mydriatics and cycloplegics

• Cycloplegic

  • Used to inhibit or paralyse the accommodation response AND pupil dilation – because of antimuscarinic drug action
  • Paralyse ciliary muscle
  • Blocks muscarinic receptors & release of Ach
  • Results in reduced accommodative function and pupil mydriasis (as pupil sphincter also affected)
  • Different drugs have different efficacy (depth of cycloplegia will vary)
  • Factors affecting absorption will also have this variable effect
• Mydriatic

  • Used to produce pupil dilation
  • Sphincter pupillae relaxation (but will also have cycloplegic effect, because of the antimuscarinic affect)
  • Dilator pupillae contraction (accommodation largely unaffected)
• Mydriatics & Cycloplegics available in UK

  • Sphincter pupillae relaxation (antimuscarinic/ Cholinergic blocker (antagonist) /cycloplegic)
  • Dilator pupillae contraction (Sympathomimetics/Adrenergic agonist)
• Tropicamide (0.5%, 1%)

  • Primarily used for mydriasis (dilate the pupil)
  • Also have cycloplegic effect - most practitioners do not use tropicamide for cycloplegic refraction
  • 1% could be used as cycloplegic in teenagers or adults
  • Evidence supports use in older children for cycloplegia
  • Many papers recommend caution when using tropicamide as the sole cycloplegic agent in infants and patients with high hyperopia or strabismus
• Cyclopentolate (0.5%, 1.0%)

  • Most widely used cycloplegic
  • Normally gives sufficient depth of cycloplegia but not full paralysis
  • Longer acting than tropicamide
  • Faster onset and shorter acting than atropine
  • Some patients may require combination drops for adequate cycloplegia
• Effect of cyclopentolate 1% over time by measuring pupil size (mydriasis) and accommodation
• Carefully consider those patients with very dark irises, particularly in children when suspicion of BV problem, anisometropia, risk of amblyopia
• Options to achieve maximum cycloplegia

  • Multiple drops of cyclopentolate 1%
  • Combination Tropicamide and cyclopentolate
  • Atropine
• Atropine 1%

  • Most potent cycloplegic
  • It is a prescription only medication (POM)
  • Systemic effects more likely than others – "ointment is preferred" – but not available in the UK. (only available in drop form in the UK)
  • Slower onset and longer duration and recovery than others
  • It may be given days before examined so it is at the peak
  • It can be toxic or potentially lethal if it is swallowed
• Indications for Atropine 1%

  • Very dark irises cycloplegic refraction
  • Penalisation therapy in amblyopia
  • Alleviation of ciliary spasm
  • Anterior Uveitis (in conjunction with corticosteroid) - stop the iris attaching to the cornea
• Phenylephrine 2.5%, 10%

  • Sympathomimetic – alpha -1 agonist
  • Produce little effect on accommodation response
  • Unlikely to be used on it's own for mydriasis – normally in combination drop
  • Vasoconstrictor properties are useful for differential diagnosis of red eye conditions
• Indications for use - diagnostic(Phenylephrine)

  • Better view – fundus, vitreous and lens
  • Refraction (cycloplegic)
  • Direct action on blood vessels (sympathomimetic)
• Indications for use - therapeutic(Phenylephrine)

  • To reduce ciliary spasm
  • To break synechiae
  • Occlusion therapy (atropine, orthoptists only!), used if patching has been unsuccessful
• Cautions

  Carefully consider advice and weigh up risks and benefits of using particular drug
• Contraindications

  Far more restrictive than Cautions. Risks outweigh the benefits of using particular drug. The drug should be avoided in a patient with a condition that is contra-indicated
• Contraindications for use - ALL

  • Confirmed angle closure
  • Risk of angle closure (occludable angle)
  • Iris supported IOL – intra ocular lens (anterior chamber implants)
  • Hypersensitivity
  • Contact lenses
• Cautions - cycloplegics

  • Systemic absorption increased in particular patient groups, young children & elderly
  • Consider performing punctal occlusion – 3 minutes
  • Use with caution in Down's Syndrome – normally in HES Doctor supervised clinic
  • Neonates, use lowest dose 0.5% (cyclo/tro) or atropine ointment
  • Darkly pigmented iris - increased resistant to pupillary dilation and caution should be exercised to avoid overdosage
  • Patient driving? Should be at least 2 hours after drops instilled
  • You cannot get atropine in ointment form – only drop form
• Interactions - cycloplegics

  • Consider other systemic meds with antimuscarinic actions
  • BNF states tropicamide interaction with 52 other drugs
• Ocular side effects - cycloplegics

  • Transient stinging
  • Transient blurring
  • Photophobia
  • Raised intraocular pressure
• A normal change in IOP post dilation is an increase of up to ~4mmHg
• IOP elevation remained significant until about four hours after dilation, thereafter, IOP decreased slowly and eventually reached pre-dilation level
• Duration and severity of IOP increase dependent upon drug used and magnitude of absorption and bioavailability
• Systemic side effects - cycloplegics

  • Dry mouth
  • Dry skin
  • Flushing
  • Increased body temperature
  • Increased heart rate
  • Headache
  • CNS effects (ataxia, hallucinations and drowsiness)
  • Anticholinergic effects (e.g. dry mouth, flushing) are more likely to occur in infants and children
  • Uncommon with tropicamide & cyclopentolate (dose dependent)
  • Atropine is more potent therefore increased risk
• A 23-year-old with Rheumatoid Arthritis with acute onset , tender red eye requiring further investigation, what drops do you use?


  phenylephrine 2.5%