Glaucoma Flashcards
What are some fo the risk factors for glaucoma?
High intraocular pressure (>21 mmHg) Family history Systemic hypertension CVD Migraine Previous ocular disease
What are the two types of glaucoma?
Open angle
Closed angle
Which type of glaucoma is primarily treated with drugs?
Open angle
What causes glaucoma?
An imbalance between the production of aqueous humour and drainage of aqueous humour
Where is aqueous humour produced?
Ciliary epithelium
Normally in the eye, why is there continuous flow and drainage of aqueous?
Because the pressure inside the eye is greater than the pressure outside in the episcleral vein and Schlemm’s canal
What are the two pathways in which aqueous humour is drained?
Trabecular meshwork - main
Uveoscleral flow
Why is there resistance to flow in the uveoscleral pathway?
Because cells are tightly packed within tissues and therefore it is harder for humour to drain through
What are the drug classes for treatment options for glaucoma?
Prostaglandin + prostamide analogues B-blockers Carbonic anhydrase inhibitors A2-adrenoreceptor agonists Parasympathomimetics
Where are FP receptors located?
Few in the trabecular meshwork
Iris sphincter
Ciliary body and muscle
Where are a2 receptors found in the eye?
Ciliary, conjunctival and corneal epithelial cells
Which drug classes reduce IOP by increasing uveoscleral outflow?
Prostaglandin and prostamide analogues
How do prostamide and prostaglandin analogues work?
They reduce resistance to uveoscleral outflow by remodelling the extracellular matrix. They do this by increasing matrix metalloproteinases which degrade collagen and the extracellular matrix, reducing the resistance of the sclera and ciliary muscle
What is the mechanism of action of timolol?
Decreases ion concentration, decreases fluid along gradient and so decreases aqueous humour production
Name a CAI used in the treatment of glaucoma
Acetazolamide - systemic CAI
Brinzolamide and dorzolamide - topical CAI