Pupil dilation with intracameral lidocaine during phacoemulsification

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The concept of preoperative dilation of the pupil by intracameral injection of preservative-free lidocaine, described in the article by Nikeghbali et al.,1 appears to be appealing. However, the effect of lidocaine on the endothelium and other safety aspects must be studied in detail. The following aspects need clarification: The pupil measurements were taken using a caliper. The authors did not mention whether the reported pupil sizes were the actual pupil size or the measurement of pupil size over the cornea. A magnification factor has to be applied to ascertain the actual pupil size from the measurement taken over the cornea. This magnification factor is dependent on the corneal power, anterior chamber depth, and refractive index of the aqueous. The measurement of pupil size over the cornea will also have the inherent parallax error. For the sake of uniformity of measurement, the magnification of the microscope used during measurements should be uniform as well. The measurements over the cornea with the caliper have a potential of interobserver variability. The article does not mention whether all the measurements using a caliper were taken by the same person.