Cirugía refractiva corneal y biomecánica

Sayas, M.a Ángeles del Buey; Martínez, Cristina Peris

doi:10.1016/b978-84-9022-649-0.50027-2

Cited by 3 publications

(11 citation statements)

References 95 publications

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“…Recent research works have confirmed a significant variation in corneal parameters after instillation of different anesthetic eye drops. It has also been demonstrated that the dramatic reduction of the intrasession repeatability of measurements in this context, so this should be considered in order to avoid inappropriate clinical decision making [ 47 ].…”

Section: Reviewmentioning

confidence: 99%

“…Corneal topographers provide different maps to represent the measurements that characterize the surface of a keratoconic cornea. The ophthalmologist has to decide what scale should be considered in each case in order to get the best information from a clinical point of view [ 47 ]: the absolute scale gives the entire diopter range that the topographer can measure on a color scale, so it loses sensitivity to small changes whereas the relative scale adjusts the dioptric measurement range for each cornea, so it is sensitive to small changes and is more appropriate for a customized analysis of corneal morphology [ 7 , 9 , 52 , 60 ].…”

Section: Reviewmentioning

confidence: 99%

“…However, this consideration is erroneous and only true in the paraxial approach since the cornea has a spherical surface. Therefore, it distorts the true picture of the cornea and provides quantitatively inaccurate values [ 9 , 47 , 61 , 62 ]. However, this map is useful for qualitative assessment through colors due to it softening the geometric contours of the cornea and facilitating the interpretation of the results by less-experienced users [ 47 ] (Fig.…”

Section: Reviewmentioning

confidence: 99%

“…This map represents more accurately the curvature of the peripheral corneal region (Fig. 6 ) [ 47 ]. This map also shows a high sensitivity to data obtained, being suitable for monitoring the conical shape of the ectatic disease; however, it is less intuitive than the axial map and its interpretation may be more complex.…”

Section: Reviewmentioning

confidence: 99%

“…This map provides, for both corneal surfaces, the elevation of the corneal apex, the elevation of the minimum thickness point [ 64 ] and the elevation of the center of the central region [ 65 ]. As the posterior surface is not altered by the excimer laser photoablation or by the generation of the corneal flap, nor is adulterated by the hyperplastic effect of corneal epithelium, data from the posterior surface could be very useful for the clinical diagnosis of keratoconus [ 9 , 13 , 47 , 65 , 66 ].

Fig.…”

Section: Reviewmentioning

confidence: 99%

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Corneal topography in keratoconus: state of the art

Sánchez²,

et al. 2016

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The morphological characterization of the cornea using corneal topographers is a widespread clinical practice that is essential for the diagnosis of keratoconus. The current state of this non-invasive exploratory technique has evolved with the possibility of achieving a great number of measuring points of both anterior and posterior corneal surfaces, which is possible due to the development of new and advanced measurement devices. All these data are later used to extract a series of topographic valuation indices that permit to offer the most exact and reliable clinical diagnosis. This paper describes the technologies in which current corneal topographers are based on, being possible to define the main morphological characteristics that the keratoconus pathology produces on corneal surface. Finally, the main valuation indices, which are provided by the corneal topographers and used for the diagnosis of keratoconus, are also defined.

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Section: Reviewmentioning

confidence: 99%

Section: Reviewmentioning

confidence: 99%

Section: Reviewmentioning

confidence: 99%

Section: Reviewmentioning

confidence: 99%

Fig.…”

Section: Reviewmentioning

confidence: 99%

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Corneal topography in keratoconus: state of the art

Sánchez²,

et al. 2016

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Spectral Transmission of the Human Corneal Layers

Peris-Martínez

García-Domene

Penadés

et al. 2021

JCM

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We have assessed the spectral transmittance of the different layers of the human cornea in the ultraviolet (UV), visible, and near-infrared (IR) spectral ranges. Seventy-four corneal sample donors were included in the study. Firstly, the corneal transmittance was measured using a spectrophotometer. Then, all samples were fixed for histopathological analysis, which allowed us to measure the thickness of each corneal layer. Finally, the absorption coefficients of the corneal layers were computed by a linear model reproducing total transmittance. The results show that corneal transmission was almost in unity at the visible and IR ranges but not at the UV range, in which the layer with higher transmission is Descemet’s membrane, whereas the stroma showed the lowest transmittance. Regarding the absorption coefficient, the most absorptive tissue was Bowman’s layer, followed by the endothelium. Variations on transmittance due to changes in the stroma, Bowman’s layer, or Descemet layer were simulated, and important transmission increases were found due to stroma and Bowman changes. To conclude, we have developed a method to measure the transmittance and thickness for each corneal layer. All corneal layers absorb UV light to a greater or lesser extent. The absorption coefficient is higher for Bowman’s layer, while the stroma is the layer with the lowest transmittance due to its thickness. Variations in stroma thickness or changes in the corneal tissue of Bowman’s layer or the endothelium layer due to some pathologies or surgeries could affect, to a greater or lesser degree, the total transmission of the cornea. Thus, obtaining accurate absorption coefficients for different layers would help us to predict and compensate these changes.

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Modification of Corneal Biomechanics and Intraocular Pressure Following Non-Penetrating Deep Sclerectomy

Barreda

Sánchez-Marín

Boned‐Murillo

et al. 2022

JCM

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Changes in the cornea can influence outcomes in patients with primary open-angle glaucoma (POAG). We aimed to evaluate the relevance of changes in corneal biomechanics and intraocular pressure (IOP) in patients undergoing non-penetrating deep sclerectomy (NPDS) with the Esnoper V2000 implant® (AJL Ophthalmic S.A., Gasteiz, Spain). We included 42 eyes of 42 patients with POAG scheduled for NPDS with the Esnoper V2000 implant. Biomechanical properties were measured by Ocular Response Analyzer® G3 (ORA; Reichert Inc., Depew, NY, USA). Corneal hysteresis (CH), corneal resistance factor (CRF), corneal compensated IOP (IOPcc), and Goldmann-correlated IOP (IOPg) were measured the day before surgery and on day 1, 7, and 30 and 2 and 3 months after surgery. CH initially increased, fell below the presurgical value at 30 days after the surgery, and increased again at 2 and 3 months. CRF, IOPcc, and IOPg decreased on the first day after surgery, then followed a trend of increasing but stayed below pre-surgery levels. All values reached statistical significance. While observed changes in corneal biomechanics after NPDS and Esnoper V2000 implant were significant, more studies are needed if we are to understand their influence on corneal biomechanics and their clinical relevance in POAG.

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Cirugía refractiva corneal y biomecánica

Cited by 3 publications

References 95 publications

Corneal topography in keratoconus: state of the art

Corneal topography in keratoconus: state of the art

Spectral Transmission of the Human Corneal Layers

Modification of Corneal Biomechanics and Intraocular Pressure Following Non-Penetrating Deep Sclerectomy

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