Расширение зрачка искажает расчеты силы внутриглазных линз

Dilation may alter IOL power calculations Key takeaways: - Dilation was linked with increased anterior chamber depth and reduced lens thickness. - Dilation resulted in significant increases in IOL power calculations for the Barrett II Universal and Haigis formulas. Pupil dilation could skew IOL power calculations by increasing anterior chamber depth and reducing lens thickness, according to a study published in Journal of Refractive Surgery. “Because biometry and IOL power calculations are commonly performed on the same day once a decision for surgery has been made, biometry is usually performed while the patient’s pupils are still dilated,” David Z. Chen, MBBS, FRCOphth, of National University Hospital in Singapore, and colleagues wrote. “Currently, there is no consensus on how mydriatics influence biometric results and, if so, which parameters are affected.” Chen and colleagues searched the literature for studies that included ocular measurements, such as anterior chamber depth, axial length, central corneal thickness, mean keratometry, lens thickness and white-to-white distance, before and after dilation. They reviewed the change in those measurements after dilation as well as how the dilation affected the predicted refractive outcome based on IOL formulas. They found that dilation resulted in a significant increase in anterior chamber depth. In 16 studies comprising more than 1,900 patients, depth increased from 3.25 mm at baseline to 3.33 mm after dilation, according to the study. Dilation resulted in a significant reduction in lens thickness. In eight studies comprising more than 800 patients, lens thickness decreased from 4.18 mm at baseline to 4.16 mm after dilation. Chen and colleagues found that dilation significantly increased IOL power calculations for the Barrett II Universal and Haigis formulas, but there was little to no impact on the other six formulas they analyzed. “As IOL calculation formulas continue to evolve, the surgeon should be aware of the factors that can affect and change these formulas and thus take into consideration the status of the patient’s pupil when sending them for preoperative biometry,” the authors wrote.