block 6 - patient cases Flashcards
How can FA be used in helping to diagnose AMD?
FA is typically used to detect the presence of a choroidal neovascular membrane (CNVM) where this is not obvious by other techniques. Since these new vessels are leaky, FA will show a brighter area in the macular area if a CNVM is present.
what is fluorescein angiography?
the gold standard for assessing retinal circulation
why is oct angiography (A) starting to be used alongside (sometimes instead of) FA?
-noninvasive technique so no need for dyes to be injected
- provides a much higher resolution of the retinal and choroidal circulation
-quicker than FA
what are the two types of dyes used in FA?
sodium fluorescein and indocyanine green (much less common)
with the latter it is icca
in FA, what could hyper fluorescence indicate?
-leakages of blood vessels
-defects of the RPE
-oedema
in FA what could hypo fluorescence indicate?
partially or totally occluded blood vessels
why is NaF good for FA
it is water soluble with high fluorescence efficiency so:
-can highlight leaky vessels
-provide a high contrast so easy to be seen
watch and be able to identify the cranial nerve palsy videos
ok
what kind of deviation is heterotropia?
manifest
what is the prevalence of heterotropia
present in 2-4% of the population
what questions may you ask a patient with double vision?
- Double check monocular? (cover RE)
- Horizontal / vertical / diagonal / torsional?
- Constant / variable / intermittent / getting worse?
- Same in all directions (comitant vs incomitant)
- More noticeable at distance or near? muscle clues)
- Pain / discomfort?
look at slide 8 of case 6 full -> in person teaching session patient case 6 -> block 6
also check slides 13-21
okay
for a patient suspected of tropia, how can you justify measuring monocular VA?
check if va is worse in the suspected eye
for a patient suspected of tropia, how can you justify measuring cover test?
allows you to quantify the tropia
for a patient suspected of tropia, how can you justify doing an internal eye examination?
so you can check the disks
for a patient suspected of tropia, how can you justify measuring pupil responses
to measure anisocoria and to check perrla for potential rapd
what signs and their corresponding muscles will mean a patient has a 3rd cranial nerve palsy?
-ptsois (levator muscle defective)
-absent adduction (MR defective)
-vertical abnormalities (SR, IR and IO) defective
-mydriasis on affected side (pupil
what is the most common cause of 3rd cranial nerve palsy in older patients?
most common being vascular cause
give an example of what a partial 3rd CV palsy is
where it can only affect the superior muscles or only affect the inferior muscles or maybe when just one muscle is affected e.g. medial rectus so the patient wont present with all the symptoms but still have a 3rd nerve palsy.
what variations of 3rd CN palsy are there?
-complete
-pupil sparing
-partial (superior division)
-partial (inferior division)
-individual muscles innervated by CN 3
what is complete CN 3 palsy
where Levator palpebrae superioris, pupil, MR, SR, IR and IO are allm involved
what is pupil sparing CN 3 palsy
where all muscles are involved but the pupil function is normal
what is partial cn 3 palsy in superior division?
where SR and levator palpebrae superioris only are affected
what is partial CN 3 palsy in the inferior division
where IR, MR IO, pupil and ciliary muscle are involved
how do you manage CN 3 palsy?
new onset can have serios underlying health conditions - urgent referral to secondary care
what are the congenital causes of EOM dyscunction?
- Neurogenic
- Mechanical
- Myogenic
- Trauma (gestational /delivery)
- Other
what are the acquired causes of EOM dysfucntion?
- Neurogenic
- Mechanical
- Myogenic
- Trauma
what are the signs of a 4th nerve palsy (in the right side)
-right hypertropia
-AHP where head tilted left, chin down and face turn left
what are the signs of a left 6th nerve palsy?
-esotropia on the affected side
-maximum laevoversion
-ahp of face turn left
what happens to the eyes in duane’s retraction syndrome?
both lateral and medial rectus retract so when the patient looks right, the eyes seem to be pulled back into their socket.
what are the signs of right Brown’s syndrome?
-Limited elevation of the eye in an adduction
-Mechanical restriction of the superior oblique tendon
-Looks like inferior oblique palsy
-Hypotropia in primary position
what are a and v patterns and how common are they?
where horizontal deviation varies in up and down gaze and affect 25% of the population
what is the A pattern?
where there’s 10 diopters more convergence in upgaze compared to primary position
what is V pattern?
where there’s 15 diopters more divergence in down gaze compared to primary position
what other patterns are there as well as A and V patterns?
X, Y and lambda patterns
what causes A and V patterns?
-abnormal horizontal/ vertical muscle action
-anatomical variations affecting muscle action
-abnormal muscle innervation
-variations in muscle insertions
how can you manage A and V patterns?
usually asymptomatic so dont need any management but it there are large symptoms like a big ahp or diplopia then you can refer for surgery
When is an abnormal head posture usually found?
usually in people with incomitant deviations and are rare in comitant deviations
why may some people develop AHPs?
-replaces lack of movement in the paretic eye by moving the head instead
-improves ease of fusion and reduction in diplopia
so overall improves BV potential
this is because the field would otherwise be asymmetrical due to the restricted eye movement
(occasionally, AHPs can increase diplopia)
are ahps found in old or new deviations?
both
how do you know if a patient has eso or exo tropia depending on their head turn?
esotropia - head is turned to the same side so to the right (to abduct the good eye)
exotropia - head is turned to the opposite side so to the left (to adduct the good eye)
how do you know if a patients head tilt means they have an excyclo or incylco tropia?
for excyclotropia - head tilts to opposite side - head tilt left - to bring the defective eye to vertical
for incyclotropia - head tilts to the same side - head tilts to the right
- to bring the defective eye to vertical
how do you know what vertical tropia a patient has by looking at their ahps?
chin down = hypertropia
chin up = hypotropia
what is muscle sequelae?
where patients with a cranial nerve palsy with time end up with changes in the actions of other muscles that control the eye movement due to sherrington’s and herring’s law - more obvious than others in some patients.
what is the pattern of development for muscle sequelae in order?
Say you want to turn your right eye out, there’s increased innervation to the eye that does not want to turn out and the contralateral synergist muscle overacts due to equal innervation (hering’s law)
Over time, you get an overaction in the ipsilateral antagonist due to sherrington’s law
Underaction of contralateral antagonist - (Hering’s law and Sherrington’s law)
