Eye practical Flashcards
How do pilocarpine and tropicamide affect the eye?
Pilocarpine = decreased pupil size, decreased accommodation reflex, no light reflex Tropicamide = opposite effects
Which side of the ANS do pilocarpine and tropicamide act on?
parasympathetic
What are the ocular effects of sympathomimetic drugs such as dipivefrine?
contraction of radial eye muscle + dilation of pupil –> similar effects to tropicamide
What are some adverse effects of sympathomimetic drugs such as dipivefrine?
poor close vision (lack of accommodation)
tachycardia
hypertension
What effect would you expect timolol (beta blocker) to have on the eye?
radial muscle is innervated by a1 adrenoceptors –> beta blockers have NO EFFECT on pupil size
What eye condition can timolol be used to treat + why?
glaucoma
b2 receptors found within smooth muscle controlling blood vessels supplying the eye and cause vasodilation –> blocking these receptors causes vasoconstriction + decreased blood flow –> decreased aqueous humour production –> IOP decreases –> glaucoma cured
What are the contra-indications of using timolol as a treatment?
heart failure, COPD, asthma
What happens to the size of the pupils following a toxic dose of heroin?
pupils become extremely constricted –> opiates bind to GABA interneurons which have inhibitory effects on the parasympathetic occulomotor nerve
How can carbonic anhydrase inhibitors be effective in the treatment of glaucoma?
mediate production of aqueous humour –> blocking the enzyme decreases IOP + other effects of glaucoma
Give an example of a carbonic anhydrase inhibitor
acetazolamide
What are the potential side effects of carbonic anhydrase inhibitors?
numbness tingling in fingers + toes parageusia (abnormal taste alteration) --> particularly strong after carbonated drinks nausea/vomiting polyuria
