A Comparison of Three Cylindrical Treatment Strategies for Topography-Guided LASIK: Manifest, Topographic, and ZZ VR Cylinders

Abstract

Purpose

This study was designed to compare the clinical outcomes of three cylindrical treatment strategies using manifest, topographic, and Zhang & Zheng vector-compensated refraction (ZZ VR) cylinders, for topography-guided laser-assisted in situ keratomileusis (LASIK) and to identify the laser programming strategy that optimizes refractive astigmatism outcomes and visual acuity.

Methods

Consecutive patients referred for therapeutic refractive surgery between March and September 2018 at a single center were prospectively analyzed. Using double-masked simple randomization, patients were randomly assigned to undergo treatment based on manifest cylinder, topographic cylinder, and ZZ VR cylinder strategies. Uncorrected distance visual acuity and astigmatic refraction were analyzed preoperatively and 6 months postoperatively.

Results

A total of 138 eyes from 71 patients met the inclusion criteria. The manifest group consisted of 46 eyes in 24 patients, the topographic group consisted of 43 eyes in 22 patients, and the ZZ VR group consisted of 49 eyes in 25 patients. The absolute residual cylindrical refractions at 6 months postoperatively in these three groups were 0.69 ± 0.32 D, 0.58 ± 0.31 D, and 0.42 ± 0.19 D, respectively (P < 0.001; adjusted P < 0.01 for manifest vs ZZ VR, adjusted P = 0.08 for topographic vs ZZ VR). The percentages of postoperative absolute residual cylindrical power within 0.50 D in the manifest, topographic, and ZZ VR groups were 30.4%, 55.8%, and 59.2%, respectively (P = 0.01; adjusted P = 0.06 for manifest vs topographic, adjusted P = 0.02 for manifest vs ZZ VR).

Conclusion

The ZZ VR strategy may achieve better outcomes, as determined by cylindrical correction and visual activity, during topography-guided LASIK.

Clinical Trial Registration Number

ChiCTR1900025779.

Keywords:

• astigmatism
• corneal wavefront aberration
• keratomileusis
• laser in situ
• refraction

Abbreviations

HOA, higher-order aberration; LOA, lower-order aberration; ZZ VR, Zhang & Zheng vector-compensation refraction; DS, diopters sphere; DC, diopters cylinder; SD, standard deviation.

Data Sharing Statement

The data supporting the findings of this study are available from the corresponding author upon reasonable request.

Ethics Approval and Informed Consent

The study protocol was approved by the Medical Research Ethics Committee of Hangzhou MSK Eye Hospital (approval number: MSKLL20180906). All procedures in this study adhered to the tenets of the Declaration of Helsinki. All participants were informed about the risks and benefits of the procedure and provided written informed consent. This study was registered in the Chinese Clinical Trials Registry (registration number: ChiCTR 1900025779).

Disclosure

All authors state that they do not have any conflicts of interest.

Additional information

Funding

This study was supported by the Zhejiang Province Medical and Health Science and Technology Project (Grant No. 2020167858).