3.2 Body Systems & the Ocular Manifestations of Systemic Disease

The four body systems the blueprint names

Taking blood pressure, pulse and respiratory rate is an explicit blueprint task. Know normal adult ranges: blood pressure below 120/80 mmHg, pulse 60 to 100 beats per minute, respiration 12 to 20 breaths per minute.

Diabetes mellitus

The single most examinable systemic disease.

• Refractive fluctuation — osmotic shifts change lens hydration. Never refract for a new prescription during a hyperglycaemic crisis; wait for stable glucose, usually several weeks.
• Cataract — earlier onset; classic snowflake cortical cataract in young type 1 patients; posterior subcapsular changes.
• Retinopathy — non-proliferative (microaneurysms, dot-blot haemorrhages, hard exudates, cotton-wool spots, venous beading, intraretinal microvascular abnormalities) progressing to proliferative disease with neovascularisation, vitreous haemorrhage and tractional detachment. Diabetic macular oedema is the leading cause of vision loss and is monitored with OCT.
• Cranial nerve palsies — microvascular third, fourth or sixth nerve palsies. A diabetic third nerve palsy is characteristically pupil-sparing because the parasympathetic fibres run superficially and keep their pial blood supply. A painful third nerve palsy with a dilated, non-reactive pupil suggests a compressive posterior communicating artery aneurysm and is a neurosurgical emergency.
• Other — recurrent erosion from epithelial basement membrane fragility, reduced corneal sensation, rubeosis iridis and neovascular glaucoma.

Thyroid disease

Thyroid eye disease (Graves orbitopathy) is the most common cause of both unilateral and bilateral proptosis in adults. Signs: lid retraction (Dalrymple sign), lid lag on downgaze (von Graefe sign), proptosis, injection over the horizontal rectus insertions, chemosis, restrictive strabismus and, in severe disease, compressive optic neuropathy. Extraocular muscle involvement follows the mnemonic I'M SLow — Inferior rectus, Medial rectus, Superior rectus, Lateral rectus — with tendon sparing distinguishing it from orbital myositis. Exophthalmometry and forced ductions are the technologist's contribution.

Hypothyroidism causes periorbital oedema, madarosis of the lateral brow and dry eye.

Cardiovascular and cerebrovascular disease

Hypertensive retinopathy progresses through generalised and focal arteriolar narrowing, copper-wire then silver-wire reflexes, arteriovenous nicking, flame haemorrhages, cotton-wool spots and hard exudates in a macular star, culminating in disc swelling in malignant hypertension — a same-day systemic emergency.

Embolic disease. A Hollenhorst plaque (bright, refractile cholesterol embolus at a bifurcation) implicates the carotid. Amaurosis fugax — transient painless monocular loss described as a curtain — is a transient ischaemic attack of the eye and requires urgent carotid evaluation. Calcific emboli come from cardiac valves; platelet-fibrin emboli are long and grey.

Carotid-cavernous fistula produces pulsatile proptosis, a bruit, corkscrew conjunctival vessels and raised intraocular pressure.

Autoimmune and inflammatory disease

• Rheumatoid arthritis — keratoconjunctivitis sicca, scleritis, peripheral ulcerative keratitis.
• Ankylosing spondylitis and other HLA-B27 disease — recurrent acute anterior uveitis.
• Juvenile idiopathic arthritis — chronic asymptomatic anterior uveitis with band keratopathy, which is why these children need scheduled screening.
• Sarcoidosis — granulomatous uveitis with mutton-fat keratic precipitates, lacrimal gland enlargement, candle-wax drippings.
• Sjögren syndrome — severe aqueous-deficient dry eye.
• Giant cell arteritis — over 50, headache, jaw claudication, scalp tenderness, raised ESR and CRP, arteritic anterior ischaemic optic neuropathy.
• Multiple sclerosis — optic neuritis, internuclear ophthalmoplegia.
• Myasthenia gravis — variable, fatigable ptosis and diplopia that worsen through the day and improve after rest or ice.

Infectious disease

HIV/AIDS — cytomegalovirus retinitis at low CD4 counts ("pizza pie" haemorrhagic necrotising retinitis), HIV retinopathy with cotton-wool spots, Kaposi sarcoma of the lid or conjunctiva. Tuberculosis — granulomatous uveitis, choroidal tubercles, phlyctenular keratoconjunctivitis. Syphilis — interstitial keratitis, uveitis, the Argyll Robertson pupil (accommodates but does not react to light). Toxoplasmosis — focal necrotising retinochoroiditis adjacent to an old pigmented scar.

Nutritional, neurologic and neoplastic

Vitamin A deficiency is the leading nutritional cause of childhood blindness worldwide: night blindness first, then conjunctival xerosis with Bitot spots, corneal xerosis and finally keratomalacia. Thiamine deficiency causes nystagmus and ophthalmoplegia in Wernicke encephalopathy.

Neurologic disorders relevant to technologist testing include stroke (homonymous field defects), idiopathic intracranial hypertension (bilateral disc swelling, transient visual obscurations, sixth nerve palsy as a false localising sign), Parkinson disease (reduced blink, dry eye) and myasthenia as above.

Cancer. Primary intraocular malignancies are choroidal melanoma in adults (a dome or mushroom-shaped lesion; low to medium internal reflectivity on standardised A-scan) and retinoblastoma in children (leucocoria, strabismus, calcification on B-scan). Metastases — most often from breast in women and lung in men — are typically creamy, plateau-shaped choroidal lesions and are the commonest intraocular malignancy overall.