Static and dynamic rotational eye tracking during LASIK treatment of myopic astigmatism with the Zyoptix laser platform and Advanced Control Eye Tracker.

PURPOSE: To evaluate the amount of cyclotorsion and the effect of static and dynamic rotational eye tracking with the Advanced Control Eye Tracker (Bausch & Lomb) based on iris recognition in the treatment of myopic astigmatism with LASIK. METHODS: All patients with myopic LASIK and attempted cylinder correction >0.75 diopters (D) on the Zyoptix 217z100 excimer laser platform between May 2005 and May 2007 were identified retrospectively through the existing databank. Pre- and postoperative refraction and the amount of cyclotorsion during treatment were extracted and analyzed in 828 eyes with >3-month follow-up. RESULTS: Preoperative mean manifest refraction spherical equivalent (MRSE) was -4.31+/-1.84 D (range: -0.37 to -9.50 D), and mean cylinder was -1.27+/-0.87 D (range: -0.75 to -6.75 D). Mean static rotation was 3.96+/-2.96 degrees (maximum 14.8 degrees ). Median dynamic rotation was 1.32+/-1.85 degrees (maximum 24 degrees). At 3 months postoperatively, MRSE was -0.10+/-0.36 D (range: -2.25 to +1.25 D), and mean cylinder was -0.33+/-0.35 D (range: -2.00 to 0 D). Predictability was 90.2% within +/-0.50 D and 98.2% within +/-1.00 D (MRSE), and 82.5% within +/-0.50 D and 96.9% within +/-1.00 D (cylinder). The efficacy ratio was 0.99. Safety was 99.4% (5 dry eyes), reaching 100% at 12 months. Stability from 3 to 12 months (n=275) was 98.2% for sphere, 95.3% for cylinder, and 96.0% for MRSE. CONCLUSIONS: Our study demonstrates that significant cyclotorsion occurs before and during treatment. By using the dynamic rotational eye tracker presented, the efficacy of cylinder correction can be improved compared to those studies not performing cyclotorsional correction.

Online optical coherence pachymetry as a safety measure for laser in situ keratomileusis treatment in 1859 cases.

PURPOSE: To evaluate the reliability and applicability of online optical coherence pachymetry (OCP) (OCPonline, Heidelberg Engineering GmbH) integrated into the Zyoptix 217z100 excimer laser platform (Bausch & Lomb) under routine clinical conditions. SETTING: Private laser clinic, Munich, Germany. METHODS: Between July 2004 and June 2006, 1859 consecutive eyes having laser in situ keratomileusis (LASIK) using the Zyoptix 217z100 excimer laser platform had preoperative pachymetry with the Orbscan II (Bausch & Lomb) and DGH II (Pachette 2, DGH Technology, Inc.) and continuous intraoperative online OCP with the OCPonline. Preoperative pachymetry values and actual flap thicknesses with the Hansatome and Zyoptix XP microkeratomes (both Bausch & Lomb) and the IntraLase FS30 femtosecond laser keratome (IntraLase Corp.) were evaluated. RESULTS: Preoperative pachymetry values showed a high correlation between the OCPonline device and the Orbscan II (R(2) = 0.78, difference = 0.37%) and DGH II (R(2) = 0.77, difference = 0.69%). The OCPonline measurements resulted in a mean flap thickness of 121.4 microm +/- 19.1 (SD) with the Hansatome (160 microm head), 126.5 +/- 15.5 microm with the Zyoptix XP (120 microm head), and 121.7 +/- 14.7 microm with the IntraLase FS30 (110 microm flap thickness). A correlation between the calculated laser ablation depth and the measured stromal thinning was established. CONCLUSION: OCPonline technology provided reliable intraoperative noncontact pachymetry measurements integrated into a clinical flow, indicating the technology has the potential to improve the safety of corneal ablation procedures.

Age-related behavior of posterior chamber lenses in myopic phakic eyes during accommodation measured by anterior segment partial coherence interferometry.

PURPOSE: To evaluate age-related position shifts of the crystalline lens and the implantable contact lens (ICL, Staar Surgical) by a new, commercially available, anterior segment partial coherence interferometer, the ACMaster (Carl Zeiss Meditec), during accommodation in myopic eyes. SETTING: ALZ Augenklinik, Munich, Germany. METHODS: Fifty-three eyes of 29 consecutive patients were measured after myopic ICL implantation before and during subjective accommodation to a stimulus of 3 diopters (D) by anterior segment partial coherence interferometry (PCI). Nine eyes were also measured with a 5.00 diopters (D) stimulus; 14 eyes were measured repeatedly at different visits. The mean patient age was 33 years +/- 9 (SD) (range 21 to 59 years). The preoperative mean sphere was -7.6 +/- 1.9 D (range -5.0 to -11.5 D) and the cylinder, -1.4 +/- 1.1 D (range 0 to -4.25 D). RESULTS: Older patients had a tendency toward smaller vaults on desaccommodation between the ICL and the crystalline lens compared to younger individuals. In younger patients, there was a decrease of the vault on accommodation, whereas it increased in older persons (P = .005). During accommodation, the more the anterior lens surface shifted forward, the more the ICL bulged (P = .005). The change in vaulting was significantly larger at 5.00 D than at 3.00 D accommodation stimulus (P = .012). CONCLUSIONS: The behavior of ICLs in relation to the crystalline lens during accommodation varied with age and could be shown by PCI. The position shift of the ICL depended on the initial vault at desaccommodation and the ability of the anterior lens surface to bulge forward. Even though the crystalline lens stiffened, and therefore accommodation deteriorated with age, there was still a movement of the ICL, pointing to the role of the ciliary muscle movement in accommodation.