[Influence of mydriatic eye drops on the aberrometer predicted phoropter refraction].

Background And Purpose: Wavefront-guided ablations are based on wavefront sensing in a pupil dilated under mesopic conditions, or in patients with insufficient natural pupil dilation, after the application of mydriatic eye drops. The aim of this study was to investigate a potential influence of mydriatic eye drops on wavefront-sensing in terms of the predicted phoropter refraction (PPR).

Method: In this prospective study 70 myopic eyes were measured in miosis and pharmacologically induced mydriasis with the Zywave aberrometer and automated refraction (Canon R-F10). 52 eyes were dilated with eye drops containing tropicamide 0.5 % and phenylephrine 2.5 %, in the remaining 18 eyes tropicamide 0.5 % was used. The PPR for a pupil diameter of 3.5 mm in miosis and in mydriasis, respectively, were compared and correlated to the corresponding values of the automated refraction.

Results: PPR values obtained in mydriasis were less myopic than in miosis. The sphere of PPR differed by an average of + 0.19 +/- 0.3 diopters (range: -1.07 to + 0.37 diopters) when using tropicamide 0.5 % and phenylephrine 2.5 %. With tropicamide 0.5 % eye drops the difference was + 0.25 +/- 0.4 diopters (range: -1.12 diopters to + 0.27 diopters). Cylinder values were not affected. Automated refraction yielded a smaller difference of + 0.16 +/- 0.33 diopters (tropicamide 0.5 % and phenylephrine 2.5 %) and + 0.1 +/- 0.19 diopters (tropicamide 0.5 %). Cylinder values changed significantly.

Conclusion: The cycloplegic effect of mydriatic eye drops should be taken into account when interpreting aberration measurements and planning a wavefront-guided laser ablation.