Smoothness assessment of corneal stromal surfaces

Marian, Anca; Nada, Ossama; Légaré, François; Meunier, Jean; Vidal, François; Roy, Sougata; Brunette, Isabelle; Costantino, Santiago

doi:10.1016/j.jcrs.2012.08.050

Cited by 8 publications

(10 citation statements)

References 42 publications

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“…Initially, subjective grading of roughness by one or more observers was utilized, however it has been shown that this grading is susceptible to variations in contrast. 9 Objective measures suffer similarly as a change between gray scale values within and between SEM images is not directly related to changes in height; it also represents changes in tilt of the image, surface contamination and enhanced emission from edges and ridges. As such traditional texture analysis or mean grayscale variation methods are not suitable summary measures of the local variation or surface roughness.…”

Section: Discussionmentioning

confidence: 99%

“…Marian et al have previously described a methodology where a 3D surface is reconstructed and the image flattened to isolate the local variation. 9 However, this methodology requires stereo SEM images and it does not address the issue of enhanced emission from edges. In this article we have used an alternative methodology, the subtraction of the background, which in addition to removing the curvature and tilt information, also removed enhanced emission from edges and ridges, isolating the local variation.…”

Section: Discussionmentioning

confidence: 99%

“…To date there have been a number of articles investigating this. [6][7][8][9][10][11][12][13][14][15] Several authors have developed subjective (observer based grading) and objective (e.g. texture analysis) scores to quantify the smoothness of stromal beds using primarily scanning electron microscopy (SEM) images for comparison.…”

Section: Scanning Electronic Microscopy Evaluation Of the Roughness Omentioning

confidence: 99%

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Scanning Electronic Microscopy Evaluation of the Roughness of the Stromal Bed After Deep Corneal Cut with the LDV Femtosecond Laser (Z6) (Ziemer) and the ONE Microkeratome (Moria)

Varga

Bergin

Roy³

et al. 2016

Current Eye Research

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Purpose: To compare the stromal bed surface quality and the accuracy of dissection depth after deep lamellar cuts using the Leonardo Da Vinci (LDV) femtosecond laser (Z6) and the ONE Microkeratome. Methods: Deep lamellar cuts were performed on nine human donor corneoscleral buttons: five with the LDV femtosecond (FS) laser (Z6) (Ziemer) and four with the ONE Microkeratome (MK) (Moria). Corneal thickness was measured with ultrasound pachymetry before and after the dissection. The Stromal bed quality was evaluated using light microscopy (n = 4) and scanning electron microscopy (SEM) (n = 9). The surface roughness on SEM images was graded on the scale of 1 (smoothest) to 5 (roughest) by four observers, blinded to the method used. Particle analysis on the SEM images was performed in order to have an objective measure of smoothness. Results: The achieved dissection depth using the FS laser was 496.4 ± 46.4 µm when attempting 500 µm and 474 ± 60 µm with the microkeratome when attempting 350 µm. Histological evaluation of the corneoscleral buttons by both light and electron microscopy showed significantly smoother surface using the FS laser compared to the microkeratome. There were fewer and smaller particles observed in the SEM images of FS laser cut buttons (p < 0.001).The average observer based score of anterior surface roughness (50×) was 2.2 for the FS laser and 3.9 for the microkeratome dissections (p < 0.001). Conclusions: The LDV femtosecond laser (Z6) platform is capable of creating deep corneal lamellar dissection with smoother surface quality and with more predictable cut depth as compared to the One Microkeratome.ARTICLE HISTORY

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Scanning Electronic Microscopy Evaluation Of the Roughness Omentioning

confidence: 99%

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Scanning Electronic Microscopy Evaluation of the Roughness of the Stromal Bed After Deep Corneal Cut with the LDV Femtosecond Laser (Z6) (Ziemer) and the ONE Microkeratome (Moria)

Varga

Bergin

Roy³

et al. 2016

Current Eye Research

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“…Image texture, defined as variations in the pixel intensities (variations in the gray-levels), was analyzed using the Haralick texture contrast parameter [25]. The usefulness of this parameter has been well documented in biomedical sciences [26], and more specifically, for the quantification of corneal stromal surface roughness as observed on a SEM image [27]. The Haralick contrast parameter was computed for each SEM image (Matlab R2009b version).…”

Section: Methodsmentioning

confidence: 99%

Effect of Corneal Hydration on the Quality of the Femtosecond Laser Anterior Lamellar Cut

et al. 2014

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The goal of this study was to assess the effect of corneal hydration on the quality of the femtosecond laser (FSL) anterior lamellar cut. The Visumax FSL was used to dissect an 8-mm-diameter corneal flap in 22 eye bank corneas showing various levels of hydration. The intended ablation depth was 220 µm in all eyes, which corresponded to the maximal depth available with this laser. After the cut, the achieved ablation depth was measured using optical coherence tomography images, flap separability was assessed by measuring the mean force generated to detach the flap, and stromal bed roughness was assessed by measuring the Haralick contrast level on the 1000× scanning electron microscopy images of the ablated surfaces. The preoperative central corneal thickness ranged from 547 to 1104 µm (mean ± SEM: 833±30 µm). A negative correlation was found between the level of corneal hydration and the ablation depth measured in the mid-peripheral cornea (r = −0.626, p = 0.003), the ablation being more superficial in more edematous corneas. The Haralick contrast also tended to increase as a function of corneal hydration (r = 0.416, p = 0.061), suggesting that laser ablation in edematous corneas results in rougher stromal surfaces. These results support the hypothesis that the quality of the FSL lamellar cut decreases as the level of corneal hydration increases. Although FSL is still considered in the field as the tool of the future for corneal dissection, a better understanding of the limits of this tool will be needed before it can replace manual or automated stromal dissection techniques in hydrated corneas.

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“…Scanning electron microscopy (SEM) images of deep stromal cuts made by the FS laser have shown an irregular and rougher appearing surface with the appearance of concentric peripheral rings. [ 17 18 19 20 21 22 ] Additionally, there are controversial findings regarding endothelial damage with higher energy settings at deeper layers.…”

mentioning

confidence: 99%

Femtosecond laser deep lamellar keratoplasty

Farid

Rostov

2022

Indian Journal of Ophthalmology

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We aimed to develop a novel and effective technique for creating a smooth deep lamellar dissection of the cornea using a femtosecond (FS) laser for deep anterior lamellar keratoplasty (DALK), we conducted a retrospective eye bank study. Thirteen fresh human corneas were mounted on an artificial anterior chamber, and deep lamellar cuts were made with a 500-kHz VisuMax FS laser at a level of 50–80 mm anterior to the Descemet’s membrane (DM). A posterior diameter of 8 mm with a side cut angle of 110° was used for the anterior penetrating side cut. The anterior lamellar tissue was bluntly dissected. The residual posterior stromal beds and side cuts were examined with microscopy and intraoperative optical coherence tomography (OCT) and post-cut endothelial cell evaluations. All corneas revealed a smooth residual posterior stromal bed without any visible irregularities or ridges by microscopy and OCT imaging. Six corneas were suitable for post-cut endothelial cell evaluation 2 days after laser cut, with no significant endothelial cell loss post-laser and blunt dissection of the posterior stroma. FS laser deep lamellar keratoplasty utilizing an ultrafast laser to produce a smooth deep stromal dissection followed by blunt dissection and removal of the anterior stromal tissue yields a consistent and smooth residual stromal bed. The creation of a smooth lamellar dissection in the deep posterior cornea may result in more consistent DALK without the need for air bubble or manual baring of DM that has the risk for DM perforation.

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Smoothness assessment of corneal stromal surfaces

Cited by 8 publications

References 42 publications

Scanning Electronic Microscopy Evaluation of the Roughness of the Stromal Bed After Deep Corneal Cut with the LDV Femtosecond Laser (Z6) (Ziemer) and the ONE Microkeratome (Moria)

Scanning Electronic Microscopy Evaluation of the Roughness of the Stromal Bed After Deep Corneal Cut with the LDV Femtosecond Laser (Z6) (Ziemer) and the ONE Microkeratome (Moria)

Effect of Corneal Hydration on the Quality of the Femtosecond Laser Anterior Lamellar Cut

Femtosecond laser deep lamellar keratoplasty

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