Ophthalmic pharmacology

Question 1

What is the effect of anti-muscarinics on the eye

Answer 1

Mydriasis (Pupil dilatation)
Loss of light reflex
Cycloplegic (Iris paralysed) → blurred vision
- Tropicamide (duration: 3 hours) - dilates eye directly
- Cyclopentolate (duration: 24 hours; preferred for paediatric use) - cycloplegic

Question 2

What is the effect of sympathomimetics on the eye

Answer 2

Mydriasis (Does not affect light reflex or accommodation)

e.g. para-hydroxyamphetamine
Phenylephrine

Question 3

What are the indications for pupil dilation (Mydriasis) and what drugs are used

Answer 3

Eye exams
Preventing synechiae (adhesions between iris and trabecular network) in anterior uveitis

Anti-muscarinics (tropicamide, cyclopentolate)
Sympathomimetics (para-hydroxyamphetamine, phenylephrine)

Question 4

What should be considered before using drugs to induce mydriasis

Answer 4

Avoid in acute glaucoma in the shallow anterior chamber

Question 5

What drugs cause miosis

Answer 5

Pilocarpine
Tetracaine
Lubricants e,g, hypromellose, carbomer
Topical antihistamines e.g. emedastine, antazoline

Question 6

What is the indication for pilocarpine

Answer 6

Acute closed-angle glaucoma

Question 7

What is the indication for tetracaine

Answer 7

LA examination for painful eyes