Corneal topography with Scheimpflug imaging and videokeratography: Comparative study of normal eyes

PURPOSE: To compare the repeatability within anterior corneal topography measurements and agreement between measurements with the Pentacam HR rotating Scheimpflug camera and with a previously validated Placido disk–based videokeratoscope (Medmont E300). SETTING: Contact Lens and Visual Optics Laboratory, School of Optometry, Queensland University of Technology, Brisbane, Queensland, Australia. METHODS: Normal eyes in 101 young adult subjects had corneal topography measured using the Scheimpflug camera (6 repeated measurements) and videokeratoscope (4 repeated measurements). The best‐fitting axial power corneal spherocylinder was calculated and converted into power vectors. Corneal higher‐order aberrations (HOAs) (up to the 8th Zernike order) were calculated using the corneal elevation data from each instrument. RESULTS: Both instruments showed excellent repeatability for axial power spherocylinder measurements (repeatability coefficients <0.25 diopter; intraclass correlation coefficients >0.9) and good agreement for all power vectors. Agreement between the 2 instruments was closest when the mean of multiple measurements was used in analysis. For corneal HOAs, both instruments showed reasonable repeatability for most aberration terms and good correlation and agreement for many aberrations (eg, spherical aberration, coma, higher‐order root mean square). For other aberrations (eg, trefoil and tetrafoil), the 2 instruments showed relatively poor agreement. CONCLUSIONS: For normal corneas, the Scheimpflug system showed excellent repeatability and reasonable agreement with a previously validated videokeratoscope for the anterior corneal axial curvature best‐fitting spherocylinder and several corneal HOAs. However, for certain aberrations with higher azimuthal frequencies, the Scheimpflug system had poor agreement with the videokeratoscope; thus, caution should be used when interpreting these corneal aberrations with the Scheimpflug system.

[1]  K. Pesudovs,et al.  Repeatability of corneal first‐surface wavefront aberrations measured with Pentacam corneal topography , 2008, Journal of cataract and refractive surgery.

[2]  Tobias Buehren,et al.  Influence of accommodation on the anterior and posterior cornea , 2007, Journal of cataract and refractive surgery.

[3]  Robert B. Mandell,et al.  A guide to videokeratography , 1996 .

[4]  C. McGhee,et al.  Orbscan computerized topography: Attributes, applications, and limitations , 2005, Journal of cataract and refractive surgery.

[5]  J. Coggins,et al.  Height measurement of astigmatic test surfaces by a keratoscope that uses plane geometry surface reconstruction. , 1996, American journal of ophthalmology.

[6]  Y. Gerber,et al.  Comparison of different techniques of anterior chamber depth and keratometric measurements. , 2007, American journal of ophthalmology.

[7]  Li Wang,et al.  Optical aberrations of the human anterior cornea , 2003, Journal of cataract and refractive surgery.

[8]  Ramin Khoramnia,et al.  Anterior chamber measurements using Pentacam rotating Scheimpflug camera , 2006, Journal of cataract and refractive surgery.

[9]  C. Maldonado-Codina,et al.  Agreement and Repeatability of Central Thickness Measurement in Normal Corneas Using Ultrasound Pachymetry and the OCULUS Pentacam , 2005, Cornea.

[10]  Yoshimichi Tanida,et al.  On Founding the Journal of Visualization , 1998 .

[11]  M. Collins,et al.  Corneal optics after reading, microscopy and computer work. , 2005, Acta ophthalmologica Scandinavica.

[12]  G. Auffarth,et al.  Reliability of corneal and total wavefront aberration measurements with the SCHWIND Corneal and Ocular Wavefront Analyzers. , 2006, Journal of refractive surgery.

[13]  B. Meinhardt,et al.  Evaluation of biometric methods for measuring the anterior chamber depth in the non-contact mode , 2006, Graefe's Archive for Clinical and Experimental Ophthalmology.

[14]  J M Coggins,et al.  Assessment of radial aspheres by the Arc-step algorithm as implemented by the Keratron keratoscope. , 1995, American journal of ophthalmology.

[15]  H. Hashemi,et al.  Central corneal thickness measurement with Pentacam, Orbscan II, and ultrasound devices before and after laser refractive surgery for myopia , 2007, Journal of cataract and refractive surgery.

[16]  L. Módis,et al.  Anterior chamber depth measurements in phakic and pseudophakic eyes: Pentacam versus ultrasound device , 2006, Journal of cataract and refractive surgery.

[17]  P Simonet,et al.  The Julius F. Neumueller Award in Optics, 1989: change of pupil centration with change of illumination and pupil size. , 1992, Optometry and vision science : official publication of the American Academy of Optometry.

[18]  K. Pesudovs,et al.  Anterior segment biometry with the Pentacam: Comprehensive assessment of repeatability of automated measurements , 2008, Journal of cataract and refractive surgery.

[19]  P. Artal,et al.  Compensation of corneal aberrations by the internal optics in the human eye. , 2001, Journal of vision.

[20]  L. Thibos,et al.  Power Vectors: An Application of Fourier Analysis to the Description and Statistical Analysis of Refractive Error , 1997, Optometry and vision science : official publication of the American Academy of Optometry.

[21]  Pauline Cho,et al.  The Performance of Four Different Corneal Topographers on Normal Human Corneas and Its Impact on Orthokeratology Lens Fitting , 2002, Optometry and vision science : official publication of the American Academy of Optometry.

[22]  R. Maloney,et al.  Determination of corneal image-forming properties from corneal topography. , 1993, American journal of ophthalmology.

[23]  Stephen A Burns,et al.  Pupil location under mesopic, photopic, and pharmacologically dilated conditions. , 2002, Investigative ophthalmology & visual science.

[24]  S. Pushpoth,et al.  Comparability and intra-/interobserver reliability of anterior chamber depth measurements with the Pentacam and IOLMaster. , 2008, Journal of refractive surgery.

[25]  K. Miyata,et al.  Comparison of central corneal thickness measurements by rotating Scheimpflug camera, ultrasonic pachymetry, and scanning-slit corneal topography. , 2006, Ophthalmology.

[26]  L. Thibos,et al.  Standards for reporting the optical aberrations of eyes. , 2002, Journal of refractive surgery.

[27]  W. Drexler,et al.  Comparison of three methods of measuring corneal thickness and anterior chamber depth. , 2006, American journal of ophthalmology.

[28]  L. Carney,et al.  Corneal Aberrations and Reading , 2003, Optometry and vision science : official publication of the American Academy of Optometry.

[29]  S. Naufal,et al.  Rasterstereography‐based classification of normal corneas , 1997, Journal of cataract and refractive surgery.

[30]  B. Lackner,et al.  Validity and Repeatability of Anterior Chamber Depth Measurements With Pentacam and Orbscan , 2005, Optometry and vision science : official publication of the American Academy of Optometry.

[31]  G Walsh.  The effect of mydriasis on the pupillary centration of the human eye , 1988, Ophthalmic & physiological optics : the journal of the British College of Ophthalmic Opticians.

[32]  W Tang,et al.  The Accuracy and Precision Performance of Four Videokeratoscopes in Measuring Test Surfaces , 2000, Optometry and vision science : official publication of the American Academy of Optometry.

[33]  Toshifumi Mihashi,et al.  Compensation of corneal horizontal/vertical astigmatism, lateral coma, and spherical aberration by internal optics of the eye. , 2004, Journal of vision.

[34]  P. Artal,et al.  Corneal wave aberration from videokeratography: accuracy and limitations of the procedure. , 2000, Journal of the Optical Society of America. A, Optics, image science, and vision.

[35]  D. Altman,et al.  Measuring agreement in method comparison studies , 1999, Statistical methods in medical research.

[36]  David Zadok,et al.  Central corneal thickness measurement with the Pentacam Scheimpflug system, optical low‐coherence reflectometry pachymeter, and ultrasound pachymetry , 2005, Journal of cataract and refractive surgery.

[38]  Ö. Uçakhan,et al.  Corneal thickness measurements in normal and keratoconic eyes: Pentacam comprehensive eye scanner versus noncontact specular microscopy and ultrasound pachymetry , 2006, Journal of cataract and refractive surgery.

[39]  S. Pieh,et al.  Anterior Chamber Depth Measurement With A-Scan Ultrasonography, Orbscan II, and IOLMaster , 2005, Optometry and vision science : official publication of the American Academy of Optometry.

[40]  A. Lam,et al.  Intrasession and intersession repeatability of the Pentacam system on posterior corneal assessment in the normal human eye , 2007, Journal of cataract and refractive surgery.

[41]  R. Khoramnia,et al.  Central and peripheral pachymetry measurements according to age using the Pentacam rotating Scheimpflug camera , 2007, Journal of cataract and refractive surgery.