Cataract Surgery Refractive Outcomes In Eyes With Previous Kamra Corneal Inlay: A Case Series.

To assess the refractive errors in intraocular lens (IOL) power calculation for patients with a history of previous KAMRA™ inlay implantation (AcuFocus, Irvine, California), using different common formulas (Barrett, Shammas, Haigis, and Pearl-DGS).

The KAMRA™ corneal inlay has been used for many years in refractive surgery as an additional option for correcting presbyopia. The IOL power calculation in patients with a previous history of KAMRA™ inlay implantation is an emergent issue due to the keratometric and corneal microstructural changes induced by this inlay. 

This retrospective multicentric study included 20 eyes that underwent cataract surgery between 2016 and 2023. All patients had a history of previous KAMRA™ inlay implantation. Among the 20 eyes studies, half had the corneal inlay removed prior to cataract surgery. Relative and absolute refractive errors were calculated postoperatively in diopters, based on the subjective refraction of patients.

On average, the four formulas presented a relative refractive error of +1.31D (+/- 1.64) and an absolute error of +1.68D. The Shammas formula was the most accurate with a relative refractive error of +1.17D (+/- 1.63) and an absolute error of 1.61D, followed by the Barrett formula (relative error: +1.36 [+/- 1.64]; absolute error: +1.75D), Haigis formula (respectively +1.42 (+/- 1.69) and +1.70D), and Pearl-DGS (respectively +1.52 (+/- 1.64) and +1.82D).  

The studied IOL power formulas result in a hyperopic shift for patients with a previous history of KAMRA inlay implantation. In this situation, the Shammas formula is associated with the least significant refractive error.