1 - Cycloplegics

Question 1

How drugs enter eye

Answer 1

Cornea is a lipid-water-lipid soluble structure.
- Eye drops exist in fat soluble form to penetrate epithelium (R3N)
- Can become in equilibriym with 2nd form thats water soluble form (R3N+) which penetrates stroma.
- Then fat-soluble form passes endothelium

Question 2

Indications for cycloplegics?

Answer 2

• Stabismus
• High plus
• Accommodative esotropia
• Suspected pseudomyope
• High phorias
• Low amp of accom for age (pseudomyope suspect?)
• Impaired BV
• < 3yrs
• Developmentally delayed
  Basically anything that can cause unexpected accom.

Question 3

Everything you need to do before cyclopleging?

Answer 3

• Sensitivity to drug?
• General health?
• Family history of angle closure glaucoma?
• Check angles
• Refract before cycloplege
• Tonometry (before and after)

Question 4

Cycloplegic mechanism of action?

Answer 4

All block mACh receptors of ciliary body smooth muscle and sphincter pupillae smooth muscle

Question 5

How to prescribe based off of cycloplegic Rx?

Answer 5

• Give full Rx for esotropia
• For latent hyperopia, cyclopentolate usage = reduce by at least 1D (since they’re probably used to constant small accommodation).
  If atropine for latent hyperopia:
• > +4.50 = reduce by 1D
• +0.5 to +4.00 = reduce by 0.5D
• < +0.50 = no reduction

Question 6

Tropicamide
- Concentration
- Time scale
- Use
- Other notes

Answer 6

• 1%
  Time:
• Mins onset
• 30min refract (45min if dark iris)
• 3hrs cyclo (6-8hrs for mydriasis)
• Useful for children >12yrs
• Better cyclopleged if used w/ TLA
• Relatively safe

Question 7

Cyclopentolate
- Concentration
- Time scale
- If darker iris…

Answer 7

1% for < 16yrs, 0.5% if older
Time:
- Minutes onset
- 30min max
- 24hrs recovery

If darker iris, use
- cyclopentolate 1% w/ tropicamide 1% or
- TLA before cyclopentolate.

Question 8

Hyoscine and Homatropine?

Answer 8

• Hyosine (0.1 - 0.25%) – Motion sickness, prevent post. Synchechiae in inflamm disease.
• Homatropine (2 - 5%) - Use mydriasis effect in inflammatory disease to prevent posterior synechiae.

Question 9

Cyclopentolate adverse events?

Answer 9

• Sting on instillation (TLA can reduce)
• Lacrimation, mucous discharge
• More CNS side effects than atropine
  Early signs of toxicity:
• Drowsiness
• Ataxia
• Disorientation
• Incoherent speech
• Restlessness
• Emotional disturbances

Question 10

Apart from cycloplegic drops, how can we perform refraction in children?

Answer 10

• Spray administration of cycloplegic (0.5% cyclopentolate + 0.5% tropicamide + 2.5% phenyleprhine)
• Photorefraction (cycloplege still required for high Rx)
• Mohindra’s near ret technique (child focuses on ret so we know their accommodation).

Question 11

Atropine

Answer 11

Mydriasis = 2 weeks
Cyclopleged = 10 - 18 days
- >+4.50 = reduce by 1D
- +0.5 to +4.00 = reduce by 0.5D
- < +0.50 = no reduction
- Drop/ointment on infants 3 days prior to cyclopleging
- Other use:
- Inflammation
- Amblyopia
- Myopia control