cornea
refraction of light
choroid
blood supply
ciliary body
secretion of vitreous fluid; helps change the lens shape
eyelid
protection
iris
controls light entering the eye through the pupil
lacrimal glands
tear secretion
lens
light refraction
optic nerve
transmits visual info to the brain
retina
transforms optic signals into nerve impulses
rods
distinguish light from dark; perceive shape and movement
cones
color vision
sclera
external protection
Daltonism
difficulty distinguishing two colors, typically red and green cones are affected. It is also an inherited disorder.
Achromatic vision
total color blindness, inability to see color at all.
Snellen chart
tests the clearness or sharpness of vision.
ophthalmometer
instrument used to measure eye.
Myopia
near-sightedness, parallel rays entering the eye are focused in front of the retina.
Hyperopia
farsightedness, or the inability of the eyes to focus on nearby objects; rays of light entering the eye are brought to focus behind the retina.
Astigmatism
uneven focusing of an image
Visual acuity
distinguish letters and numbers at a given distance.
Tonometry
measurement of intraocular pressure.
Presbyopia
hyperopia and impairment of vision caused by age.
amblyopia, strabismus
Reduced vision in one eye, not correctable by glasses but by wearing eye patch.
blepharitis
Inflammation of the eyelid
cataract
An abnormal progressive condition of the lens, characterized by loss of transparency
achromatopsia
Profound inability to see color
conjunctivitis
Inflammation of the conjunctiva; also called red eyes or pink eye.
glaucoma
An abnormal condition of increased pressure within the eye. Prolonged pressure can damage the retina and optic nerve.
hordeolum
Sty, or stye, resulting from an infected sebaceous gland of an eyelash
macular degeneration
A progressive deterioration of the retina associated with new vessel formation that can progress to blindness
nyctalopia
Poor vision at night or in dim light.
photophobia
Excessive sensitivity of the eyes to light.
Macular Degeneration
the blind spot in the center shows the loss of central vision.
ptosis
Drooping of the upper eyelids; blepharoptosis.
retinal detachment
Separation of the retina from the choroid, usually resulting from a hole or tear in the retina
retinopathy
Any disease of the retina. Diabetic retinopathy is an abnormality of the retina caused by diabetes mellitus
,iridectomy
surgical removal of part of the iris