The primary outcome of this study is to compare cyclopentolate 1% and tropicamide 1% for cycloplegic refractions in pediatric populations. This will be a prospective double-blinded randomized clinical trial (RCT), multi center, with randomized sequencing of cycloplegic agent; each patient received one agent at one visit, and the other agent in the next visit (2 different visits ≥ 1 week apart) within 3 months.

Refractive errors assessment especially in pediatric populations is usually affected by the accommodative spasm and possibly a myopic shift in the results. Spasm of accommodation become evident as pesudomyopia or latent hyperopia. Therefore, cycloplegic refraction using cycloplegic drugs is an effective way to reduce fluctuation in accommodation or spasm of ciliary muscle. The drug of choice should have a rapid onset, appropriate cyclopegic effect and minimum side effects. Cyclopentolate and Tropicamide are well known drugs used for accommodation relaxation. Cyclopentolate is widely accepted drug of first choice for patients of all ages. Its cycloplegic effects begins at 25-75 min after administration of the drop and recovery appears through 6-24 h later.6 Ocular side effects may include irritation, lacrimation, allergic blepharoconjunctivitis, conjunctival hyperemia, and increase in intraocular pressure. Some of its systemic side effects are drowsiness, ataxia, disorientation, incoherent speech, restlessness, and visual hallucinations. Tropicamide, as an alternative, is a synthetic analog of tropic acid and is known as a safe agent for cycloplegic refraction. It characterized by a rapid onset and the cycloplegia effect appears 20-30 min after administration. Its recovery appears 6 h later with safer profile compared to cyclopentolate. Several studies have been conducted to compare the cycloplegic effect of these two agents and different results have been reported. Because of inconsistencies in the previous reported results, this randomized clinical trial was conducted to compare the cycloplegic effect between cyclopentolate and tropicamide among pediatric populations (aged between 3 and 16).

Inclusion Criteria:

• Age: 3-16 years
• Brown irides; grade 4 and 5 using iris color classification system developed by Seddon et al (16)
• Duration: 2 different visits ≥ 1 weeks apart within 3 months

Exclusion Criteria:

• Abnormal red reflex (e.g., media opacity)
• History of heart or neurological diseases
• History of developmental delay
• History of a previous allergy to cycloplegic agents
• Presence of syndromes (e.g., Down's syndrome)
• History of intraocular surgery