Barbara R, Castillo JH, Hanna R, Berkowitz E, Tiosano B, Barbara A. Keratoconus Expert Meeting, London, 2014. Practical Observations on Conical Cornea: and on the Short Sight, and Other Defects of Vision Connected with it. Aim: To define variables for the evaluation of keratoconus progression and to determine cut-off values. The “enhanced BFS” is generated by utilizing all the valid elevation data from within the 8.0 mm central cornea, and outside the exclusion zone (Fig. recommend the use of Kmax as a good single criterion to diagnose progression of keratoconus . 2014 Apr;98(4):459-63. doi: 10.1136/bjophthalmol-2013-304132. Future work, however, will evaluate patients with mild to moderate disease. A one-sided confidence interval was chosen because progression is indicated by thinning and/or steepening of the anterior and/or posterior corneal surfaces. Keratoconus is relatively uncommon with a reported annual incidence of 2 per 100,000 and prevalence of 54.5 per 100,000, though rates vary greatly in different geographic regions [5–7]. Mahmoud AM, Nuñez MX, Blanco C, Koch DD, Wang L, Weikert MP, et al. 2009;148:760–5. Diagnosis can be made by slit-lamp examination and observation of central or inferior corneal thinning. Among the topographic indices used, simulated K (SimK), astigmatism, irregularity index of 3 … Cornea. Hersh PS, Greenstein SA, Fry KL. 2) . Atypical unilateral superior keratoconus in young males. looked at seven anterior surface Pentacam-derived topometric indices, concluding that the index of surface variance (ISV) and the index of height decentration (IHD) may be the most sensitive and specific criteria in the diagnosis and progression of keratoconus . Assessment of Corneal Pachymetry Distribution and Morphologic Changes in Subclinical Keratoconus with Normal Biomechanics. Wittig-silva C, Chan E, Islam FM, Wu T, Whiting M, Snibson GR. Lee LR, Hirst LW, Readshaw G. Clinical detection of unilateral keratoconus. Additionally, changes on the posterior cornea may occur without concurrent anterior changes and they may be posterior progression in spite of a normal anterior surface (subclinical keratoconus) (Fig. Videokeratography of the fellow eye in unilateral keratoconus. It is indicated for patients with progressive keratoconus or ectasia because it offers the opportunity to preserve visual function by slowing or halting progression of the condition. This webinar will consider different alternatives to treat keratoconus according to the stage and evolution, will explain the selection criteria to take into account, and how to halt the progression of keratoconus in its initial stages. 44, no. Ophthalmology. 2006;32(8):1281–7. Keratoconus is relatively uncommon with a reported annual incidence of 2 per 100,000 and prevalence of 54.5 per 100,000, though rates vary greatly in different geographic regions [5, 6, 7]. Google Scholar. Comparison of multimetric D index with keratometric, pachymetric, and posterior elevation parameters in diagnosing subclinical keratoconus in fellow eyes of asymmetric keratoconus patients. The map of the left highlights in red the 3.0 mm exclusion zone centered on the thinnest point that is removed from the calculation of the enhanced reference surface. O’Brart DP, Chan E, Samaras K, Patel P, Shah SP. Correlation of topometric and tomographic indices with visual acuity in patients with keratoconus. The limitation of the study is that the confidence intervals were determined on normal subjects and it is highly likely that measurement variability would be greater in ectatic corneas, though these values probably reflect early disease fairly well. Article Lecturer: Dr. Carlos H. Gordillo, … California Privacy Statement, Additionally, these methods suffer from either being limited only to the anterior cornea or representing a small portion of the cornea, which may not properly depict changes in the ectatic region. J Cataract Refract Surg. Therefore, we used … However, to the best of our knowledge, none of these have been validated in peer-reviewed literature as methods to monitor progression. Early in the disease, and in subclinical keratoconus, there may be minimal or no symptoms, whereas in advanced disease there is significant distortion of vision accompanied by profound visual loss . Part of Kanellopoulos et al. A number of other parameters or systems have been advocated to document progression [22, 25, 26, 34–40]. Here, the normal patient variation is probably more applicable and more closely approximates very early disease than values determined from known cases of keratoconus. View at: Google Scholar R. L. Epstein and G. L. Epstein, “On keratoconus incidence in prospective refractive surgery patients,” Scripta Medica (Banja Luka) , vol. However some progression may be experienced by persons 50 or older. It displays the elevation data against the commonly used best-fit-sphere (BFS) taken from the central 8.0 mm zone, but also uses a newly developed reference surface called the “Enhanced Reference Surface.”. Clipboard, Search History, and several other advanced features are temporarily unavailable. Google Scholar. 1). Suzuki M, Amano S, Honda N, Usui T, Yamagami S, Oshika T. Longitudinal changes in corneal irregular astigmatism and visual acuity in eyes with keratoconus. [Epub ahead of print]. J Cataract Refract Surg. Author Information . Article http://creativecommons.org/licenses/by/4.0/, http://creativecommons.org/publicdomain/zero/1.0/, https://doi.org/10.1186/s40662-016-0038-6. The standard anterior map (upper left) shows minimal changes against the enhanced reference surface (lower left) as the anterior surface is normal. 2013;2(3):95–103. Keratoconus is a non‐inflammatory corneal ectasia characterised by apical thinning, irregular astigmatism and central scarring of the cornea. Receiver-operating characteristic curve (ROC) analysis was performed and Youden Index calculated to determine cut-off values. To develop a criterion for determining the topographic progression of keratoconus and to analyze the prognostic factors of progression. NIH PubMed ferent criteria for progression have been used, including clinical progression to penetrating keratoplasty [3-12]. 6). Conclusions: To evaluate the inter-day repeatability in the measurement of parameters used for the detection of progression of keratoconus by prediction limits (PL… 1994;35:2749–57. Epstein et al. Kmax fails to reflect the degree of ectasia, ignores the contribution of the posterior cornea to progression and marked ectatic progression can occur with no change or even a reduction in Kmax [32–34]. Progression was defined based on … Google Scholar. Surv Ophthalmol. The remaining authors have no competing interests. Eye and Vision The “Belin ABCD” grading system has been incorporated in the OCULUS Pentacam software version 6.08r16 as part of the Topometric/Keratoconus Grading Display (Fig. Am J Ophthalmol. By using this website, you agree to our In this test your eye doctor uses special equipment that measures your eyes to check for vision problems. The authors describe how modern corneal tomography, including both anterior and posterior elevation and pachymetric data can be used to screen for ectatic progression, and how software programs such as the Enhanced Reference Surface and the Belin-Ambrosio Enhanced Ectasia Display (BAD) can be employed to detect earlier changes. A new method for grading the severity of keratoconus: the Keratoconus Severity Score (KSS). Correspondence to Highlights Ophthalmol. Measuring corneal thickness change at the thinnest point should be a more sensitive indicator of progression than apical pachymetry. Khachikian SS, Belin MW, Ciolino JB. Progression usually occurs to an age of around 40-45 years and then tends to stabilize. 2006;22:539–45. Ambrósio Jr R, Caiado AL, Guerra FP, Louzada R, Roy AS, Luz A. Clinical data include distance UCVA and Progression of keratoconus by longitudinal assessment with corneal topography. RESULTS: There was a significant, albeit moderate, correlation between the change in Kmax between T0 and T-1 and the change in both A (rho=0.391) and B values (rho= 0.339). Kasparova and Kasparov  reported that 8.6% of eyes showed keratoconus progression within the first six months following refractive surgery. 2014;121(4):812–21. Each technician imaged each patient three times for each time period for a total of 27 images per patient, 135 images total. Invest Ophthalmol Vis Sci. 2013;39(11):1707–12. The panel, however, acknowledged that specific quantitative data to define progression is lacking . 2012;1(3):167–72. Article Independent population validation of the Belin/Ambrosio enhanced ectasia display: implications for keratoconus studies and screening. Defining Keratoconus Progression With our ability to stop the progression of keratoconus with treatments such as corneal cross linking it becomes that much more important to come to some consensus about defining progression of the disease. Usually both eyes are affected. Keratoconus and Ectatic… Klin Monatsbl Augenheilkd 2020; 237: 740–744 This document was downloaded for personal use only. CAS J Cataract Refract Surg. Past treatments were for late disease and typically never returned the patient to normal visual function. J Kerat Ect Cor Dis. Jonas JB, Nangia V, Matin A, Kulkarni M, Bhojwani K. Prevalence and associations of keratoconus in rural maharashtra in central India: the central India eye and medical study. Exclusion criteria included past ocular surgery, recent rigid contact lens wear, and corneal scarring. Excluding this zone from the standard 8 mm BFS results in a reference surface that closely mimics the more normal portions of the cornea. The cornea is substantially thinned with a prominent posterior ectasia in spite of a normal anterior surface (BAD display, Oculus Pentacam). Kanellopoulos AJ, Asimellis G. Revisiting keratoconus diagnosis and progression classification based on evaluation of corneal asymmetry indices, derived from Scheimpflug imaging in keratoconic and suspect cases. A prospective cohort study demonstrated that the new scoring system, compared with conventional measures of maximum keratometry, could better identify eyes that were properly withheld treatment by 35%. Chatzis N, Hafezi F. Progression of keratoconus and efficacy of pediatric corneal collagen cross-linking in children and adolescents. Round and oval cones in keratoconus. Sykakis E, Karim R, Evans JR, Bunce C, Amissah-Arthur KN, Patwary S, et al. PubMed Die Krankheit ist immer beidseitig, kann aber auf einem Auge schwächer ausgeprägt sein oder überhaupt nicht symptomatisch werden. Nottingham J. 2015;34:359–69. Ophthalmology. Similarly, the determination of progression, or the lack of, is paramount to determine when and if to treat and to document treatment efficacy. Terms and Conditions, Expanding the cone location and magnitude index to include corneal thickness and posterior surface information for the detection of keratoconus. Please take a look at published article that evaluated key corneal parameters from Scheimpflug corneal tomography which were most reliable in … PubMed Central In this retrospective cohort study (2010-2016), 265 eyes of 165 patients diagnosed with keratoconus underwent two Scheimpflug measurements (Pentacam) that took place 1 year apart ±3 months. volume 3, Article number: 6 (2016) 2015;4(3):55–63. A table listing the criteria for keratoconus progression in previous studies was generated. Others have used this system with various modification and additions in an attempt to better diagnosis or characterize the severity of disease [21, 22]. 1980;87:905–9. Eye Contact Lens. Published by BMJ. 2011;37(1):149–60. 2019 Mar 1;13:445-452. doi: 10.2147/OPTH.S189183. As with the older grading systems, the problem with many of the commonly used progression parameters is that they were either limited to the anterior corneal surface (Kmax), or were measured on the corneal apex (Kmax, apical pachymetry) which often does not adequately reflect the cone. Feng MT, Belin MW, Ambrósio Jr R, Grewal SP, Yan W, Shaheen MS, et al. In 2015, a global Delphi panel published a consensus report recognizing cross-linking as the standard of care for progressive keratoconus. Tests to diagnose keratoconus include: 1. Changes in the cone may occur with little or any changes in the apical cornea. Increased choroidal thickness is not a disease progression marker in keratoconus. The corneal thinning induces irregular astigmatism, myopia, and conical protrusion, leading to mild to marked impairment in the quality of vision, and often has a significant impact on patient’s quality of life . Purpose To compare the rate of disease progression in keratoconus before and after corneal collagen crosslinking (CXL). 1946;111:96–101. An example of subclinical keratoconus. 2019 Nov 19;2019:1748579. doi: 10.1155/2019/1748579. Automated keratoconus screening with corneal topography analysis. In patients without earlier progression in Kmax, follow-up exam (T-2) was used to determine whether any of the ABC parameters reached statistical significance for progression. Weed KH, McGhee CN, Mac Ewen CJ. 4). 1, p. 32, 2013. By logistic regression analysis, a keratoconus progression index (KPI) was defined. Cornea. Keratoconus and Ectatic Disease: Evolving Criteria for Diagnosis Keratokonus und Hornhautektasie: Weiterentwicklung der diagnostischen Kriterien Übersicht 740 Belin MW. As opposed to excluding the 3.0 to 4.0 mm zone to normalize the reference surface, we employed the exclusion zone centered on the thinnest point as this area more globally represents the ectatic region than a single point parameter such as Kmax or maximal elevation. As earlier noted, according to Global Consensus on Keratoconus and Ectatic Diseases (2015), there is no consistent or clear definition of ectasia progression . Corneal thickness map (left) and Posterior elevation (right). Google Scholar. Rabinowitz YS. Klin Monbl Augenheilkd. Its genetics is complex with undefined pattern of inheritance. 2015;69(2):91–4. PubMed USA.gov. The only abnormality seen here (BAD display) is a mild abnormality in the pachymetric progression (Oculus Pentacam), The additional information available from anterior segment tomographic devices has led to the development of various refractive surgery screening programs. Scheimpflug optical cross section with edge detection turned on, showing the anterior corneal surface, posterior corneal surface, anterior and posterior lens surfaces identified (Oculus Pentacam). Die Erkrankung ist also durch zwei Eigenschaften charakterisiert: Progression: Die Hornhaut wird immer dünner und spitzer Sehschwäche: Durch die unregelmäßige Verformung der Hornhaut nimmt die Sehschärfe ab. Aim: Visual acuity methods are very variable, as many practitioners have seen how unpredictable these subjective measurements can be in a keratoconic patient . More than 50 gene loci and 200 variants are associated with keratoconus, some through association studies with quantitative traits of cornea … Corneal elevation indices in normal and keratoconic eyes. To diagnose keratoconus, your eye doctor (ophthalmologist or optometrist) will review your medical and family history and conduct an eye exam. Oshika T, Tanabe T, Tomidokoro A, Amano S. Progression of keratoconus assessed by fourier analysis of videokeratography data. Ophthalmology. Ophthalmology. Methods Eligibility Criteria for Considering Studies for Review Inclusion Criteria . Indian J Ophthalmol. Other imaging techniques using Fourier series harmonic videokeratography and Fourier-Domain Optical Coherence Tomography (OCT) have been used to evaluate progression of keratoconus. CXL has the potential to alter the natural course of the disease and, if implemented early enough in the disease process, to prevent visual loss. 22 In a longitudinal study, Li et al identiﬁed videokeratographic indices predictive . Exclusion criteria were advanced keratoconus with stromal scarring, corneal thickness less than microns, corneal hydrops, severe dry eye, corneal infections, previous ocular surgery, and autoimmunediseases. No commercial re-use. Posteriorly, normal eyes showed an average change in apex and maximum elevation of 2.86±1.9µm and 2.27±1.1µm. Lopes BT, Ramos IC, Faria-Correia F, Luz A, de Freitas Valbon B, Belin MW, et al. Belin MW, Duncan J. Keratoconus: The ABCD Grading System. Tomidokoro A, Oshika T, Amano S, Higaki S, Maeda N, Miyata K. Changes in anterior and posterior corneal curvatures in keratoconus. Kuechler SJ(1), Tappeiner C, Epstein D, Frueh BE. criteria in making an early diagnosis and assessing pro - gression in keratoconus patients. 2014;98(4):459–63. Google Scholar. One such program is the Belin-Ambrosio Enhanced Ectrasia Display (BAD). Morphogeometric analysis for characterization of keratoconus considering the spatial localization and projection of apex and minimum corneal thickness point. For progression analysis, the authors only used parameters that are commonly accepted as progression markers with described cutoffs (although not validated) 21, 29, 35. Several methods have been described in the literature to both evaluate and document progression in keratoconus, but there is no consistent or clear definition of ectasia progression. For each of these parameters (corneal thickness, ARC, PRC) a decrease would be indicative of progression. Here, using parameters deduced from keratoconus patients would probably delay treatment. Google Scholar. Novel pachymetric parameters based on corneal tomography for diagnosing keratoconus. Keratoconus causes increasing blurriness and shortsightedness in vision, light sensitivity and halos and ghosting around light sources. Various keratoconus diagnosis, staging, and progression crite-ria are in clinical use. Identifying progression of subclinical keratoconus by serial topography analysis. The progressive group was defined as 36 eyes, which showed progression according to the definition of the global consensus on keratoconus and ectatic diseases when 2 of the 3 criteria were met, and the other 45 eyes were considered the nonprogressive group. criteria in mak ing an ea rly diagnosis and assessi ng pro- gression in keratoconus patients. 2005;28:177–9. The corneal thickness map shows a thinnest point that is displaced inferiorly and the posterior elevation reveals a prominent posterior island in an eye that has a normal anterior surface (Oculus Pentacam). Am J Ophthalmol. 2016;233:701-707 2. Because all three parameters are centered on the thinnest point (surrogate for center of the cone) and limited to the conical region, they should reflect change earlier than more global parameters (e.g. Michael W. Belin. Various keratoconus diagnosis, staging, and progression criteria are in clinical use. This is a newer treatment that has the potential to prevent you from needing a cornea transplant in the future 2014;3(1):1–8. Alió JL, Shabayek MH. 1998;114:38–40. KERALINK is a randomised controlled, observer-masked, multicentre trial in progressive keratoconus comparing epithelium-off CXL with standard care, including spectacles or contact lenses … Unauthorized distribution is strictly prohibited. Kmax, however, has been acknowledged as a poor parameter for both progression and crosslinking efficacy [31–35]. Duncan, J.K., Belin, M.W. The use of normal subjects was based on practical reasons since it would be difficult to have patients return on multiple days for measurements, though this is something we will pursue in the future. Department of Ophthalmology & Vision Science, University of Arizona, Tucson, AZ, USA, University of Arizona, University Information Technology Services, Tucson, AZ, USA, You can also search for this author in This article describes the statistical analysis plan for this trial as an update to the published protocol. Specifically, Oshika et al. Amsler M. Keratocone classique et keratocone fruste; arguments unitaires. J Refract Surg. Criteria can include data from clinical evaluation and topography- and topometry-derived indicators. According to Global Consensus on Keratoconus and Ectatic Diseases (2015), there is no consistent or clear definition of ectasia progression . National Center for Biotechnology Information, Unable to load your collection due to an error, Unable to load your delegates due to an error. Kmax (maximum anterior sagittal curvature) is the most commonly used parameter to detect or document ectatic progression and is regularly used as an indicator for crosslinking’s efficacy [27–29]. Cut-off for KPI was -0.78196 (84.7% sensitivity) and a Youden Index of 0.747; both 90% specificity. Gilani F, Cortese M, Ambrósio Jr RR, Lopes B, Ramos I, Harvey EM, et al. These values were obtained by imaging five normal patients using three different technicians on three separate days. IHD, ISV) and/or parameters measured from the corneal apex. 2013;156(6):1102–11. To determine the measurement noise of the three parameters (corneal thickness at the thinnest point, and anterior and posterior radius of curvature (ARC, PRC) taken from the 3.0 mm optical zone centered on the thinnest point), five volunteer subjects were imaged, after obtaining informed consent, by three different technicians on three different days separated by 2 weeks (Pentacam HR, software version 6.08r13). While the Best-Fit-Sphere (BFS) is both quantitatively and qualitatively useful, the clinician typically assumes that the reference surface closely approximates a “normal” cornea. 1 (see “ Keratoconus: An Overview ”). light the criteria used for keratoconus detection that Figure 1. These include; observing for change on the posterior elevation maps, change in best corrected distance visual acuity, reduction in apical corneal thickness, or an increase in anterior corneal asymmetry. This new classification/grading system has advantages over the older Amsler-Krumeich classification in that it recognizes the importance of the posterior corneal surface and each component (anterior, posterior, thickness, visual acuity) are individually graded. The degree of progression in each eye is often unequal, and it isn’t unusual for the condition to be significantly more advanced in one eye. Am J Ophthalmol. J Refract Surg. 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