Week 3 Visual Dysfunction Flashcards
how often does someone in the United States become permanently blind
every 7 minutes
Definition of blind
central visual acuity of 20/200 or less in the better eye with best correction, or field limited to less than 20 degrees
definition of partially sighted or low vision
visual acuity better than 20/200 but less than 20/70 in better eye with best correction
how do blind people learn
through tactile or auditory materials
how do partially sighted or low vision people learn
enlarged print, optic aids like a magnifying glass or lens
decrease vision loss with AIDS
35-75% of AIDS patients have vision loss, can be totally blind. Early diagnosis is good, but vision loss is a late complication of AIDS
Anopsia
lack of vision in an eye, due to the interruption of an optic nerve
what is cortical visual impairment
cortical blindness, which is damage to the visual cortex.
does the eye show pathology in cortical blindness? what is the physiology
no, it is neurologic damage. The signal isn’t reaching the brain, or there is a hindered organization or decoding of information when it reaches the brain
TF: you may be able to get some degree of functional vision if vision stimulation is provided in cortical blindness
true
what is diabetic retinopathy
proliferation of blood vessels may cause hemorrhaging into the vitreous or scar formation of the retina.
when do vision problems start to occur in people with diabetes
20 years after the onset of the diabetes
can vision problems worsen if diabetes is uncontrolled
yes
what does diabetic retinopathy look like (if you were the patient)
black spots showing up in the visual fields or areas.
what is glaucoma, caused by what
increased pressure in the eye, from faulty drainage of the eye
what happens if pressure in the eye continues
decreased blood supply so the peripheral retinal cells die, and the optic nerve may be damaged.
what are symptoms of glaucoma
- poor night vision
- halos around lights
- fear of light/ sensitivity (photophobia)
- loss of contrast
- kids: tearing, sensitivity and spasming eye lids
what will the patient see if they have glaucoma
peripheral vision is lost, and a dark ring around their field of vision
what is hemianopia
interruption of the optic tract, resulting in loss of vision on one side of the visual field, in both eyes. so… images from only 1/2 of each eye will reach the brain. Only receives half-fields for each eye
when do we see hemianopia
in CVA/stroke
is there a treatment for hemianopia? what can we do
no treatment, we want to alleviate the cause (tumor or bleeding)
can we improve visual field loses in hemianopia
maybe with prisms
what is the most common hemianopia
right homonymous hemianopia (occurs in corresponding halves of the right visual field
what other kinds of hemianopia are there
left homonymous hemianopia (left visual fields)
superior hemianopia (upper field)
inferior hemianopia (lower field)
outer halves of the fields (bitemporal hemianopsia)
what happens to vision with brain stem strokes
ocular motility issues diplopia oscillopsia visual distortions paralysis of conjugate gaze
what two things must we differentiate with vision after a stroke
homonymous hemianopsia
neglect
is neglect a visual or perception problem
perception
can we treat both visual problems and neglect with scanning compensation
no, because you are not aware you have the neglect
nystagmus
oscillation of the eyes, movements that are jerky or slow, and decreased acuity because they cannot maintain a steady fixation
what happens with a farsighted (hyperopic) eye. symptoms?
the eyeball is too small, and light rays focus behind the fovea of the retina. may not want to read, may rub eyes, HA, dizzy, nausea.
what happens with a nearsighted (myopic eye). Symptoms?
eyeball is too long, and light rays focus before they reach the fovea. So you squint and frown.
What is astigmatism
irregular curvature of the cornea, causes visual fatigue, HA, frowning and squinting.
what is presbyopia
when the lens is less flexible and less able to accommodate for near point viewing. Middle age this happens
TF: refractive errors tend to be inherited?
true
what are some variables of the eye that can cause refractive errors
size, shape of cornea, shape of lens
what are the treatments of refractive errors in the absence of disease
glasses, contacts, lasik
can eye exercises help refractive errors
no
what is retinitis pigmentosa
hereditary, progressive retinal deterioration, and a slow progressive field loss
what does retinitis pigmentosa affect first, rods or cones? what can this lead to
rods, causes night blindness
what can retinitis pigmentosa lead to (vision wise)
tunnel vision
what is retinopathy of prematurity (ROP)
retrolental fibroplasia (RFL). occurs in premies that get high or prolonged oxygen. it is the proliferation of blood vessels and fibrous tissue through the retina and vitreous, stretches the retina, and can cause a retinal detachment. can have scattered vision
what is strabismus. when can it occur
deviation in position of one or both eyes due to muscle imbalance. can at certain distances or time
what is amblyopia
lazy eye, (a characteristic of strabismus)
TF: strabismus can be corrected with surgery, visual training (patching or eye exercises) or injecting paralyzing drugs into the muscles involved.
true
what are the three types of strabismus and which is the most common, least common
estropia (most common)
extropia
hypertropia (least)
estropia
deviation of the eye towards the nose.
extropia
deviation of one eye outward
hypertropia
deviation of one eye upwards, and is the least common
