of the lower eyelid, causing it to pull away from the eye, generally associated with aging and weakness of the small muscles around the eyelid

entropion

Inversion, or inward turning, of the edge of the lower eyelid, commonly causing friction as the eyelashes and outer eyelid rub against the surface of the eye

epiphora

abnormal overflow of tears (sometimes caused by obstruction of the tear ducts)

metamorphopsia

visual distortion of objects (commonly associated with errors of refraction, retinal disease, choroiditis, detachment of the retina, and tumors of the retina or choroid)

nyctalopia

Impaired vision in dim light; also called night blindness (causes include cataracts, vitamin A deficiency, certain medications, and hereditary causes)

nystagmus

Type of involuntary eye movements that appear jerky and may reduce vision or be associated with other, more serious conditions that limit vision

papilledema

Swelling and hyperemia of the optic disc, usually associated with increased intracranial pressure; also called choked disc

photophobia

Unusual intolerance of and sensitivity to light (commonly occurs in diseases such as meningitis, inflammation of the eyes, measles, and rubella)

retinopathy

any disorder of retinal blood vessels

strabismus

Misalignment of the eyes so that they do not focus on the same object at the same time, sending two different images to the brain; also called heterotropia or tropia (most common forms are esotropia (ST) and exotropia (XT))

trachoma

Chronic, contagious form of conjunctivitis that typically leads to blindness