Ophthalmology: Diplopia and Pupil Changes Flashcards
T/F imaging is needed for monocular diplopia
false.
Definition: a single eye registers two images because of anomalous bending of light into a single eye causing two images to form on the retina. Non-urgent but should be referred
Etiology: corneal warpage (ex keratoconus), cataract development, retinal anomalies (ex epiretinal membrane) Management: non-urgent ophtho consult. No imaging needed
Causes?
Investigations?
third nerve palsy: third nerve innervates SR, IR, MR, IO
the effected eye is down (SO) and out (LR) due to the unopposed actin of the SO and LR. If the pupil is dilated suggest compression; if the pupil is normal suggests ischemia
Investigation: STAT CTA/MRA: if pupil is dilated (Rule of the Pupil). Some pitfalls of the Rule of Pupil: non-isolate palsy or partial muscle paresis. So basically, image all CNIII Palsies, you don’t want to miss a deadly aneurysm.
Etiology: ischemic, aneurysm, tumour mass effect, increase intracranial pressure
Treatment: Treat underyling cause. glasses with prisms are required for unresolbed double vision> 6 months.
T/F if a person has 3rd CN palsy, but the pupil is involved, is it likely that the palsy is due to ischemia?
false. pupil is classically involved in compressie lesions of the 3rd CN. Classically uninvolved in ischemia.
MUST R/O ANEURYSM IN THE POSTERIOR COMMUNICATING ARTERY.
What muscle does CN4 innervate?
Symptoms of 4th nerve palsy?
SO4LR6: the CN4 innervates the superior oblique.
- can cause vertical diplopia, worsened with down gaze
“up and in”
What is this condition? In what demographic is it normal in? How can you correct it?
Esotropia: a 6th NERVE PALSY. It innervates the lateral rectus muscle. Therefore, the eye turns medially since the lateral rectus can’t really pull the eye ball laterally–> cannot adduct
- strabismus is normal in <3 months, but you should give glasses to anyone above that age.
STRABISMUS IN CHILDREN CAN BE DUE TO ELEVATED ICP
Esotropia = ___ palsy
exotropia = ___ palsy
Hypertropia = ____ palsy
Esotropia = 6th palsy
exotropia = 3rd palsy
Hypertropia = 4th palsy (could also be due to inferior rectus impingement from orbital blowout)
3rd CN palsy:
___ ____ or ____ = blown pupil dilation
____ causes = normal pupils
PCA ANEURYSM OR COMPRESSIVE 3RD CN PALSY = blown pupil dilation
ISCHEMIC causes = normal pupils–> little microvascular disease due to diabetes.
central (first order neuron) causes of Horner’s Syndrome
Thalamus, brainstem, or spinal cord; stroke, demyelination, neoplasm (could be lung cancer met to the brain)
pregnaglionic (second order neuron) causes of horner’s syndrome
thoracic outlet, mediastinum or pulmonary apex
o Tumour, thyroid tumours, trauma to thoracic spinal cord, chest tube placement, jugular vein cannulation
Classic triad of horner’s syndrome
Classic triad of PTOSIS (due to lack of sympathetic innervation of Muller’s muscle in the eyelid), ANHIDROSIS and MIOSIS (due to lack of sympathetic innervation to the dilator muscle)
Investigation
Urgent CTA head/neck (to r/o carotid dissection) + less urgent CXR (to r/o Pancoast’s tumour)
• Cocaine test: blocks the reuptake of norepinephrine. In the normal eye,
the pupil will dilate. In Horner’s syndrome, the pupil dilates poorly
Cranial Nerve III Palsy
Etiology: compression (tumour, aneurysm), vascular ischemia, trauma, intracranial neoplasm, hemorrhage, congenital, idiopathic
Symptoms: ptosis, pupil down and out (due to unopposed superior oblique + lateral rectus) + pupil dilation (sphincter pupillae)
Investigation: urgent CT-A
Damage to the optic chaism via pituitary tumor (example) causes ___ __
bitermporal hemianopsia
damage to specific occipital region of the brain=
homonymous hemianopsia
