To compare the clinical sedative effect and safety using 10% chloral hydrate during ophthalmic examinations for oral vs enema group.The patients were randomly divided into two groups (oral group and enema group) using a computer random number generator with a 1:1 allocation (simple randomization, odd number for oral group and even number for enema group).

To compare the clinical sedative effect and safety using 10% chloral hydrate during ophthalmic examinations for oral vs enema group.The patients were randomly divided into two groups (oral group and enema group) using a computer random number generator with a 1:1 allocation (simple randomization, odd number for oral group and even number for enema group).One hundred and twenty children aged from 3 to 36 months (5-15 kg) scheduled to ophthalmic examinations were randomly sedated by oral chloral hydrate(80 mg×kg-1, n = 60) or enema chloral hydrate(80 mg×kg-1, n = 60). The primary endpoint was successful sedation to complete the examinations including slit-lamp photography, tonometry, anterior segment analysis, and refractive error inspection. The secondary endpoints included onset time, duration of examination, recovery time, discharge time, any side effects during examination, and within 48 h after discharge.

Inclusion Criteria:

• diagnosed with congenital cataract aged from 3 to 36 months weight from 5 to 15 kg with American Society of Anesthesiologists (ASA) physical status 1-2

Exclusion Criteria:

• with gastro-esophageal reflux, nausea and vomiting, apnea in the past 3 months recent pneumonia exacerbation of asthma, bronchitis and upper respiratory tract infection bradycardia, and facial abnormalities, allergy to chloral hydrate, weight <2 or >20 kg .