Drugs that harm the eye flashcards
13 high-yield MRCP Part 1 cards from the Intellect Medicos Ophthalmology course. Try to answer each question before you open it — then study them properly with spaced repetition, which brings each card back just before you would forget it.
Study these 13 cards Save progress — free account
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What is the characteristic retinal toxicity of hydroxychloroquine?
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Bull's-eye maculopathy (irreversible).
Why? The drug builds up in the retinal pigment epithelium; damage can progress even after stopping, so it must be caught before symptoms.
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When should retinal screening start for a patient on long-term hydroxychloroquine with no extra risk factors (RCOphth)?
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Annual screening after 5 years of treatment (after 1 year if risk factors), using SD-OCT and widefield fundus autofluorescence.
Why? Risk factors that bring screening forward include dose above 5 mg/kg/day, eGFR below 60 and taking tamoxifen. A baseline eye examination is no longer recommended.
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Which antituberculous drug causes optic neuritis with red–green colour vision loss?
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Ethambutol.
Why? It is dose-related and worse in renal impairment. Check visual acuity (and colour vision) before starting and tell patients to report visual change and stop the drug.
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What is the most common ocular side effect of amiodarone?
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Corneal microdeposits (vortex keratopathy).
Why? They occur in almost everyone on long-term treatment, rarely affect vision (night glare) and reverse on stopping. Optic neuropathy is rare but serious.
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Which antiepileptic causes irreversible concentric visual field loss, needing perimetry before and during treatment?
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Vigabatrin.
Why? Field defects occur in about a third of patients and are usually irreversible, so vision is assessed at baseline (within 4 weeks of starting) and at least every 6 months.
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Name the two main ocular complications of long-term corticosteroids.
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Posterior subcapsular cataract and raised intraocular pressure (steroid-induced glaucoma).
Why? This applies to systemic, inhaled and especially topical steroids; steroid use is listed as a risk factor for open-angle glaucoma.
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Which drug class can cause blue-tinged vision and has been linked with non-arteritic ischaemic optic neuropathy?
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PDE-5 inhibitors (e.g. sildenafil).
Why? They also weakly inhibit PDE-6 in the retina, giving a blue tinge (cyanopsia). Patients with sudden visual loss should stop the drug and seek urgent help; sildenafil is contraindicated after NAION in either eye.
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What maximum daily dose of hydroxychloroquine is advised to limit the risk of retinopathy (RCOphth)?
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5 mg/kg/day (based on body weight).
Why? A dose above 5 mg/kg/day is a risk factor that brings retinal screening forward to after 1 year of treatment.
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Which cardiac drug, in toxicity, classically causes yellow-green tinted vision (xanthopsia)?
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Digoxin.
Why? Blurred vision and haloes may also occur. Toxicity is more likely with hypokalaemia or renal impairment; check levels and potassium.
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Which osteoporosis drug class can cause anterior uveitis or scleritis?
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Bisphosphonates (e.g. alendronate, zoledronic acid).
Why? Ocular inflammation is uncommon but listed in the product information; a painful red eye on a bisphosphonate needs ophthalmology review.
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Methanol poisoning can cause optic neuropathy and blindness. What is the first-line antidote?
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Fomepizole (ethanol if fomepizole is not available).
Why? Both block alcohol dehydrogenase, stopping methanol being converted to toxic formic acid. Haemodialysis is used for severe poisoning.
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What is the mechanism of action of vigabatrin?
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Irreversible inhibition of GABA transaminase, raising brain GABA levels.
Why? Its key ocular risk is irreversible concentric visual field loss, so fields are checked before and during treatment.
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Which GLP-1 receptor agonist carries a 2026 MHRA warning about a very rare risk of non-arteritic anterior ischaemic optic neuropathy?
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Semaglutide (Ozempic, Wegovy, Rybelsus).
Why? Anyone on it with sudden vision loss needs urgent ophthalmology review; stop semaglutide if NAION is confirmed. Ask about private prescriptions, which may not be on the GP record.