Epithelial, stromal, and total corneal thickness in keratoconus: three-dimensional display with artemis very-high frequency digital ultrasound.

PURPOSE To characterize the epithelial, stromal, and total corneal thickness profile in a population of eyes with keratoconus. METHODS Epithelial, stromal, and total corneal thickness profiles were measured in vivo by Artemis very high-frequency (VHF) digital ultrasound scanning (ArcScan) across the central 6- to 10-mm diameter of the cornea on 54 keratoconic eyes. Maps of the average, standard deviation, minimum, maximum, and range of epithelial, stromal, and total corneal thickness were plotted. The average location of the thinnest epithelium, stroma, and total cornea were found. The cross-sectional semi-meridional stromal and total corneal thickness profiles were calculated using annular averaging. The absolute stromal and total corneal thickness progressions relative to the thinnest point were calculated using annular averaging as well as for 8 semi-meridians individually. RESULTS The mean corneal vertex epithelial, stromal, and total corneal thicknesses were 45.7+/-5.9 microm, 426.4+/-38.5 microm, and 472.2+/-41.4 microm, respectively. The average epithelial thickness profile showed an epithelial doughnut pattern characterized by localized central thinning surrounded by an annulus of thick epithelium. The thinnest epithelium, stroma, and total cornea were displaced on average by 0.48+/-0.66 mm temporally and 0.32+/-0.67 mm inferiorly, 0.31+/-0.45 mm temporally and 0.54+/-0.37 mm inferiorly, and 0.31+/-0.43 mm temporally and 0.50+/-0.35 mm inferiorly, respectively, with reference to the corneal vertex. The increase in semi-meridional absolute stromal and total corneal thickness progressions was greatest inferiorly and lowest temporally. CONCLUSIONS Three-dimensional thickness mapping of the epithelial, stromal, and total corneal thickness profiles characterized thickness changes associated with keratoconus and may help in early diagnosis of keratoconus.

[1]  R. Silverman,et al.  Arc-scanning very high-frequency digital ultrasound for 3D pachymetric mapping of the corneal epithelium and stroma in laser in situ keratomileusis. , 2000, Journal of refractive surgery.

[2]  M. Sargon,et al.  Ultrastructure of the cornea epithelium in keratoconus. , 1998, Okajimas folia anatomica Japonica.

[3]  T. Avitabile,et al.  Keratoconus Staging: A Computer-Assisted Ultrabiomicroscopic Method Compared With Videokeratographic Analysis , 2004, Cornea.

[4]  Lyndon Jones,et al.  Corneal and epithelial thickness in keratoconus: a comparison of ultrasonic pachymetry, Orbscan II, and optical coherence tomography. , 2006, Journal of refractive surgery.

[5]  O. Yılmaz,et al.  Evaluation of the Corneal Topographic Characteristics of Keratoconus With Orbscan II in Patients With and Without Atopy , 2007, Cornea.

[6]  D. Reinstein,et al.  Epithelial and stromal changes induced by intacs examined by three-dimensional very high-frequency digital ultrasound. , 2001, Journal of refractive surgery.

[7]  Carlo F. Lovisolo,et al.  Complications of Refractive Keratotomy , 2008 .

[8]  T. Avitabile,et al.  Evaluation of central and peripheral corneal thickness with ultrasound biomicroscopy in normal and keratoconic eyes. , 1997, Cornea.

[9]  R. Silverman,et al.  Very high-frequency ultrasound corneal analysis identifies anatomic correlates of optical complications of lamellar refractive surgery: anatomic diagnosis in lamellar surgery. , 1999, Ophthalmology.

[10]  S. Hosking,et al.  Corneal pachymetry in normal and keratoconic eyes: Orbscan II versus ultrasound , 2004, Journal of cataract and refractive surgery.

[11]  G. Auffarth,et al.  Keratoconus evaluation using the Orbscan Topography System. , 2000, Journal of cataract and refractive surgery.

[12]  Renato Ambrósio,et al.  [Corneal thickness progression from the thinnest point to the limbus: study based on a normal and a keratoconus population to create reference values]. , 2006, Arquivos brasileiros de oftalmologia.

[13]  Ronald H Silverman,et al.  Stromal thickness in the normal cornea: three-dimensional display with artemis very high-frequency digital ultrasound. , 2009, Journal of refractive surgery.

[14]  S. Gromacki,et al.  Central and Peripheral Corneal Thickness in Keratoconus and Normal Patient Groups , 1994, Optometry and vision science : official publication of the American Academy of Optometry.

[15]  Renato Ambrósio,et al.  Progressão da espessura corneana do ponto mais fino em direção ao limbo: estudo de uma população normal e de portadores de ceratocone para criação de valores de referência , 2006 .

[16]  R. Mandell,et al.  Keratoconus: spatial variation of corneal thickenss as a diagnostic test. , 1969, Archives of ophthalmology.

[17]  A. Proia,et al.  Histopathological Variation in Keratoconus , 1992, Cornea.

[18]  S. Yoloğlu,et al.  Evaluation of anterior segment parameters in keratoconic eyes measured with the Pentacam system , 2007, Journal of cataract and refractive surgery.

[19]  T. Avitabile,et al.  Keratoconus Staging with Ultrasound Biomicroscopy , 1998, Ophthalmologica.

[20]  S. Tuft,et al.  A study of corneal thickness, shape and collagen organisation in keratoconus using videokeratography and X-ray scattering techniques. , 2007, Experimental eye research.

[21]  T. Oshika,et al.  Central Corneal Thickness Measurements Using Orbscan II Scanning Slit Topography, Noncontact Specular Microscopy, and Ultrasonic Pachymetry in Eyes With Keratoconus , 2005, Cornea.

[22]  Ronald H Silverman,et al.  Epithelial thickness profile changes induced by myopic LASIK as measured by Artemis very high-frequency digital ultrasound. , 2009, Journal of refractive surgery.

[23]  L. Jones,et al.  Corneal and Epithelial Thickness Changes After 4 Weeks of Overnight Corneal Refractive Therapy Lens Wear, Measured With Optical Coherence Tomography , 2004, Eye & contact lens.

[24]  Marine Gobbe,et al.  Corneal epithelial thickness profile in the diagnosis of keratoconus. , 2009, Journal of refractive surgery.

[25]  T. Seiler,et al.  [Treatment of keratoconus by collagen cross linking]. , 2003, Der Ophthalmologe : Zeitschrift der Deutschen Ophthalmologischen Gesellschaft.

[26]  L. Richiardi,et al.  Reproducibility and repeatability of central corneal thickness measurement in keratoconus using the rotating Scheimpflug camera and ultrasound pachymetry. , 2007, American journal of ophthalmology.

[27]  D J Coleman,et al.  Corneal pachymetric topography. , 1994, Ophthalmology.

[28]  D. Lam,et al.  Repeatability and reproducibility of pachymetric mapping with Visante anterior segment-optical coherence tomography. , 2007, Investigative ophthalmology & visual science.

[29]  R. Silverman,et al.  High-frequency ultrasound measurement of the thickness of the corneal epithelium. , 1993, Refractive & corneal surgery.

[30]  D. Reinstein,et al.  Artemis very high-frequency digital ultrasound-guided repositioning of a free cap after laser in situ keratomileusis. , 2006, Journal of cataract and refractive surgery.

[31]  D. Reinstein,et al.  Combined Artemis very high-frequency digital ultrasound-assisted transepithelial phototherapeutic keratectomy and wavefront-guided treatment following multiple corneal refractive procedures. , 2006, Journal of cataract and refractive surgery.

[32]  H. Owens,et al.  An evaluation of the keratoconic cornea using computerised corneal mapping and ultrasonic measurements of corneal thickness. , 1996, Ophthalmic & physiological optics : the journal of the British College of Ophthalmic Opticians.

[33]  R. Silverman,et al.  Epithelial thickness in the normal cornea: three-dimensional display with Artemis very high-frequency digital ultrasound. , 2008, Journal of refractive surgery.

[34]  Allan Luz,et al.  Corneal‐thickness spatial profile and corneal‐volume distribution: Tomographic indices to detect keratoconus , 2006, Journal of cataract and refractive surgery.

[35]  Ronald H. Silverman,et al.  Epithelial Thickness in the Normal Cornea: Three-dimensional Display With Very High Frequency Ultrasound , 2008 .