Visual System Disorders Flashcards
what are the 3 “vital signs” of ophthalmology?
1) Visual acuity
2) Pupils
3) intraocular pressure
What is an easy way to determine if decreased vision is only a refractive error?
Have them read a chart with only one eye open… and then have them read the same chart with only one eye open looking through a “pinhole”… If it’s easier to read, then its a refractive problem
*because a small hole will only allow perpendicular light to travel back to the retina, thus it won’t require focusing
What are the 5 steps involved in pupillary constriction?
1) retinal ganglion cells
2) pretectal nuclei
3) edinger-westfall nuclei
4) Parasympathetics via CN 3
5) Ciliary Ganglion to ciliary muscle for constriction
Give an example of left eye relative affarent pupillary defect
RAPD is a optic nerve problem (afferent signal). In this case, the left eye would not constrict with direct stimulation (AND there wouldn’t be a consensual response). But if light was shined in the right eye, the left eye would constrict (be consensual response) because that is efferent, not afferent.
How do you determine if double vision is neurologic or non-neurologic?
have the pt. cover one eye, if their vision is still “double” then it is a refractive problem (aka monocular diplopia = non-neurological)
if the pt. sees double ONLY with both eyes open, then it is neurological (binocular dipoplia = neurological)
What does an increased cup:disc ratio indicate?
Glaucoma (increased intraocular pressure) tends to cause an increased cup size… thus the C:D ratio will increase (because normally the disc is larger than the cup)
What does a diabetic retinopathy look like?
numerous microaneurisms in vessels of retina
what should you suspect in a person with blurry vision, visual field loss, and loss of color vision?
optic nerve probs
clinical characteristics of optic neuritis (3 of em)
1) 92% have ocular pain
2) rapid onset of central vision loss (5ish days)
3) unilateral presentation!
* 77%female, mean age 32
What is best treatment for optic neuritis?
IV steroids
*oral prednisone actually increased the risk of recurrence (bad!)
what are the outcomes of optic neuritis?
with IV steroids, they will recover most (if not all 70% back to 20/20) visual acuity and stays with them for a long time
what is the risk of developing MS with optic neuritis?
Depends on # of other white matter lesions at the time of optic neuritis…
- 0 other lesions = 22% chance of MS @ 10 years
- 1 or more white matter lesions = 56% chance of MS @ 10 years
Giant Cell arteritis characteristics (3 of em)
1) Rapid (hours to days) visual acuity loss
2) Jaw pain is very sensitive (headache, wt. loss also common)
3) extremely high erythrocyte sedimentation rate (measure of inflammation in body)
Diagnosis and treatment of Giant cell arteritis
temporal artery biopsy = gold standard
9-12 mo. of steroids!
visual field loss with pituitary tumor
optic chiasm compression (aka only the axons that cross) resulting in a bitemporal hemianopsia