Ophthalmology Flashcards
Causes of Optic Neuropathy
Unilateral
- Ischaemic e.g. GCA
- Demyelination e.g. MS, NPO
- Compressive e.g. Anterior fossa SoL, dysthyroid eye disease, CN II glioma
- Inflammatory e.g. sarcoidosis, vasculitides
- Infective e.g. TB, syphilis, lyme disease
Bilateral
- Inherited causes e.g. Leber’s optic neuropathy
- Nutritional e.g. B12 deficiency
- Toxic e.g. methanol, ethambutol
Causes of Sudden Loss of Vision
UNILATERAL
- Optic neuropathy e.g. MS, NPO
- GCA
- TIA
- Retinal vein occlusion
- Retinal artery occlusion
- Retinal detachment
- PVD
- Vitreous haemorrhage
BILATERAL
- Stroke - occipital/CA (homonymous hemaniopia)
- NMO (bilateral optic neuritis)
- Pituitary apoplexy (bitemporal hemaniopia)
What is RAPD?
Rapid Afferent Pupil Defect
A.k.a Marcus Gunn pupil
Shining light in affected eye = both pupils remain dilated
Shining light in normal eye = both pupils constrict
Causes of RAPD
1) Retinal pathology
- Retinal detachment
- Retinal artery occlusion
- Retinal vein occlusion
2) Optic nerve pathology
- Ischaemic optic neuropathy
- Demyelination of optic nerve e.g. MS, NPO
Causes of bitemporal hemaniopia
Due to compression of the optic chiasm
Pituitary tumours/apoplexy
= compress inferior chiasmal fibres first = superior bitemporal quadrantopia
Craniopharyngiomas
= compress superior chiasmal fibres first = inferior bitemporal quadrantopia
Causes of Papilloedema
Papilloedema = optic disc swelling
Main cause = raised intracranial pressure
- Space-occupying lesion
- Disruption of venous drainage e.g. CVST
- Malignant HTN
- Idiopathic Intracranial HTN
- Hydrocephalus
Hypercapnia
Carbon monoxide poisoning
Hypocalcaemia
Thyroid Eye Disease
Due to autoimmune inflammation of extra-ocular muscles and retro-orbital fat
No signs or symptoms
Only signs
Soft tissue involvement
Proptosis
Extraocular muscle involvement
Corneal involvement
Sight loss (optic nerve compression!)
SMOKING makes thyroid eye disease worse!
Management of Thyroid Eye Disease
Evidence of optic nerve compression =
EMERGENCY decompression (surgical or radiotherapy) + IV steroids
Acute Disease
- Artificial tears
- PO steroids
- Optimise thyroid function
- STOP smoking!!
“Burnt-out Disease”
= quiescent orbital inflammation, stable
= usually within 1 - 5 years
- Surgical correction (to improve diplopia/cosmetics)
Retinitis Pigmentosa
Group of inherited disorders
FEATURES
- Tunnel vision
- Night blindness (often first sign)
- Black “bone spicule” pattern on peripheral retina
ASSOCIATED CONDITIONS
- Refsum disease = cerebellar ataxia, peripheral neuropathy, ichthyosis, deafness
- Usher syndrome = deafness
- Alports = renal failure, deafness
- Kearns-Sayre syndrome = mitochondrial, ataxia, 1st degree heart block
Most will become partially sighted/blind, no cure
DVLA
Hypertensive Retinopathy
I) Silver wiring, increased arteriolar tortuosity
II) AV nipping
III) Cotton wool spots, flame & blot haemorrhages
IV) Papilloedema
Diabetic Retinopathy
Most common cause of blindness in adults (35-65)
1) Background Retinopathy
= Micro aneurysms and blot haemorrhages
2) Pre-proliferative Retinopathy
= “…” + cotton wool spots + exudates
3) Proliferative Retinopathy
= “…” and formation of new vessels
- 2WW referral to ophthalmology
4) High Risk Proliferative Retinopathy
= new vessels on/adjacent to optic disc
Treatment of Diabetic/Hypertensive Retinopathy
Improve glycaemic/BP control
Panretinal laser photocoagulation
- risk of visual field loss, reduced night vision (may loss ability to drive)
?Intravitreal VEGF inhibitors
Diabetic Maculopathy
= due to oedema from leaking capillaries and/or ischaemic due to capillary loss
Central visual loss
Exudates over macula
Rx = focal laser therapy
= improve glycaemic control
Causes of Tunnel Vision
Glaucoma
Retinitis Pigmentosa
Choroidretinitis
Optic atrophy
What is Horner’s Syndrome?
= oculosympathetic paresis
= paresis of the sympathetic innervation of the eye
Sympathetic innervation of the eye involves 3 neuron arc
1) 1st order = hypothalamus to T1/2
2) 2nd order = T1/2 to superior cervical ganglion of the sympathetic chain
3) 3rd order = sympathetic chain to eye (follows course of internal carotid artery)
FEATURES
- Miosis (still reacts to light but to lesser effect)
- Ptosis
- Enophthalmos
- Anhidrosis (location depends on where the lesion is)
- Hypochromia (if congenital or longstanding)
