March 9, 2018 Conference


Advanced Planning Strategies of Topography guided LASIK for the correction of regular and irregular astigmatism

Mr. Ronald Krueger (Presenter)
Vinicius Silbiger De Stefano, Cleveland Clinic Cole Eye Institute

Purpose: Since the U.S. approval of topography-guided customized treatments (TCAT), much debate has ensued regarding the appropriate planning strategies when manifest and topographically measured cylinder values differ in axis and magnitude. We wish to analyze our pattern of success among the eyes that gained one or more lines of best corrected visual acuity (BCVA).

Methods: 256 eyes undergoing TCAT by a single surgeon from Feb 2016 to May 2017 were enrolled in this retrospective study at the Cleveland Clinic. All eyes were healthy, and had at least 4 good quality topographic maps. The corneal shape was captured with the Topolyzer, and coupled with the eye’s refraction to generate an ablation profile with the Allegretto Wave Eye-Q laser. The cylinder magnitude and axis of laser entry were decided by the surgeon, based on both the manifest and measured values, assisted by additional data from a tomographer (Pentacam) and ocular wavefront (LADARWave). All patients were followed at 1 day, 1 week and 3 months.

Results: At three months, 95.7% achieved UDVA of 20/20 or better, while 81.4% were 20/15 or better. 25.6% gained one or more lines of BCVA. Among these eyes, measured and manifest axis differed by less than 15° in 59%, between 15° and 30° in 18% and more than 30° in 23%. When it differed by at least 5°, the measured axis was treated in 79%, 67% and 73% of eyes, respectively. In the 68% of eyes with greater measured cylinder magnitude, 75% were treated between manifest and measured with only 7% at full measured value (TMR). By contrast, when manifest was greater, 60% were treated at total measured value and 40% in between. Despite the improvement in vision, whole-eye aberrometry showed a significant increase in coma, spherical aberration and total RMS (all p < 0.001).

Conclusion: TCAT can achieve better than glasses vision in more than a quarter of eyes. In eyes gaining a line of vision, the measured axis is treated in ~75%. When the measured magnitude is higher, a value between the measured and manifest is chosen in 75% to avoid overcorrection. Tomography and ocular wavefront values assist in the selection process.