Abstract

A novel imaging keratometer by the aid of modern optoelectronic technology is proposed. The optical system consists of an annular object, a first imaging subsystem, a second imaging subsystem, and a CCD detector. The measurement range of corneal refraction is from 30D to 60D (5.5–11 mm in radius of curvature), and the accuracy reaches 0.156D, 0.072D, and 0.036D, respectively, for the corneal surface of the steepest, the radius of curvature of 7.8 mm, and the corneal surface of the flattest. The accuracy of corneal astigmatism is verified to be 0.05D for cylindrical refraction of 0.75D. Compared with the traditional keratometer, the proposed keratometer possesses advantages of high accuracy.

© 2013 Optical Society of America

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References

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    [CrossRef]
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    [CrossRef]
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    [CrossRef]
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    [CrossRef]
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    [CrossRef]
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    [CrossRef]

2010 (1)

R. Gutmark and D. L. Guyton, “Origins of the keratometer and its evolving role in ophthalmology,” Surv. Ophthalmol. 55, 481–497 (2010).
[CrossRef]

2008 (1)

W. H. Seiple and J. P. Szlyk, “Clinical investigation into the vision performance provided by the iZon spectacle lens system,” Rev. Ophthalmol. 145(2), 1 (2008).

2005 (4)

J. Lee, “Wavefront technology for spectacle lenses,” Rev. Ophthalmol. 12(3), 91 (2005).

H. Guo, Z. Wang, Q. Zhao, W. Quan, and Y. Wang, “Individual eye model based on wavefront aberration,” Optik 116, 80–85 (2005).
[CrossRef]

B. Lackner, G. Schmidinger, S. Pieh, M. A. Funvoics, and C. Skorpik, “Repeatability and reproducibility of central corneal thickness measurement with Pentacam, Orbscan, and ultrasound,” Optom. Vis. Sci. 82, 892–899 (2005).
[CrossRef]

D. A. Atchison and G. Smith, “Chromatic dispersions of the ocular media of human eyes,” J. Opt. Soc. Am. A 22, 29–37 (2005).
[CrossRef]

2004 (3)

J. G. Pérez, A. Cerviño, M. J. Giraldez, M. Parafita, and E. Yebra-Pimentel, “Accuracy and precision of EyeSys and Orbscan systems on calibrated spherical test surfaces,” Eye Contact Lens 30, 74–78 (2004).
[CrossRef]

Y. Sun, S. Duthaler, and B. J. Nelson, “Autofocusing in computer microscopy: selecting the optimal focus algorithm,” Microsc. Res. Tech. 65, 139–149 (2004).
[CrossRef]

L. N. Thibos, X. Hong, A. Bradley, and R. A. Applegate, “Accuracy and precision of objective refraction from wavefront aberrations,” J. Vision 4(4), 329–351 (2004).
[CrossRef]

2003 (1)

1999 (1)

Z. Liu, A. Huang, and S. Pflugfelder, “Evaluation of corneal thickness and topography in normal eyes using the Orbscan corneal topography system,” Br. J. Ophthalmol. 83, 774–778 (1999).
[CrossRef]

1994 (1)

1989 (1)

S. B. Hannush, S. L. Crawford, G. O. Waring, M. C. Gemmill, M. J. Lynn, and A. Nizam, “Accuracy and precision of keratometry, photokeratoscopy, and corneal modeling on calibrated steel balls,” Arch. Ophthalmol. 107, 1235–1239 (1989).
[CrossRef]

Applegate, R. A.

L. N. Thibos, X. Hong, A. Bradley, and R. A. Applegate, “Accuracy and precision of objective refraction from wavefront aberrations,” J. Vision 4(4), 329–351 (2004).
[CrossRef]

S. MacRae, R. R. Krueger, and R. A. Applegate, Customized Corneal Ablation: The Quest for Supervision (Slack, 2001).

Atchison, D. A.

Bille, J. F.

Bradley, A.

L. N. Thibos, X. Hong, A. Bradley, and R. A. Applegate, “Accuracy and precision of objective refraction from wavefront aberrations,” J. Vision 4(4), 329–351 (2004).
[CrossRef]

Cerviño, A.

J. G. Pérez, A. Cerviño, M. J. Giraldez, M. Parafita, and E. Yebra-Pimentel, “Accuracy and precision of EyeSys and Orbscan systems on calibrated spherical test surfaces,” Eye Contact Lens 30, 74–78 (2004).
[CrossRef]

Crawford, S. L.

S. B. Hannush, S. L. Crawford, G. O. Waring, M. C. Gemmill, M. J. Lynn, and A. Nizam, “Accuracy and precision of keratometry, photokeratoscopy, and corneal modeling on calibrated steel balls,” Arch. Ophthalmol. 107, 1235–1239 (1989).
[CrossRef]

Duthaler, S.

Y. Sun, S. Duthaler, and B. J. Nelson, “Autofocusing in computer microscopy: selecting the optimal focus algorithm,” Microsc. Res. Tech. 65, 139–149 (2004).
[CrossRef]

Funvoics, M. A.

B. Lackner, G. Schmidinger, S. Pieh, M. A. Funvoics, and C. Skorpik, “Repeatability and reproducibility of central corneal thickness measurement with Pentacam, Orbscan, and ultrasound,” Optom. Vis. Sci. 82, 892–899 (2005).
[CrossRef]

Gemmill, M. C.

S. B. Hannush, S. L. Crawford, G. O. Waring, M. C. Gemmill, M. J. Lynn, and A. Nizam, “Accuracy and precision of keratometry, photokeratoscopy, and corneal modeling on calibrated steel balls,” Arch. Ophthalmol. 107, 1235–1239 (1989).
[CrossRef]

Giraldez, M. J.

J. G. Pérez, A. Cerviño, M. J. Giraldez, M. Parafita, and E. Yebra-Pimentel, “Accuracy and precision of EyeSys and Orbscan systems on calibrated spherical test surfaces,” Eye Contact Lens 30, 74–78 (2004).
[CrossRef]

Goelz, S.

Grimm, B.

Guo, H.

H. Guo, Z. Wang, Q. Zhao, W. Quan, and Y. Wang, “Individual eye model based on wavefront aberration,” Optik 116, 80–85 (2005).
[CrossRef]

Gutmark, R.

R. Gutmark and D. L. Guyton, “Origins of the keratometer and its evolving role in ophthalmology,” Surv. Ophthalmol. 55, 481–497 (2010).
[CrossRef]

Guyton, D. L.

R. Gutmark and D. L. Guyton, “Origins of the keratometer and its evolving role in ophthalmology,” Surv. Ophthalmol. 55, 481–497 (2010).
[CrossRef]

Gwiazda, J.

Hannush, S. B.

S. B. Hannush, S. L. Crawford, G. O. Waring, M. C. Gemmill, M. J. Lynn, and A. Nizam, “Accuracy and precision of keratometry, photokeratoscopy, and corneal modeling on calibrated steel balls,” Arch. Ophthalmol. 107, 1235–1239 (1989).
[CrossRef]

Harner, C. F. H.

J. F. Bille, C. F. H. Harner, and F. F. Loesel, Aberration-Free Refractive Surgery: New Frontiers in Vision (Springer, 2002).

He, J.

Held, R.

Hong, X.

L. N. Thibos, X. Hong, A. Bradley, and R. A. Applegate, “Accuracy and precision of objective refraction from wavefront aberrations,” J. Vision 4(4), 329–351 (2004).
[CrossRef]

Huang, A.

Z. Liu, A. Huang, and S. Pflugfelder, “Evaluation of corneal thickness and topography in normal eyes using the Orbscan corneal topography system,” Br. J. Ophthalmol. 83, 774–778 (1999).
[CrossRef]

Krueger, R. R.

S. MacRae, R. R. Krueger, and R. A. Applegate, Customized Corneal Ablation: The Quest for Supervision (Slack, 2001).

Lackner, B.

B. Lackner, G. Schmidinger, S. Pieh, M. A. Funvoics, and C. Skorpik, “Repeatability and reproducibility of central corneal thickness measurement with Pentacam, Orbscan, and ultrasound,” Optom. Vis. Sci. 82, 892–899 (2005).
[CrossRef]

Lee, J.

J. Lee, “Wavefront technology for spectacle lenses,” Rev. Ophthalmol. 12(3), 91 (2005).

Liang, J.

Liu, Z.

Z. Liu, A. Huang, and S. Pflugfelder, “Evaluation of corneal thickness and topography in normal eyes using the Orbscan corneal topography system,” Br. J. Ophthalmol. 83, 774–778 (1999).
[CrossRef]

Loesel, F. F.

J. F. Bille, C. F. H. Harner, and F. F. Loesel, Aberration-Free Refractive Surgery: New Frontiers in Vision (Springer, 2002).

Lynn, M. J.

S. B. Hannush, S. L. Crawford, G. O. Waring, M. C. Gemmill, M. J. Lynn, and A. Nizam, “Accuracy and precision of keratometry, photokeratoscopy, and corneal modeling on calibrated steel balls,” Arch. Ophthalmol. 107, 1235–1239 (1989).
[CrossRef]

MacRae, S.

S. MacRae, R. R. Krueger, and R. A. Applegate, Customized Corneal Ablation: The Quest for Supervision (Slack, 2001).

Nelson, B. J.

Y. Sun, S. Duthaler, and B. J. Nelson, “Autofocusing in computer microscopy: selecting the optimal focus algorithm,” Microsc. Res. Tech. 65, 139–149 (2004).
[CrossRef]

Nizam, A.

S. B. Hannush, S. L. Crawford, G. O. Waring, M. C. Gemmill, M. J. Lynn, and A. Nizam, “Accuracy and precision of keratometry, photokeratoscopy, and corneal modeling on calibrated steel balls,” Arch. Ophthalmol. 107, 1235–1239 (1989).
[CrossRef]

Parafita, M.

J. G. Pérez, A. Cerviño, M. J. Giraldez, M. Parafita, and E. Yebra-Pimentel, “Accuracy and precision of EyeSys and Orbscan systems on calibrated spherical test surfaces,” Eye Contact Lens 30, 74–78 (2004).
[CrossRef]

Pérez, J. G.

J. G. Pérez, A. Cerviño, M. J. Giraldez, M. Parafita, and E. Yebra-Pimentel, “Accuracy and precision of EyeSys and Orbscan systems on calibrated spherical test surfaces,” Eye Contact Lens 30, 74–78 (2004).
[CrossRef]

Pflugfelder, S.

Z. Liu, A. Huang, and S. Pflugfelder, “Evaluation of corneal thickness and topography in normal eyes using the Orbscan corneal topography system,” Br. J. Ophthalmol. 83, 774–778 (1999).
[CrossRef]

Pieh, S.

B. Lackner, G. Schmidinger, S. Pieh, M. A. Funvoics, and C. Skorpik, “Repeatability and reproducibility of central corneal thickness measurement with Pentacam, Orbscan, and ultrasound,” Optom. Vis. Sci. 82, 892–899 (2005).
[CrossRef]

Quan, W.

H. Guo, Z. Wang, Q. Zhao, W. Quan, and Y. Wang, “Individual eye model based on wavefront aberration,” Optik 116, 80–85 (2005).
[CrossRef]

Schmidinger, G.

B. Lackner, G. Schmidinger, S. Pieh, M. A. Funvoics, and C. Skorpik, “Repeatability and reproducibility of central corneal thickness measurement with Pentacam, Orbscan, and ultrasound,” Optom. Vis. Sci. 82, 892–899 (2005).
[CrossRef]

Seiple, W. H.

W. H. Seiple and J. P. Szlyk, “Clinical investigation into the vision performance provided by the iZon spectacle lens system,” Rev. Ophthalmol. 145(2), 1 (2008).

Skorpik, C.

B. Lackner, G. Schmidinger, S. Pieh, M. A. Funvoics, and C. Skorpik, “Repeatability and reproducibility of central corneal thickness measurement with Pentacam, Orbscan, and ultrasound,” Optom. Vis. Sci. 82, 892–899 (2005).
[CrossRef]

Smith, G.

Sun, Y.

Y. Sun, S. Duthaler, and B. J. Nelson, “Autofocusing in computer microscopy: selecting the optimal focus algorithm,” Microsc. Res. Tech. 65, 139–149 (2004).
[CrossRef]

Szlyk, J. P.

W. H. Seiple and J. P. Szlyk, “Clinical investigation into the vision performance provided by the iZon spectacle lens system,” Rev. Ophthalmol. 145(2), 1 (2008).

Thibos, L. N.

L. N. Thibos, X. Hong, A. Bradley, and R. A. Applegate, “Accuracy and precision of objective refraction from wavefront aberrations,” J. Vision 4(4), 329–351 (2004).
[CrossRef]

Thorn, F.

Wang, Y.

H. Guo, Z. Wang, Q. Zhao, W. Quan, and Y. Wang, “Individual eye model based on wavefront aberration,” Optik 116, 80–85 (2005).
[CrossRef]

Wang, Z.

H. Guo, Z. Wang, Q. Zhao, W. Quan, and Y. Wang, “Individual eye model based on wavefront aberration,” Optik 116, 80–85 (2005).
[CrossRef]

Waring, G. O.

S. B. Hannush, S. L. Crawford, G. O. Waring, M. C. Gemmill, M. J. Lynn, and A. Nizam, “Accuracy and precision of keratometry, photokeratoscopy, and corneal modeling on calibrated steel balls,” Arch. Ophthalmol. 107, 1235–1239 (1989).
[CrossRef]

Yebra-Pimentel, E.

J. G. Pérez, A. Cerviño, M. J. Giraldez, M. Parafita, and E. Yebra-Pimentel, “Accuracy and precision of EyeSys and Orbscan systems on calibrated spherical test surfaces,” Eye Contact Lens 30, 74–78 (2004).
[CrossRef]

Zhao, Q.

H. Guo, Z. Wang, Q. Zhao, W. Quan, and Y. Wang, “Individual eye model based on wavefront aberration,” Optik 116, 80–85 (2005).
[CrossRef]

Arch. Ophthalmol. (1)

S. B. Hannush, S. L. Crawford, G. O. Waring, M. C. Gemmill, M. J. Lynn, and A. Nizam, “Accuracy and precision of keratometry, photokeratoscopy, and corneal modeling on calibrated steel balls,” Arch. Ophthalmol. 107, 1235–1239 (1989).
[CrossRef]

Br. J. Ophthalmol. (1)

Z. Liu, A. Huang, and S. Pflugfelder, “Evaluation of corneal thickness and topography in normal eyes using the Orbscan corneal topography system,” Br. J. Ophthalmol. 83, 774–778 (1999).
[CrossRef]

Eye Contact Lens (1)

J. G. Pérez, A. Cerviño, M. J. Giraldez, M. Parafita, and E. Yebra-Pimentel, “Accuracy and precision of EyeSys and Orbscan systems on calibrated spherical test surfaces,” Eye Contact Lens 30, 74–78 (2004).
[CrossRef]

J. Opt. Soc. Am. A (3)

J. Vision (1)

L. N. Thibos, X. Hong, A. Bradley, and R. A. Applegate, “Accuracy and precision of objective refraction from wavefront aberrations,” J. Vision 4(4), 329–351 (2004).
[CrossRef]

Microsc. Res. Tech. (1)

Y. Sun, S. Duthaler, and B. J. Nelson, “Autofocusing in computer microscopy: selecting the optimal focus algorithm,” Microsc. Res. Tech. 65, 139–149 (2004).
[CrossRef]

Optik (1)

H. Guo, Z. Wang, Q. Zhao, W. Quan, and Y. Wang, “Individual eye model based on wavefront aberration,” Optik 116, 80–85 (2005).
[CrossRef]

Optom. Vis. Sci. (1)

B. Lackner, G. Schmidinger, S. Pieh, M. A. Funvoics, and C. Skorpik, “Repeatability and reproducibility of central corneal thickness measurement with Pentacam, Orbscan, and ultrasound,” Optom. Vis. Sci. 82, 892–899 (2005).
[CrossRef]

Rev. Ophthalmol. (2)

J. Lee, “Wavefront technology for spectacle lenses,” Rev. Ophthalmol. 12(3), 91 (2005).

W. H. Seiple and J. P. Szlyk, “Clinical investigation into the vision performance provided by the iZon spectacle lens system,” Rev. Ophthalmol. 145(2), 1 (2008).

Surv. Ophthalmol. (1)

R. Gutmark and D. L. Guyton, “Origins of the keratometer and its evolving role in ophthalmology,” Surv. Ophthalmol. 55, 481–497 (2010).
[CrossRef]

Other (2)

S. MacRae, R. R. Krueger, and R. A. Applegate, Customized Corneal Ablation: The Quest for Supervision (Slack, 2001).

J. F. Bille, C. F. H. Harner, and F. F. Loesel, Aberration-Free Refractive Surgery: New Frontiers in Vision (Springer, 2002).

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Figures (8)

Fig. 1.
Fig. 1.

Schematic diagram of the keratometer’s optical system.

Fig. 2.
Fig. 2.

Layout of (a) first imaging subsystem, (b) second imaging subsystem, (c) imaging keratometer’s optical system, and (d) alignment system.

Fig. 3.
Fig. 3.

MTF curves of imaging system corresponding to different radii of curvature of corneal surfaces. (a) r=5.5mm, (b) r=7.8mm, and (c) r=11mm.

Fig. 4.
Fig. 4.

Irradiance color map of the image surface.

Fig. 5.
Fig. 5.

Schematic diagram of calculating the radius of annulus by the centroid algorithm

Fig. 6.
Fig. 6.

Relevance between the radius of curvature of the corneal surface and the radius of the annular image.

Fig. 7.
Fig. 7.

Irradiance maps of annular images. (a) r=5.5mm, (b) r=5.514mm, (c) r=7.8mm, (d) r=7.813mm, (e) r=11mm, and (f) r=10.987mm.

Fig. 8.
Fig. 8.

Irradiance map of image in the case of cornea with astigmatism.

Tables (6)

Tables Icon

Table 1. Specific Parameters of Design

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Table 2. Structural Parameters of First Imaging Subsystem

Tables Icon

Table 3. Structural Parameters of Second Imaging Subsystem

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Table 4. Radius of Annular Image (R) Calculated by Centroid Algorithm for Different Radius of Curvature (r) of Corneal Surface

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Table 5. Measurement Accuracy (A) of Optical System for Corneas with Different Radii of Curvature (r)

Tables Icon

Table 6. Verification Result of Accuracya

Equations (11)

Equations on this page are rendered with MathJax. Learn more.

r=2(β1L0d)1+β1β2y0y2,
β1=f1f1+L0,
β2=f2L2f2.
P=1000(n1)r,
r1=2(β1L0d)1+β1β2,1y0y2,1,
r2=2(β1L0d)1+β1β2,2y0y2,2.
C=P1P2.
X¯θi=xil(xi,yi)li(xi,yi),
Y¯θi=yil(xi,yi)li(xi,yi),
R¯θi=X¯θi2+Y¯θi2,
R=1mR¯θim,

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