Neuro Test #4
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- Transparent membrane that lines the eyelids
- Also located over white of eye on anterior surface
An enzyme that tears contain that inhibits growth of bacteria on surface of eye
Bony socket that provides protection from trauma
Cranial nerves involved in movement of eye
- Oculomotor (III)
- Trochlear (IV)
- Abducens (VI)
3 layers of wall of the eyeball
- Outer fibrous tunic (sclera and cornea)
- Middle vascular tunic (Choroid, ciliary body, iris)
- Inner nervous tunic (retina)
Choroid layer contains what
blood vessels and melanin which prevents glare by absorbing light
Two parts of eye that don't have capillaries
- Cornea (first part of eye that refracts light rays)
- Lens (permits focusing of light at varying distances)
Contraction of radial fibers of iris
Is a sympathetic response and dilates the pupil
Contraction of the circular fibers of iris
Is a parasympathetic response and constricts the pupil.
The area of most acute color vision
Fovea centralis - contains only cones
- Lines 2/3 of eyeball and contains rods and cones (photoreceptors)
- Rods: detect light
- Cones: Detects colors
Neuron cells that transmit impulses generated by rods and cones
Substance that keeps retina in place
- Vitreous humor
- Aqueous humor is the tissue fluid that nourishes the lens and cornea
Where are the visual areas in the brain
- Occipital lobes of cerebral cortex
- Upside down images are uprighted and converged into one image (binocular vision)
Most common changes in aging eye are located where
- Loses elasticity, may become opaque
Normal age related changes to eye
- Color vision fades
- Glare adaption difficult
- Decreased peripheral vision
- Decreased depth perception
- Increase in farsightedness
Visual impairment occurs at ____?
Legal blindness occurs at____?
Involuntary, cyclical, rapid movement of eyes in response to vertical, horizontal, or rotary movement
- Movement of eye away from visual axis
- Estropia: movement toward nose
- Extropia: movement laterally
- Ability of pupil to respond to near and far distances
- Normally, eyes turn inward and pupils constrict
One of the most simple ways to improve vision for older adult
Make sure eyeglasses are clean
The distance between the upper and lower eyelid
- Whitening of the outer rim of cornea.
- Considered normal and doesn't affect vision
Optometrist vs. opthalmologist vs. optician
- Optometrist: Treatment of visual problems (glasses)
- Opthalmologist: diagnoses and treats eye diseases
- Optician: Grinds and fits lenses
Diet and eyes
- Not enough Vit A: night blindness, corneal damage
- Not enough Vit B: Optic neuritis
- Obesity, high fat diet, low zinc: macular degeneration
What kind of solution is used for eye irrigation
- Contains eardrum that transmits vibrations through malleus, incus and stapes bones.
- The stapes then transmits vibrations to inner ear
Contains receptors for hearing and equilibrium
Auditory areas of brain
Temporal lobes of cerebral cortex
Aging and the ear
- Damage to hair cells in organ of corti
- Presbycusis (high pitched range lost) caused by loss of hair cells and decreased blood supplying the ear.
- Inability to distinguish s, z, t, f, and g
What disease is related to ear disorders
Test - patient stands with eyes closed. If there is swaying, it's positive and patient may have inner ear problem
Water is instilled into ear and if no nystagmus occurs, patient may have meniere's disease
- Postauricular - most common. Fits behind the ear.
- All in one eyeglasses aid - least common
Treatment for someone who is profoundly deaf
Coclear implant. Converts sounds into electrical signals.
Menieres disease diet
Low sodium. Increased fluid contributes to symptoms.
Ringing in the ear
- May indicate that damage may be occurring
- Occupational noise is the primary cause of hearing loss
- Bacterial (pink eye) caused mostly by strep or staph.
- Very contagious
- Treated with antibiotic eyedrops
- Cipro to treat - give on empty stomach
- Chronic inflammation of eyelids
- Treatment: Long term daily cleansing
- If infection occurs, erythromycin or bacitracin to treat
Hordeolum & Chalazion
- Hordeolum: external sty. No treatment unless doesn't heal
- Chalazion: Internal sty. May require surgical incision to treat
- Inflammation of cornea.
- Herpes simplex keratitis is most common
- Wearing contacts overnight increases risk of pseudomonas pathogen
- S/S:Photophobia, blepharospasm, opaque cornea
- Serious and often sight threatening
- See images far better than close.
- Eyeball is too short.
- Corrected with convex lenses
- Eyeball elongated
- See close better than far
- Corrected with concave lenses
Unequal curvatures of cornea
- Lenses lose elasticity
- Decrease in ability to focus on close objects
- Associated with aging and usually occurs after age 40
- 3 stages: Background, preproliferative and proliferative
- S/S: reduction is visual acuity or color vision
- Common to have no symptoms until proliferative stage
- Dx: exam of internal eye yearly if you have diabetes
- Separation of retina from choroid
- 3 causes: tear in retina, fibrous tissue in vitreous, fluid accumulation in subretinal space
- S/S: sudden change in vision, flashing lights or floaters, progressing to curtain being lowered, no pain
Primary open angle glaucoma
- Schlenm's canal degenerates and blocks flow of aqueous, Increase in IOPrisk ↑ >40
- S/S: Develops bilaterally. Gradual, painless, halos around light, visual changes
- Isopto or Pilocar to constrict pupil. Diamox, propine, Timoptic to slow progression.
- Lifelong use of eyedrops
Acute angle-closure glaucoma
- Occurs in people who have narrowed junction where iris meets cornea.
- Medical emergency , blindness if not treated
- Unilateral, rapid onset
- S/S: severe pain, blurred vision, rainbows around lights, photophobia
- Treatment: mannitol to reduce IOP, analgesics, complete bedrest.
- Mydriatics (atropine, benadryl) contra and may cause blindness
- Opacity of lens
- S/S: painless, halos around lights, difficulty reading in bright light, ↓ color vision, blurring of vision
Treatment: removal of cloudy lens
- Leading cause of visual impairment over 50
- Degeneration of macula.
- S/S: slow loss of near vision, dark or empty spot in center of vision, ↓ in color distinction
- No treatment for dry
Conductive hearing loss
- Inner ear not involved
- Many causes may be corrected. Hearing devices are usually effective
- Causes: Otosclerosis, fluid, perforation of eardrum, foreign bodies
Sensorineural hearing loss
- Originates in cochlea and involves hair cells and nerve endings
- Casues: Infections (measles, mumps, meningitis) drugs, noise, aging
- Most common infection of ear
- Staph is most common organism
- Swimmers ear when water left in ear
When irrigating ear, what position do you put ear?
- Adults: Upward and back
- Children: Downward and back
- Most common disease of middle ear
- S/S: fever, earache, feeling of fullness
- Complications: perforation of tympanic membrane (causes hearing loss), cholesteatoma, tympanosclerosis, mastoiditis
- Formation of new bone along stapes that causes conductive hearing loss
- No cure. Hearing aids to improve
- Stapedectomy is treatment of choice
- Balance disorder
- S/S: vertigo, hearing loss, tinnitus.
- Acute attacks occur 2-3 times yearly with eventual remission
- Avoid alcohol, caffeine and tobacco
- May be placed on methotrexate or given gentamicin injection
- Lasix (Furosemide)
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