Intraocular Pressure Control

• Many therapies utilise the pharmacology of the autonomic nervous system
• Carbonic anhydrase: numerous subtypes throughout ocular tissues
• Carbonic anhydrase isoenzyme II works in the non-pigmented ciliary epithelium

• Formation of aqueous relies on bicarbonate which is produced by carbonic anhydrase catalysing the hydration of carbon dioxide to bicarbonate

• Note: carbonic anhydrase has a high turnover

• Carbonic anhydrase inhibitors like acetazolamide reduce aqueous production

• Part of the sulfonamide class of diuretics, related to sulphonylureas (eg. gliclazide) and sulfonamide antibiotics (eg. sulfamethoxazole)

• Side effects
• Ocular: tearing, allergic blepharoconjunctivitis, transient myopia
• Potassium depletion
• Dermatitis
• Renal calculi
• Metabolic acidosis
• Peripheral paraesthesia
• Thrombocytopenia 
• Agranulocytosis and aplastic anaemia
• Can precipitate sickling in those with sickle cell anaemia
• Hepatic encephalopathy
• Steven-Johnson syndrome
• Teratogenicity is documented in mouse models

• Prostaglandin analogues (eg. latanoprost): prostaglandin F2-alpha analogues and prostanoid FP receptor agonists which reduce IOP by increasing aqueous outflow via the uveoscleral route.

• Prodrugs that are activated by corneal esterases

• Bimatoprost is a synthetic prostamide analogue and increases both uveoscleral and conventional outflow

Pregnancy

• Prostaglandin analogues, carbonic anhydrase inhibitors and beta-blockers have all been found to have teratogenic effects

• Brimonidine and other alpha-2 agonists are the safest in pregnancy. However they should be avoided while breastfeeding