Master Ophthalmology
for PLAB 1

Core Concepts

Ophthalmology is the study of the anatomy, physiology, and diseases of the eye. Key areas for PLAB 1 include understanding common eye conditions, their presenting symptoms (e.g., red eye, vision loss, pain), basic diagnostic techniques, and initial management strategies. Focus on differentiating urgent from non-urgent conditions.

Clinical Presentation

• Red Eye:
  • Conjunctivitis: Bilateral, discharge (purulent in bacterial, watery in viral), itching (allergic), no pain, normal vision, no photophobia, clear cornea.
  • Acute Angle Closure Glaucoma: Sudden onset severe pain, headache, nausea/vomiting, unilateral, blurred vision with halos, fixed mid-dilated pupil, ciliary flush, high intraocular pressure (IOP).
  • Uveitis (Anterior): Pain, photophobia, blurred vision, ciliary flush, miotic pupil, cells/flare in anterior chamber (slit lamp).
  • Keratitis (Corneal Ulcer): Severe pain, photophobia, blurred vision, foreign body sensation, corneal opacity/infiltrate, ciliary flush. Associated with contact lens use, trauma.
  • Scleritis/Episcleritis: Localised or diffuse redness. Scleritis is painful, deep, and associated with systemic disease. Episcleritis is less painful, superficial.
  • Subconjunctival Haemorrhage: Painless, bright red patch, normal vision. Resolves spontaneously.
• Vision Loss:
  • Sudden Painless Monocular:
    • Central Retinal Artery Occlusion (CRAO): 'Cherry-red spot' on fundoscopy, profound vision loss.
    • Central Retinal Vein Occlusion (CRVO): 'Blood and thunder' fundus, vision loss varies.
    • Retinal Detachment: Flashes, floaters, 'curtain' coming over vision.
    • Vitreous Haemorrhage: Sudden onset floaters/cobwebs, blurred vision.
    • Ischaemic Optic Neuropathy (AION): Painless, altitudinal visual field defect, often associated with GCA.
  • Sudden Painful Monocular: Acute Angle Closure Glaucoma, Optic Neuritis (pain on eye movement, RAPD), Keratitis, Anterior Uveitis.
  • Gradual Painless:
    • Cataract: Progressive blurring, glare, 'misty' vision.
    • Open Angle Glaucoma: Peripheral vision loss first (tunnel vision), high IOP, optic disc cupping.
    • Age-related Macular Degeneration (ARMD): Central vision loss, distortion (metamorphopsia).
    • Diabetic Retinopathy: Variable, dependent on stage (proliferative, macular oedema).
• Diplopia (Double Vision):
  • Monocular: Often refractive error, cataract, corneal irregularity. Persists with one eye closed.
  • Binocular: Resolves with one eye closed. Indicates misalignment, typically cranial nerve palsies (III, IV, VI), thyroid eye disease, myasthenia gravis, orbital mass.
• Flashes & Floaters: Posterior Vitreous Detachment (PVD), Retinal Detachment, Vitreous Haemorrhage.

Diagnosis (Gold Standard)

**Essential for all eye exams:** Visual Acuity (Snellen chart), Pupil assessment (direct/consensual, RAPD), Extraocular Movements. **Key diagnostic tools:**

• Slit Lamp Examination: Detailed view of anterior segment (cornea, anterior chamber, iris, lens).
• Ophthalmoscopy (Fundoscopy): Direct (general practitioner) or Indirect (specialist) for posterior segment (optic disc, retina, vessels, macula).
• Tonometry: Measures Intraocular Pressure (IOP) (e.g., Goldmann applanation, non-contact).
• Visual Fields (Perimetry): Detects field defects (e.g., glaucoma, neurological lesions).
• Fluorescein Staining: Detects corneal abrasions, ulcers, herpes simplex dendritic lesions.
• Gonioscopy: Assesses anterior chamber angle (e.g., for glaucoma type).
• Optical Coherence Tomography (OCT): Cross-sectional imaging of retina/optic nerve (e.g., ARMD, glaucoma, diabetic maculopathy).

Management (First Line)

• Acute Angle Closure Glaucoma: IV Acetazolamide, topical beta-blocker (e.g., timolol), topical pilocarpine (after IOP drop), systemic analgesia/anti-emetics. Definitive: Laser Peripheral Iridotomy (LPI).
• Open Angle Glaucoma: Topical prostaglandin analogues (e.g., Latanoprost), topical beta-blockers (e.g., Timolol), topical carbonic anhydrase inhibitors (e.g., Dorzolamide).
• Bacterial Conjunctivitis: Topical broad-spectrum antibiotics (e.g., Chloramphenicol, Fusidic acid).
• Viral Conjunctivitis: Supportive (cold compresses, lubricants). Highly contagious.
• Allergic Conjunctivitis: Topical antihistamines/mast cell stabilizers (e.g., Olopatadine, Sodium cromoglicate).
• Cataract: Surgical extraction (phacoemulsification) with intraocular lens (IOL) implant.
• Diabetic Retinopathy: Strict blood glucose and BP control. Laser photocoagulation (panretinal for proliferative), anti-VEGF injections (e.g., Ranibizumab, Aflibercept) for macular oedema.
• Age-related Macular Degeneration (ARMD):
  • Dry ARMD: Antioxidant vitamins (AREDS formulation).
  • Wet ARMD: Intravitreal anti-VEGF injections.
• Retinal Detachment: Urgent surgical repair (vitrectomy, scleral buckle).
• Optic Neuritis: High-dose IV methylprednisolone (may speed recovery, but no long-term vision benefit). Investigation for multiple sclerosis.
• Chemical Eye Injury: IMMEDIATE copious irrigation with water/saline for at least 15-30 minutes before transport. Urgent ophthalmology referral.

Exam Red Flags