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JAYPEE JOURNALS
International Scientific Journals from Jaypee
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1.  Review Article
Reevaluating the Effectiveness of Corneal Collagen Cross-linking and Its True Biomechanical Effect in Human Eyes
Damien Gatinel
[Year:2017] [Month:January-June] [Volume:6 ] [Number:1] [Pages:44] [Pages No:34-41] [No of Hits : 1240]
Full Text PDF | Abstract | DOI : 10.5005/jp-journals-10025-1140 | FREE

ABSTRACT

The induction of cross-links in corneal tissue appears to be a promising technique to increase its stiffness and this has been the basis of treatment of keratoconus (KC) and corneal ectatic disease. However, there exists a striking discrepancy between the reported biomechanical effects of corneal collagen cross-linking (CXL) in vitro compared to in vivo, and this has not received much attention in the literature.
Despite the documentation of an increase in corneal stiffness in vitro by many investigators, reports that provide evidence of measurable and consistent biomechanical changes in corneal rigidity in vivo after CXL are lacking. Indeed, the absence of documented in vivo biomechanical improvement in CXL-treated corneas is a conundrum, which needs to be further explored. To explain this discrepancy, it has been postulated that biomechanical changes induced by CXL are too subtle to be measured by currently available diagnostic tools or have characteristics not discernible by these technologies. However, the dynamic bidirectional applanation device (Ocular Response Analyzer) and dynamic Scheimpflug analyzer instruments (Corvis ST) have demonstrated the ability to quantify even subtle biomechanical differences in untreated KC corneas of different ectatic degree, and document the reduction in corneal hysteresis (CH) and corneal resistance factor (CRF) in situations where the corneal stiffness is reduced, such as after laser in situ keratomileusis and surface ablation procedures. It has also been possible to demonstrate an altered CH and CRF in patients with diabetes, smoking habit, glaucoma, Fuchs’ dystrophy, and corneal edema. It is puzzling that these diagnostic tools could document subtle biomechanical changes in these situations, yet fail to measure the purported changes induced by CXL on corneas with progressive KC. This failure to document significant and consistent biomechanical changes in corneal rigidity could suggest that CXL does not induce a simple reversal of the particular biomechanical deficits that characterize KC, or make the cornea significantly more resistant to bending forces as has been widely postulated. The absence of measurable biomechanical change in living KC corneas after CXL could be a consequence of biomechanical strengthening which is insignificant compared to the marked weakening caused by preexisting alteration of the collagen structure, disorganization of collagen fiber intertwining, and compromised structural-mechanical homogeneity that are hallmarks of keratoconic disease, especially in corneas with progressive KC.
The changes in the cornea induced by CXL that have been described in vivo may instead be driven by a wound healing process in response to the removal of the corneal epithelial layer and subsequent exposure to riboflavin and ultraviolet-A (UVA). This paper will present evidence that sustains this hypothesis.

Keywords: Corneal biomechanics, Corneal epithelium, Crosslinking, Ectasia, Hysteresis, Keratoconus.

How to cite this article: Gatinel D. Reevaluating the Effectiveness of Corneal Collagen Cross-linking and Its True Biomechanical Effect in Human Eyes. Int J Kerat Ect Cor Dis 2017;6(1):34-41.

Source of support: Nil

Conflict of interest: None

 
2.  Original Article
Assessing Progression of Keratoconus and Cross-linking Efficacy: The Belin ABCD Progression Display
Michael W Belin, Jay J Meyer, Josh K Duncan, Rachel Gelman, Mark Borgstrom, Renato Ambrósio Jr
[Year:2017] [Month:January-June] [Volume:6 ] [Number:1] [Pages:44] [Pages No:1-10] [No of Hits : 544]
Full Text PDF | Abstract | DOI : 10.5005/jp-journals-10025-1135 | FREE

ABSTRACT

Several methods have been described to both evaluate and document progression in keratoconus and to show efficacy of cross-linking, however, there are no consistent generally accepted parameters. Modern corneal tomography, including both anterior and posterior elevation and pachymetric data can be used to screen for ectatic progression, be employed to detect earlier change and additionally to show efficacy of new treatment modalities, such as crosslinking.
To describe specific quantitative values that can be used as progression and efficacy determinants, the normal noise measurements of the three parameters used in the ABCD keratoconus classification (corneal thickness at the thinnest point, anterior and posterior radius of curvature taken from the 3.0 mm optical zone centered on the thinnest point), were determined. Values were obtained from both a normal population and a known keratoconic population. The 80 and 95% one-sided confidence intervals for all three parameters were surprisingly small, suggesting that they may perform well as progression and efficacy determinants.

Keywords: Collagen cross-linking, Ectatic disease, Keratoconus, Tomography, Topography.

How to cite this article: B elin M W, M eyer J J, D uncan J K, Gelman R, Borgstrom M, Ambrósio Jr R. Assessing Progression of Keratoconus and Cross-linking Efficacy: The Belin ABCD Progression Display. Int J Kerat Ect Cor Dis 2017;6(1):1-10.

Source of support: Nil

Conflict of interest: None

 
3.  Review Article
Eye Rubbing, a Sine Qua Non for Keratoconus?
Damien Gatinel
[Year:2016] [Month:January-April] [Volume:5 ] [Number:1] [Pages:51] [Pages No:6-12] [No of Hits : 3476]
Full Text PDF | Abstract | DOI : 10.5005/jp-journals-10025-1114 | FREE

ABSTRACT

Keratoconus, a dystrophy of unknown origin, remains an ophthalmic enigma. The contrast between the presence of marked structural changes and deformation of the corneal wall and the relative absence of specific genetic and biomolecular findings continues to intrigue ophthalmologists. In Marfan syndrome, where genetic and molecular abnormalities are well identified, and similar changes in collagen observed, the cornea tends not to be steeper, irregular or ectatic, but are globally flatter. This suggests that an external mechanical force may be necessary to induce the apparition and progression of the ectatic process in keratoconus. Eye rubbing has long been acknowledged as a risk factor for keratoconus and its progression, but could it in fact be the root cause? Many clinical observations and reports support the hypothesis of eye rubbing as a first and necessary hit for inducing progressive ectatic deformation of the corneal wall. Validating or refuting this hypothesis on the basis of patient admission may be impossible. It is difficult to document the frequency, duration and intensity of eye rubbing in patients with keratoconus, and virtually impossible to prove that every patient who denies the habit truly does not rub his eyes. Both the increase in incidence of atopy and the time spent in front of the computer screen in the general population may account for an increased tendency for eye rubbing, and lead to the perceived increased prevalence of keratoconus in both urban and non-urban areas. This paper explores the possibility that the mechanical stress imposed on the cornea by rubbing may not be as much a second hit evoking the structural changes of a predisposed cornea exhibiting unknown collagen progressive alteration, but rather the necessary trigger and sine qua non of the keratoconic process. Even if this provocative hypothesis is impossible to prove, it is equally difficult to refute, and acknowledging eye rubbing as a possible root cause increases awareness within the general population and if true, could dramatically reduce the incidence of keratoconus, and halt its progression in eyes already affected.

Keywords: Computer vision syndrome, Corneal biomechanics, Crosslinking, Ectasia, Eye rubbing, Etiology of keratoconus, Keraotoconus, Marfan syndrome.

How to cite this article: Gatinel D. Eye Rubbing, a Sine Qua Non for Keratoconus? Int J Kerat Ect Cor Dis 2016;5(1):6-12.

Source of support: I thank Cordelia Chan, MD, for assisting the revision of the manuscript.

Conflict of interest: None

 
4.  Review Article
Progression in Keratoconus
Paolo Vinciguerra, Raffaele Piscopo, Fabrizio Camesasca, Riccardo Vinciguerra
[Year:2016] [Month:January-April] [Volume:5 ] [Number:1] [Pages:51] [Pages No:21-31] [No of Hits : 617]
Full Text PDF | Abstract | DOI : 10.5005/jp-journals-10025-1117 | FREE

ABSTRACT

The study of keratoconus progression was once based upon slitlamp study, keratometry, and placido disk image examination. Today we have a lot of new corneal devices and indexes wich can help the ophthalmologist to make earlier the diagnosis and also to recognize as much is possible a progressive keratoconus. Only a deep knowledge of the meaning of all these indexes and values, together with the ability to interlock one another, increases reliability in the evaluation of Corneal Ectasia. Some pratical instructions are provided to help the early diagnosis of progressive Keratoconus.

Keywords: Corneal tomography, Corneal topography, Ectasia, Keratoconus.

How to cite this article: Vinciguerra P, Piscopo R, Camesasca F, Vinciguerra R. Progression in Keratoconus. Int J Kerat Ect Cor Dis 2016;5(1):21-31.

Source of support: Nil

Conflict of interest: None

 
5.  Case Report
Unilateral Ectasia characterized by Advanced Diagnostic Tests
Isaac C Ramos, Dan Z Reinstein, Timothy J Archer, Marine Gobbe, Marcella Q Salomão, Bernardo Lopes, Allan Luz, Fernando Faria-Correia, Damien Gatinel, Michael W Belin, Renato Ambrósio Jr
[Year:2016] [Month:January-April] [Volume:5 ] [Number:1] [Pages:51] [Pages No:40-51] [No of Hits : 550]
Full Text PDF | Abstract | DOI : 10.5005/jp-journals-10025-1120 | FREE

ABSTRACT

To describe a case of very asymmetric ectasia successfully treated by femtosecond laser-assisted intracorneal ring segment implantation, in which the diagnosis of unilateral ectasia in the right eye was based on the clinical findings including history, follow-up, and advanced diagnostic data. The patient’s history was positive for ocular allergy with moderateto- intense eye rubbing only in the right eye. The uncorrected distance visual acuity was 20/63 in the right eye and 20/32 in the left eye. The corrected distance visual acuity (CDVA) was 20/40 in the right eye (-1.75-4.00 × 35°) and 20/16 in the left eye (-0.50-0.25 × 115°). After femtosecond laser-assisted intracorneal ring segment implantation, the right eye improved CDVA to 20/20-1. Concerning ectasia/keratoconus diagnosis, the left eye remained stable over 1 year of follow-up with unremarkable topometric, tomographic, and biomechanical findings. Epithelial thickness mapping by spectral domain optical coherence tomography and very-high-frequency digital ultrasound demonstrated epithelial thickness within normal limits in the left eye. Advanced diagnostic methods along with clinical data enable the distinction from unilateral ectasia cases and subclinical (fruste) keratoconus. Literature review is also performed along with case presentation and discussion.

Keywords: Corneal tomography, Keratoconus, Unilateral ectasia.

How to cite this article: Ramos IC, Reinstein DZ, Archer TJ, Gobbe M, Salomão MQ, Lopes B, Luz A, Faria-Correia F, Gatinel D, Belin MW, Ambrósio R Jr. Unilateral Ectasia characterized by Advanced Diagnostic Tests. Int J Kerat Ect Cor Dis 2016;5(1):40-51.

Source of support: Nil

Conflict of interest: Drs. Ambrósio and Belin are consultants for Oculus (Wetzlar, Germany); Dr. Reinstein is a consultant for Carl Zeiss Meditec (Carl Zeiss Meditec AG, Jena, Germany) and has proprietary interest in the Artemis technology (ArcScan Inc, Morrison, Colorado, USA) through patents administered by the Center for Technology Licensing at Cornell University (CTL), Ithaca, New York, USA. Dr. Gatinel is a consultant for TECHNOLAS Perfect Vision (Munich, Germany). The remaining authors have no proprietary or financial interest in the materials presented herein.

 
6.  Review Article
High-order Aberrations in Keratoconus
Hagar Hefner-Shahar, Nir Erdinest
[Year:2016] [Month:September-December] [Volume:5 ] [Number:3] [Pages:45] [Pages No:128-131] [No of Hits : 506]
Full Text PDF | Abstract | DOI : 10.5005/jp-journals-10025-1133 | FREE

ABSTRACT

With all the technological advances today and the increasing number of people undergoing refractive surgery, the importance of detecting keratoconus (KC) prior to surgery has become evident. Although by using a topographer we can detect early stage KC, however, by using wavefront analysis technology, we are able to detect KC at an even earlier stage.
Every eye possesses a number of aberrations. However, in a KC patient’s eye, there are approximately five to six times the numbers of high-order aberrations (HOAs) than in a healthy eye. Using this technology to detect and assess the HOAs, it was found that in a KC cornea, it is possible to detect at a very early stage a much higher value of vertical coma aberrations compared with a normal eye. By using this technology, it is possible to study and understand the characteristics of the quality of the image on the retina, thereby understanding its impact on the patient’s visual quality.

Keywords: Aberrations, High-order, Keratoconus, Vertical coma, Wavefront.

How to cite this article: Hefner-Shahar H, Erdinest N. Highorder Aberrations in Keratoconus. Int J Kerat Ect Cor Dis 2016;5(3):128-131.

Source of support: Nil

Conflict of interest: None

 
7.  
Keratoconus Management Guidelines
Jorge L Alió, Alfredo Vega-Estrada, Pablo Sanz-Díez, Pablo Peña-García, María Luisa Durán-García, Miguel Maldonado
[Year:2015] [Month:January-April] [Volume:4 ] [Number:1] [Pages:39] [Pages No:1-39] [No of Hits : 7774]
Full Text PDF | Abstract | DOI : 10.5005/jp-journals-10025-1095 | FREE

ABSTRACT

This study was partly financed by a project of the Spanish Ministry of Economy and Competitiveness, the Carlos III Health Institute and the Cooperative Health Research Thematic Network on ‘Age-related Eye Disease, Visual Quality and Quality-of-Life’, sub-project ‘Visual Quality’ (RD07/0062); and another project of the Spanish Ministry for Economy and Competitiveness, the Carlos III Health Institute, the Cooperative Health Research Thematic Network ‘Prevention, Early Detection and Treatment of Prevalent, Degenerative and Chronic Eye Diseases’, sub-program ‘Ocular Structures and Common Pathologies’ (RD12/0034).

 
8.  Original Article
A New Tomographic Method of Staging/Classifying Keratoconus: The ABCD Grading System
Michael W Belin, Josh Duncan, Renato Ambrósio Jr, José AP Gomes
[Year:2015] [Month:September-December] [Volume:4 ] [Number:3] [Pages:37] [Pages No:85-93] [No of Hits : 1990]
Full Text PDF | Abstract | DOI : 10.5005/jp-journals-10025-1105 | FREE

ABSTRACT

Purpose: To incorporate advanced corneal imaging into a new keratoconus classification system that utilizes posterior curvature, thinnest pachymetry, and best-corrected distance vision (CDVA) in addition to standard anterior parameters.

Materials and methods: A total of 672 eyes of 336 normal patients were imaged with the Oculus Pentacam HR. Anterior and posterior radius of curvature measurements were taken using a 3.0 mm zone centered on the thinnest area and corneal thickness was measured at the thinnest point. Mean and standard deviations were recorded and anterior data were compared to the existing Amsler-Krumeich (AK) classification.

Results: A total of 672 eyes of 336 patients were analyzed. Anterior and posterior values were 7.65 ± 0.236 mm / 6.26 ± 0.214 mm respectively and thinnest pachymetry values were 534.2 ± 30.36 um. Comparing anterior curvature values to AK staging yielded 2.63, 5.47, 6.44 standard deviations for stages 1, 2, and 3 respectively. Posterior staging uses the same standard deviation gates. Comparative pachymetric values yielded 4.42, and 7.72 standard deviations for stages 2 and 3 respectively.

Conclusion: A new keratoconus staging system incorporates posterior curvature, thinnest pachymetric values, and distance visual acuity in addition to the standard anterior curvature and consists of stages 0 to 4 (5 stages), closely matches the existing AK classification stages 1 to 4 on anterior curvature. The new classification system by incorporating curvature and thickness measurements based on the thinnest point, as opposed to apical, better reflects the anatomic changes in keratoconus.

Keywords: Classification, Ectasia, Keratoconus, Radius of curvature.

How to cite this article: Belin MW, Duncan J, Ambrósio R Jr, Gomes JAP. A New Tomographic Method of Staging/ Classifying Keratoconus: The ABCD Grading System. Int J Kerat Ect Cor Dis 2015;4(3):85-93.

Source of support: Nil

Conflict of interest: None

 
9.  Review Article
Collagen Cross-linking for Pellucid Marginal Degeneration
Cheryl MacGregor, Rakesh Jayaswal, Nick Maycock
[Year:2015] [Month:September-December] [Volume:4 ] [Number:3] [Pages:37] [Pages No:100-102] [No of Hits : 1668]
Full Text PDF | Abstract | DOI : 10.5005/jp-journals-10025-1107 | FREE

ABSTRACT

Pellucid marginal degeneration (PMD) is a rare progressive condition resulting in inferior corneal thinning and astigmatism. Alongside keratoconus and keratoglobus, it is considered one of noninflammatory corneal ectasias. The focus of corneal thinning is greatest inferiorly resulting in diminished visual acuity and overall reduction in visual quality. Traditional methods of treatment or disease management have been similar to those proposed for keratoconus, contact lenses, escalating to intrastromal rings, lamellar keratoplasty or penetrating keratoplasty.
Collagen cross-linking (CXL) has steadily gained acceptance as the treatment of choice for progressive corneal ectasias. Although it has been described at length for keratoconus, there is little literature describing or advocating its use in PMD. In this article, we will review the evidence for CXL and its use in PMD.

Keywords: Cornea, Corneal collagen cross-linking, Pellucid marginal degeneration, Review article.

How to cite this article: MacGregor C, Jayaswal R, Maycock N. Collagen Cross-linking for Pellucid Marginal Degeneration. Int J Kerat Ect Cor Dis 2015;4(3):100-102.

Source of support: Nil

Conflict of interest: None

 
10.  CASE REPORT
Corneal Collagen Cross-linking in a Prepubescent 10-Year-Old Girl with Aggressive Keratoconus
Marco Abbondanza, Margherita Guidobaldi
[Year:2015] [Month:May-August] [Volume:4 ] [Number:2] [Pages:42] [Pages No:63-65] [No of Hits : 1324]
Full Text PDF | Abstract | DOI : 10.5005/jp-journals-10025-1101 | FREE

ABSTRACT

Keratoconus (KC) is a corneal ectatic disease that results in bilateral and asymmetrical corneal distortion, altered refractive powers and reduced vision. In 20 to 25% of cases, corneal transplantation may be required, although a number of conservative procedures are available. We report a case of an aggressive stage II keratoconus in a prepubescent 10-year-old girl, successfully treated with corneal collagen cross-linking (CXL) with epithelium removal.

Keywords: Cornea, Corneal collagen cross-linking, Keratoconus, Pediatric.

How to cite this article: Abbondanza M, Guidobaldi M. Corneal Collagen Cross-linking in a Prepubescent 10-Year- Old Girl with Aggressive Keratoconus. Int J Kerat Ect Cor Dis 2015;4(2):63-65.

Source of support: Nil

Conflict of interest: None

 
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