The authors investigated optical biometry in an Indian paediatric population on normal and cataract paediatric eyes and studied the effect of cycloplegia on different parameters measured in these eyes. This was a prospective study of 76 eyes aged five to 15 years. Optical biometry was taken on 56 eyes; axial length, central corneal thickness and lens thickness significantly decreased after cycloplegia. There was no change for average K values and mean IOL powers. Anterior chamber depth significantly increased. On 20 cataract eyes significant effects were only noted for anterior chamber depth and lens thickness. The authors conclude that biometry in paediatric patients can be easily done (they used the Lenstar LS900 optical biometer). Cycloplegia was confirmed to affect various ocular parameters but the authors suggest further research in a larger sample size to evaluate the effects of cycloplegia given its frequent use in paediatric ophthalmic practice.