The effect of cycloplegia on anterior chamber depth measured by non–contact biometry in children aged 6 years.

Abstract

Abstract: : Purpose: To examine pre and post–cycloplegia /dilatation measures of anterior chamber depth using the Zeiss non–contact IOLMaster. Method: The Sydney Myopia Study is a large population–based study of refraction and other measures of eye health in 2 age groups (6 and 12 years) of children from randomly selected schools across the Sydney metropolitan region of Australia. Anterior chamber depth and axial length were each measured 5 times using the IOLMaster both before and one hour after instillation of cyclopentolate (1%) and tropicamide (1%), two drops each, 5 minutes apart. Results: In 179 children aged 6 years the mean axial length was not significantly different between right (22.68mm, 95% CI 22.58 – 22.7) and left eyes (22.66mm, 95% CI 22.55 – 22.76). Anterior chamber depth was also similar in the right (3.37mm, 95% CI 3.35–3.40) and left eyes (3.41mm, 95% CI 3.38–3.44). The mean axial length, however, was longer in boys (22.94mm, 95% CI 22.82 – 23.06) than girls (22.37mm, 95% CI 22.21 – 22.53). Similarly, anterior chamber depth was slightly deeper in boys (3.41mm, 95% CI 3.38–3.44) than in girls (3.34mm, 95% CI 3.30–3.38). After cycloplegia /dilatation the axial length was unchanged (p = 0.55) while anterior chamber depth deepened in both boys (0.19mm, 95% CI 0.17–0.22) and in girls (0.21mm, 95% CI 0.17–0.24). Conclusion: This is the first report of pre– and post–cycloplegia and dilatation measures of axial length and anterior chamber depth using the IOLMaster. As previously reported using ultrasonic measures, axial length and anterior chamber depth is greater in boys than girls. The increase in anterior chamber depth found following cycloplegia /dilatation is mostly likely due to a decrease in lens thickness and backward movement of the lens in response to cycloplegia.

Keywords: clinical (human) or epidemiologic studies: biostatistics/epidemiology methodology • anterior chamber