Primary Topography-Guided LASIK: Treating Manifest Refractive Astigmatism Versus Topography-Measured Anterior Corneal Astigmatism

Wallerstein, Avi; Gauvin, Mathieu; Qi, Susan Ruyu; Bashour, Mounir; Cohen, Mark E.

doi:10.3928/1081597x-20181113-01

Cited by 50 publications

(27 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Various alternative strategies have been proposed, therefore, to determine the appropriate laser entry for the Treatment sphero-cylindrical refraction. 4,6,9,10,12 The current study was designed to address the question of how to program the WaveLight Contoura ® Vision laser to produce optimal refractive outcomes for eyes in which there is a disparity between Manifest and Topo refractions.…”

Section: Discussionmentioning

confidence: 99%

“…They found that the outcomes using the Topo axis were inferior to those obtained with the cylinder axis measured by the manifest refraction. 6 These published findings and the unpublished experiences of others, including the authors of this paper, have led to further discussions about whether the method of programming the laser that was used during the FDA clinical trial produces optimal outcomes.…”

Section: Introductionmentioning

confidence: 85%

“…Optimally, the Manifest and Topo cylinder will be the same or similar, but in some cases, they differ by more than a trivial amount. Possible explanations for this difference include the presence of significant high-order corneal aberrations [3][4][5][6] posterior corneal astigmatism, and lenticular astigmatism. Manifest and Topo cylinders tend to differ in eyes with high-order aberrations because the subject may choose a sphero-cylindrical refraction in an attempt to correct high-order aberrations.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

<p>Topography-Guided Refractive Astigmatism Outcomes: Predictions Comparing Three Different Programming Methods</p>

Stulting

Durrie

Potvin³

et al. 2020

OPTH

View full text Add to dashboard Cite

Purpose: To identify the laser programming strategy that will achieve optimal refractive outcomes of LASIK with a topography-guided laser for eyes with a disparity between cylinder measured by manifest refraction and cylinder measured by topography. Setting: Six surgeons at 5 clinical sites in the USA. Design: Retrospective data review. Methods: Preoperative, treatment, and postoperative data on 52 eyes that underwent topographyguided LASIK with the WaveLight EX500 Contoura ® Vision excimer laser ablation profile in which the vectors representing the preoperative refractive cylinder and the cylinder measured by the WaveLight ® Topolyzer™ VARIO Diagnostic Device (Vario cylinder) differed by >/= 0.50D and/or >/= 10 degrees of orientation were analyzed retrospectively. Data were contributed by six surgeons using the laser at 5 different clinical sites. Vector analysis of postoperative cylindrical refractive error and the actual laser programming strategy was used to calculate the cylindrical correction that would, theoretically, have completely eliminated postoperative refractive cylinder. This was compared to expected results using the preoperative manifest cylinder, the topographic cylinder, and the Phorcides Analytic Engine (Phorcides LLC, North Oaks MN; Phorcides). For analysis, subjects were stratified on the basis of the vector difference between Manifest and Topo cylinder (High, >0.75 D; and Low, ≤0.75 D). Results: The poorest calculated theoretical outcomes were obtained with the manifest refraction (centroid: −0.43, 0.22; mean calculated error vector: 0.56 ± 0.42 D; p=ns). Better outcomes were obtained with the topographically measured refraction (centroid: 0.37, 0.02; mean calculated error vector: 0.47 ± 0.33 D; p=ns). The best outcomes were obtained with Phorcides (centroid: −0.15, 0.06; mean calculated error vector: 0.39 ± 0.28 D; p=ns). The mean error vector magnitude in the Phorcides Low group was significantly lower than for the Manifest and Topo Low groups (0.26 D vs 0.48 D and 0.33 D; p<0.01). The mean error magnitude in the Phorcides High group was nearly 0.25 D lower than for the Manifest High group (0.48 D vs 0.70 D; p<0.01), but was the same as for the Topo High group (0.48 D vs 0.48 D). Conclusion: Our study suggests that using the topographically measured cylinder or the cylinder selected by Phorcides will produce more desirable refractive outcomes than entry of the preoperative refractive cylinder as the basis for correction of myopia and myopic astigmatism with the WaveLight Contoura Vision excimer laser.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 85%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

<p>Topography-Guided Refractive Astigmatism Outcomes: Predictions Comparing Three Different Programming Methods</p>

Stulting

Durrie

Potvin³

et al. 2020

OPTH

View full text Add to dashboard Cite

show abstract

“…3 We recently discussed how poorer outcomes are expected in ACA-treated eyes that ignore ORA, unrelated to a comparison of WFO versus Contoura technology. 4 Much of the study's discussion is a repetition of the research of Motwani, who first described the LYRA protocol. Ozulken et al state: "Motwani showed that HOAs [higher order aberrations] interacting with lower order astigmatism is the main reason for the differences between manifest refraction," 1 but they do not discuss our mathematical three-dimensional quantification that shows that his theory is not valid.…”

Section: Targeting Anterior Corneal Astigmatism With Topography-guidementioning

confidence: 99%

“…Similarly, in a study of 100 eyes of 50 patients, Kanellopoulos 2 reported that topography-guided treatment using topography-modified refraction values yielded better results than the treatment using manifest refraction.In addition, in their study comparing wavefront-optimized (WFO) and topography-guided treatment methods, Kim et al 3 used topography-modified refraction values in the topography-guided treatment group and reported that topography-guided laser in situ keratomileusis induced fewer higher order aberrations (HOAs) and significantly reduced ocular trefoil, corneal total HOAs, and coma. On the contrary, Wallerstein et al 4 have long advocated the use of manifest refraction with topography-guided ablation, and this viewpoint would have us believe that the removal of light scatter via corneal HOA reduction has no effect on the measurable astigmatism whatsoever and that the hand-measured, post-cortical processing-derived astigmatism number is sacrosanct and the correct way to treat.…”

Section: Replymentioning

confidence: 99%

Targeting Anterior Corneal Astigmatism With Topography-Guided Ablation Ignores Ocular Residual Astigmatism, Resulting in Inferior Outcomes

Wallerstein¹,

Gauvin²,

Cohen³

2020

J Refract Surg

Self Cite

View full text Add to dashboard Cite

Hemidivisional vector planning to reduce and regularize irregular astigmatism by laser treatment

Alpins

Ong²,

Stamatelatos

2022

Graefes Arch Clin Exp Ophthalmol

View full text Add to dashboard Cite

Purpose To demonstrate how hemidivisional vector planning of refractive laser treatments of astigmatism can be used to directly address idiopathic corneal irregular astigmatism that has an asymmetrical, non-orthogonal bow tie topography appearance. Design Case study. Methods The cornea is conceptually divided into two hemidivisions along the flat meridian of the corneal topographic astigmatism (CorT), which means that each hemidivision will approximately correspond to one lobe of the asymmetric, non-orthogonal topographic bow tie. An astigmatism reduction treatment can then be planned separately for each hemidivision using the vector planning technique, based on both its two hemidivisional CorT measures and common manifest refractive cylinder. The remaining irregularity is then regularized, and the junctional zone smoothed across the flat meridian. The final intended treatment thus combines hemidivisional astigmatism reduction and regularization of the corneal astigmatism and spherical refractive error in one treatment application. This could be applied to LASIK, PRK, SMILE, and Transepithelial PRK procedures using Designer Cornea® software. Results A theoretical treatment profile is derived from an actual example of a cornea with idiopathic asymmetric non-orthogonal astigmatism. The three steps of the derivation are as follows: (i) astigmatism reduction through the use of the vector planning technique; (ii) regularization, and (iii) smoothing across the hemidivisional midline. Conclusions Hemidivisional vector planning treatments could potentially both reduce and regularize asymmetric non-orthogonal astigmatism. These treatments can be systematically customized to account for qualitative and quantitative differences between the two corneal hemidivisions at the same time as correction of coexistent myopia or hyperopia.

show abstract

Primary Topography-Guided LASIK: Treating Manifest Refractive Astigmatism Versus Topography-Measured Anterior Corneal Astigmatism

Cited by 50 publications

References 20 publications

<p>Topography-Guided Refractive Astigmatism Outcomes: Predictions Comparing Three Different Programming Methods</p>

<p>Topography-Guided Refractive Astigmatism Outcomes: Predictions Comparing Three Different Programming Methods</p>

Targeting Anterior Corneal Astigmatism With Topography-Guided Ablation Ignores Ocular Residual Astigmatism, Resulting in Inferior Outcomes

Hemidivisional vector planning to reduce and regularize irregular astigmatism by laser treatment

Contact Info

Product

Resources

About