7.1.2 Uses appropriate diagnostic drugs to aid refraction

Question 1

What are the features of cyclopentolate?

Answer 1

• Available as: 0.5% or 1%
• Time to cycloplegia: 30 – 60 mins
• Duration: 6 – 24 hours
• Antimuscarinic Drug
• POM drug

Question 2

When can resistance to cycloplegia occur?

Answer 2

Resistance to cycloplegia can occur in:
* Patients with dark skin
* Patients with dark iris
Therefore, the strength, concentration & dose of cyclopentolate used should be adjusted
accordingly

Question 3

What are the adult and child doses of cyclopentolate?

Answer 3

Adult Doses:
* Blue Iris: use 0.5% à mydriasis + cycloplegia in 20 mins
* Brown Iris: Use 1% à mydriasis + cycloplegia in 30 – 40 mins
* Children with highly active accommodation à 1%
* Anterior/Posterior Uveitis and Posterior Synechiae breakdown: 1-2 drops of 1%
every 6-8 hours
* Alleviation of ciliary spasm: 1 drop of 1% 2-3 times a day
Child Doses:
* Less than 3 months old: Sweetman advises 0.5% à EMC SPC advises not at all.
* 3 months – 12 years: 1 drop of 1% solution to each eye, regardless of eye colour
* 12 years+: adult doses

Question 4

What are the indications for cycloplegia?

Answer 4

o Hx & Sx indicate accommodative problems (DV blur after lots of near work)
o All new child Px
o Unable to obtain satisfactory acuity
o Unable to obtain satisfactory level of stereopsis
o FH of strabismus
o Px report of eye turn
o Anisometropia >1D
o Poor Co-operation
o SOT or convergence excess SOP
o Accommodative fluctuations during retinoscopy
o Retinoscopy much more plus than subjective result
o Subjective more minus than expected for unaided VA
o Myopia with SOP
o Suspected latent hyperopia, psuedomyopia or accommodative spasm (-ve accommodative lag)
o Px with accommodative infacility (poor ability to change focus +-2.00 flippers)
* For anterior & posterior uveitis (if associated with signs of anterior uveitis)
* To breakdown posterior synechiae
* Relieve ciliary spasm in uveitis
* Cycloplegic refraction
* Penalisation therapy in amblyopia

Question 5

What are the advantages and disadvantages of cyclopentolate?

Answer 5

• Advantages
  o Reveals latent hyperopia
  o Accurate fixation for ret is less crucial
  o Aids fundus examination
• Disadvantages
  o Distress child on instillation of drops, Photophobia with dilation, decreased ability in near work, risk of adverse
  reactions

Question 6

What are the ocular and systemic effects of cyclopentolate?

Answer 6

Ocular Effects of Cyclopentolate
* Irritation
* Lacrimation
* Conjunctival Hyperaemia
* Allergic blephero-conjunctivitis
* Elevated Intraocular Pressure
Systemic Effects of Cyclopentolate
* Drowsiness
* Ataxia
* Disorientation
* Incoherent speech
* Restlessness
* Visual Hallucinations

Question 7

What should you write down when instilling cyclopentolate?

Answer 7

• Give Patient Information Leaflet and Sign the sheet.
• Any Allergies
• Name, Batch Number, Exp Date, Time of instillation

Question 8

How does cyclopentolate hydrochloride work?

Answer 8

• Antimuscarinic - competitive antagonist (prevents activiation) of muscarinic receptors. Bocks acetylcholine receptors in eye’s muscles - causes ciliary muscle to relax and suspensory ligaments to loosen which paralyses ciliary muscle. Causes mydriasis too.
• ADRs rare
• Hypersensitivity may occur - facial and upper body rash may occur 4-6 hours post instillation
• Transient stinging due to pH 5