Sanders Donald R, Bernitsky David A, Harton Paul J, Rivera Robert R
University of Illinois Eye and Ear Infirmary, Chicago, Ill, USA.
J Refract Surg. 2008 Nov;24(9):957-9. doi: 10.3928/1081597X-20081101-17.
To compare pre- to postoperative axial length measurements with the IOLMaster (Zeiss Humphrey Systems) to determine whether a correction factor for later intraocular lens (IOL) power calculation is necessary with an Implantable Collamer Lens (ICL; STAAR Surgical) in place.
The commercially approved Visian ICL was implanted in 60 eyes from 3 separate sites (20 eyes each). Pre- and postoperative axial length measurements were obtained using partial coherence interferometry.
The pre- and postoperative axial lengths were highly correlated with an R2 value of 0.9963. For all ranges of axial lengths tested, the use of postoperative axial length instead of preoperative axial length resulted in a <0.1-mm error in axial length measurements.
Based on the SRK formula, a 0.1-mm axial length difference would result in a 0.25-diopter (D) change in calculated IOL power; possibly a 0.20-D change in manifest refraction. These differences are so small as to make any correction to IOL power calculation formula based on the presence of an ICL unnecessary.
