Post refractive patients, especially those choosing premium IOL's, are increasing in number and are challenging as they have higher expectations.
K-values from keratometry, IOL Master and topography on post refractive patients are difficult due to the fact that these instruments only measure the front corneal surface and use the ratio of 82% to assume the back surface. In post refractive patients, this ratio may no longer be valid and could lead to post operative surprises.
Scheimpflug imaging systems directly capture front and back measurements however the slow capture speed, 15 micron resolution (versus 5 micron for SD-OCT), and fluctuating angle of capture make addressing post refractive patients problematic.
RTVue with Total Corneal Power (TCP™)
Unique in the market - The only SD-OCT that provides corneal power to date
Directly measures the anterior and posterior surface of the cornea – no assumed ratio
5 micron resolution
The accuracy of the FD-OCT IOL power calculation method is higher than with any other tool available, making it an integral part of the preoperative diagnostic testing in cataract eyes that have previously undergone refractive laser surgery. RTVue Total Corneal Power measurement has excellent repeatability, 0.17 D STDev on the post-lasik/PRK patient. Utilization of TCP provides an important and novel piece to the puzzle in obtaining accurate biometry. This is particularly crucial in eyes that have had prior corneal procedures including refractive procedures such as LASIK. Incorporating this measurement into IOL selection has given additional assurance of proper lens selection.