Pentacam® Corneal Tomography for Screening of Refractive Surgery Candidates: A Review of the Literature, Part I
Medical hypothesis discovery and innovation in ophthalmology,
Vol. 8 No. 3 (2019),
20 September 2019
,
Page 177-203
Abstract
Corneal tomography and Scheimpflug imaging are frequently used to analyze the corneal surface, especially in the field of cataract and refractive surgery. The Pentacam system is one of the most commonly used commercially available systems for this purpose. Through a rotating Scheimpflug camera, the system is capable of creating a three-dimensional map of the cornea. These advances in tomography have simultaneously enhanced the ability of clinicians to screen surgical candidates and detect subtle corneal changes in diseases such as keratoconus. However, there remains a need to enhance diagnosis in order to recognize mild and early forms of corneal ectasia. As iatrogenic ectasia and keratoconus are dreaded complications of refractive surgery, it is imperative to screen patients appropriately prior to surgery. The Pentacam is one of many systems utilized in the screening process, but the literature has not identified specific protocol nor parameters that are capable of carrying out this process appropriately. Post-operative keratoconus continues to occur despite the advances in technology seen in corneal imaging. Therefore, clear indices for screening are required in order to diagnose early forms of keratoconus and other corneal diseases that may exclude the seemingly asymptomatic patient from undergoing refractive surgery. This article aims to summarize the indices available on the Pentacam system and to identify the most accurate parameters for screening of the refractive surgery candidate.References
REFERENCES
Belin MW, Ambrosio R, Jr. Corneal ectasia risk score: statistical validity and clinical relevance. J Refract Surg. 2010;26:238-40. doi: 10.3928/1081597X-20100318-01 pmid: 20415320
Randleman JB, Russell B, Ward MA, Thompson KP, Stulting RD. Risk factors and prognosis for corneal ectasia after LASIK. Ophthalmology. 2003;110:267-75. doi: 10.1016/S0161-6420(02)01727-X pmid: 12578766
Randleman JB, Woodward M, Lynn MJ, Stulting RD. Risk assessment for ectasia after corneal refractive surgery. Ophthalmology. 2008;115:37-50. doi: 10.1016/j.ophtha.2007.03.073 pmid: 17624434
Liu YC, Konstantopoulos A, Riau AK, Bhayani R, Lwin NC, Teo EP, et al. Repeatability and Reproducibility of Corneal Biometric Measurements Using the Visante Omni and a Rabbit Experimental Model of Post-Surgical Corneal Ectasia. Transl Vis Sci Technol. 2015;4:16. doi: 10.1167/tvst.4.2.16 pmid: 25938004
Ambrósio R, Klyce SD, Wilson SE. Corneal topographic and pachymetric screening of keratorefractive patients. Journal of Refractive Surgery. 2003;19:24-9.
Twa M. Irregular Astigmatism: Diagnosis and Treatment. Optom Vis Sci. 2009;86:1209. doi: 10.1097/OPX.0b013e3181bafce1
Maeda N, Klyce SD, Smolek MK, Thompson HW. Automated keratoconus screening with corneal topography analysis. Invest Ophthalmol Vis Sci. 1994;35:2749-57. pmid: 8188468
Wilson SE, Klyce SD. Advances in the analysis of corneal topography. Surv Ophthalmol. 1991;35:269-77. doi: 10.1016/0039-6257(91)90047-J pmid: 2011820
Wilson SE, Lin DT, Klyce SD. Corneal topography of keratoconus. Cornea. 1991;10:2-8. doi: 10.1097/00003226-199101000-00002 pmid: 2019102
Rabinowitz YS, Rasheed K, Yang H, Elashoff J. Accuracy of ultrasonic pachymetry and videokeratography in detecting keratoconus. J Cataract Refract Surg. 1998;24:196-201. doi: 10.1016/s0886-3350(98)80200-9 pmid: 9530594
Rabinowitz YS, Rasheed K. KISA% index: a quantitative videokeratography algorithm embodying minimal topographic criteria for diagnosing keratoconus. J Cataract Refract Surg. 1999;25:1327-35. doi: 10.1016/s0886-3350(99)00195-9 pmid: 10511930
Ambrosio R, Jr., Belin MW. Imaging of the cornea: topography vs tomography. J Refract Surg. 2010;26:847-9. doi: 10.3928/1081597X-20101006-01 pmid: 21053870
Salomão M, Hoffling-Lima A, Lopes B, Belin M, Sena N, Dawson D, et al. Recent developments in keratoconus diagnosis. Expert Rev Ophthalmol. 2018;13:329-41. doi: 10.1080/17469899.2018.1555036
Ambrosio R, Jr., Valbon BF, Faria-Correia F, Ramos I, Luz A. Scheimpflug imaging for laser refractive surgery. Curr Opin Ophthalmol. 2013;24:310-20. doi: 10.1097/ICU.0b013e3283622a94 pmid: 23680761
Donaldson K, Fernandez-Vega-Cueto L, Davidson R, Dhaliwal D, Hamilton R, Jackson M, et al. Perioperative assessment for refractive cataract surgery. J Cataract Refract Surg. 2018;44:642-53. doi: 10.1016/j.jcrs.2018.02.022 pmid: 29891157
Wilson SE, Ambrosio R. Computerized corneal topography and its importance to wavefront technology. Cornea. 2001;20:441-54. doi: 10.1097/00003226-200107000-00001 pmid: 11413395
Ambrósio R, Faria-Correia F, Ramos I, Valbon BF, Lopes B, Jardim D, et al. Enhanced screening for ectasia susceptibility among refractive candidates: the role of corneal tomography and biomechanics. Current Ophthalmology Reports. 2013;1:28-38. doi: 10.1007/s40135-012-0003-z
Meyer JJ, Gokul A, Vellara HR, Prime Z, McGhee CN. Repeatability and Agreement of Orbscan II, Pentacam HR, and Galilei Tomography Systems in Corneas With Keratoconus. Am J Ophthalmol. 2017;175:122-8. doi: 10.1016/j.ajo.2016.12.003 pmid: 27993593
Hashemi H, Yekta A, Khabazkhoob M. Effect of keratoconus grades on repeatability of keratometry readings: Comparison of 5 devices. J Cataract Refract Surg. 2015;41:1065-72. doi: 10.1016/j.jcrs.2014.08.043 pmid: 26049838
Crawford AZ, Patel DV, McGhee CN. Comparison and repeatability of keratometric and corneal power measurements obtained by Orbscan II, Pentacam, and Galilei corneal tomography systems. Am J Ophthalmol. 2013;156:53-60. doi: 10.1016/j.ajo.2013.01.029 pmid: 23540708
Montalban R, Pinero DP, Javaloy J, Alio JL. Intrasubject repeatability of corneal morphology measurements obtained with a new Scheimpflug photography-based system. J Cataract Refract Surg. 2012;38:971-7. doi: 10.1016/j.jcrs.2011.12.029 pmid: 22541828
McAlinden C, Khadka J, Pesudovs K. A comprehensive evaluation of the precision (repeatability and reproducibility) of the Oculus Pentacam HR. Invest Ophthalmol Vis Sci. 2011;52:7731-7. doi: 10.1167/iovs.10-7093 pmid: 21810981
Shetty R, Arora V, Jayadev C, Nuijts RM, Kumar M, Puttaiah NK, et al. Repeatability and agreement of three Scheimpflug-based imaging systems for measuring anterior segment parameters in keratoconus. Invest Ophthalmol Vis Sci. 2014;55:5263-8. doi: 10.1167/iovs.14-15055 pmid: 25074774
Modis L, Jr., Szalai E, Kolozsvari B, Nemeth G, Vajas A, Berta A. Keratometry evaluations with the Pentacam high resolution in comparison with the automated keratometry and conventional corneal topography. Cornea. 2012;31:36-41. doi: 10.1097/ICO.0b013e318204c666 pmid: 22081146
Martin R, Jonuscheit S, Rio-Cristobal A, Doughty MJ. Repeatability of Pentacam peripheral corneal thickness measurements. Cont Lens Anterior Eye. 2015;38:424-9. doi: 10.1016/j.clae.2015.05.001 pmid: 26072988
Belin MW, Ambrosio R. Scheimpflug imaging for keratoconus and ectatic disease. Indian J Ophthalmol. 2013;61:401-6. doi: 10.4103/0301-4738.116059 pmid: 23925323
Walker RN, Khachikian SS, Belin MW. Scheimpflug photographic diagnosis of pellucid marginal degeneration. Cornea. 2008;27:963-6. doi: 10.1097/ICO.0b013e318170ae98 pmid: 18724166
Guber I, McAlinden C, Majo F, Bergin C. Identifying more reliable parameters for the detection of change during the follow-up of mild to moderate keratoconus patients. Eye Vis (Lond). 2017;4:24. doi: 10.1186/s40662-017-0089-3 pmid: 29124079
Huang J, Ding X, Savini G, Pan C, Feng Y, Cheng D, et al. A Comparison between Scheimpflug imaging and optical coherence tomography in measuring corneal thickness. Ophthalmology. 2013;120:1951-8. doi: 10.1016/j.ophtha.2013.02.022 pmid: 23672973
Hernandez-Camarena JC, Chirinos-Saldana P, Navas A, Ramirez-Miranda A, de la Mota A, Jimenez-Corona A, et al. Repeatability, reproducibility, and agreement between three different Scheimpflug systems in measuring corneal and anterior segment biometry. J Refract Surg. 2014;30:616-21. doi: 10.3928/1081597X-20140815-02 pmid: 25250418
Amsler M. The "forme fruste" of keratoconus. Wien Klin Wochenschr. 1961;73:842-3. pmid: 13861052
Krumeich JH, Daniel J, Knulle A. Live-epikeratophakia for keratoconus. J Cataract Refract Surg. 1998;24:456-63. doi: 10.1016/s0886-3350(98)80284-8 pmid: 9584238
Gomes JA, Tan D, Rapuano CJ, Belin MW, Ambrosio R, Jr., Guell JL, et al. Global consensus on keratoconus and ectatic diseases. Cornea. 2015;34:359-69. doi: 10.1097/ICO.0000000000000408 pmid: 25738235
Mahmoud AM, Roberts CJ, Lembach RG, Twa MD, Herderick EE, McMahon TT, et al. CLMI: the cone location and magnitude index. Cornea. 2008;27:480-7. doi: 10.1097/ICO.0b013e31816485d3 pmid: 18434854
Zadnik K, Barr JT, Edrington TB, Everett DF, Jameson M, McMahon TT, et al. Baseline findings in the Collaborative Longitudinal Evaluation of Keratoconus (CLEK) Study. Invest Ophthalmol Vis Sci. 1998;39:2537-46. pmid: 9856763
McMahon TT, Szczotka-Flynn L, Barr JT, Anderson RJ, Slaughter ME, Lass JH, et al. A new method for grading the severity of keratoconus: the Keratoconus Severity Score (KSS). Cornea. 2006;25:794-800. doi: 10.1097/01.ico.0000226359.26678.d1 pmid: 17068456
Maeda N, Klyce SD, Smolek MK. Neural network classification of corneal topography. Preliminary demonstration. Invest Ophthalmol Vis Sci. 1995;36:1327-35. pmid: 7775110
Maeda N, Klyce SD, Smolek MK. Comparison of methods for detecting keratoconus using videokeratography. Arch Ophthalmol. 1995;113:870-4. doi: 10.1001/archopht.1995.01100070044023 pmid: 7605277
Rabinowitz YS, McDonnell PJ. Computer-assisted corneal topography in keratoconus. Refract Corneal Surg. 1989;5:400-8. doi: 10.3928/1081-597X-19891101-10 pmid: 2488838
Randleman JB, Trattler WB, Stulting RD. Validation of the Ectasia Risk Score System for preoperative laser in situ keratomileusis screening. Am J Ophthalmol. 2008;145:813-8. doi: 10.1016/j.ajo.2007.12.033 pmid: 18328998
Febbraro J-L, Khan H, Koch D. Surgical Correction of Astigmatism. Cham: Springer International Publishing; 2018.
Pinero DP, Nieto JC, Lopez-Miguel A. Characterization of corneal structure in keratoconus. J Cataract Refract Surg. 2012;38:2167-83. doi: 10.1016/j.jcrs.2012.10.022 pmid: 23195256
Ambrosio R, Jr., Randleman JB. Screening for ectasia risk: what are we screening for and how should we screen for it? J Refract Surg. 2013;29:230-2. doi: 10.3928/1081597X-20130318-01 pmid: 23557219
Rabinowitz YS, Yang H, Brickman Y, Akkina J, Riley C, Rotter JI, et al. Videokeratography database of normal human corneas. Br J Ophthalmol. 1996;80:610-6. doi: 10.1136/bjo.80.7.610 pmid: 8795372
Belin MW, Villavicencio OF, Ambrosio RR, Jr. Tomographic parameters for the detection of keratoconus: suggestions for screening and treatment parameters. Eye Contact Lens. 2014;40:326-30. doi: 10.1097/ICL.0000000000000077 pmid: 25320954
Belin MW, Kim J, Zloty P, Ambrosio Jr R. Simplified nomenclature for describing keratoconus. Int J Keratoco Ectatic Corneal Dis. 2012;1:31-5. doi: 10.5005/jp-journals-10025-1006
Klyce SD. Chasing the suspect: keratoconus. Br J Ophthalmol. 2009;93:845-7. doi: 10.1136/bjo.2008.147371 pmid: 19553507
Mandell RB, Polse KA. Keratoconus: spatial variation of corneal thickenss as a diagnostic test. Arch Ophthalmol. 1969;82:182-8. doi: 10.1001/archopht.1969.00990020184006 pmid: 5796090
Rowsey JJ, Reynolds AE, Brown R. Corneal topography. Corneascope. Arch Ophthalmol. 1981;99:1093-100. doi: 10.1001/archopht.1981.03930011093022 pmid: 7236109
Orucoglu F, Toker E. Comparative analysis of anterior segment parameters in normal and keratoconus eyes generated by scheimpflug tomography. J Ophthalmol. 2015;2015:925414. doi: 10.1155/2015/925414 pmid: 25878897
Chan TC, Wang YM, Yu M, Jhanji V. Comparison of corneal dynamic parameters and tomographic measurements using Scheimpflug imaging in keratoconus. Br J Ophthalmol. 2018;102:42-7. doi: 10.1136/bjophthalmol-2017-310355 pmid: 28559422
Shetty R, Rao H, Khamar P, Sainani K, Vunnava K, Jayadev C, et al. Keratoconus Screening Indices and Their Diagnostic Ability to Distinguish Normal From Ectatic Corneas. Am J Ophthalmol. 2017;181:140-8. doi: 10.1016/j.ajo.2017.06.031 pmid: 28687218
Hashemi H, Khabazkhoob M, Pakzad R, Bakhshi S, Ostadimoghaddam H, Asaharlous A, et al. Pentacam Accuracy in Discriminating Keratoconus From Normal Corneas: A Diagnostic Evaluation Study. Eye Contact Lens. 2019;45:46-50. doi: 10.1097/ICL.0000000000000531 pmid: 30005053
Ucakhan OO, Cetinkor V, Ozkan M, Kanpolat A. Evaluation of Scheimpflug imaging parameters in subclinical keratoconus, keratoconus, and normal eyes. J Cataract Refract Surg. 2011;37:1116-24. doi: 10.1016/j.jcrs.2010.12.049 pmid: 21596255
Huseynli S, Abdulaliyeva F. Evaluation of Scheimpflug Tomography Parameters in Subclinical Keratoconus, Clinical Keratoconus and Normal Caucasian Eyes. Turk J Ophthalmol. 2018;48:99-108. doi: 10.4274/tjo.89587 pmid: 29988819
Kovacs I, Mihaltz K, Kranitz K, Juhasz E, Takacs A, Dienes L, et al. Accuracy of machine learning classifiers using bilateral data from a Scheimpflug camera for identifying eyes with preclinical signs of keratoconus. J Cataract Refract Surg. 2016;42:275-83. doi: 10.1016/j.jcrs.2015.09.020 pmid: 27026453
Luz A, Ramos I, Correia FF, Lopes B, Salomão MQ, Correa RO. Topometric and Tomographic Indices for the Diagnosis of Keratoconus. International Journal of Keratoconus and Ectatic Corneal Diseases. 2012;1:92-9. doi: 10.5005/jp-journals-10025-1018
Lopes BT, Ramos IC, Salomao MQ, Guerra FP, Schallhorn SC, Schallhorn JM, et al. Enhanced Tomographic Assessment to Detect Corneal Ectasia Based on Artificial Intelligence. Am J Ophthalmol. 2018;195:223-32. doi: 10.1016/j.ajo.2018.08.005 pmid: 30098348
Haddad JS, Barnwell E, Rocha KM, Waring Iv GO, Ambrosio Jr R. First Clinical Impressions on the Integrated Corneal Tomography and Corneal Deformation with Scheimpflug Imaging. International Journal of Keratoconus and Ectatic Corneal Diseases. 2017;6:101-9. doi: 10.5005/jp-journals-10025-1151
Xu Z, Li W, Jiang J, Zhuang X, Chen W, Peng M, et al. Characteristic of entire corneal topography and tomography for the detection of sub-clinical keratoconus with Zernike polynomials using Pentacam. Sci Rep. 2017;7:16486. doi: 10.1038/s41598-017-16568-y pmid: 29184086
Mihaltz K, Kovacs I, Takacs A, Nagy ZZ. Evaluation of keratometric, pachymetric, and elevation parameters of keratoconic corneas with pentacam. Cornea. 2009;28:976-80. doi: 10.1097/ICO.0b013e31819e34de pmid: 19724217
Jafarinasab MR, Shirzadeh E, Feizi S, Karimian F, Akaberi A, Hasanpour H. Sensitivity and specificity of posterior and anterior corneal elevation measured by orbscan in diagnosis of clinical and subclinical keratoconus. J Ophthalmic Vis Res. 2015;10:10-5. doi: 10.4103/2008-322X.156085 pmid: 26005546
de Sanctis U, Loiacono C, Richiardi L, Turco D, Mutani B, Grignolo FM. Sensitivity and specificity of posterior corneal elevation measured by Pentacam in discriminating keratoconus/subclinical keratoconus. Ophthalmology. 2008;115:1534-9. doi: 10.1016/j.ophtha.2008.02.020 pmid: 18405974
Muftuoglu O, Ayar O, Hurmeric V, Orucoglu F, Kilic I. Comparison of multimetric D index with keratometric, pachymetric, and posterior elevation parameters in diagnosing subclinical keratoconus in fellow eyes of asymmetric keratoconus patients. J Cataract Refract Surg. 2015;41:557-65. doi: 10.1016/j.jcrs.2014.05.052 pmid: 25708211
Kamiya K, Ishii R, Shimizu K, Igarashi A. Evaluation of corneal elevation, pachymetry and keratometry in keratoconic eyes with respect to the stage of Amsler-Krumeich classification. Br J Ophthalmol. 2014;98:459-63. doi: 10.1136/bjophthalmol-2013-304132 pmid: 24457362
Bae GH, Kim JR, Kim CH, Lim DH, Chung ES, Chung TY. Corneal topographic and tomographic analysis of fellow eyes in unilateral keratoconus patients using Pentacam. Am J Ophthalmol. 2014;157:103-9 e1. doi: 10.1016/j.ajo.2013.08.014 pmid: 24452012
Hashemi H, Beiranvand A, Yekta A, Maleki A, Yazdani N, Khabazkhoob M. Pentacam top indices for diagnosing subclinical and definite keratoconus. J Curr Ophthalmol. 2016;28:21-6. doi: 10.1016/j.joco.2016.01.009 pmid: 27239598
Du XL, Chen M, Xie LX. Correlation of basic indicators with stages of keratoconus assessed by Pentacam tomography. Int J Ophthalmol. 2015;8:1136-40. doi: 10.3980/j.issn.2222-3959.2015.06.10 pmid: 26682161
Muftuoglu O, Ayar O, Ozulken K, Ozyol E, Akinci A. Posterior corneal elevation and back difference corneal elevation in diagnosing forme fruste keratoconus in the fellow eyes of unilateral keratoconus patients. J Cataract Refract Surg. 2013;39:1348-57. doi: 10.1016/j.jcrs.2013.03.023 pmid: 23820305
Sedaghat MR, Momeni-Moghaddam H, Ambrosio R, Jr., Heidari HR, Maddah N, Danesh Z, et al. Diagnostic Ability of Corneal Shape and Biomechanical Parameters for Detecting Frank Keratoconus. Cornea. 2018;37:1025-34. doi: 10.1097/ICO.0000000000001639 pmid: 29847493
Lim HB, Tan GS, Lim L, Htoon HM. Comparison of keratometric and pachymetric parameters with Scheimpflug imaging in normal and keratoconic Asian eyes. Clin Ophthalmol. 2014;8:2215-20. doi: 10.2147/OPTH.S66598 pmid: 25419113
Ruisenor Vazquez PR, Galletti JD, Minguez N, Delrivo M, Fuentes Bonthoux F, Pfortner T, et al. Pentacam Scheimpflug tomography findings in topographically normal patients and subclinical keratoconus cases. Am J Ophthalmol. 2014;158:32-40 e2. doi: 10.1016/j.ajo.2014.03.018 pmid: 24709808
Wahba SS, Roshdy MM, Elkitkat RS, Naguib KM. Rotating Scheimpflug Imaging Indices in Different Grades of Keratoconus. J Ophthalmol. 2016;2016:6392472. doi: 10.1155/2016/6392472 pmid: 27579178
Ambrosio R, Jr., Caiado AL, Guerra FP, Louzada R, Sinha RA, Luz A, et al. Novel pachymetric parameters based on corneal tomography for diagnosing keratoconus. J Refract Surg. 2011;27:753-8. doi: 10.3928/1081597X-20110721-01 pmid: 21800785
Ferreira-Mendes J, Lopes BT, Faria-Correia F, Salomao MQ, Rodrigues-Barros S, Ambrosio R, Jr. Enhanced Ectasia Detection Using Corneal Tomography and Biomechanics. Am J Ophthalmol. 2019;197:7-16. doi: 10.1016/j.ajo.2018.08.054 pmid: 30201341
Ahmadi Hosseini SM, Abolbashari F, Niyazmand H, Sedaghat MR. Efficacy of corneal tomography parameters and biomechanical characteristic in keratoconus detection. Cont Lens Anterior Eye. 2014;37:26-30. doi: 10.1016/j.clae.2013.07.007 pmid: 23910506
Demir S, Ortak H, Yeter V, Alim S, Sayn O, Tas U, et al. Mapping corneal thickness using dual-scheimpflug imaging at different stages of keratoconus. Cornea. 2013;32:1470-4. doi: 10.1097/ICO.0b013e3182a7387f pmid: 24071809
Reddy JC, Rapuano CJ, Cater JR, Suri K, Nagra PK, Hammersmith KM. Comparative evaluation of dual Scheimpflug imaging parameters in keratoconus, early keratoconus, and normal eyes. J Cataract Refract Surg. 2014;40:582-92. doi: 10.1016/j.jcrs.2013.08.061 pmid: 24680519
Toprak I, Yaylali V, Yildirim C. A combination of topographic and pachymetric parameters in keratoconus diagnosis. Cont Lens Anterior Eye. 2015;38:357-62. doi: 10.1016/j.clae.2015.04.001 pmid: 25936634
Ahmadi Hosseini SM, Mohidin N, Abolbashari F, Mohd-Ali B, Santhirathelagan CT. Corneal thickness and volume in subclinical and clinical keratoconus. Int Ophthalmol. 2013;33:139-45. doi: 10.1007/s10792-012-9654-x pmid: 23138667
Dienes L, Kranitz K, Juhasz E, Gyenes A, Takacs A, Mihaltz K, et al. Evaluation of intereye corneal asymmetry in patients with keratoconus. A scheimpflug imaging study. PLoS One. 2014;9:e108882. doi: 10.1371/journal.pone.0108882 pmid: 25296183
Shetty R, Nuijts RM, Srivatsa P, Jayadev C, Pahuja N, Akkali MC, et al. Understanding the Correlation between Tomographic and Biomechanical Severity of Keratoconic Corneas. Biomed Res Int. 2015;2015:294197. doi: 10.1155/2015/294197 pmid: 25945330
Labiris G, Giarmoukakis A, Gatzioufas Z, Sideroudi H, Kozobolis V, Seitz B. Diagnostic capacity of the keratoconus match index and keratoconus match probability in subclinical keratoconus. J Cataract Refract Surg. 2014;40:999-1005. doi: 10.1016/j.jcrs.2013.08.064 pmid: 24713585
Montalban R, Alio JL, Javaloy J, Pinero DP. Comparative analysis of the relationship between anterior and posterior corneal shape analyzed by Scheimpflug photography in normal and keratoconus eyes. Graefes Arch Clin Exp Ophthalmol. 2013;251:1547-55. doi: 10.1007/s00417-013-2261-3 pmid: 23334367
Steinberg J, Aubke-Schultz S, Frings A, Hulle J, Druchkiv V, Richard G, et al. Correlation of the KISA% index and Scheimpflug tomography in 'normal', 'subclinical', 'keratoconus-suspect' and 'clinically manifest' keratoconus eyes. Acta Ophthalmol. 2015;93:e199-207. doi: 10.1111/aos.12590 pmid: 25873278
Cui J, Zhang X, Hu Q, Zhou WY, Yang F. Evaluation of Corneal Thickness and Volume Parameters of Subclinical Keratoconus Using a Pentacam Scheimflug System. Curr Eye Res. 2016;41:923-6. doi: 10.3109/02713683.2015.1082188 pmid: 26605668
Ishii R, Kamiya K, Igarashi A, Shimizu K, Utsumi Y, Kumanomido T. Correlation of corneal elevation with severity of keratoconus by means of anterior and posterior topographic analysis. Cornea. 2012;31:253-8. doi: 10.1097/ICO.0B013E31823D1EE0 pmid: 22316650
Kovacs I, Mihaltz K, Ecsedy M, Nemeth J, Nagy ZZ. The role of reference body selection in calculating posterior corneal elevation and prediction of keratoconus using rotating Scheimpflug camera. Acta Ophthalmol. 2011;89:e251-6. doi: 10.1111/j.1755-3768.2010.02053.x pmid: 21106048
Mohammadi SF, Mohammadzadeh V, Kadivar S, Beheshtnejad AH, Norooznezhad AH, Hashemi SH. Topographic typology in a consecutive series of refractive surgery candidates. Int Ophthalmol. 2018;38:1611-9. doi: 10.1007/s10792-017-0631-2 pmid: 28676992
Lopes BT, Ramos IC, Dawson DG, Belin MW, Ambrosio R, Jr. Detection of ectatic corneal diseases based on pentacam. Z Med Phys. 2016;26:136-42. doi: 10.1016/j.zemedi.2015.11.001 pmid: 26777318
Belin MW, Khachikian SS. An introduction to understanding elevation-based topography: how elevation data are displayed - a review. Clin Exp Ophthalmol. 2009;37:14-29. doi: 10.1111/j.1442-9071.2008.01821.x pmid: 19016811
Orucoglu F, Toker E. A Novel scoring system for distinguishing keratoconus from normal eyes. Cont Lens Anterior Eye. 2016;39:369-74. doi: 10.1016/j.clae.2016.07.002 pmid: 27478053
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. Clin Ophthalmol. 2013;7:1539-48. doi: 10.2147/OPTH.S44741 pmid: 23935360
Arbelaez MC, Versaci F, Vestri G, Barboni P, Savini G. Use of a support vector machine for keratoconus and subclinical keratoconus detection by topographic and tomographic data. Ophthalmology. 2012;119:2231-8. doi: 10.1016/j.ophtha.2012.06.005 pmid: 22892148
Quisling S, Sjoberg S, Zimmerman B, Goins K, Sutphin J. Comparison of Pentacam and Orbscan IIz on posterior curvature topography measurements in keratoconus eyes. Ophthalmology. 2006;113:1629-32. doi: 10.1016/j.ophtha.2006.03.046 pmid: 16949447
Reinstein DZ, Archer TJ, Urs R, Gobbe M, RoyChoudhury A, Silverman RH. Detection of Keratoconus in Clinically and Algorithmically Topographically Normal Fellow Eyes Using Epithelial Thickness Analysis. J Refract Surg. 2015;31:736-44. doi: 10.3928/1081597X-20151021-02 pmid: 26544561
Schlegel Z, Hoang-Xuan T, Gatinel D. Comparison of and correlation between anterior and posterior corneal elevation maps in normal eyes and keratoconus-suspect eyes. J Cataract Refract Surg. 2008;34:789-95. doi: 10.1016/j.jcrs.2007.12.036 pmid: 18471634
Tomidokoro A, Oshika T, Amano S, Higaki S, Maeda N, Miyata K. Changes in anterior and posterior corneal curvatures in keratoconus. Ophthalmology. 2000;107:1328-32. doi: 10.1016/s0161-6420(00)00159-7 pmid: 10889107
Nilforoushan MR, Speaker M, Marmor M, Abramson J, Tullo W, Morschauser D, et al. Comparative evaluation of refractive surgery candidates with Placido topography, Orbscan II, Pentacam, and wavefront analysis. J Cataract Refract Surg. 2008;34:623-31. doi: 10.1016/j.jcrs.2007.11.054 pmid: 18361985
Labiris G, Giarmoukakis A, Koutras A, Chrysochou T, Sideroudi H, Kozobolis VP. Clinical usefulness of best-fit toric ellipsoid reference body in ectatic and crosslinked corneas. J Cataract Refract Surg. 2015;41:889-91. doi: 10.1016/j.jcrs.2014.11.042 pmid: 25840310
Labiris G, Giarmoukakis A, Rampotas A, Symeou M, Bougatsou P, Sideroudi H, et al. Variability of different reference bodies in normal, keratoconus, and collagen crosslinked corneas. Eur J Ophthalmol. 2015;25:468-73. doi: 10.5301/ejo.5000621 pmid: 26044373
de Sanctis U, Aragno V, Dalmasso P, Brusasco L, Grignolo F. Diagnosis of subclinical keratoconus using posterior elevation measured with 2 different methods. Cornea. 2013;32:911-5. doi: 10.1097/ICO.0b013e3182854774 pmid: 23572130
Saad A, Gatinel D. Topographic and tomographic properties of forme fruste keratoconus corneas. Invest Ophthalmol Vis Sci. 2010;51:5546-55. doi: 10.1167/iovs.10-5369 pmid: 20554609
Alio JL, Pinero DP, Aleson A, Teus MA, Barraquer RI, Murta J, et al. Keratoconus-integrated characterization considering anterior corneal aberrations, internal astigmatism, and corneal biomechanics. J Cataract Refract Surg. 2011;37:552-68. doi: 10.1016/j.jcrs.2010.10.046 pmid: 21333878
Li Y, Meisler DM, Tang M, Lu AT, Thakrar V, Reiser BJ, et al. Keratoconus diagnosis with optical coherence tomography pachymetry mapping. Ophthalmology. 2008;115:2159-66. doi: 10.1016/j.ophtha.2008.08.004 pmid: 18977536
Martinez-Abad A, Pinero DP. New perspectives on the detection and progression of keratoconus. J Cataract Refract Surg. 2017;43:1213-27. doi: 10.1016/j.jcrs.2017.07.021 pmid: 28991620
Belin MW, Duncan JK. Keratoconus: The ABCD Grading System. Klin Monbl Augenheilkd. 2016;233:701-7. doi: 10.1055/s-0042-100626 pmid: 26789119
Duncan J, Gomes JAP. A new Tomographic Method of Staging/Classifying Keratoconus: The ABCD Grading System. International Journal of Keratoconus and Ectatic Corneal Diseases. 2015;4:85-93. doi: 10.5005/jp-journals-10025-1105
Sedaghat MR, Momeni-Moghaddam H, Belin MW, Akbarzadeh R, Sakhaee M, Armanfar F, et al. Anatomical and Visual Effects of the MyoRing Implantation Measured by the ABCD Keratoconus Grading System. Eye Contact Lens. 2019. doi: 10.1097/ICL.0000000000000595 pmid: 30913096
Sedaghat MR, Momeni-Moghaddam H, Belin MW, Zarei-Ghanavati S, Akbarzadeh R, Sabzi F, et al. Changes in the ABCD Keratoconus Grade After Intracorneal Ring Segment Implantation. Cornea. 2018;37:1431-7. doi: 10.1097/ICO.0000000000001648 pmid: 29863546
Imbornoni LM, Padmanabhan P, Belin MW, Deepa M. Long-Term Tomographic Evaluation of Unilateral Keratoconus. Cornea. 2017;36:1316-24. doi: 10.1097/ICO.0000000000001295 pmid: 28742621
Ambrosio R, Jr., Nogueira LP, Caldas DL, Fontes BM, Luz A, Cazal JO, et al. Evaluation of corneal shape and biomechanics before LASIK. Int Ophthalmol Clin. 2011;51:11-38. doi: 10.1097/IIO.0b013e31820f1d2d pmid: 21383577
Villavicencio OF, Gilani F, Henriquez MA, Izquierdo L, Ambrósio RR. Independent Population Validation of the Belin/Ambrósio Enhanced Ectasia Display: Implications for Keratoconus Studies and Screening. International Journal of Keratoconus and Ectatic Corneal Diseases. 2014;3:1-8. doi: 10.5005/jp-journals-10025-1069
Ambrósio Jr R, Ramos I, Lopes B, Canedo ALC, Correa R, Guerra F, et al. Assessing ectasia susceptibility prior to LASIK: the role of age and residual stromal bed (RSB) in conjunction to Belin-Ambrósio deviation index (BAD-D). Revista Brasileira de Oftalmologia. 2014;73. doi: 10.5935/0034-7280.20140018
Parafita M, Yebra-Pimentel E, Giraldez MaJ, González-Pérez J, érez-MartıÌn MaVP, González-Meijome J. Further information on the knowledge of topographical corneal thickness. International Contact Lens Clinic. 1999;26:128-37. doi: 10.1016/s0892-8967(00)00037-7
Price FW, Koller DL, Price MO. Central corneal pachymetry in patients undergoing laser in situ keratomileusis11The authors have no proprietary or financial interest in any product mentioned in this article. Ophthalmology. 1999;106:2216-20. doi: 10.1016/s0161-6420(99)90508-0
Rapuano CJ, Fishbaugh JA, Strike DJ. Nine point corneal thickness measurements and keratometry readings in normal corneas using ultrasound pachymetry. Insight. 1993;18:16-22. pmid: 8301187
Ucakhan OO, Ozkan M, Kanpolat A. Corneal thickness measurements in normal and keratoconic eyes: Pentacam comprehensive eye scanner versus noncontact specular microscopy and ultrasound pachymetry. J Cataract Refract Surg. 2006;32:970-7. doi: 10.1016/j.jcrs.2006.02.037 pmid: 16814055
Ambrosio R, Jr., Alonso RS, Luz A, Coca Velarde LG. Corneal-thickness spatial profile and corneal-volume distribution: tomographic indices to detect keratoconus. J Cataract Refract Surg. 2006;32:1851-9. doi: 10.1016/j.jcrs.2006.06.025 pmid: 17081868
Shildkrot Y, Liebmann JM, Fabijanczyk B, Tello CA, Ritch R. Central corneal thickness measurement in clinical practice. J Glaucoma. 2005;14:331-6. doi: 10.1097/01.ijg.0000176929.83734.b4 pmid: 16148579
Wickham L, Edmunds B, Murdoch IE. Central corneal thickness: will one measurement suffice? Ophthalmology. 2005;112:225-8. doi: 10.1016/j.ophtha.2004.08.020 pmid: 15691555
Guarnieri FA. Corneal Biomechanics. In: Guarnieri FA, editor. Corneal Biomechanics and Refractive Surgery. New Yourk: Springer; 2015. p. 7-31.
Kling S, Hafezi F. Corneal biomechanics - a review. Ophthalmic Physiol Opt. 2017;37:240-52. doi: 10.1111/opo.12345 pmid: 28125860
Luce DA. Determining in vivo biomechanical properties of the cornea with an ocular response analyzer. J Cataract Refract Surg. 2005;31:156-62. doi: 10.1016/j.jcrs.2004.10.044 pmid: 15721708
Roberts CJ, Dupps WJ, Jr. Biomechanics of corneal ectasia and biomechanical treatments. J Cataract Refract Surg. 2014;40:991-8. doi: 10.1016/j.jcrs.2014.04.013 pmid: 24774009
Gokhale NS. Epidemiology of keratoconus. Indian J Ophthalmol. 2013;61:382-3. doi: 10.4103/0301-4738.116054 pmid: 23925318
Gordon-Shaag A, Millodot M, Shneor E, Liu Y. The genetic and environmental factors for keratoconus. Biomed Res Int. 2015;2015:795738. doi: 10.1155/2015/795738 pmid: 26075261
Kok YO, Tan GF, Loon SC. Review: keratoconus in Asia. Cornea. 2012;31:581-93. doi: 10.1097/ICO.0b013e31820cd61d pmid: 22314815
Owens H, Gamble G. A profile of keratoconus in New Zealand. Cornea. 2003;22:122-5. doi: 10.1097/00003226-200303000-00008 pmid: 12605045
Ziaei H, Jafarinasab MR, Javadi MA, Karimian F, Poorsalman H, Mahdavi M, et al. Epidemiology of keratoconus in an Iranian population. Cornea. 2012;31:1044-7. doi: 10.1097/ICO.0b013e31823f8d3c pmid: 22710491
McMonnies CW. Screening for keratoconus suspects among candidates for refractive surgery. Clin Exp Optom. 2014;97:492-8. doi: 10.1111/cxo.12169 pmid: 25331075
Belin MW, Khachikian SS. New devices and clinical implications for measuring corneal thickness. Clin Exp Ophthalmol. 2006;34:729-31. doi: 10.1111/j.1442-9071.2006.01395.x pmid: 17073893
Feng MT, Belin MW, Ambrosio R, Jr., Grewal SP, Yan W, Shaheen MS, et al. International values of corneal elevation in normal subjects by rotating Scheimpflug camera. J Cataract Refract Surg. 2011;37:1817-21. doi: 10.1016/j.jcrs.2011.04.030 pmid: 21840680
Feng MT, Belin MW, Ambrosio R, Jr., Grewal SP, Yan W, Shaheen MS, et al. Anterior chamber depth in normal subjects by rotating scheimpflug imaging. Saudi J Ophthalmol. 2011;25:255-9. doi: 10.1016/j.sjopt.2011.04.005 pmid: 23960933
Gilani F, Cortese M, Ambrosio RR, Jr., Lopes B, Ramos I, Harvey EM, et al. Comprehensive anterior segment normal values generated by rotating Scheimpflug tomography. J Cataract Refract Surg. 2013;39:1707-12. doi: 10.1016/j.jcrs.2013.05.042 pmid: 24054966
Khachikian SS, Belin MW, Ciolino JB. Intrasubject corneal thickness asymmetry. J Refract Surg. 2008;24:606-9. doi: 10.3928/1081597X-20080601-09 pmid: 18581786
T. Kim J, Cortese M, W. Belin M, Ambrosio Jr R, S. Khachikian S. Tomographic Normal Values for Corneal Elevation and Pachymetry in a Hyperopic Population. Journal of Clinical & Experimental Ophthalmology. 2011;02:1-4. doi: 10.4172/2155-9570.1000130
Mirzajani A, Asharlous A, Kianpoor P, Jafarzadehpur E, Yekta A, Khabazkhoob M, et al. Repeatability of curvature measurements in central and paracentral corneal areas of keratoconus patients using Orbscan and Pentacam. Journal of Current Ophthalmology. 2019;In press:1-5.
Sinjab MM. Classifi cations and Patterns of Keratoconus and Keratectasia. In: Sinjab MM, editor. Quick Guide to the Management of Keratoconus. Berlin, Heidelberg: Springer Berlin Heidelberg; 2012. p. 13-58.
Hidalgo I, Rozema J, Saad A, Gatinel D, Rodriguez P, Zakaria N, et al. Validation of an Objective Keratoconus Detection System Implemented in a Scheimpflug Tomographer and Comparison With Other Methods. Cornea. 2017;36:689-95. doi: 10.1097/ICO.0000000000001194 pmid: 28368992
Silverman RH, Urs R, Roychoudhury A, Archer TJ, Gobbe M, Reinstein DZ. Epithelial remodeling as basis for machine-based identification of keratoconus. Invest Ophthalmol Vis Sci. 2014;55:1580-7. doi: 10.1167/iovs.13-12578 pmid: 24557351
Martinez-Abad A, Pinero DP, Chorro E, Bataille L, Alio JL. Development of a Reference Model for Keratoconus Progression Prediction Based on Characterization of the Course of Nonsurgically Treated Cases. Cornea. 2018;37:1497-505. doi: 10.1097/ICO.0000000000001673 pmid: 29923863
Santhiago MR, Giacomin NT, Smadja D, Bechara SJ. Ectasia risk factors in refractive surgery. Clin Ophthalmol. 2016;10:713-20. doi: 10.2147/OPTH.S51313 pmid: 27143849
Roshdy MMS, Wahba SS, Elkitkat RS, Hakim AM, Fikry RR. Effect of Age on Pentacam Keratoconus Indices. J Ophthalmol. 2018;2018:2016564. doi: 10.1155/2018/2016564 pmid: 29850200
Gencer B, Ozgurhan EB, Kara S, Tufan HA, Arikan S, Bozkurt E, et al. Obesity and obstructive sleep apnea in patients with keratoconus in a Turkish population. Cornea. 2014;33:137-40.
Kristinsson J, Carlson A, Kim T. Keratoconus and Obesity-A Connection? Investigative Ophthalmology & Visual Science. 2003;44:812-.
Pihlblad MS, Schaefer DP. Eyelid laxity, obesity, and obstructive sleep apnea in keratoconus. Cornea. 2013;32:1232-6. doi: 10.1097/ICO.0b013e318281e755 pmid: 23471083
Slater JA, Misra SL, Braatvedt G, McGhee CN. Keratoconus and obesity: can high body mass alter the shape of the cornea? Clin Exp Ophthalmol. 2018;46:1091-3. doi: 10.1111/ceo.13320 pmid: 29781198
West SD, Turnbull C. Eye disorders associated with obstructive sleep apnoea. Curr Opin Pulm Med. 2016;22:595-601. doi: 10.1097/MCP.0000000000000322 pmid: 27635626
Gupta PK, Stinnett SS, Carlson AN. Prevalence of sleep apnea in patients with keratoconus. Cornea. 2012;31:595-9. doi: 10.1097/ICO.0b013e31823f8acd pmid: 22333661
Saidel MA, Paik JY, Garcia C, Russo P, Cao D, Bouchard C. Prevalence of sleep apnea syndrome and high-risk characteristics among keratoconus patients. Cornea. 2012;31:600-3. doi: 10.1097/ICO.0b013e318243e446 pmid: 22495032
Mojon DS, Goldblum D, Fleischhauer J, Chiou AG, Frueh BE, Hess CW, et al. Eyelid, conjunctival, and corneal findings in sleep apnea syndrome. Ophthalmology. 1999;106:1182-5. doi: 10.1016/S0161-6420(99)90256-7 pmid: 10366090
Culbertson WW, Tseng SC. Corneal disorders in floppy eyelid syndrome. Cornea. 1994;13:33-42. doi: 10.1097/00003226-199401000-00007 pmid: 8131404
Donnenfeld ED, Perry HD, Gibralter RP, Ingraham HJ, Udell IJ. Keratoconus associated with floppy eyelid syndrome. Ophthalmology. 1991;98:1674-8. doi: 10.1016/s0161-6420(91)32070-0 pmid: 1800928
Davidson AE, Hayes S, Hardcastle AJ, Tuft SJ. The pathogenesis of keratoconus. Eye (Lond). 2014;28:189-95. doi: 10.1038/eye.2013.278 pmid: 24357835
McMonnies CW. Abnormal rubbing and keratectasia. Eye Contact Lens. 2007;33:265-71. doi: 10.1097/ICL.0b013e31814fb64b pmid: 17993819
Meek KM, Tuft SJ, Huang Y, Gill PS, Hayes S, Newton RH, et al. Changes in collagen orientation and distribution in keratoconus corneas. Invest Ophthalmol Vis Sci. 2005;46:1948-56. doi: 10.1167/iovs.04-1253 pmid: 15914608
Seiler T, Koufala K, Richter G. Iatrogenic keratectasia after laser in situ keratomileusis. J Refract Surg. 1998;14:312-7. pmid: 9641422
Ertan A, Muftuoglu O. Keratoconus clinical findings according to different age and gender groups. Cornea. 2008;27:1109-13. doi: 10.1097/ICO.0b013e31817f815a pmid: 19034122
Lim N, Vogt U. Characteristics and functional outcomes of 130 patients with keratoconus attending a specialist contact lens clinic. Eye (Lond). 2002;16:54-9. doi: 10.1038/sj.eye.6700061 pmid: 11913889
Naderan M, Shoar S, Kamaleddin MA, Rajabi MT, Naderan M, Khodadadi M. Keratoconus Clinical Findings According to Different Classifications. Cornea. 2015;34:1005-11. doi: 10.1097/ICO.0000000000000537 pmid: 26203749
Ramdas WD, Vervaet CJ, Bleyen I. Corneal topography for pancorneal toric edge rigid gas-permeable contact lens fitting in patients with keratoconus, and differences in age and gender. Cont Lens Anterior Eye. 2014;37:20-5. doi: 10.1016/j.clae.2013.07.005 pmid: 23953969
Naderan M, Shoar S, Rezagholizadeh F, Zolfaghari M, Naderan M. Characteristics and associations of keratoconus patients. Cont Lens Anterior Eye. 2015;38:199-205. doi: 10.1016/j.clae.2015.01.008 pmid: 25707930
Brancati F, Valente EM, Sarkozy A, Feher J, Castori M, Del Duca P, et al. A locus for autosomal dominant keratoconus maps to human chromosome 3p14-q13. J Med Genet. 2004;41:188-92. doi: 10.1136/jmg.2003.012872 pmid: 14985379
Burdon KP, Vincent AL. Insights into keratoconus from a genetic perspective. Clin Exp Optom. 2013;96:146-54. doi: 10.1111/cxo.12024 pmid: 23387289
Bykhovskaya Y, Li X, Epifantseva I, Haritunians T, Siscovick D, Aldave A, et al. Variation in the lysyl oxidase (LOX) gene is associated with keratoconus in family-based and case-control studies. Invest Ophthalmol Vis Sci. 2012;53:4152-7. doi: 10.1167/iovs.11-9268 pmid: 22661479
Bykhovskaya Y, Margines B, Rabinowitz YS. Genetics in Keratoconus: where are we? Eye Vis (Lond). 2016;3:16. doi: 10.1186/s40662-016-0047-5 pmid: 27350955
Hughes AE, Bradley DT, Campbell M, Lechner J, Dash DP, Simpson DA, et al. Mutation altering the miR-184 seed region causes familial keratoconus with cataract. Am J Hum Genet. 2011;89:628-33. doi: 10.1016/j.ajhg.2011.09.014 pmid: 21996275
Hughes AE, Dash DP, Jackson AJ, Frazer DG, Silvestri G. Familial keratoconus with cataract: linkage to the long arm of chromosome 15 and exclusion of candidate genes. Invest Ophthalmol Vis Sci. 2003;44:5063-6. doi: 10.1167/iovs.03-0399 pmid: 14638698
Levy D, Hutchings H, Rouland JF, Guell J, Burillon C, Arne JL, et al. Videokeratographic anomalies in familial keratoconus. Ophthalmology. 2004;111:867-74. doi: 10.1016/j.ophtha.2003.12.024 pmid: 15121361
Tang YG, Picornell Y, Su X, Li X, Yang H, Rabinowitz YS. Three VSX1 gene mutations, L159M, R166W, and H244R, are not associated with keratoconus. Cornea. 2008;27:189-92. doi: 10.1097/ICO.0b013e31815a50e7 pmid: 18216574
Tyynismaa H, Sistonen P, Tuupanen S, Tervo T, Dammert A, Latvala T, et al. A locus for autosomal dominant keratoconus: linkage to 16q22.3-q23.1 in Finnish families. Invest Ophthalmol Vis Sci. 2002;43:3160-4. pmid: 12356819
Udar N, Atilano SR, Brown DJ, Holguin B, Small K, Nesburn AB, et al. SOD1: a candidate gene for keratoconus. Invest Ophthalmol Vis Sci. 2006;47:3345-51. doi: 10.1167/iovs.05-1500 pmid: 16877401
Wang Y, Rabinowitz YS, Rotter JI, Yang H. Genetic epidemiological study of keratoconus: evidence for major gene determination. Am J Med Genet. 2000;93:403-9. pmid: 10951465
Udar N, Atilano SR, Small K, Nesburn AB, Kenney MC. SOD1 haplotypes in familial keratoconus. Cornea. 2009;28:902-7. doi: 10.1097/ICO.0b013e3181983a0c pmid: 19654524
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