Test 4 Eye Flashcards
What structures do vision consists of?
- cornea
- pupil
- iris
- lens
- ciliary muscles
- chambers
- retina
vision
Sight is achieved when light is reflected into the cornea
light then passes through the pupil.
what does the pupil control?
The amount of light that enters the eye
dilating to enhance light entry
constricting to decrease
what happens to the eye when light enters?
The eye contracts the lens which is responsible for fine tuning and focus
Vision gives what?
The ability of the lens to changes its shape or accommodate, allows clear vision at a variety of distances
What are the chambers/compartments of the eye?
Anterior chamber
Posterior Chamber
what is the anterior chamber
Behind the cornea to the lens and iris
Contains a fluid called AQUEOUS HUMOR that nourishes the lens and cornea
what is the posterior chamber
Behind the iris
Contains a gelatinous fluid called VITREOUS HUMOR
The light that passes through the lens and vitreous humor is what?
Refracted, onto the retina
what does the retina contain?
Photoreceptors called rods and cones
Rods produce what?
photopigment (rhodopsin) allowing vision in dim light (night vision)
Cons provide what?
The ability to see bright light and color
what are the three types retinal cones?
- Erythrolabe- red cone
- Chlorolabe- green cone
- Cyanolabe- blue cone
Color vision is determined by what?
The combination of cones stimulated by light from a particular image
The absence of a single group of color receptive cones results in what?
The ability to distinguish colors (color-blindness)
sex linked recessive genetic trait
predominantly affects male
what is at the center of the retina?
The macula which is responsible for central vision, color vision and fine detail
Rods and cones convert light into what?
electrical impulses
which is transmitted to the bipolar neurons then the ganglion neurons
The axons of ganglion neurons meet where?
The optic disk and exit the eye as the optic nerve
The impulse travels to the optic tract…?
The thalamus, and the occipital lobe for processing
Extraocular muscles are responsible for what?
Rotation, horizontal, and vertical movement of the eyes
The six muscles that control eye movement are innervated by what?
oculomotor (III), Trochlear (IV), Abducens (VI)
Aqueous Humor
The ciliary processes secrete aqueous humor that helps maintain the shape of the anterior chamber
also nourishes the the structures in this part of the eye
Visual Acuity
to determine the status of vision
snellen eye chart is used
placed 20 feet from patient
what do you use to measure the pressure in the eye?
Tono-Pen- Handheld electronic device that contacts the cornea with latex tip plunger
Slit Lamp Biomicroscopic examination
To examine the surface of the eye
detect “floater” in the vitreous humor and abnormalities
Retinoscopy
To inspect the fundus (back portion) of the eyeball
Arcus Senilis (age related)
an opaque RING outlining the cornea, sometimes resulting in fatty globules
Xanthelasma
soft, raised, yellow areas, sometimes appears in eye;id after age 50 made up of cholesterol deposits that accumulate underneath the skin.
Different conjunctivitis?
Viral- usually affects one eye, watery discharge
Bacterial- usually affects both eyes, heavy discharge
Allergic- usually affects both eyes, itching, redness, tearing (allergies)
Hordeolum
External stye; infected swelling near the lid margin on inside
Hordeolum s/s
Sharp pain that becomes dull and throbbing
rupture and drainage of pus bring relief
redness and swelling
Chalazion
internal stye; infection of meibomian gland
distorted vision. may require surgery
Chalazion s/s
small, hard tumor on eyelid
really angry
what contributes to vision loss?
Diabetes and hypertension
Macular degeneration
another cause of impaired vision
Myopia
Nearsighted
The eye focuses a image in front of the retina due to lens thickness
Hyperopia
farsighted
caused my focusing on an image behind the retina, which alters transmission of light
Astigmatism
irregular curvature of the cornea or lens
prevents the focusing of images, blurring vision
Presbyopia
condition of farsightedness associated with aging
correcting errors of refraction
prescription of eyeglasses or contact lens
photorefractive keratecomy (PRK) laser used to remove a thin layer of tissues from cornea
LASIK (laser) procedure for nearsightedness
Uvetits
inflammation of the uveal tract
corneal transplantation (keratoplasty)
replaces corneas that have been damaged by genetic disorders, trauma, ulcers, or disease such as keratitis
Cataract
causes blurred vision, becomes cloudy
Cataracts signs and symptoms
hazy, blurred, double vision
Glaucoma
comes on slowly and cause irreversible vision loss without presenting any other noticeable symptoms
Glaucoma patho
The IOP is determined by the rate of aqueous humor
Narrow angle angle (angle closure)
blocked drainage from getting out
medical emergency
