[Influence of the instillation of two versus three eyedrops of cyclopentolate 0.5% on refraction of Caucasian nonstrabismic children].

INTRODUCTION

Children's refraction can usually be measured using cyclopentolate 0.5%. Instilling three drops is time-consuming and inconvenient to both the clinical staff and the child. To remedy this situation, we investigated the refractive results of instilling two drops of cyclopentolate 0.5% at a 10-min interval compared with three drops at a 5-min interval in a group of a Caucasian nonstrabismic children. The kinetics of refraction in this population was also assessed.

PATIENTS AND METHODS

We conducted a randomized cross-over study on 36 children aged between 4 and 13 years from March 1st to August 1st, 2003 at the University of Tours School of Ophthalmology. In protocol I, two cyclopentolate eyedrops were instilled in both eyes at a 10-min interval. In protocol II, three eyedrops were instilled at a 5-min interval. The refractive results were evaluated in terms of sphere and cylinder strength and axis. We used an auto-kerato-refractometer every 15 min from the first instillation for both protocols until the 90th min.

RESULTS

Before the first drop instillation, there was no significant influence on skiascopy results for both eyes (-0.30+/-0.20 D for the right eye; -0.37+/-0.24 D for the left eye). The strength and the axis of the cylinder were comparable and stable (-0.5+/-0.18 D for strength; 5 degrees +/-22 for the axis) for all protocols and subjects tested. Sphere variation reached +1+/-0.6 D between t0 and t30 min for both protocols and remained stable between t30 and t90 min (+0.01+/-0.2 D).

CONCLUSION

Instilling two eyedrops of cyclopentolate 0.5% at a 10-min interval in Caucasian nonstrabismic children aged 4-13 years is as effective as instilling three eyedrops at a 5-min interval in terms of kinetics and depth of cycloplegia. In addition, skiascopy can be performed as early as 30 min after the first instillation and until the 90th minute with the same effectiveness. The stability of astigmatism should be underlined in this population. Since these refractive results cannot be extrapolated for strabismic and ametropic children, we recommend, especially for the latter, instilling three drops for the first exam and only two thereafter, depending on the results.