Ophthalmology Flashcards
Visual field defects: Parietal lobe tumour
A parietal lobe tumour is associated with disturbed sensation including localisation of touch and disturbed two point discrimination. The typical associated visual field defect is a lower homonymous quadrantanopia and it affects the upper fibres of the optic radiation. This is the classical lesion and tumours of the temporal lobe tend to produce superior homomomous quadrantanopia. However,very large tumours can produce homonymous hemianopia.
Visual field defects: Bilateral occipital lobe infarction
Bilateral occipital infarction results in cortical blindness where the brain is unable to process the light signals it receives from the retina and optic nerves.
Visual field defects: Central retinal artery occlusion
A central retinal artery occlusion would typically result in sudden uniocular blindness. Causes of central retinal artery occlusion include emboli (carotid stenosis, AF) and giant cell arteritis.
Fracture of the floor of the orbit
There is a fracture of the floor of the right orbit with haemorrhage in the associated maxilla.
An important clinical feature is whether there is any diplopia (the usual reason for requiring a CT scan).
A CT is performed to assess whether the rectus muscle is trapped by the fracture necessitating surgery.
A 68-year-old female patient is seen on the ward.
She complains of severe pain in her right eye. There is blurring of vision and she feels nauseated and has vomited several times.
Earlier in the day she has undergone colonoscopy for evaluation of her longstanding Crohn’s disease. The endoscopist has made a comment that the examination was difficult.
What is the likely cause of her painful red eye?
Acute angle closure glaucoma
Anticholinergic agents are sometimes used during endoscopy to cause smooth muscle relaxation to aid examination when difficulty is encountered.
These agents cause pupillary dilatation thus precipitating acute angle closure glaucoma in susceptible patients.
In patients with a history of glaucoma, glucagon is used instead of anticholinergics.
Orbital emphysema
The diagnosis is of orbital and subcutaneous emphysema. This is the black tracks of air seen related to the temporal muscles, and in the orbits. There should normally be no air in relations to these structures. The patient had been assaulted and the appearances relate to associated fractures of the sinuses.
Third nerve palsy
In a third nerve palsy there is typically ptosis with a dilated, unreactive pupil and the eyeball is displaced downwards and outwards.
Enophthalmos is seen in Horner’s syndrome. There would be a dilated not constricted pupil and a divergent squint - affected eye deviated ‘down and out’.
Increased lacrimation may be seen in VIIth nerve palsy.
Pancoast tumour
Horners syndrome
Pancoast’s tumour of the lung, (apical tumour) is associated with infiltration of the lower fibres of the brachial plexus (wasting and weakness of the small muscles of the hand and C8, T1 sensory loss) together with infiltration of the sympathetic nerve fibres producing ptosis, miosis (small pupil) and loss of sweating on that side of the face. Other causes of Horner’s syndrome include cervical rib, lateral medullary syndrome and syringomyelia.
Graves disease
Chemosis
Graves’ ophthalmopathy is associated with chemosis, conjunctival oedema, exophthalmos and proptosis. The condition is associated with TSH receptor antibodies that cross react with antigens within the orbital fat cells.
Familial hypercholesterolaemia
Corneal arcus
Familial hypercholesterolaemia, an autosomal recessive condition, is associated with elevated cholesterol concentrations due to reduced hepatic LDL receptors. The condition is associated with premature coronary artery disease and is manifest by tendon zanthomas, xanthelasma and corneal arcus.
A 38-year-old female presents with sudden loss of vision but fundoscopy is normal. She had a similar episode about one year back, which resolved completely within three months. On examination, she has mild weakness of right upper limb and the reflexes are exaggerated.
Periodic visual loss in a young female suggests relapsing and remitting multiple sclerosis presenting as optic neuritis. Of patients with multiple sclerosis, 15-20% initially present with an episode of optic neuritis and approximately 70% have an optic neuritis episode at some point during the illness.
Flashes of light and sudden loss of vision suggest retinal detachment which is more common in myopic patients. There is usually no pain associated with retinal detachment. Extremely nearsighted (myopic) subjects have longer eyeballs with thinner retinas that are more prone to detaching. Scleral buckling bends the wall of the eye to meet the hole in the retina.
A 54-year-old male with myopia develops flashes of light, floaters preceding loss of vision.
These symptoms of floaters and flashes of light preceding visual loss suggest retinal detachment. Surgical treatment is often required
A 65-year-old female presents with headache and loss of vision. Her ESR is markedly elevated.
The third patient presents with giant cell arteritis (GCA), and should be treated with high dose steroids. When GCA involves the arteries that supply blood to the eyes, blindness in one or both eyes may develop suddenly. Strokes may rarely occur.
Some of the more common symptoms in GCA include headaches, pain in the jaw or tongue muscles when eating or talking, and tenderness of the scalp over the temples. GCA and polymyalgia rheumatica (PMR) seem to be related, as they often occur together. Over 10 % of people with PMR also have GCA; approximately 50 % of people with GCA also have PMR.
A 55-year-old male hypertensive suddenly lost his vision. The retina is pale and the fovea appears as a bright cherry red spot.
Pressure over eyeball
This is central retinal artery occlusion and occasionally pressure over the eyeball or aspiration of vitreous may be effective in dislodging the clot.
The fourth patient is older and has hypertension, and sudden loss of vision with a pale disc and a cherry red spot suggests central retinal artery occlusion. photo.
A 55-year-old man presents with mild headache. He has changed his spectacles thrice in one year. There is mild cupping present in the disc and sickle shaped scotoma present in both eyes.
Pilocarpine eyedrops
Pilocarpine, a drug that promotes pupillary constriction, miotic, is a treatment for glaucoma.
In chronic simple glaucoma a sickle-shaped scotoma called Seidel’s sign may be seen as a significant field defect. Pilocarpine 1 - 4% is a direct cholinergic agonist which will cause miosis and accommodative spasm. It is used to reverse the action of mydriatics but its greatest therapeutic use is in lowering ocular pressure in both acute and chronic glaucoma by acting through the ciliary muscle to increase aqueous outflow.
Pilocarpine may cause parasympathetic actions, for example, salivation, sweating, hypertension, tachycardia, diarrhoea and vomiting, and pulmonary oedema. Ciliary spasm may cause browache which may be more severe in the initial two to four weeks of treatment.
