Low-dose atropine
Key Points
- Researchers classify a patient as having myopia if they have a mean spherical equivalent ametropia of -0.50DS or more, and high myopia when -6.00DS or more.
- Complications increase with higher myopia and these include retinal detachment, cataract, glaucoma and maculopathy; all causes of visual impairment.
- Atropine is an anti-muscarinic agent used in doses of 1% and 2% concentration as a cycloplegic agent and in amblyopia therapy, but recently has been used in lower concentrations to slow myopia progression by a mechanism yet to be fully understood.
- 0.01% atropine may block M1 and M4 receptors that may influence myopic progression, but not the M3 receptors influencing pupil size and accommodation.
- Topical use of 0.01% atropine has fewer adverse ocular effects, and cessation is not found to cause any significant rebound effects as occurs with 1%. Also, the lower dose is far less likely to cause systemic adverse effects.
- 0.01% atropine in Asian children may slow myopia progression by up to 50%, but is influenced by age of the patient at first intervention and the severity of the myopia. The effect in Caucasian children is yet to be established.
- Axial length may be measured using optical biometry, and myopia changes by refraction (researchers tend to use cycloplegic autorefraction).
- Low-dose atropine is yet to be licensed in the UK, but trials into its use as a myopia treatment are under way.