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International Journal of Keratoconus and Ectatic Corneal Diseases
Current Issue : Volume 6, Issue 1, January-June 2017
 
 
1.  Editorial
REFLECTIONS ON THE CONTROVERSIES ON COLLAGEN CORNEAL CROSS LINKING FOR ARRESTING KERATOCONUS
Adel Barbara
[Pages No:iv-viii]
Full Text PDF | Abstract | FREE

ABSTRACT

Since the first publication on collagen corneal cross-linking (CXL) for arresting the progression of keratoconus (KC) by the Dresden group1 several hundreds of publications were published most of them reporting positive results of CXL in arresting the progression of the disease, improvement of uncorrected visual acuity (UCVA) and best spectacle corrected visual acuity (BSCVA), reduction of astigmatism and of maximum keratometry reading (K max) In April 2016, the treatment was approved by the FDA after a controlled randomized study. The beneficial effect of the treatment was reported even after 10 years2 corneal topography, and endothelial cell count (ECC).

 
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
[Pages No:1-10]
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.  Original Article
Two Years' Experience in Keratoconus Treatment using Collagen Cross-linking
Dimitrii Dementiev, Maria Sysoeva, Anna Shipunova
[Pages No:11-13]
Full Text PDF | Abstract | DOI : 10.5005/jp-journals-10025-1136 | FREE

ABSTRACT

Purpose: To evaluate safety, efficacy, and stability of crosslinking (CLX) procedure as a method for keratoconus treatment in the I and II stage of disease.

Materials and methods: Twenty eyes of 15 patients (13 males, 2 females, average age 31 years) with keratoconus I stage (13 eyes) and II stage (2 eyes) (by Krumeich classification) were treated by CLX procedure, using riboflavin Medio Cross for standard CLX); riboflavin Medio Cross TE for transepithelial CLX was used to treat keratectasia after previous keratorefractive surgery; in all the cases UV CBM X linker (Vega, CSO) was used. The study included evaluation of uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA) pre- and postoperative, pachymetry (central cornea thickness) (Visante OCT, Zeiss) pre- and postoperative, total astigmatism pre- and postoperative, using keratotopography (Atlas, Zeiss). Diagnosis and analysis have been performed at the International Center for Ophthalmology in Moscow, Russian Federation, since 2012 to 2014 years. Follow-up period was from 1 to 24 months.

Results: Average UCVA preoperative was 0.4 (Decimal), and average BCVA was 0.64. Average UCVA postoperative was 0.49; average BCVA was 0.66. Total astigmatism preoperative was 2.81 D; total astigmatism postoperative 2.80 D. Central cornea thickness (CCT) preoperative 454 mkm; CCT postoperative 447 mkm.

Conclusion: Cross-linking indicated safety, stability, and efficacy for treatment of I and II stage keratoconus at the end of follow-up period. Cross-linking is not effective in the treatment of II and III stage of disease. Further study is required.

Keywords: Cross-linking, Keratectasia, Keratoconus.

How to cite this article: Dementiev D, Sysoeva M, Shipunova A. Two Years’ Experience in Keratoconus Treatment using Collagen Cross-linking. Int J Kerat Ect Cor Dis 2017;6(1):11-13.

Source of support: Nil

Conflict of interest: None

 
4.  Original Article
Technology of the Local Cross-linking (Part 1): Keratotensotopography and Vacuum-compression Topographic Test—New Diagnostic Possibilities for Studying the Local Biomechanical Properties of Cornea
SI Anisimov, SYAnisimova, AS Mistryukov, NS Anisimova
[Pages No:14-16]
Full Text PDF | Abstract | DOI : 10.5005/jp-journals-10025-1137 | FREE

ABSTRACT

Aim: The aim of this study is the development and evaluation of clinical significance methodology for determining mechanical stress (MS) and elasticity of the cornea comparable to its topographic settings.

Materials and methods: Combining the data of optical pachymeter, keratotopography, and pneumotonometry through our special software allows us to get Lokolink MS distribution in the cornea in the form of maps, which we propose to call keratotensotopogram (KTT).

Results: Normal KTT has the form of concentric, uniform, and symmetrical zones. In keratoconus (KC), the corneal center is more tense than peripheral part of cornea. The focus zone of KC may coincide with the region of maximum MS or may be out of this area. In the process of vacuum-compression test, the reaction of profile of the cornea was markedly different in patients with healthy corneas and in patients with KC. In all cases of healthy cornea, the curvature increased in the center. In KC, the cornea became more flat in the center under high intraocular pressure (in 100% of cases).

Conclusion: The KTT ineyes with the cornea without pathology differs from KTT in the different cases of KC. The KTT can be used for the diagnosis and prediction of cornea’s state to perform the plan of UV irradiation areas for corneal collagen cross-linking.

Keywords: Corneal collagen cross-linking, Corneal topography, Keratotensotopogram, Vacuum-compression test.

How to cite this article: Anisimov SI, Anisimova SY, Mistryukov AS, Anisimova NS. Technology of the Local Cross-linking (Part 1): Keratotensotopography and Vacuumcompression Topographic Test—New Diagnostic Possibilities for Studying the Local Biomechanical Properties of Cornea. Int J Kerat Ect Cor Dis 2017;6(1):14-16.

Source of support: Nil

Conflict of interest: None

 
5.  Original Article
Incidence and Indices of Keratoconus in Patients presenting for LASIK in Egypt
Mohammed Othman Abdel Khalek El Sayed, Naglaa Hassan Ali
[Pages No:17-22]
Full Text PDF | Abstract | DOI : 10.5005/jp-journals-10025-1138 | FREE

ABSTRACT

Background: Keratoconus (KC) is a progressive, non-inflammatory bilateral but (usually asymmetrical) ecstatic corneal disease, characterized by paraxial stromal thinning and weakening that leads to corneal surface distortion. The reported incidence and prevalence of KC varies widely depending upon the geographic location, diagnostic criteria used and the cohort of patients selected.

Aim: To estimate the incidence and indices of KC in patients seeking refractive procedures in Beni Sueif governorate at a span period of one year from March 2013 to March 2014. To describe and analyze the characteristics of the KC population under study.

Materials and methods: This study as designed as a prospective surveillance study. All clinical records in the computerized database from pentacam with the clinical diagnosis of KC and / or suspected were included and statistically analyzed.

Results: Data from 2116 cases with the average 28.8 ± 6.5 years old were analyzed over the span of 1 year starting from March 2013 to March 2014. Based on topographic images of the pentacam 36 eyes were diagnosed as KC. The incidence of KC was 1.7% ( 95% confidence interval, 0.55-1.45). In keratoconic patients, the mean age was 28.1 years, the mean K1 and K2 were 45.18±3.44 D and 49.49 ± 4.28 D respectively. The mean minimal pachymetry value was 463± 6.51um, the mean index of surface variance (ISV) was 61± 32, the mean index of vertical asymmetry (IVA) was 0.63±0.38, the mean keratoconus indices (KI) was 1.08±0.14.

Conclusion: This study provides the first population-based estimate of the incidence of keratoconus in Beni suef governorate in the upper Egypt. According to this study incidence rate of KC is comparable to the rate among the Caucasian people in middle Asia e.g. Iran while incidence rate is much higher among Malaysia and Kingdom of Saudi Arabia citizens.

Keywords: Incidence, Indices, Keratoconus.

How to cite this article: El Sayed MOAK, Ali NH. Incidence and Indices of Keratoconus in Patients presenting for LASIK in Egypt. Int J Kerat Ect Cor Dis 2017;6(1):17-22.

Source of support: Nil

Conflict of interest: None

 
6.  Original Article
Enhanced Screening for Ectasia Risk prior to Laser Vision Correction
Renato Ambrósio Jr, Michael W Belin
[Pages No:23-33]
Full Text PDF | Abstract | DOI : 10.5005/jp-journals-10025-1139 | FREE

ABSTRACT

Aim: To prospectively review current understanding and future trends of screening for keratectasia risk prior refractive laser vision correction (LVC).

Background: Progressive keratectasia is an uncommon but severe complication of LVC. Preoperative ectatic corneal disease is the most important risk factor. Screening for subclinical ectasia relies on proper interpretation of advanced diagnostic technologies, including front surface corneal topography, three-dimensional tomography, and biomechanical assessments.

Summary: Studies involving eyes with normal and stable corneas, compared to eyes with frank ectatic diseases and to eyes with normal topography from patients with very asymmetric ectasia, allow for developing advanced methods and testing its sensitivity. However, the ideal study populations for testing the sensitivity and specificity of ectasia risk assessments are respectively the preoperative of cases that developed ectasia and the ones with stable outcomes after LVC. Young age and low thickness are surrogates of corneal biomechanics, which may be replaced as risk factors by direct measurements. Keratectasia may also occur due to the surgical impact on corneal structure or due to significant trauma postoperatively. Percentage tissue altered higher than 40% is a more sensitive parameter than a fixed value for minimal residual stromal bed of 250 ìm. However, the biomechanical impact from surgery is related to the region and number of lamellae that are severed, so that flap thickness and geometry should play a more relevant role, which is in agreement with finite element simulations. Artificial intelligence methods allow for combining parameters, which significantly enhance the accuracy for detecting ectasia risk.

Conclusion: An enhanced screening approach for preventing keratectasia should consider both preoperative patient-related data and procedure-related parameters to individually characterize ectasia susceptibility or predisposition.

Clinical Significance: Keratectasia is an uncommon, however, severe complication of LVC. Although prevention is the best strategy, an individualized enhanced ectasia screening approach for ectasia risk assessment prior to LVC procedures should integrate patient-related (individual ectasia susceptibility) and procedure-related parameters (biomechanical impact).

Keywords: Ectasia susceptibility, Keratectasia, Keratoconus, Laser vision correction.

How to cite this article: Ambrósio Jr R, Belin MW. Enhanced Screening for Ectasia Risk prior to Laser Vision Correction. Int J Kerat Ect Cor Dis 2017;6(1):23-33.

Source of support: Nil

Conflict of interest: None

 
7.  Review Article
Reevaluating the Effectiveness of Corneal Collagen Cross-linking and Its True Biomechanical Effect in Human Eyes
Damien Gatinel
[Pages No:34-41]
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

 
8.  Review Article
Water Soluble Tetrazolium Salt-11 as an Alternative to Riboflavin for Corneal Collagen Cross-linking for the Treatment of Keratoconus
Sajjad Abbas, Ramez Barbara, Adel Barbara
[Pages No:42-44]
Full Text PDF | Abstract | DOI : 10.5005/jp-journals-10025-1141 | FREE

ABSTRACT

Corneal collagen cross-linking (CXL) is effective in halting progression of keratoconus, nevertheless, it is not without its drawbacks. Water soluble tetrazolium salt (WST) that generates superoxide and hydroxyl radicals following near-infrared (NIR) illumination result in a three-fold increase in corneal stiffness. This seems to be comparable to riboflavin/ultraviolet A (UVA)- mediated cross-linking. Moreover, WST is able to penetrate faster and deep into the cornea while offering protection to endothelial cells and reducing corneal keratocyte loss in the posterior cornea. Early studies suggest good safety and efficacy profile when tested on rabbit eyes in vivo and ex vivo.

Keywords: Corneal collagen cross-linking, Keratoconus, Palladium bacteriochlorin 13’-(2-sulfoethyl) amide dipotassium salt, Water Soluble Tetrazolium Salt-11, Water soluble tetrazolium Salt-11 formulated with dextran T500.

How to cite this article: Abbas S, Barbara R, Barbara A. Water Soluble Tetrazolium Salt-11 as an Alternative to Riboflavin for Corneal Collagen Cross-linking for the Treatment of Keratoconus. Int J Kerat Ect Cor Dis 2017;6(1):42-44.

Source of support: Nil

Conflict of interest: None

 
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