TY - JOUR
T1 - Clinical Validation of Point-Source Corneal Topography in Keratoplasty
AU - Vrijling, A C L
AU - Braaf, B.
AU - Snellenburg, J.J.
AU - de Lange, F.
AU - Zaal, M.J.W.
AU - van der Heijde, G.L.
AU - Sicam, V.A.D.P.
PY - 2011
Y1 - 2011
N2 - Purpose. To validate the clinical performance of point-source corneal topography (PCT) in postpenetrating keratoplasty (PKP) eyes and to compare it with conventional Placido-based topography. Methods. Corneal elevation maps of the anterior corneal surface were obtained from 20 post-PKP corneas using PCT (VU topographer, prototype; VU University Medical Center, Amsterdam, The Netherlands) and Placido-based topography (Keratron, Optikon 2000, Rome, Italy). Corneal surface parameters are calculated in terms of radius and asphericity. Corneal aberrations were characterized using standard Zernike convention. An artificial surface with quadrafoil feature (SUMIPRO, Almelo, The Netherlands) was measured and used as a reference to assess instrument performance compared with the gold standard. Results. The differences (mean ± std of PCT - Placido) found between the two types of topographers in measurements of post-PKP eyes are 0.02 ± 0.21 mm (p = 0.64) for radius of curvature, 0.14 ± 0.49 (p = 0.23) for asphericity, -0.19 ± 1.67 μm (p = 0.61) for corneal astigmatism, -0.25 ± 1.34 μm (p = 0.41) for corneal coma, 0.23 ± 0.82 μm (p = 0.23) for corneal trefoil, and 0.15 ± 0.28 μm (p = 0.02) for corneal quadrafoil. The PCT measured the artificial surface more accurate (rms error 0.16 μm; 0.12 eq. Dpt.) than the Placido-based topographer (rms error 1.50 μm; 1.15 eq. Dpt.). Conclusions. PCT is more accurate than Placido-based topography in measuring quadrafoil aberration. Copyright © 2011 American Academy of Optometry.
AB - Purpose. To validate the clinical performance of point-source corneal topography (PCT) in postpenetrating keratoplasty (PKP) eyes and to compare it with conventional Placido-based topography. Methods. Corneal elevation maps of the anterior corneal surface were obtained from 20 post-PKP corneas using PCT (VU topographer, prototype; VU University Medical Center, Amsterdam, The Netherlands) and Placido-based topography (Keratron, Optikon 2000, Rome, Italy). Corneal surface parameters are calculated in terms of radius and asphericity. Corneal aberrations were characterized using standard Zernike convention. An artificial surface with quadrafoil feature (SUMIPRO, Almelo, The Netherlands) was measured and used as a reference to assess instrument performance compared with the gold standard. Results. The differences (mean ± std of PCT - Placido) found between the two types of topographers in measurements of post-PKP eyes are 0.02 ± 0.21 mm (p = 0.64) for radius of curvature, 0.14 ± 0.49 (p = 0.23) for asphericity, -0.19 ± 1.67 μm (p = 0.61) for corneal astigmatism, -0.25 ± 1.34 μm (p = 0.41) for corneal coma, 0.23 ± 0.82 μm (p = 0.23) for corneal trefoil, and 0.15 ± 0.28 μm (p = 0.02) for corneal quadrafoil. The PCT measured the artificial surface more accurate (rms error 0.16 μm; 0.12 eq. Dpt.) than the Placido-based topographer (rms error 1.50 μm; 1.15 eq. Dpt.). Conclusions. PCT is more accurate than Placido-based topography in measuring quadrafoil aberration. Copyright © 2011 American Academy of Optometry.
U2 - 10.1097/OPX.0b013e31821bbd68
DO - 10.1097/OPX.0b013e31821bbd68
M3 - Article
SN - 1040-5488
VL - 88
SP - 837
EP - 842
JO - Optometry and Vision Science
JF - Optometry and Vision Science
IS - 7
ER -