Keratektasie nach refraktiver Chirurgie

Mohrenfels, C. Winkler von; Salgado, J.P.; Khoramnia, Ramin

doi:10.1055/s-0029-1245754

Cited by 9 publications

(6 citation statements)

References 10 publications

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“…assessment; if an inserted ICL is too large, it might bow anteriorly, causing anterior chamber shallowing and introducing a risk of pupillary block and angle-closure glaucoma [52,53] In contrast, if the ICL vault is insufficient, it might potentially result in contact between the ICL and the crystalline lens, causing subsequent cataract formation [54]. Corneal tomography characterizes the elevation of the front and back corneal surfaces and reconstructs the pachymetric mapping, which has significantly enhanced the sensitivity and specificity for detecting corneal ectasia [8,55]. A significant advantage of tomography compared to topography is the possibility to determine the true corneal power; to calculate it, it is required to assess the posterior corneal surface.…”

Section: Corneal Tomographymentioning

confidence: 99%

“…Therefore, accurate assessment of the total corneal power, and specifically its astigmatism, with corneal tomography devices could potentially increase the refractive outcome in cataract and refractive lens extraction surgery [57][58][59][60]. Currently, the Zeiss IOL Master 700, Oculus Pen- Corneal tomography characterizes the elevation of the front and back corneal surfaces and reconstructs the pachymetric mapping, which has significantly enhanced the sensitivity and specificity for detecting corneal ectasia [8,55]. A significant advantage of tomography compared to topography is the possibility to determine the true corneal power; to calculate it, it is required to assess the posterior corneal surface.…”

Section: Corneal Tomographymentioning

confidence: 99%

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Current Developments in Corneal Topography and Tomography

2021

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Introduction: Accurate assessment of the corneal shape is important in cataract and refractive surgery, both in screening of candidates as well as for analyzing postoperative outcomes. Although corneal topography and tomography are widely used, it is common that these technologies are confused. The aim of this study was to present the current developments of these technologies and particularly distinguish between corneal topography and tomography. Methods: The PubMed, Web of Science and Embase databases were the main resources used to investigate the medical literature. The following keywords were used in various combinations: cornea, corneal, topography, tomography, Scheimpflug, Pentacam, optical coherence tomography. Results: Topography is the study of the shape of the corneal surface, while tomography allows a three-dimensional section of the cornea to be presented. Corneal topographers can be divided into large- and small-cone Placido-based devices, as well as devices with color-LEDs. For corneal tomography, scanning slit or Scheimpflug imaging and optical coherence tomography may be employed. In several devices, corneal topography and tomography have been successfully combined with tear-film analysis, aberrometry, optical biometry and anterior/posterior segment optical coherence tomography. Conclusion: There is a wide variety of imaging techniques to obtain corneal power maps. As different technologies are used, it is imperative that doctors involved in corneal surgery understand the science and clinical application of devices for corneal evaluation in depth.

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Section: Corneal Tomographymentioning

confidence: 99%

Section: Corneal Tomographymentioning

confidence: 99%

Current Developments in Corneal Topography and Tomography

2021

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“…[3839] The main risk-factor for iatrogenic ectasia is irregular topography pre-operatively, including asymmetric inferior corneal steepening or asymmetric bowtie patterns with skewed steep radial axes above and below the horizontal meridian. [4142] Additional risk-factors include, a thin residual stromal bed (225-250 μm), high myopia, young age at operation, and deep ablation. [4142]…”

Section: Iatrogenic Corneal Ectasiamentioning

confidence: 99%

“…[4142] Additional risk-factors include, a thin residual stromal bed (225-250 μm), high myopia, young age at operation, and deep ablation. [4142]…”

Section: Iatrogenic Corneal Ectasiamentioning

confidence: 99%

Corneal biomechanics in iatrogenic ectasia and keratoconus: A review of the literature

et al. 2013

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The Ocular Response Analyzer (ORA) (Reichert Ophthalmic Instruments, Buffalo, NY) allows direct measurement of corneal biomechanical properties. Since its introduction, many studies have sought to elucidate the clinical applications of corneal hysteresis (CH) and corneal resistance factor (CRF). More recently, detailed corneal deformation signal waveform analysis (WA) has potentially expanded the diagnostic capabilities of the ORA. In this review, the role of CH, CRF, and WA are examined in keratoconus (KC) and iatrogenic ectasia (IE). The PubMed database was searched electronically for peer-reviewed literature in July 2012 and August 2012 without date restrictions. The search strategy included medical subject heading (MeSH) and natural language terms to retrieve references on corneal biomechanics, CH, CRF, corneal deformation signal WA, IE, and KC. The evidence suggests that while CH and CRF are poor screening tools when used alone, increased sensitivity and specificity of KC and IE screening result when these parameters are combined with tomography and topography. Recent advances in WA are promising, but little is currently understood about its biomechanical and clinical relevance. Future studies should seek to refine the screening protocols for KC and IE as well as define the clinical applicability of WA parameters.

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“…Laser in situ keratomileusis (LASIK) is a type of refractive surgery with proven safety and efficacy;[ 1 ] however, it entails complications just like any other kind of surgical procedure. A rare, but serious complication is post LASIK ectasia,[ 2 3 4 5 6 7 8 ] which is characterized by progressive thinning and steepening of the cornea resulting in loss of best corrected visual acuity (BCVA). Post-LASIK ectasia is clinically important from two aspects: first, the condition is preventable[ 4 ] and secondly, most LASIK patients are young adults in whom the burden of the condition is greater.…”

Section: Introductionmentioning

confidence: 99%

A modified risk assessment scoring system for post laser in situ keratomileusis ectasia in topographically normal patients

Miraftab¹,

Fotouhi²,

Hashemi³

et al. 2014

J Ophthalmic Vis Res

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Purpose:To evaluate and modify the Randleman Ectasia Risk Score System for predicting post-laser in situ keratomileusis (LASIK) ectasia in patients with normal preoperative corneal topography.Methods:In this retrospective study we reviewed data from 136 eyes which had undergone LASIK including 34 ectatic and 102 normal eyes between 1999 and 2009. After determining the sensitivity and specificity of the Randleman system, a modified model was designed to predict the risk of post-LASIK corneal ectasia more accurately. Next, the sensitivity and specificity of this modified scoring system was determined and compared to that of the original scoring system.Results:In our sample, the sensitivity and specificity of the Randleman system was 70.1% and 50.5%, respectively. Our modified model included the following parameters: preoperative central corneal thickness, manifest refraction spherical equivalent, and maximum keratometry, as well as the number of months elapsed from surgery. Sensitivity and specificity rates of the modified system were 74.2% and 76.2%, respectively. The difference in receiver operating characteristic curves between the Randleman and modified scoring systems was statistically significant (P<0.001). The best sensitivity and specificity for our model occurred with a cumulative cutoff score of 4.00; a low risk was considered if the score was ≤4.00, and high risk was defined with a score > 4.00.Conclusion:Our modified ectasia risk scoring system for patients with normal corneal topography can predict post LASIK ectasia risk with acceptable sensitivity and specificity. However, there are still unidentified risk factors for which further studies are required.

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Keratektasie nach refraktiver Chirurgie

Cited by 9 publications

References 10 publications

Current Developments in Corneal Topography and Tomography

Current Developments in Corneal Topography and Tomography

Corneal biomechanics in iatrogenic ectasia and keratoconus: A review of the literature

A modified risk assessment scoring system for post laser in situ keratomileusis ectasia in topographically normal patients

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