Key points 16 Flashcards
What gene does retinoic acid impact?
alters Hox gene expression.
Why does a focimeter use green light?
Eliminates chromatic aberration
A patient with a chiasmal lesion undergoes Goldman visual fields, which shows a uniocular “pie in the sky” defect on the left.
Where is the lesion located?
This patient has a junctional scotoma, caused by a chiasmal lesion at the junction of the optic nerve and chiasm. This usually causes an ipsilateral central scotoma and a contralateral, uniocular “pie-in-the-sky” supero-temporal scotoma. The reason for these defects is that the lesion involves the ipsilateral optic nerve and von Willebrand’s knee, which is a group of fibres from the contralateral infero-nasal retina representing the contralateral supero-temporal field.
What are the causes of bilateral central or cecocentral scotomas
hereditary optic neuropathy
nutritional optic neuropathy (vitamin B12 and folate deficiency)
drug toxicity
tobacco-alcohol amblyopia
infiltrative disorders including syphilis and tuberculosis
What do Haab’s striae represent?
healed breaks in Descemet’s membrane and appear as horizontal curvilinear lines.
A 42-year-old Afro-Caribbean man with a history of sickle cell disease (SS) is found to have venous tortuosity and a pre-retinal haemorrhage at the equator superiorly. There are also new vessels in the periphery temporally in a sea-fan formation sprouting into the vitreous.
What is the most appropriate treatment?
This patient has Stage 3 proliferative sickle-cell retinopathy. New vessels (sea-fans) in sickle-cell retinopathy do not require urgent treatment, because they usually spontaneously regress by auto-infarction. Treatment in the form of pars plana vitrectomy is indicated for complications such as non-resorbing vitreous haemorrage or tractional retinal detachment threatening the macula.
Hypertension controlled by which medication has been shown to reduce the progression of diabetic retinopathy over 2 years?
The EUCLID study showed that lisinopril reduced the progression of diabetic retinopathy over 2 years.
What are the features of recessive CHED?
corneal oedema present at birth
non-progressive
nystagmus
What are the features of Dominant CHED?
decompensation occurs in the first or second year of life
progressive
nystagmus is NOT a feature
What ocular tumour closely resembles a regressed retinoblastoma:
A mulberry astrocytoma is endophytic and protrudes into the vitreous. Its appearance may be very similar to an endophytic or regressed retinoblastoma. Astrocytoma is benign, and is associated with tuberous sclerosis.
How is the Hess chart testing performed?
each square is 5 degrees. The central field is 15 degrees from primary position while the peripheral field is 30 degrees from primary position. The patient is seated at 50cm from the screen. To test the left eye, the red lens is placed in front of the right eye, and green lens in front the left eye. The red targets are seen only by the right eye (fixing eye). The patient is asked to superimpose the green light onto the red light and these positions are marked
A man wakes up from a coma with bilateral complete ophthalmoplegia involving the pupils and visual disturbance. His motor function in arms and legs is otherwise preserved.
In which vessel is the embolus?
The ‘top of the basilar artery’ syndrome is caused by an embolus at the top of the basilar artery, which causes ischaemia of the rostral brainstem, thalamus and portions of the cerebral hemispheres fed by the posterior cerebral arteries.
What are the features of serpiginous chorioretinopathy?
a bilateral condition that usually spreads outward from the optic nerve and/or macula in a serpentine fashion. Serpiginous chorioretinopathy is chronic and recurrent with poor visual prognosis and scotomata affecting the areas of involvement. Treatment with potent immunosuppressives may slow down the disease in some cases, but generally the visual prognosis is poor, especially with macular involvement.
A 4-year-old girl has a progressive right exotropia noticed by parents over the past 12 months. Her visual acuity is 6/60 right eye, 6/6 left eye. Dilated fundoscopy reveals a slightly elevated, charcoal grey mass centred at the optic disc and involving the retina. The lesion appears to involve both the RPE and retina and it is covered by thickened grey-white retinal and preretinal glial tissue. There is no associated retinal detachment, haemorrhage, exudation, or vitreous inflammation. There is a strong family history of hearing loss and skin lesions.
What is the most likely diagnosis?
The description of the retinal lesion in the question above is consistent with a combined hamartoma of the RPE and retina, which is associated with NF-2. Bilateral acoustic neuromas and skin neurofibromas are common features of NF-2.
Which iris nodules are grey or white in appearance:
Koeppe nodules are small nodules seen at the inner margin of the iris in patients with granulomatous anterior uveitis (or less commonly non-granulomatous uveitis). The nodules are composed of epithelioid cells and giant cells surrounded by lymphocytes. Busacca nodules are inflammatory nodules located on the surface of the iris within the stroma seen in granulomatous anterior uveitis.
What are Dalen Fuchs nodules?
focal accumulations of epithelioid-like cells between Bruch’s membrane and the retinal pigment epithelium (RPE). They may include depigmented RPE cells. They are classically associated with sympathetic ophthalmia (SO) and Vogt-Koyanagi-Harada (VKH) syndrome. They also may be found in tuberculous choroiditis and sarcoidosis.
What diseases are part of the ICE syndrome spectrum?
Progressive (essential) iris atrophy
Chandler’s syndrome
Cogan-Reese syndrome (iris-naevus syndrome)
100% SF6 expands to what proportion of its initial volume:
SF6 expands to twice its original volume, while C3F8 expands to 4x its original volume.
A patient has short stature, aortic stenosis and mental retardation. On examination the discs are cupped consistent with glaucoma. What is the most likely diagnosis?
Rieger’s syndrome involves posterior embryotoxon (anteriorly displaced Schwalbe’s line with 50% risk of glaucoma)
What are the EOG findings in chloroquine?
An abnormally low light-peak to dark-trough ratio on EOG may occur in retinal toxicity from hydroxychloroquine and chloroquine.
Which contralateral EOM does the 3rd nerve supply?
superior rectus (contralateral palsy)
Which (ipsilateral/contralateral) EOM is supplied by the 4th nerve
superior oblique (fourth) nucleus is paired and supplies the contralateral muscle.
What is Frosted Branch Angitis associated with ?
may be idiopathic or it may be secondary to other forms of retinal inflammation (infectious or non-infectious), most characteristically CMV retinitis.
What are associations of optic disc drusen?
idiopathic (often familial in an AD pattern)
pseudoxanthoma elasticum
angioid streaks
retinitis pigmentosa
Which sub-type of glaucomatous disc damage is associated with younger age at presentation, high IOP at presentation and diffuse field loss?
Type 4 (concentrically enlarging): characterised by thinning of the entire rim in the absence of notching. It is associated with a high IOP at presentation and tends to occur in younger patients. Field loss is frequently diffuse.
What are ocular features suggestive of CB melanoma?
Growth of lesion anteriorly or erosion through iris root into anterior chamber
Growth into the lens which may produce sectoral or diffuse cataract, subluxation, lenticular astigmatism
Extension through sclera producing a dark epibulbar mass
Diffuse growth pattern extending around the circumference of the ciliary body, a ring melanoma.
Localized displacement of the iris anteriorly or infiltration of the trabecular meshwork which can produce tumor- induced glaucoma
Separation from and/or disruption of overlying ciliary epithelium, decreasing the production of aqueous humor and thus decreasing the intraocular pressure.
An 18-month-old child has essential esotropia of 40PD for near and distance. Cycloplegic refraction is +1.50DS both eyes. The child is due to undergo right medial rectus recession with lateral rectus resection.
Using the strabismus surgical tables, which of the following is the MOST appropriate target to aim for in this case?
It is good practice in essential esotropia to aim for a small residual esotropia of between 7 and 10 PD post-operatively as this is well tolerated, allows good peripheral fusion and reduces the chance of consecutive exotropia.
