Exam 2 Material Flashcards
Where is the visual center located in the brain?
Occipital lobe
Half of the neocortex is involved with processing visual information
What protects the eye?
Protected by the bony orbital cavity and cushioned by fat 3/4 protected by bone, 1/4 protected by eyelids
Palpebral fissure
Where eyelids touch
Limbus
White goes into color; cornea and sclera
Pupil
Absence of tissue; aperture of the eye
Medial and lateral canthus
Corners of the eye
Conjunctiva (palpebral and bulbar)
Always clear unless pathology is present
Lacrimal apparatus
Tear glands
Palpated in exam to determine if there is lacrimal reguritation
Extraocular muscles
Multiple muscles that are attached to the eyeball that twists and turn the eyeball to where it needs to go.
Innervated by cranial nerves III, IV, and VI
CN IV allows eyes to look toward the nose
CN VI lets the eyes look laterally
CN III does all other movements
If eye is not moving correctly, what is the likely cause?
Innervation problem. Muscles normally are fine unless there is trauma.
What cranial nerve innervates the extraocular muscles that moves the eyes laterally?
CN VI
What cranial nerve innervates the extraocular muscles that moves the eyes toward the nose
CN IV
Layers of the eye
The eye is a sphere of three concentric coats
- Outer layer -sclera
- Middle layer - choroid: ciliary body, iris, pupil, lens, anterior chamber
- Inner layer - retina: optic disc, retinal vessels, macula
What is the center of vision in the eye
Macula
Does not coincide with where the optic nerve innervates
Dense cones and rods
Fovea: center of the macula - highest density of cones, no rods
What is in the retina
Macula (center of vision) and optic disc (where the optic nerve is attached to the eye)
Visual reflexes
- Pupillary light reflex (direct light reflex vs consensual light reflex)
- Light causes pupils to constrict
- Both eyes should constrict evenly with light shown only in one eye
- Accomodation
Vision pathway
Light to cornea to lens to retina to nerve impulses to optic nerve to visual cortex
What happens to depth perception when blind in one eye?
Do not have depth preception
Health history questions for eyes
- Vision difficulty? acuity, blurring, blind spots
- Pain
- Strabismus, diplopia
- Redness, swelling
- Watering, discharge
- Past history of eye problem
- Glaucoma
- Use of glasses or contact lenses
- Self-care behaviors - make up?
Equipment needed for Eye Exam
- Snellen or Rosenbaum
- Opaque card
- Penlight
- Ophthalmoscope
Snellen/Rosenbaum
Tests visual acuity (CN II)
Myopia
- Near sighted
- Flatter eyeball; more oblong
- Light focuses in front of the retina
- Develops in childhood
Hypermyopia
- Far-sighted
- Retina is too high
- Light focuses behind the retina
- Develops in childhood
How do glasses help with vision acuity?
Change the way the light foces so that it is cetnered on the macule
Hyperopia uses convex lenses
Myopia uses concave lenses