Optic Nerve Work-Up and Testing Flashcards
What is the most common optic neuropathy?
Glaucoma
What type of disorders can patients experience photopsias?
retinal disease, optic nerve dysfunction, cerebral dysfunction from migraine and other disorders
Why might past meds be important?
relevant to optic nerve disease
(amiodarone, ethambutol, tretinoin)
Which medications are relevant to optic nerve disease?
ischemic, toxic and intracranial pressure
- Ischemic: amiodarone
- Toxic: ethambutol
- Intracranial pressure: vitamin A related compounds (tretinoin)
Why is it important to cross reference meds and medical history?
Meds might reveal undisclosed medical conditions
How can we formulate differential diagnoses?
localizing visual loss
What does Ishihara test detect?
gross red-green only (designed for X-linked deficiencies)
What does the Angel Anomaloscope detect?
sensitive R/G (there is a blue-yellow version now)
What does HRR detect?
mild R/G or B/Y
What does D-15 detect?
Gross R/G or B/Y
What does FM-100 detect?
Sensitive R/G or B/Y
What comprises the majority of acquired color vision deficiencies?
Tritan
Congenital/ hereditary color deficiencies are almost ALWAYS which type?
red-green and males
Where is the defect when a patient has reduced contrast sensitivity but normal acuity?
non-specific: may be media, retina, optic nerve
Unilateral traumatic optic neuropathy does/does not cause an afferent pupillary defect?
does
which eye do you place a neutral density filter over to grade an APD?
the “good eye”
How do you perform the “Tilt Test”?
place 0.3 (50%) ND filter over the “bad eye”- should become a 1+ APD; place 0.3 (50%) ND filter over the “good” eye- should be NO APD
-penalizing the suspected bad eye should make the APD more obvious while putting it over the good eye should make it go away
which visual field measurement can roughly correspond to APD grade?
mean deviation; a large difference in mean deviation should show a large APD
Which pupil pathway starts at the outer retina?
afferent (rods and cones have input to intrinsically photosensitive ganglion cells)
Where do the afferent pupil fibers synapse?
midbrain (NOT LGN)
What 3 components contribute to the pupillary light reflex?
rods, cones and melanopsin
What does melanopsin do?
causes a constriction that is maintained for many seconds after light offset
Melanopsin is relatively sensitive to shorter-wavelength light
What are the two ways the optic disc responds to acquired pathologic processes?
swelling; pallor
Edema/ Atrophy is a sign of an active disease process while Edema/Atrophy may be either active or old
Edema, Atrophy
Neither swelling nor pallor appearance alone give the diagnosis
What are signs of true disc swelling?
Blurring of disc margin and small vessels
may have flame heme, CWS, hard exudates
What is the cause of true optic disc swelling?
Obstruction of axonal transport at the lamina cribrosa
What are late signs of disc swelling?
- gray or yellow atrophic appearance
- “Drusen like” hard exudates
- peripapillary retinal vasculature may be narrowed with a sheathed quality
- disc may no longer be capable of swelling even if there is a new insult
What should you suspect if a patient presents with a hyperemic disk with flame-shaped hemes?
ischemia
especially if small cup and segmental (superior or inferior)
What should you suspect if a patient presents with mild disc swelling without heme?
compressive/ infiltrative cause if subacute; inflammatory if acute and painful, toxic or matabolic if bilateral
What should you suspect if a patient presents with pallid edema?
if acute: severe infarct of optic nerve
Late-stage changes that occur in the optic nerve are a result of axonal degeneration in what pathway?
pathway between retina and LGN
visual function is disturbed. appearance of optic nerve head is changed
What type of pallor occurs in Retinitis Pigmentosa and cone-rod dystrophy?
“waxy”
caused by glial proliferation
What type of pallor occurs with macular conditions?
temporal disc pallor
not waxy
what are 4 causes of cupping that are non-glaucomatous optic neuropathies?
- compressive lesions
- Ischemic (severe)
- toxic
- hereditary
non-glaucoma cupping usually has more pallor than cupping
5 examples of optic neuropathy with disc swelling
- papilledema
- papillitis
- compressive
- NAION
- AAION
4 examples of optic neuropathy without disc swelling?
- retrobulbar optic neuritis
- PION
- compresssive
- toxic/nutritional
