📚 Glaucoma Pharmacology — Complete Reference
Vancouver School of Optometry • Exam Preparation Guide • February 2026
Study Tip: Glaucoma treatment aims to lower intraocular pressure (IOP) by either decreasing aqueous humor production or increasing aqueous outflow. All drug classes work through one or both of these mechanisms.
🔴 Beta Blockers (Beta-Adrenergic Antagonists) Sympatholytic
Mechanism of Action: Decrease aqueous humor production by blocking beta receptors in ciliary epithelium
| Brand | Generic | Concentration | Notes |
|---|---|---|---|
| Timoptic | Timolol maleate | 0.25%, 0.5% | Non-selective (β1 & β2); gold standard |
| Betoptic-S | Betaxolol | 0.25% susp | β1-selective; safer for pulmonary patients |
| Betagan | Levobunolol | 0.25%, 0.5% | Non-selective |
| OptiPranolol | Metipranolol | 0.3% | Non-selective |
| Ocupress | Carteolol | 1% | Non-selective with ISA |
Contraindications
- Cardiovascular disease
- Low blood pressure (<100/60)
- Bradycardia
- Asthma / COPD
- Heart block
Side Effects
- Bradycardia
- Hypotension
- Bronchospasm
- Depression
- Fatigue
- Decreased libido
Clinical Pearl: Teach patients nasolacrimal occlusion (punctal occlusion) for 2-3 minutes after instillation to minimize systemic absorption and side effects.
🟡 Alpha Agonists (Alpha-Adrenergic Agonists) Sympathomimetic
Mechanism of Action: Increase outflow via alpha & beta receptors; increase uveoscleral outflow
| Brand | Generic | Concentration | Notes |
|---|---|---|---|
| Alphagan-P | Brimonidine tartrate | 0.15% | α2-selective; also decreases production |
| Iopidine | Apraclonidine | 1% | Short-term use; high tachyphylaxis rate |
Side Effects / Precautions
- Watch with MAO inhibitors
- Dry mouth
- Local allergy (up to 25%)
- Fatigue / drowsiness
- Ocular hyperemia
🟢 Prostaglandin Analogs First-Line Therapy
Mechanism of Action: Increase uveoscleral outflow
| Brand | Generic | Concentration | Preservative / Notes |
|---|---|---|---|
| Lumigan | Bimatoprost | 0.03% / 0.01% | BAK 0.005% / 0.02% |
| Travatan Z | Travoprost | 0.04% | No BAK; SofZia preservative system. Good for dry eye / ocular surface disease |
| Rescula | Unoprostone isopropyl | 0.15% | — |
| Xalatan | Latanoprost | 0.005% | BAK 0.02%. Must refrigerate (until opened) |
| Zioptan | Tafluprost | 0.0015% | Preservative-free |
Side Effects
- Iris color change (darkening)
- Eyelash changes (longer, thicker, darker)
- Darkening of periorbital skin
- Cystoid macular edema
- Skin rash
- Migraine trigger
- Herpes Simplex Keratitis reactivation
Clinical Pearl: Prostaglandin analogs are dosed once daily at bedtime — greatest IOP reduction of any single drug class (25-35%).
🔵 Carbonic Anhydrase Inhibitors (CAIs)
Mechanism of Action: Decrease aqueous production; interfere with active secretion (inhibit carbonic anhydrase enzyme)
| Brand | Generic | Form | Notes |
|---|---|---|---|
| Trusopt | Dorzolamide | 2% topical | Topical sulfonamide |
| Azopt | Brinzolamide | 1% topical | Suspension; less stinging than dorzolamide |
| Diamox | Acetazolamide | 250 mg, 500 mg oral | Systemic; used for acute IOP spikes |
| Neptazane | Methazolamide | 25 mg, 50 mg oral | Fewer systemic side effects than acetazolamide |
Side Effects (Oral)
- Paresthesias (tingling)
- Metallic taste
- GI upset
- Kidney stones
- Aplastic anemia (rare)
- Sulfa allergy cross-reaction
🟤 Hyperosmotic Agents
Mechanism of Action: Reduce active secretion; increase osmotic pressure in ciliary body → dehydrate vitreous
| Drug | Route | Notes |
|---|---|---|
| Glycerol | Oral | Sweet taste; avoid in diabetics (caloric) |
| Mannitol | IV | Used in acute angle-closure crisis |
🟣 Rho-Kinase Inhibitors (ROCK Inhibitors)
Mechanism of Action: Alter actin cytoskeleton of trabecular meshwork & inner lining of Schlemm's canal; increase outflow — synergistic with prostaglandins
| Brand | Generic | Notes |
|---|---|---|
| Rhopressa | Netarsudil | 0.02%; once daily |
| Rocklatan | Netarsudil + Latanoprost | Combination: ROCK inhibitor + PGA |
Side Effects
- Conjunctival hyperemia
- Cornea verticillata
- Subconjunctival hemorrhage
⚪ Nitric Oxide Donors
Mechanism of Action: Possibly alters contractility of trabecular meshwork via nitric oxide release
| Brand | Generic | Notes |
|---|---|---|
| Vyzulta | Latanoprostene bunod | Nitric oxide-donating prostaglandin F2α analogue; dual mechanism |
💚 Miotics / Cholinergic Agents Parasympathomimetic
Mechanism of Action: Contract ciliary muscle → open trabecular meshwork → increase conventional outflow
| Brand | Generic | Type | Notes |
|---|---|---|---|
| Isopto Carpine | Pilocarpine | Direct-acting | 1%, 2%, 4%; most commonly used miotic |
| Miostat | Carbachol | Direct-acting | Intraocular use during surgery |
| Phospholine Iodide | Echothiophate | Indirect (anti-ChE) | Irreversible; rarely used; cataract risk |
Side Effects
- Miosis (dim vision)
- Brow ache
- Myopic shift
- Retinal detachment risk
🔁 Combination Drugs
| Brand | Components | Classes |
|---|---|---|
| Cosopt | Timolol + Dorzolamide | Beta Blocker + CAI |
| Combigan | Timolol + Brimonidine | Beta Blocker + Alpha Agonist |
| Extravan | Timolol + Travoprost | Beta Blocker + Prostamide (commercially undeveloped in U.S.) |
| Simbrinza | Brimonidine + Brinzolamide | Alpha Agonist + CAI |
| Rocklatan | Netarsudil + Latanoprost | ROCK Inhibitor + PGA |
🧠 Autonomic Nervous System Pharmacology in Ophthalmology
Understanding how the ANS controls the eye is foundational for glaucoma pharmacology. The pupil and ciliary body are innervated by both sympathetic and parasympathetic divisions.
Key Concept: Sympathetic = "Fight or Flight" (dilate pupil, decrease aqueous). Parasympathetic = "Rest and Digest" (constrict pupil, accommodate for near).
Sympathomimetic
Adrenergic Agonists — MIMIC sympathetic system
- Action on eye: Mydriasis (dilate pupil), may ↓ aqueous production, ↑ uveoscleral outflow
- Receptors: Stimulate α and/or β adrenergic receptors
- Glaucoma drugs: Brimonidine, Apraclonidine (α2-selective agonists)
- Diagnostic drugs: Phenylephrine (2.5%, 10%) for dilation
- Mnemonic: "Sympatho-MIMIC = copies adrenaline"
Sympatholytic
Adrenergic Antagonists — BLOCK sympathetic system
- Action on eye: ↓ Aqueous humor production by blocking β receptors on ciliary body
- Receptors: Block β1 and/or β2 adrenergic receptors
- Glaucoma drugs: Timolol, Betaxolol, Levobunolol, Carteolol, Metipranolol
- Key concept: "-olol" suffix = beta blocker = sympatholytic
- Mnemonic: "Sympatho-LYTIC = lyse/destroy sympathetic signal"
Parasympathomimetic
Cholinergic Agonists (Miotics) — MIMIC parasympathetic system
- Action on eye: Miosis (constrict pupil), ↑ outflow by opening trabecular meshwork, accommodation
- Receptors: Stimulate muscarinic (acetylcholine) receptors
- Direct-acting: Pilocarpine, Carbachol
- Indirect-acting: Echothiophate (inhibits acetylcholinesterase)
- Mnemonic: "Para-MIMIC = copies 'rest & digest'"
Parasympatholytic
Anticholinergic / Cycloplegic / Mydriatic — BLOCK parasympathetic system
- Action on eye: Mydriasis (dilate pupil) + cycloplegia (paralyze accommodation)
- Receptors: Block muscarinic acetylcholine receptors
- Drugs: Atropine, Homatropine, Cyclopentolate, Tropicamide
- NOT for glaucoma: Can worsen angle closure!
- Used for: Refraction exams, uveitis, post-op
- Mnemonic: "Para-LYTIC = lyse/destroy rest signal = dilate"
🔍 ANS Quick-Reference Table
| Category | Action | Pupil Effect | IOP Effect | Examples |
|---|---|---|---|---|
| Sympathomimetic | Mimic sympathetic | Mydriasis | ↓ (via α2) | Brimonidine, Apraclonidine |
| Sympatholytic | Block sympathetic | Minimal | ↓↓ | Timolol, Betaxolol |
| Parasympathomimetic | Mimic parasympathetic | Miosis | ↓ | Pilocarpine, Carbachol |
| Parasympatholytic | Block parasympathetic | Mydriasis + Cycloplegia | ↑ (danger!) | Atropine, Tropicamide |
Exam Tip: Remember: "-mimetic" = copies/mimics the system. "-lytic" = blocks/destroys the signal. "Sympatho-" = adrenaline pathway. "Parasympatho-" = acetylcholine pathway.
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