VECTOR ANALYSIS REVEALS THAT TOPOGRAPHY-GUIDED LASIK TARGETING THE MANIFEST REFRACTION (MR) IS SUPERIOR TO TOPOGRAPHY-MODIFIED REFRACTION (TMR) AND LAYER YOLKED REDUCTION OF ASTIGMATISM (LYRA)

Wallerstein A, Gauvin M. Clin Ophthalmol. 2021;15:889–890.

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We read with interest “Primary Topography-Guided LASIK: A Comparative Study Comparing Treating the Manifest versus the Topographic Astigmatism”. We commend the authors for performing vector analysis of surgical astigmatic changes using the standardized Alpins Method for their outcomes analysis paper. However, the papers’ conclusion is not supported by the vector analysis findings.

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Aboalazayem et al compared treating the manifest refractive astigmatism (Manifest group), vs the anterior corneal astigmatism with spherical adjustment (Full TMR group), vs the anterior corneal astigmatism without spherical adjustment (Partial TMR group). They concluded that treating the anterior corneal astigmatism is best. Yet their data shows superior vector analysis outcomes in the Manifest group, where the difference vector (DV) was as low as 0.20 D, compared to 0.90 D in the Full TMR group, or 0.50 D in the Partial TMR group. These results indicate that eyes in the TMR group and Partial TMR group had by far the greatest astigmatism treatment errors postoperatively in this comparative study. It is hard to reconcile how these groups are presented as having better vision. In addition, the coefficient of determination between the TIA and SIA was 0.82 in the Manifest group, compared to 0.62 in the full TMR group and 0.70 in the Partial TMR group. These findings indicate that the Manifest group had the most accurate treatment predictability.

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