Master Ophthalmology
for MRCP Part 1

Core Concepts

The eye is a complex organ vital for vision. Key structures include the cornea (clear front window, primary refractive surface), iris (controls pupil size), lens (focuses light, changes shape via ciliary body), retina (light-sensitive tissue, converts light into electrical signals), and optic nerve (transmits signals to brain). Aqueous humor fills the anterior and posterior chambers, maintaining intraocular pressure (IOP) and providing nutrition; it's produced by the ciliary body and drains via the trabecular meshwork (angle). Vitreous humor is a gel filling the posterior segment. Vision is measured via Snellen charts (e.g., 6/6 normal). Pupillary light reflex involves optic nerve (afferent), pretectal nucleus, Edinger-Westphal nucleus, and oculomotor nerve (efferent). Fundoscopy visualizes the optic disc, retinal vessels, and macula.

Clinical Presentation

• Red Eye:
  • Painful: Acute Angle-Closure Glaucoma (AACG), Keratitis/Corneal Ulcer, Anterior Uveitis, Scleritis.
  • Painless: Conjunctivitis (allergic/viral/bacterial), Subconjunctival Haemorrhage, Episcleritis.
• Sudden Painless Vision Loss:
  • Central Retinal Artery Occlusion (CRAO), Central Retinal Vein Occlusion (CRVO), Retinal Detachment, Vitreous Haemorrhage, Ischaemic Optic Neuropathy (e.g., Non-arteritic AION).
• Sudden Painful Vision Loss:
  • Acute Angle-Closure Glaucoma (AACG), Optic Neuritis, Giant Cell Arteritis (GCA) causing Arteritic AION, Keratitis, Endophthalmitis.
• Gradual Vision Loss:
  • Cataract, Chronic Open-Angle Glaucoma, Age-related Macular Degeneration (AMD), Diabetic Retinopathy, Optic Atrophy.
• Flashes & Floaters: Posterior Vitreous Detachment (PVD), Retinal Tear/Detachment, Vitreous Haemorrhage.
• Diplopia (Double Vision):
  • Monocular: Refractive error, Cataract, Corneal pathology.
  • Binocular: Cranial nerve palsies (III, IV, VI), Myasthenia Gravis, Thyroid Eye Disease, Orbital mass.
• Visual Field Defects: Glaucoma (arcuate scotoma), Stroke/Tumour (hemianopia, quadrantanopia), Optic nerve lesions (central scotoma).
• Proptosis/Exophthalmos: Thyroid Eye Disease, Orbital Cellulitis, Orbital Tumours.
• Photophobia: Uveitis, Keratitis, Meningitis, Migraine.

Diagnosis (Gold Standard)

Comprehensive eye exam: Visual acuity, pupillary reactions (checking for Relative Afferent Pupillary Defect - RAPD), extraocular movements, slit lamp examination (cornea, anterior chamber, iris, lens), tonometry (IOP measurement), and fundoscopy (optic disc, retina, vessels, macula). Specific gold standards for conditions:

• Glaucoma: Ocular coherence tomography (OCT) for retinal nerve fibre layer (RNFL) thickness, visual field testing (perimetry).
• Retinal Detachment: Indirect ophthalmoscopy (detailed retinal view).
• Macular Degeneration: OCT, Fluorescein angiography (for wet AMD).
• Diabetic Retinopathy: Fundoscopy (dilated), Fluorescein angiography.
• Optic Neuritis: MRI orbits/brain (demyelination).
• Giant Cell Arteritis (GCA): Temporal artery biopsy, raised ESR/CRP.

Management (First Line)

• Acute Angle-Closure Glaucoma (AACG): Topical beta-blocker (e.g., Timolol), topical alpha-agonist (e.g., Brimonidine), topical pilocarpine, systemic acetazolamide. Urgent laser peripheral iridotomy.
• Central Retinal Artery Occlusion (CRAO): Ocular massage, anterior chamber paracentesis, CO2 rebreathing (paper bag), sublingual isosorbide dinitrate. Aim for urgent referral within 90 minutes.
• Retinal Detachment: Urgent ophthalmology referral for surgical repair (e.g., vitrectomy, scleral buckle).
• Giant Cell Arteritis (GCA): High-dose IV methylprednisolone immediately upon suspicion, followed by oral prednisolone. Temporal artery biopsy within 1-2 weeks.
• Orbital Cellulitis: Urgent IV broad-spectrum antibiotics (e.g., Co-amoxiclav, Ceftriaxone). Surgical drainage if abscess.
• Keratitis/Corneal Ulcer: Topical broad-spectrum antibiotics (e.g., Moxifloxacin). Acyclovir for herpetic keratitis.
• Anterior Uveitis: Topical corticosteroids (e.g., Prednisolone), topical cycloplegics (e.g., Cyclopentolate, Atropine) to relieve pain and prevent synechiae.
• Chemical Eye Injury: Immediate and copious irrigation with saline/water for at least 30 minutes, then urgent ophthalmology review.

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