Ophthalmology Revision Guide ✅

👁️ Ophthalmology is pattern recognition with sight-saving urgency. Start with: is vision reduced?, is there pain?, is the eye red?, is the pupil abnormal?, and is there trauma, contact lens use, immunosuppression or neurological deficit? For exams, the key distinction is simple: painless gradual visual loss is usually chronic eye disease, whereas painful red eye or sudden visual loss can be an emergency.

✅ 1. Core Eye Anatomy and Physiology

👁️ 1.1 Anatomical Layers

• Cornea: clear anterior surface; major refractive structure; richly innervated, so corneal disease is painful.
• Anterior chamber: fluid-filled space containing aqueous humour; angle blockage causes acute glaucoma.
• Iris/pupil: controls light entry; pupil shape/reactivity gives important diagnostic clues.
• Lens: focuses light; cataract causes gradual painless visual loss and glare.
• Retina: neural tissue detecting light; macula provides central detailed vision.
• Optic nerve: transmits visual signals; affected by glaucoma, optic neuritis and ischaemia.
• Uvea: iris, ciliary body and choroid; inflammation causes uveitis.

💧 1.2 Aqueous Humour and Intraocular Pressure

• Aqueous humour is produced by the ciliary body.
• It flows from posterior chamber through pupil into anterior chamber.
• It drains mainly through the trabecular meshwork at the iridocorneal angle.
• Blocked drainage raises intraocular pressure and can damage the optic nerve.
• Acute angle closure causes sudden painful pressure rise; chronic open-angle glaucoma is usually silent until late.

🧠 Exam pearl: The cornea, anterior chamber angle, retina and optic nerve are the four emergency structures to think about in red eye or visual loss.

🔍 2. Ophthalmic History and Examination

🗣️ 2.1 Key History

• Onset: sudden, gradual, intermittent, progressive.
• Vision: blurred, field loss, central distortion, diplopia, transient blackout, curtain/shadow.
• Pain: gritty, photophobic, deep boring pain, headache, pain on eye movement.
• Redness: diffuse, ciliary flush, sectoral, discharge, trauma.
• Associated symptoms: flashes, floaters, halos, nausea/vomiting, headache, jaw claudication, rash.
• Risk factors: contact lenses, diabetes, hypertension, anticoagulation, immunosuppression, autoimmune disease, previous eye surgery.
• Medication: steroids, anticholinergics, anticoagulants, hydroxychloroquine, ethambutol, amiodarone.

🧪 2.2 Examination Sequence

• Visual acuity first — before drops or treatment if possible.
• Pupils: size, shape, reactivity, relative afferent pupillary defect.
• Eye movements and diplopia assessment.
• External inspection: lids, lashes, conjunctiva, cornea, discharge, trauma.
• Fluorescein staining for corneal epithelial defect, abrasion, ulcer or dendrite.
• Anterior chamber: cells/flare, hypopyon, hyphema if slit lamp available.
• Intraocular pressure when safe and open globe is not suspected.
• Fundoscopy: red reflex, disc, macula, vessels, peripheral retina if possible.
• Visual fields by confrontation when neurological or glaucoma concern.

⚠️ Safety pearl: Do not press on the eye or measure intraocular pressure if open globe injury is suspected. Shield the eye and get urgent ophthalmology input.

🔴 3. Red Eye

🧠 3.1 Red Eye Triage

🦠 3.2 Conjunctivitis

• Common cause of red eye with gritty discomfort and discharge but usually normal vision.
• Viral: watery discharge, preauricular nodes, often bilateral/URTI.
• Bacterial: mucopurulent discharge, eyelids stuck together.
• Allergic: itch, bilateral redness, watery discharge, atopy.
• Red flags against simple conjunctivitis: pain, photophobia, reduced vision, corneal opacity, contact lens use, trauma, abnormal pupil.

🩸 3.3 Subconjunctival Haemorrhage

• Bright red well-demarcated blood under conjunctiva.
• Usually painless with normal vision.
• Causes: spontaneous, coughing/vomiting/straining, trauma, hypertension, anticoagulation.
• Check blood pressure and anticoagulation history if recurrent or extensive.
• Traumatic subconjunctival haemorrhage can hide globe injury — assess carefully.

🔥 3.4 Episcleritis and Scleritis

• Episcleritis: sectoral redness, mild discomfort, usually self-limiting.
• Scleritis: severe deep boring pain, tenderness, pain with eye movement, may wake patient at night.
• Scleritis is associated with systemic autoimmune disease such as rheumatoid arthritis, vasculitis and IBD.
• Scleritis can threaten sight and needs urgent ophthalmology assessment.

🧿 3.5 Anterior Uveitis

• Features: painful red eye, photophobia, blurred vision, ciliary flush, small/irregular pupil.
• Associated with HLA-B27 disease, ankylosing spondylitis, IBD, psoriasis, sarcoidosis, infection.
• Slit lamp may show cells and flare.
• Treatment usually involves topical steroids and cycloplegics under ophthalmology guidance.

🧠 Exam pearl: Photophobia is not typical of simple conjunctivitis. Think corneal disease or uveitis.

🪟 4. Corneal Disease

🩹 4.1 Corneal Abrasion

• Caused by trauma, foreign body, contact lens, fingernail or dry eye.
• Features: severe foreign body sensation, tearing, photophobia, blepharospasm.
• Fluorescein shows epithelial defect.
• Check for retained foreign body, especially under upper lid.
• Contact lens-related abrasion needs antipseudomonal cover and urgent review if any concern.

🦠 4.2 Infective Keratitis / Corneal Ulcer

• Potentially sight-threatening infection of cornea.
• Risk factors: contact lenses, trauma, ocular surface disease, immunosuppression, steroid drops.
• Features: pain, photophobia, reduced vision, corneal opacity/white infiltrate, discharge, fluorescein staining.
• Contact lens use plus painful red eye is keratitis until proven otherwise.
• Needs same-day ophthalmology; do not patch contact lens-related corneal infection.

🌿 4.3 Herpes Simplex Keratitis

• Features: painful red eye, photophobia, watery discharge, reduced vision.
• Fluorescein may show dendritic branching ulcer.
• Topical steroids can worsen untreated HSV keratitis and should only be used under specialist guidance.
• Treatment involves antiviral therapy and ophthalmology follow-up.

👁️ 4.4 Dry Eye and Blepharitis

• Dry eye: gritty/burning sensation, fluctuating vision, worse with screens, wind or dry environments.
• Blepharitis: inflamed lid margins, crusting, irritation, recurrent chalazia/styes.
• Management: lid hygiene, warm compresses, lubricants, treat meibomian gland dysfunction.
• Consider Sjögren’s syndrome if severe dry eyes plus dry mouth, arthralgia or systemic features.

🌊 5. Glaucoma

NICE NG81 covers diagnosis and management of glaucoma and ocular hypertension in adults. Chronic open-angle glaucoma is usually silent until late, whereas acute angle closure is a painful emergency.

🕳️ 5.1 Chronic Open-Angle Glaucoma

• Progressive optic neuropathy with visual field loss, often associated with raised intraocular pressure.
• Risk factors: age, family history, African/Caribbean ethnicity, myopia, diabetes, steroid use.
• Symptoms: usually none until advanced; peripheral vision loss occurs late from patient perspective.
• Signs: optic disc cupping, raised IOP, visual field defects.
• Management: IOP-lowering drops, laser or surgery depending on severity and response.
• Adherence is critical because treatment prevents future sight loss rather than improving symptoms.

🚨 5.2 Acute Angle-Closure Glaucoma

• Sudden blockage of aqueous drainage causing rapid IOP rise.
• Features: painful red eye, blurred vision, halos around lights, headache, nausea/vomiting.
• Signs: mid-dilated fixed pupil, hazy cornea, hard eye, reduced vision.
• Risk factors: older age, hypermetropia, shallow anterior chamber, Asian ethnicity, anticholinergic/sympathomimetic drugs.
• Emergency: urgent ophthalmology, IOP-lowering treatment and definitive laser peripheral iridotomy.

🚨 Safety pearl: Acute angle closure can mimic migraine or gastroenteritis because headache and vomiting are prominent. Always look at the eye.

🌫️ 6. Cataract

NICE NG77 covers management of cataracts in adults, aiming to improve care before, during and after surgery.

• Cataract is lens opacity causing gradual painless visual loss.
• Symptoms: blurred/cloudy vision, glare, halos, difficulty driving at night, faded colours, monocular diplopia.
• Risk factors: ageing, diabetes, steroids, smoking, UV exposure, trauma, previous uveitis.
• Examination: reduced red reflex, lens opacity, otherwise quiet white eye.
• Management: referral for cataract surgery when visual impairment affects daily activities and patient wishes intervention.
• Surgery: phacoemulsification with intraocular lens implant; complications include posterior capsule rupture, infection, cystoid macular oedema and retinal detachment.

🧬 7. Retina and Macula

⚡ 7.1 Retinal Detachment

• Separation of neurosensory retina from retinal pigment epithelium.
• Symptoms: flashes, floaters, “curtain” or shadow over vision, peripheral field loss.
• Risk factors: myopia, trauma, previous cataract surgery, family history, lattice degeneration.
• Macula-on detachment is time-critical to preserve central vision.
• Needs same-day ophthalmology assessment.

🕸️ 7.2 Posterior Vitreous Detachment

• Age-related vitreous separation causing flashes and floaters.
• Common and often benign, but can cause retinal tear/detachment.
• Red flags: sudden shower of floaters, visual field defect, reduced vision, vitreous haemorrhage.
• Requires retinal examination to exclude tear.

🩸 7.3 Vitreous Haemorrhage

• Bleeding into vitreous causing sudden painless floaters, haze or visual loss.
• Causes: proliferative diabetic retinopathy, retinal tear/detachment, trauma, retinal vein occlusion.
• Fundus view may be poor; ultrasound may be needed to exclude retinal detachment.

🟡 7.4 Age-Related Macular Degeneration

NICE NG82 covers diagnosis and management of age-related macular degeneration, aiming to improve rapid diagnosis and treatment to prevent sight loss.

• Dry AMD: gradual central visual loss, drusen, pigmentary change, geographic atrophy.
• Wet AMD: choroidal neovascularisation causing rapid central visual distortion or loss.
• Symptoms: metamorphopsia, central scotoma, difficulty reading/recognising faces.
• Amsler grid may reveal distortion but is not a substitute for assessment.
• Wet AMD needs urgent retinal referral; anti-VEGF injections can preserve vision.
• Smoking cessation is important; visual rehabilitation supports function.

🍬 7.5 Diabetic Retinopathy

NICE NG242, published in 2024, covers management and monitoring of diabetic retinopathy and diabetic macular oedema in people under hospital eye services.

• Non-proliferative disease: microaneurysms, dot-blot haemorrhages, hard exudates, cotton wool spots.
• Proliferative disease: retinal neovascularisation from ischaemia; high risk of vitreous haemorrhage and tractional detachment.
• Diabetic macular oedema causes central visual impairment.
• Risk reduction: optimise HbA1c, blood pressure, lipids and kidney disease management.
• Treatments include laser, anti-VEGF injections, steroid implants and vitrectomy depending on disease pattern.
• Pregnancy can worsen diabetic retinopathy; retinal assessment is important in diabetes pregnancy pathways.

🩸 7.6 Retinal Vascular Occlusion

🚨 Exam pearl: Central retinal artery occlusion is an eye stroke. Treat it as a vascular emergency and assess for embolic and giant cell arteritis causes.

👁️ 8. Neuro-Ophthalmology

🔌 8.1 Optic Neuritis

• Inflammation/demyelination of optic nerve.
• Features: subacute painful visual loss, pain on eye movement, reduced colour vision, relative afferent pupillary defect.
• Often associated with multiple sclerosis, but also NMOSD, MOG disease and infection/inflammation.
• Fundoscopy may be normal in retrobulbar neuritis.
• Requires ophthalmology/neurology assessment and MRI consideration.

🧠 8.2 Visual Field Defects

👀 8.3 Diplopia and Cranial Nerves

• Binocular diplopia resolves when either eye is covered and suggests ocular misalignment.
• Third nerve palsy: ptosis, eye down and out; pupil involvement suggests compressive aneurysm until proven otherwise.
• Fourth nerve palsy: vertical diplopia, worse looking down stairs.
• Sixth nerve palsy: impaired abduction, horizontal diplopia; can occur with raised intracranial pressure.
• Myasthenia gravis causes variable fatigable ptosis/diplopia with normal pupils.
• Thyroid eye disease causes proptosis, lid retraction and restrictive diplopia.

🩸 8.4 Giant Cell Arteritis

• Large-vessel vasculitis usually in people over 50.
• Symptoms: new headache, scalp tenderness, jaw claudication, visual symptoms, constitutional symptoms, polymyalgia rheumatica.
• Ocular risk: arteritic anterior ischaemic optic neuropathy causing sudden irreversible visual loss.
• Check ESR/CRP/FBC, but do not delay treatment if suspected.
• Immediate high-dose steroids are needed if GCA is suspected, especially with visual symptoms.

🚨 Safety pearl: Jaw claudication plus visual symptoms in an older patient is GCA until proven otherwise. Treat first; confirm after.

🧒 9. Paediatric Ophthalmology

👶 9.1 Red Reflex and Leukocoria

• Absent or abnormal red reflex requires urgent assessment.
• Leukocoria causes include retinoblastoma, cataract, retinal detachment, Coats disease and persistent fetal vasculature.
• Retinoblastoma can present with white pupil, squint or poor vision.
• Do not reassure leukocoria — urgent ophthalmology referral is needed.

👀 9.2 Squint and Amblyopia

• Squint after early infancy can cause amblyopia if not treated.
• Assess corneal light reflex and cover test where trained.
• Red flags: new painful squint, abnormal red reflex, neurological signs, headache/vomiting.
• Treatment may include glasses, patching/occlusion, atropine penalisation or surgery depending on cause.

👓 9.3 Refractive Error

• Myopia: difficulty seeing distance; image focuses in front of retina.
• Hypermetropia: difficulty near vision; can contribute to accommodative squint.
• Astigmatism: irregular corneal/lens curvature causing distorted vision.
• Children may present with headaches, school difficulties, eye rubbing or squint rather than reporting blurred vision.

🧴 10. Lids, Lacrimal and Orbit

🧼 10.1 Blepharitis, Stye and Chalazion

• Blepharitis: chronic lid margin inflammation with irritation and crusting.
• Stye/hordeolum: acute painful infected gland at lid margin.
• Chalazion: chronic painless meibomian cyst within lid.
• Management: warm compresses, lid hygiene, lubricants; persistent/recurrent lesions may need ophthalmology.
• Recurrent chalazion in older adults should prompt consideration of sebaceous gland carcinoma.

🧪 10.2 Preseptal and Orbital Cellulitis

• Orbital cellulitis can cause optic nerve compression, cavernous sinus thrombosis and intracranial infection.
• Red flags: reduced vision, proptosis, ophthalmoplegia, pain with eye movement, RAPD, systemic toxicity.
• Requires urgent hospital assessment, imaging and IV antibiotics.

🦋 10.3 Thyroid Eye Disease

• Autoimmune orbital disease, usually associated with Graves’ disease.
• Features: lid retraction, proptosis, gritty eyes, diplopia, exposure keratopathy.
• Smoking worsens disease and reduces treatment response.
• Sight-threatening features: reduced vision, colour desaturation, corneal breakdown, optic neuropathy.
• Requires urgent specialist assessment if vision threatened.

🧨 11. Eye Trauma

🧪 11.1 Chemical Injury

• True ophthalmic emergency — irrigate immediately before detailed history/exam.
• Alkali burns are especially dangerous because they penetrate tissues deeply.
• Use copious irrigation with saline/water and check pH until neutral.
• Remove particulate matter from fornices if safe.
• Urgent ophthalmology after irrigation.

🩹 11.2 Corneal Foreign Body

• Features: foreign body sensation, tearing, photophobia, visible particle or rust ring.
• Check visual acuity and fluorescein staining.
• High-velocity metal-on-metal injury raises concern for intraocular foreign body.
• Do not remove deeply embedded or penetrating foreign bodies outside specialist setting.

🌍 11.3 Open Globe Injury

• Suspect with penetrating trauma, irregular/teardrop pupil, shallow anterior chamber, uveal prolapse, reduced vision, positive Seidel test.
• Do not press on eye, remove protruding object, or measure IOP.
• Place rigid eye shield, keep nil by mouth, give analgesia/antiemetic, urgent ophthalmology and IV antibiotics/tetanus assessment.

🩸 11.4 Hyphema and Blunt Trauma

• Hyphema is blood in anterior chamber after blunt trauma.
• Complications: raised IOP, rebleeding, corneal blood staining.
• Requires ophthalmology assessment, eye protection and activity restriction.
• Blowout fracture may cause diplopia, infraorbital numbness and restricted upgaze.

🚨 Exam pearl: Chemical eye injury is treated before visual acuity, before pH documentation and before referral — irrigate immediately.

💊 12. Drug-Related Eye Disease

⚠️ Prescribing pearl: Steroid eye drops can worsen herpes keratitis and raise intraocular pressure. They should generally be started only with ophthalmology guidance unless the indication is clear.

🚨 13. Ophthalmology Emergencies

📚 14. OSCE / Exam Pearls

• Always check visual acuity in an eye presentation.
• Painful red eye with reduced vision is an emergency until proven otherwise.
• Photophobia suggests corneal disease or uveitis, not simple conjunctivitis.
• Contact lens wearer with painful red eye has keratitis until proven otherwise.
• Halos, vomiting and fixed mid-dilated pupil suggest acute angle closure.
• Flashes, floaters and curtain-like shadow suggest retinal tear/detachment.
• Sudden painless monocular visual loss suggests retinal vascular occlusion, vitreous haemorrhage or retinal detachment.
• Jaw claudication plus visual symptoms in over-50s suggests GCA — treat immediately.
• Chemical injuries: irrigate first, ask details later.
• Open globe: shield, do not press, do not remove penetrating object.

📌 15. Quick Differentials Table

📚 References

• NICE. Cataracts in adults: management. NG77.
• NICE. Glaucoma: diagnosis and management. NG81.
• NICE. Age-related macular degeneration. NG82.
• NICE. Diabetic retinopathy: management and monitoring. NG242.
• The Royal College of Ophthalmologists guidance should be checked for specialist pathways including AMD, diabetic retinopathy, glaucoma, cataract, retinal detachment and emergency eye care.
• Local eye casualty, optometry referral and same-day emergency ophthalmology pathways should always be followed.

⚠️ Disclaimer

This article is for medical education and exam revision. Clinical decisions should follow current local ophthalmology, eye casualty, optometry referral, antimicrobial, trauma, stroke, diabetes and emergency pathways, formularies, senior advice, NICE guidance and Royal College of Ophthalmologists guidance. Ophthalmology emergencies such as chemical eye injury, open globe, acute angle-closure glaucoma, keratitis, retinal detachment, CRAO, GCA-related visual symptoms, orbital cellulitis and endophthalmitis require urgent specialist input.