eye lecture 9 Flashcards
strabismus causes
congenital vs acquired
accommodative esotropia
- child has hyperopia
- focus so hard that eye turns in (esotropia)
what is the most common cause of strabismus?
hyperopia (far-sightedness)
intermittent exotropia
-a convergence error
Focus harder and bring eye in but eye will drift out sometimes
what medical conditions cause strabismus?
- Down’s syndrome
- Cerebral palsy
- Stroke – if stroke affects the nerve that causes an eye turn
- Head injury
- Prematurity and low birthweight
what is the problem in hypertropia?
CN IV palsy
how do people with hypertropia accommodate?
head turn/head tilt
what is worse, vertical diplopia or horizontal diplopia?
vertical
-person will start to function with using one eye only
txt of hyperopia
- Lenses
- Prisms (no more diplopia)
- Vision therapy
- Surgery – eye turns are too big to train them to fuse together
- Botulinum toxin – take the muscle that is over acting and put some botox in them and help the eyes align again
amblyopia
Condition where have one eye that isn’t functioning properly (e.g., exotropia) and brain suppresses it -> amblyopia (eye stops functioning)
-affects one in every 40 children
why don’t miss children with strabismus?
b/c associated with retinoblastoma
-20% of retinoblastoma have strabismus
what does a new onset strabismus/diplopia in adult mean?
aneurysm until proven otherwise
-EMERGENCY!!!
where does aneurysm occur with new onset strabismus/diplopia in adults?
posterior communicating artery (of circle of willis)
-pushes on CN3 - pushes eye down and out -> diplopia
what does gradual onset diplopia mean?
intracranial tumor - need MRI
what does transient or persisting diplopia mean?
temporal arteritis - HA, jaw claudication, scalp tenderness (painful to brush hair)
-seen in >50 y.o
what tests do you run for transient or persisting diplopia?
erythrocyte sedimentation rate or C-Reactive protein
variable diplopia seen in what?
myasthenia gravis - fatigue
- 2 forms: ocular and systemic
- starts with ocular and w/in 3 years can turn into systemic
what layer of the cornea results in a scar?
2nd lays - bowman’s layer
what side is most common for pterygium?
nasal side
what does pterygium start as in terms of symptoms?
Starts asymptomatic, but proceeds to dry eye, burning, gritty sensation
pathogenesis of pterygium
- Benign fibro-vascular proliferation and basophilic degeneration of corneal collagen
- Matrix metalloproteinase (enzymes responsible for degradation of extracellular matrix proteins) show signs of necrosis (surface of eye is changing and also starting to die)
- Destroys Bowman’s layer and superior layer of stroma of the cornea
what part of the pterygium is comprised of blood vessels?
body/tail
not cap or head
what is a pterygium a result of?
UV light exposure, dust, smoke, and low humidity
SURFERS EYE
diff dx of pterygium
Pannus
- Contact lens over wear
- Trauma to limbal stem cell area (stem cells that grow at edge of cornea)
Phlyctenular keratitis
-Delayed sensitivity – pt is experiencing hypersensitivity d/t staphylococcus (most common) or TB
txt of pterygium
-sunglasses/hats
-topical lubricants/mild steroid
-surgical:
Bare sclera – reoccurs
Auto graft from other area of eye
Amniotic membrane grafting
Mitomycin C and Beta irradiation – prevents growing of tissue
complications of pterygium
- Irritated, gritty eyes
- Cosmetic appearance – most of eye will be white except for pterygium that will be inflamed
- Contact lens intolerance
- Astigmatism – changes shape of cornea and makes it more of a football shape and get induced stigmatism
- Decrease vision
nuclear cataract
- Sits in center of lens
- most likely congenital (occurs while being developed)
- Can be due to infections that affect the mother or toxins (e.g., fetal alcohol syndrome)
- Usually so small that barely affect vision; usually not noticed until routine eye exam
- Typically don’t progress
when do you start to have difficulty seeing?
around 40 years old
why is nuclear cataract usually congenital?
b.c nucleus of lens is the first part of the lens that forms during fetal development
cortical cataract
spokes that come through from the side of the lens into the visual access
aka peripheral cataract
posterior capsular cataract
- Forms at the back of the lens (back surface on capsule)
- Looks like dirty smudge on lens, reflects bright colors
- Most visually devastating and grows fast
types of cataracts
- congenital
- age related (as you get older)
- secondary