In their study of patients with pseudoexfoliation (PXF) syndrome having phacoemulsification cataract surgery and implantation of a single-piece foldable intraocular lens (IOL) in the capsular bag,1 Ishikawa et al. considered the hypothesis that the study eyes might obtain different refractive outcomes than the control eyes.
This hypothesis is interesting, as a weaker zonular apparatus might determine a different effective lens position, hence a different behavior in terms of predicted postoperative refractive error. Although the axial length distribution was similar in the 2 groups, the optical biometry was performed for all the eyes, and the same IOL was implanted, we believe that the authors should also provide further clarification to enable acceptance of their results.
Given the 3-year study period and the relative small number of patients (62 eyes with PXF), we believe that only a sample was studied: Did the authors study a consecutive series? And how did they identify the controls?
Details regarding the IOL power in the 2 groups and the distribution of the astigmatic error were not provided, and the IOL formula(s) adopted not stated. Given that the main measure of the study was the postoperative refraction, we would also like the authors to clarify how that was assessed.
Although it remains impossible to quantify the degree of zonular impairment in different patients affected by PXF, we feel that eyes with manifest iridophacodonesis and those in which a capsular tension ring was inserted should have been excluded from the analysis.
Finally, were the samples large enough to enable meaningful statistical data analysis?
1. Ishikawa N, Hayashi Y, Miyamoto T, Saika S. Errors in the prediction of postoperative refraction following intraocular lens implantation in eyes with pseudoexfoliation syndrome. J Cataract Refract Surg