Examqo › Examqo library › Ophthalmology › Optics and pharmacology · IMLE
Ocular pharmacology
Eye drugs act through a few mechanisms — the autonomic nervous system (pupil dilation and constriction, cycloplegia), reducing production or increasing outflow of aqueous in glaucoma, and suppressing inflammation or infection — and a drop in the eye is absorbed into the body through the nose, so drops also have systemic side effects.
Why it matters in the exam
Mydriatics: phenylephrine — an alpha-1 agonist, dilating without cycloplegia, with caution in hypertension and infants; tropicamide — a short anticholinergic, about 4–6 hours; cyclopentolate — up to a day, may cause confusion and hallucinations in children; atropine — 7–14 days. Miotics: pilocarpine. Apraclonidine reverses the ptosis of Horner syndrome and is used for diagnosis. Topical anaesthetics (oxybuprocaine, tetracaine) are for examination only — home use causes a toxic corneal ulcer.
Glaucoma drugs and their side effects: prostaglandin analogues (latanoprost) — increase uveoscleral outflow; redness, iris darkening, lash growth, periorbital fat loss, and worsening of inflammation and macular oedema. Beta-blockers (timolol) — reduce aqueous production; bronchospasm, bradycardia and masking of hypoglycaemia. Alpha-2 agonists (brimonidine) — follicular allergy, and forbidden under age two because of respiratory and CNS depression. Carbonic anhydrase inhibitors — as drops (dorzolamide) or by mouth (acetazolamide): paraesthesia, kidney stones, metabolic acidosis, hypokalaemia and sulfa sensitivity. ROCK inhibitors (netarsudil) — redness and corneal deposits.
Steroids: prednisolone acetate 1% penetrates well; all may raise pressure, cause posterior subcapsular cataract and worsen infection — especially herpes and fungi; loteprednol and fluorometholone raise pressure less. NSAID drops prevent macular oedema after surgery, but with long use may cause corneal melting. Intravitreal anti-VEGF injections — a small risk of endophthalmitis with each injection. Fluorescein for angiography — nausea, yellow skin and urine and rarely anaphylaxis. Pressing on the lacrimal punctum for 2 minutes after the drop and closing the eyes reduce systemic absorption; wait 5 minutes between different drops.
Key points
- Tropicamide short, cyclopentolate a day, atropine 7–14 days.
- Prostaglandin: iris darkening and lashes.
- Beta-blocker: not in asthma or bradycardia.
- Brimonidine: not under age two.
- Steroid: pressure, cataract and infection.
Summary table
| Class | Example | Mechanism | Main side effects |
|---|---|---|---|
| Prostaglandin | Latanoprost | Uveoscleral outflow | Iris darkening, lashes, redness, macular oedema |
| Beta-blocker | Timolol | Less aqueous production | Bronchospasm, bradycardia |
| Alpha-2 agonist | Brimonidine | Less production and more outflow | Allergy; forbidden under age two |
| CAI | Dorzolamide, acetazolamide | Less aqueous production | Paraesthesia, stones, acidosis, sulfa |
| ROCK inhibitor | Netarsudil | Trabecular outflow | Redness, corneal deposits |
| Anticholinergic | Cyclopentolate, atropine | Dilation and cycloplegia | Confusion in children, angle closure |
A free exam question
מה מהבאים נכון לגבי רצפטורים כולינרגיים? (the question as examined, in Hebrew)
- א. רצפטורים מסוג ניקוטיני )Nicotinic( נמצאים בנוירונים הפרה-סינפטים )pre-synaptic
- ב. רצפטורים מסוג מוסקריני )muscarinic( נמצאים ב- organs end של המערכת הפארא-סימפטטית
- ג. אטרופין חוסם רצפטורים ניקוטינים )Nicotinic( ולכן גורם להרחבת אישונים
- ד. במדולה )Medulla( של האדרנל ניתן למצוא רצפטורים מסוג מוסקריני )Muscarinic
In the full version for subscribers
- A simple algorithm
- Memory aid
- Exam traps
- 5 review cards
- Enough for IMLE
The full version is open to subscribers of: Ophthalmology, Medical licensing exam (IMLE).
Subscriber? Read the full topic Plans and prices 25 free questions
Sources
- AAO Basic and Clinical Science Course, Section 2: Fundamentals and Principles of Ophthalmology, 2024-2025 — Ocular pharmacology
- European Glaucoma Society: Terminology and Guidelines for Glaucoma, 5th edition (2020) — Medical treatment
- Kanski's Clinical Ophthalmology, 9th edition (2020) — Glaucoma — medical treatment
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.