Key points 11 Flashcards
Which sign is considered classic for CT imaging in thyroid eye disease?
multiple extra-ocular muscles are involved. There is fusiform muscle enlargement with sparing of tendons.
What are the features of MEWDS?
typically occurs in females in the third to fourth decades. It typically presents with shimmering photoposias and paracentral scotomas. These scotomas often correspond to an enlarged blind spot on visual field testing. The condition is usually self-limiting with recovery in 4 to 10 weeks. Usually no treatment is necessary.
What cataract is seen in Myotonic dystrophy patients?
fine cortical iridescent opacities (Christmas tree cataract), which are visually innocuous and occur in 90% of patients by the third decade. These evolve into visually disabling stellate posterior sub-capsular opacity by the fifth decade.
What lesion is felt to be the immediate precursor to a full-thickness macular hole
Idiopathic macular holes are believed to arise because of both tangential and anteroposterior vitreous traction. The earliest change is loss of the normal foveal depression due to elevation of the fovea itself off the retinal pigment epithelium (RPE), thereby constituting a tiny sensory retinal detachment. This appears clinically as a yellow dot or ring (stages IA and IB, respectively).
What are differentials of nystagmus in an infant?
albinism
Leber’s congenital amaurosis
achromatopsia or rod monochromatism
optic nerve hypoplasia
aniridia
The presence of polychromatic cataract in association with chronic progressive external ophthalmoplegia (CPEO) suggests the diagnosis of:
myotonic dystrophy
Why is subtenon corticosteroid injection contraindicated in sclerokeratitis?
it may cause scleral thinning and increased potential for perforation.
What are the Causes of cicatrical conjunctival changes:
Stevens-Johnson syndrome
ocular cicatricial pemphigoid
atopic keratoconjunctivitis
chemical burns
trachoma
squamous cell carcinoma
infectious conjunctivitis
scleroderma
What are the Risk factors for steroid-induced raised IOP
POAG
pigmentary glaucoma
family history of glaucoma
family history of steroid response
high myopes
diabetics
Broad nasal bridges with abnormally large angle kappa may lead to an error in the diagnosis of strabismus with which methods?
The Krimsky and Hirschberg methods use apparent eccentricity of pupillary reflexes and may be misguided by these factors.
After dark adaptation, how much more sensitive are rods than cones?
Rods are approximately 1,000 times more sensitive than cones during dark adaptation.
Causes of optic nerve hypoplasia:
de Morsier’s syndrome (rare but exam favourite!)
aniridia
high myopia
albinism
coloboma
Goldenhar
Duane’s
microphthalmos
Aicardi
Potter’s
midline facial defects: cleft palate, hare lip
What is the incidence of clinically relevant cystoid macular oedema requiring treatment after phacoemulsification cataract surgery?
The incidence of clinically relevant CMO post-cataract surgery is about 1% across studies, although angiographic and OCT evidence of CMO may be found in up to 10% of patients.
What percentage of patients initially diagnosed with a non-ischemic central retinal vein occlusion (CRVO) of less than 1 year duration will develop iris or angle neovascularisation within 4 months of follow-up as determined by the CVOS study?
For central retinal vein occlusions initially diagnosed as non-ischaemic, 5% developed iris or angle neovascularisation at 4 months and 10% developed iris or angle neovascularisation at 3 years.
A patient presents with bilateral reduced vision. On examination, there is bilateral flare, anterior chamber cells, cataract and cells in the vitreous. The fundi show multiple naevus-like pigmented choroidal lesions. B-scan shows diffuse choroidal thickening. ERG is reduced.
This presentation is most typical of:
The features are most in keeping with diffuse uveal melanocytic proliferation which is a paraneoplastic syndrome occurring in patients with systemic, often occult malignancy.
What is variance?
a measure of the spread of observations about the mean and it is equal to the SD (Standard deviation) squared
What are The units of z-score in a standard deviation?
a value with a z-score of +1 lies 1 standard deviation above the mean
Where do 68% of distributions fall in a normal distribution?
within 1 s.d. on the either side of the mean
Where do 95% of distributions fall in a normal distribution?
within 2 s.d. on the either side of the mean (more exactly, 95% observations fall within 1.96 s.d. either side)
Where do 99% of distributions fall in a normal distribution?
fall within 3 s.d. on the either side of the mean
A right homonymous hemianopia with asymmetric OKN drum responses suggests a lesion in the:
Parietal lobe lesions classically produce an inferior quadrantanopia, but they can also produce an incongruous homonymous hemianopia. The parietal lobe is responsible for ipsilateral pursuit, which means lesions of the parietal lobe cause asymmetric OKN drum responses with slowing of the response when the drum is rotated towards the side of the lesion (away from the visual field defect).
