Upgrade to remove ads
2012.02.06 - PDX - Vision
Terms in this set (31)
How does a lesion posterior to the optic chiasm affect vision?
1. Bilateral 2. Homonymous (symmetrical) 3. Hemianopia (doesn't cross the vertical midline) 4. DOESN'T affect visual acuity
How does a lesion anterior to the optic chiasm affect vision?
1. Affect visual acuity 2. Cross both vertical and horizontal midlines 3. Unilateral or bilateral
How would a pituitary tumor affect vision?
It would compress the optic chiasm leading to 1. bitemporal hemianopsia 2. headaches 3. endocrine abnormalities
How would a retinal lesion affect vision?
1. Unilateral (mostly), but if bilateral it is asymmetric 3. One side of horizontal midline (usually)
What are the most common causes of visual impairment?
1. Refractive errors (hyperopia, myopia) 2. Cataracts (nuclear, posterior subcapsular, cortical) 3. Defects in Retina (macular degeneration) 4. Defects in cognitive process (amblyopia = cortical unresponsiveness) 5.
What is ametropia?
Refractive errors in eye (a - metr -opia 'without' 'measure' 'eye')
What are the causes of refractive errors?
1. hyperopia (far sightedness) 2. myopia (near sightedness) 3. astigmatism (oval cornea) 4. presbyopia (non-accommodating lens) 5. anisometropia (asymmetric refraction of eyes)
How do eyes refract light?
70% by tear layer and cornea, 30% by lens
What is hypermyopia, what causes it, how is it fixed?
1. Far sightedness, 2. Caused by an eye that is too short so focal point is behind the eye, 3. Fixed by a convex lens, converging lens, or positive diopter [green numbers on ophthalmoscope] ( lens with a shorter focal length).
What is myopia, what causes it, how is it fixed?
NORMAL in babies until 5 years of age!!! 1. Near sightedness, 2. Cause by an eye that is too long, 3. Fixed by a concave lens, diverging lens, or negative diopter [red numbers on ophthalmoscope] (lens with a longer focal length).
How does a pinhole test work, and what does a pinhole test assess?
It removes uncorrected refractive error so lens is able to accommodate for smaller visual field. 1. If vision normalizes, the patient only needs glasses. 2. If vision isn't fixed, patient has other problems (ie astigmatism, cataract)
What is an astigmatism, what symptoms would occur with it, and how is it corrected for?
1. Oval cornea => multiple points of focus 2. Frontal headaches 3. Cylindrical lens
What is presbyopia, who gets it, and what are the symptoms?
1. It is an inability of the lens to accommodate for near objects. 2. It occurs in EVERYONE (usually beginning by age 40). 3. People hold things out further to see them (ie books). [from 4 inches at age 35, to 39 inches at age 50]
What is anismetropia?
When a patient's two eyes have markedly different refractive errors.
What causes a cataract and what are the three types?
1. Smoking, UV light, Diabetes Mellitus for all three (nuclear, posterior subcortical, and cortical), 2. Chronic steroid [glucocorticoid] use (posterior subcortical).
What tests can you use to tell if a patient has a cataract?
1. Pinhole test (visual acuity is NOT fixed) 2. Red Reflex (obscured by cataract -> black shadows/small dots on red background)
How do you do the Red Reflex test?
Hold ophthalmoscope 12 inches away from eye with the diopter at 0. See if you can see all red in the pupil. OR hold it at 6 inches from eye with diopter at 5+ with a dilated pupil.
Who is most likely to have a cataract?
People 65+ years old. Babies born with congenital cataracts.
How can you tell if a patient has a nuclear cataract?
1. Visual acuity is not improved with pinhole. 2. They have "second sight" from improved near sight with enlargement of the lens. 3. Night vision gets worse and has a glare. 4. Red Reflex has central dark spot
How can you tell if a patient has a posterior subcapsular cataract?
1. Visual acuity is not improved with pinhole.2. Patient has a decrease in near vision 3. Commonly associated with chronic steroid use or radiation 4. Red Reflex has spots in the middle 5. Most rapidly progressing
How can you tell if a patient has a cortical cataract?
1. Visual acuity is not improved with pinhole. 2. Have better far vision (due to pinhole effect), but then lose both near and far vision. 3. Vision isn't affected until it covers the middle of the lens (it starts peripherally)
What are risk factors for macular degeneration?
1. Age 2. Smoking 3. Female 4. Light skin
Describe the normal development of visual acuity.
Visual cortex NEEDS stimulation in order to maintain connection to eye. Without stimulation, the visual cortex becomes inable to receive stimulus if not corrected by age 10-14 years. Macular maturity by 3-4 months. Normal acuity by 3 years.
What is amblyopia and what causes it?
Cortical unresponsiveness of one eye (eyes are 2+ lines different on Snellen chart), while both eyes are normal appearing. Caused by 1. strabismus (developmental or aquired misalignment of the eyes) 2. anismetropia (difference in refractive error btw eyes) 3. congentical cataracts (occlusive amblyopia or retinoblastoma)
What is strabismus, what kinds are there, and who has it?
It is developmentally or aquired misaligned eyes (normal until 4 months of age). Convergent/divergent comitant/noncomitant, vertical, heterotropia, heterophoria, and mechanical.
How do you test for strabismus?
1. Corneal Reflection Test (<6months old) - hold light 3 ft away from child to see if there is asymmetry in light relfection. 2. Cover Test (>6months old) - hold light 3 ft away while covering one eye of patient. Move cover to other eye and see if eye moves. If eyes move after moving cover = strabismus.
What is heterophoria? And how do you test for it?
(Type of strabismus) Misalignment of the eyes only when binocular vision is interrupted. Test for it by having the patient cover one eye (positive if the uncovered eye deviates either esotrophia [nasally] or exophocia [temporally] or vertically).
What is heterotropia? And how do you test for it?
(Type of strabismus) Misalignment of the eyes with both eyes open (esotropia [nasally] or exotropia [temporally] or vertically).
What is a comitant strabimus? And what would cause it?
Misaligned eyes that maintain their relative misalignment regardless of eye movement. Caused by congenital strabismus.
What is a noncomitant strabismus? And what causes it?
Misaligned eyes that don't maintain their relationship with different eye movements. Caused by cranial nerve palsies.
Early detection and correction of strabismus, anismetropia, and congentical cataracts will prevent amblyopia. MUST correct before 5-10 years!
THIS SET IS OFTEN IN FOLDERS WITH...
2011.10.05 - EBM - PrognosisCohortStudy
2011.10.14 - Embryo - Week 2-3
2011.10.14 - Biochem - Regulation of Blood Glucose
2011.10.05 - Physio - ArteriesVeinsCapillaries
YOU MIGHT ALSO LIKE...
Chp 14 - Eyes
Exam 3: Eyes & Visual System
Physical Exams Medical Terms and Info
OTHER SETS BY THIS CREATOR
Spanish - Chapter 2
Spanish - Chapter 1
PDX - 2012.02.27 - Thyroid
Physio - 2012.02.13 - HCO3-
OTHER QUIZLET SETS
What type of Jaundice?
Chapter 1 - Principles of Management