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International Journal of Keratoconus and Ectatic Corneal Diseases
Current Issue : Volume 2, Issue 3, September-December 2013
 
 
1.  Original Article
Evaluation of Visual Acuity, Pachymetry and Anterior-Surface Irregularity in Keratoconus and Crosslinking Intervention Follow-up in 737 Cases
Anastasios John Kanellopoulos, Vasiliki Moustou, George Asimellis
[Pages No:95-103]
Full Text PDF | Abstract | DOI : 10.5005/jp-journals-10025-1060 | FREE

ABSTRACT

Purpose: To investigate visual acuity, corneal pachymetry, and anterior-surface irregularity indices correlation with keratoconus severity in a very large pool of clinically-diagnosed untreated keratoconic eyes, and in keratoconic eyes subjected to cross-linking intervention.

Materials and methods: Total of 737 keratoconic (KCN) cases were evaluated. Group A was formed from 362 untreated keratoconic eyes, and group B from 375 keratoconic eyes subjected to partial normalization via topography-guided excimer laser ablation and high-fluence collagen crosslinking. A control group C of 145 healthy eyes was employed for comparison. We investigated distance visual acuity, uncorrected (UDVA), best-spectacle corrected (CDVA), and Scheimpflug-derived keratometry, pachymetry (central corneal thickness, CCT and thinnest, TCT), and two anterior-surface irregularity indices, the index of surface variance (ISV) and the index of height decentration (IHD). The correlations between these parameters vs topographic keratoconus classification (TKC) were investigated.

Results: Keratometry for group A was K1 (flat) 46.67 ± 3.80 D and K2 (steep) 50.76 ± 5.02 D; for group B K1 44.03 ± 3.64 D and K2 46.87 ± 4.61 D; for group C, K1 42.89 ± 1.45 D and K2 44.18 ± 1.88 D. Visual acuity for group A was UDVA 0.12 ± 0.18 and CDVA 0.59 ± 0.25 (decimal), for group B, 0.51 ± 0.28 and 0.77 ± 0.22, and for group C, 0.81 ± 0.31 and 0.87 ± 0.12.
Correlation between ISV and TKC (r2) was for group A 0.853, and for group-B 0.886. Correlation between IHD and TKC was for group A r2 = 0.731, and for group B 0.701. The ROC analysis ‘area under the curve’ was for CDVA 0.550, TCT 0.596, ISV 0.876 and IHD 0.887.

Conclusion: Our study indicates that the traditionally employed metrics of visual acuity and corneal thickness may not be robust indicators nor provide accurate assessment on either keratoconus severity or postoperative evaluation. Two anterior surface irregularity indices, derived by Scheimpflug-imaging, ISV and IHD, may be more sensitive and specific tools.

Precis: Visual acuity, Scheimpflug-derived pachymetry and anterior-surface irregularity correlation to keratoconus severity in untreated cases (A), treated with crosslinking (B), and in a control group (C) reveals that visual acuity and pachymetry do not correlate well with keratoconus severity.

Keywords: Athens Protocol, Combined topography guided PRK and higher fluence CXL, Visual rehabilitation in keratoconus, Severity criteria, Keratoconus progression, Keratoconus classification, Pentacam, Keratoconic Scheimpflug topometric indices, Visual acuity, Keratoconus, Grading anterior surface Pentacam indices, Keratoconus Amsler and Krumeich grading, Corneal pachymetry, Receiver operating characteristic ROC analysis.

How to cite this article: Kanellopoulos AJ, Moustou V, Asimellis G. Evaluation of Visual Acuity, Pachymetry and Anterior-Surface Irregularity in Keratoconus and Crosslinking Intervention Follow-up in 737 Cases. J Kerat Ect Cor Dis 2013;2(3):95-103.

Source of support: Nil

Conflict of interest: None declared

 
2.  Original Article
Corneal Pachymetry measured with Pentacam and CorvisST in Normal and Keratoconic Eyes
José M González-Méijome, Daniela Lopes-Ferreira, Laura Rico-del-Viejo, Patrícia Neves, Helena Ferreira, José Salgado-Borges
[Pages No:104-107]
Full Text PDF | Abstract | DOI : 10.5005/jp-journals-10025-1061 | FREE

ABSTRACT

Purpose: To evaluate the agreement of pachymetry data provided by a new instrument to measure intraocular pressure (IOP) and the corneal biomechanical response with the values provided by Pentacam in healthy and keratoconic eyes.

Methods: Fifty-four right eyes from 54 healthy patients (32 females, 22 males) and 82 eyes from 43 keratoconus patients (20 females, 23 males) were included in the study. All patients were evaluated with Pentacam and CorvisST (Oculus, Wetzlar, Germany) in random order in the same session. CorvisCCT was compared to Pentacam pachymetry in at the corneal center (PentacamCCT) and at the thinnest point (PentacamMinCT).

Results: Average pachymetry provided by CorvisST was 534 ± 34 microns in the healthy population and 476 ± 56 microns in the population with keratoconus. Pachymetric values obtained with Pentacam were highly correlated between them as well as with the Corvis value in both groups, but the correlation coefficients were higher in the healthy group.

Conclusion: Corvis pachymetry can be used interchangeably with Pentacam thinnest point pachymetry in healthy corneas. However, in keratoconic corneas, the difference between both parameters will be higher as the disease progresses and increases the difference between Pentacam pachymetry at cornea center and at the thinnest point.

Keywords: Pachymetry, Scheimpflug photography, Keratoconus.

How to cite this article: Gonzalez-Meijome JM, Lopes-Ferreira D, Rico-del-Viejo L, Neves P, Ferreira H, Salgado-Borges J. Corneal Pachymetry measured with Pentacam and CorvisST in Normal and Keratoconic Eyes. Int J Kerat Ect Cor Dis 2013;2(3):104-107.

Source of support: The authors want to thank Antonio Moutinho Lda and Oculus for the loan of the corvis ST. The authors have no proprietary interest in any of the devices mentioned in this article. Data presented in part at ESCRS Meeting, Amsterdam 5-9 October 2013.

Conflict of interest: None

 
3.  Original Article
Accuracy of Topometric Indices for Distinguishing between Keratoconic and Normal Corneas
Marcella Q Salomao, Frederico P Guerra, Isaac C Ramos, Livia F Jordao, Ana Laura C Canedo, Bruno F Valbon, Allan Luz, Rosane Correa Bernardo Lopes, Renato Ambrósio Jr
[Pages No:108-112]
Full Text PDF | Abstract | DOI : 10.5005/jp-journals-10025-1062 | FREE

ABSTRACT

Purpose:To evaluate the sensitivity and specificity of the Pentacam topometric indices derived from the corneal surface curvature to distinguish between normal and keratoconic corneas.

Methods: The study consisted of 226 normal corneas from 113 patients and 88 keratoconic eyes from 44 patients. Eyes were defined as keratoconus based on comprehensive ocular examination, including Placido-disk-based corneal topography (Atlas Corneal Topography System; Humphrey, San Leandro, California) and rotating Scheimpflug corneal tomography (Pentacam HR; Oculus, Wetzlar, Germany). Corneal Topometric indices ISV, IVA, KI, CKI, IHA and IHD, along with the TKC (Topometric Keratoconus Classification) score were calculated from the Pentacam HR exam. Statistical analysis were accomplished using BioEstat 5.0 (Instituto Mamiraua, Amazonas, Brazil) and MedCalc 12.0 (MedCalc Software, Mariakerke, Belgium) using unpaired nonparametric Mann Whitney test (Wilcoxon ranked-sum). ROC curves were calculated for each topometric parameter to determine the best cut off values from the significantly different parameters. A logistic regression analysis was performed to provide a combined parameter for optimizing accuracy.

Results: Statistical significant differences were found between keratoconic and normal corneas for all topometric indices (Mann Whitney, p < 0.05). There were four false negative cases among the keratoconic cases on the TKC classification (4.54%) and 16 false positive cases among normal (7.08%), so that the sensitivity and specificity of the TKC were 95.54 and 92.92% respectively. The areas under the ROC curves (AUC) for the individual topometric indices varied from 0.843 (CKI) and 0.992 (ISV). The sensitivity and specificity of the most accurate ISV were 97.7 and 96.5% respectively. The calculated parameter from logistic regression had AUC of 0.996, with sensitivity of 97.7% and specificity of 98.7%.

Conclusion: Pentacam topometric indices were useful for distinguishing between normal and keratoconic corneas. The TKC classification should be expected to have false positives and negatives and should not be considered alone. TKC had more false positives and false negatives than some individual topometric parameters. A novel combined parameter based on logistic regression analysis may improve accuracy for the diagnosis of keratoconus. Further studies are necessary to evaluate if adding other curvature derived indices is beneficial for the regression analysis, as well as for testing the sensitivity of such parameters for the diagnosis of milder forms of ectasia and for testing correlations with severity of the disease.

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

How to cite this article:Salomao MQ, Guerra FP, Ramos IC, Jordao LF, Canedo ALC, Valbon BF, Luz A, Correa R, Lopes B, Ambrósio Jr R. Accuracy of Topometric Indices for Distinguishing between Keratoconic and Normal Corneas. J Kerat Ect Cor Dis 2013;2(3):108-112.

Source of support: Nil

Conflict of interest: None

 
4.  Review Article
Corneal Collagen Crosslinking for Keratectasia after Laser in situ Keratomileusis: A Review of the Literature
Leopoldo Spadea, Francesca Verboschi, Stefano Valente, Enzo Maria Vingolo
[Pages No:113-120]
Full Text PDF | Abstract | DOI : 10.5005/jp-journals-10025-1063 | FREE

ABSTRACT

Corneal ectasia is a serious vision-threatening complication of laser in situ keratomileusis (LASIK). It is associated with progressive corneal steepening, an increase in myopia and astigmatism, and decrease in uncorrected visual acuity. Before LASIK presence of risk factors (corneal thickness, refractive error, presence of clinical and subclinical corneal pathologies) should be studied so patients should be risk-stratified. Forme fruste keratoconus or marginal pellucid degeneration should be investigated before LASIK in order to inform the patients of the possibility to develop a corneal complication. Management of post-LASIK ectasia enlists crosslinking, INTACTS, contact lenses and, in the most serious cases, lamellar keratoplasty and corneal transplantation. Crosslinking is a technique to treat and even prevent post-LASIK corneal ectasia. LASIK is a technique that reduces the corneal strength and stability. Crosslinking increases the number of collagen interfibrillar covalent bonds, using ultraviolet A and riboflavin. This result increases stability in corneal strength, reducing the risk to develop corneal ectasia (if performed simultaneously with LASIK) or it treats ectasia (if performed after LASIK keratectasia).

Keywords: Collagen crosslinking, Cornea, Keratectasia, LASIK.

How to cite this article: Spadea L, Verboschi F, Valente S, Vingolo EM. Corneal Collagen Crosslinking for Keratectasia after Laser in situ Keratomileusis: A Review of the Literature. J Kerat Ect Cor Dis 2013;2(3):113-120.

Source of support: Nil

Conflict of interest: None

 
5.  Review Article
Intacs Intracorneal Ring Segments Complications in Patients Suffering from Keratoconus
Adel Barbara, Ramez Barbara
[Pages No:121-128]
Full Text PDF | Abstract | DOI : 10.5005/jp-journals-10025-1064 | FREE

ABSTRACT

Intacs, intrastromal corneal rings are widely used to reduce myopia, astigmatism, keratometry readings and high order aberrations in patients suffering from keratoconus, almost 15 years have passed from the first procedure which was performed in the eye of a patient with unsatisfactory visual acuity and contact lenses intolerance.
Many publications including book chapters, retrospective studies, case reports and literatures reviews have been published on this issue.
In this review, we are reporting on the complications of Intacs implanted in keratoconic eyes, we are reporting on intraoperative and postoperative complications. The review although focusing on complications of the does not contradict the positive results of the procedure on the quality of life of the patients suffering from keratoconus and the its safety.

Keywords: Keratoconus, Intacs, Perforation, Keratitis, Extrusion, Astigmatism, Keratometry, High order aberrations, Intrastromal and corneal rings.

How to cite this article: Barbara A, Barbara R. Intacs Intracorneal Ring Segments Complications in Patients Suffering from Keratoconus. J Kerat Ect Cor Dis 2013;2(3):121-128.

Source of support: Nil

Conflict of interest: None declared

 
6.  Case Report
Double Descemet Membrane Forming a Double Anterior Chamber
Shmuel Graffi, Modi Naftali
[Pages No:129-132]
Full Text PDF | Abstract | DOI : 10.5005/jp-journals-10025-1065 | FREE

ABSTRACT

Purpose: To report a case of double descemet membrane forming a double anterior chamber following ‘ Big bubble’ DALK converted to PKP.

Results: A 52-year-old man with keratoconus underwent DALK operation converted to PKP due to macro perforation of the descemet membrane. On the postoperative evaluation a remnant of the host’s descemet membrane formed a double anterior chamber. After a few months with no intervention, an attempt to deflect a thickened descemet membrane had failed, making entrance into the anterior chamber in order to excise the membrane inevitable. Two years following the second surgery a graft endothelial failure and cataract formation was documented, leading to a second corneal transplantation and lens implantation.

Conclusion: Double DM is an unusual condition following a DALK procedure which was converted into PKP. In the above case this complication resulted in multiple procedures and graft failure. We believe that early interventions such as gas injection or YAG laser could have resulted in a more favorable outcome.



Keywords: Double descemet membrane, Double anterior chamber, DALK, Big bubble.

How to cite this article:Graffi S, Naftali M. Double Descemet Membrane Forming a Double Anterior Chamber. J Kerat Ect Cor Dis 2013;2(3):129-132.

Source of support: Nil

Conflict of interest: None

 
7.  Case Report
Corneal Neovascularization and Lipid Keratopathy after Intacs SK in Keratoconus
Adel Barbara, David Zadok, Shay Gutfreund, Ramez Barbara
[Pages No:133-138]
Full Text PDF | Abstract | DOI : 10.5005/jp-journals-10025-1066 | FREE

ABSTRACT

Intacs have yielded positive results for the treatment of keratoconus in terms of reducing the keratometry readings astigmatism and spherical equivalent and consequently improving the uncorrected and best corrected visual acuity. Intacs severe keratoconus (SK) are new design of Intacs with a smaller optical zone (6 mm) and oval shape, they are indicated for severe keratocnus.
Pannus is one of the complications of Intacs, as it has never been reported after Intacs SK.
We report on corneal neovascularization in the corneal periphery which developed few months after Intacs SK implantation in the cornea of a young female who suffered from advanced keratoconus. The uncorrected visual (UCVA) acuity was satisfactory and the Intacs SK where not removed. Four years after the implantation she presented to our clinic complaining about eye irritation and photophobia, lipid keratopathy was observed.
We gave here the choice of explanting the Intacs SK or to try to treat the neovascularization by subconjunctival Avastin, she preferred the second option because of a satisfactory UCVA (0.9).
Avastin was injected in the subconjunctival, 10 weeks later Avastin and Kenelog were injected in the subconjunctival, few days after the second injection perforation and melting developed in the cornea, the patient underwent a tectonic graft and few months later penetrating keratoplasty with no intraoperative or postoperative complications.

Keywords: Intacs, Intacs SK, Intrastromal, Keratoconus, Corneal rings, Perforation, Pannus, Corneal neovascularization, Astigmatism, Irregular astigmatism Keratometry.

How to cite this article: Barbara A, Zadok D, Gutfreund S, Barbara R. Corneal Neovascularization and Lipid Keratopathy after Intacs SK in Keratoconus. J Kerat Ect Cor Dis 2013;2(3): 133-138.

Source of support: Nil

Conflict of interest: None declared

 
8.  Case Report
Case of Corneal Perforation as a Complication after Uneventful CXL without Infection
Goktug Demirci, Akif Ozdamar
[Pages No:139-142]
Full Text PDF | Abstract | DOI : 10.5005/jp-journals-10025-1067 | FREE

ABSTRACT

Purpose: To demonstrate that UVA/riboflavin crosslinking (CXL) can cause corneal melting in some unpredictable cases.

Materials and methods: We will present a case report of 25-year-old male patient referred for emergency keratoplasty which is due to corneal melting and perforation developed after uneventful CXL procedure for the treatment of keratoconus.

Results: We performed uncomplicated penetrating keratoplasty of the left eye in our hospital.

Conclusion: CXL is gradually becoming the standard treatment procedure for progressive keratoconus and the only major safety concerns associated with CXL are ocular surface damage and endothelial cell damage. This case has shown, however, that even if CXL seems to have been successful, there is still a risk of adverse outcomes. Our report suggests that further research is necessary regarding the safety of corneal collagen crosslinking in corneas with keratoconus.

Keywords: Corneal melt, CXL, Enzymatic activity and keratoconus, Penetrating keratoplasty.

How to cite this article: Demirci G, Ozdamar A. Case of Corneal Perforation as a Complication after Uneventful CXL without Infection. J Kerat Ect Cor Dis 2013;2(3):139-142.

Source of support: Nil

Conflict of interest: None declared

 
9.  Case Report
Long-term Improvement after the Athens Protocol for Advanced Keratoconus with Significant Ectasia Progression in the Fellow Eye
Jorge Augusto Siqueira, Luis Claudio Dias, Renata Siqueira, Bruno Valbon, Rodrigo Santos, Daniel Dawson, Renato Ambrósio Jr
[Pages No:143-146]
Full Text PDF | Abstract | DOI : 10.5005/jp-journals-10025-1068 | FREE

ABSTRACT

To describe the long-term result of the Athens protocol (custom topography-guided advanced surface ablation followed by riboflavin-UVA collagen crosslinking in the same day) for progressive advanced keratoconus in the left eye, while the fellow right eye first presented with relatively mild keratoconus that was treated with a more conservative therapeutic approach of continuous contact lenses use with the goal for ectasia stabilization. Five years after the Athens protocol, a regression of over 10 D (diopters) was observed on the sagittal curvature with significant regularization of corneal shape and improvement of distance corrected visual acuity (DVCA) in the left eye. The right eye, which was treated more conservatively, had an over 12 D increase on sagittal curvature along with significant distortion of the corneal shape and reduction of DCVA..

Keywords: Keratoconus, Athens protocol, Contact lens .

How to cite this article: Siqueira JA, Dias LC, Siqueira R, Valbon B, Santos R, Dawson D, Ambrósio Jr R. Long-term Improvement after the Athens Protocol for Advanced Keratoconus with Significant Ectasia Progression in the Fellow Eye. J Kerat Ect Cor Dis 2013;2(3):143-146.

Source of support: Nil

Conflict of interest: None declared

 
 
     

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