Abstract

We present an improved method for remote eye-fixation detection, using a polarization-modulated approach to retinal birefringence scanning (RBS), without the need for individual calibration or separate background measurements and essentially independent of corneal birefringence. Polarization-modulated RBS detects polarization changes generated in modulated polarized light passing through a unique pattern of nerve fibers identifying and defining the retinal region where fixation occurs (the fovea). A proof-of-concept demonstration in human eyes suggests that polarization-modulated RBS has the potential to reliably detect true foveal fixation on a specified point with an accuracy of at least ± 0.75°, and that it can be applied to the general population, including individuals with sub-optimal eyes and young children, where early diagnosis of visual problems can be critical. As could be employed in an eye-controlled display or in other devices, polarization-modulated RBS also enables and paves the way for new and reliable eye-fixation-evoked human-machine interfaces.

© 2014 Optical Society of America

Full Article  |  PDF Article

References

  • View by:
  • |
  • |
  • |

  1. A. T. Duchowski, “A breadth-first survey of eye-tracking applications,” Behav. Res. Methods Instrum. Comput. 34(4), 455–470 (2002).
    [CrossRef] [PubMed]
  2. L. R. Young, D. Sheena, “Survey of eye movement recording methods,” Behav. Res. Meth. Instrum. 7(5), 397–429 (1975).
    [CrossRef]
  3. A. T. Duchowski, Eye Tracking Methodology: Theory and Practice, 2nd ed. (Springer, 2007).
  4. C. H. Moriomto, M. R. M. Mimica, “Eye gaze tracking techniques for interactive applications,” Comput. Vis. Image Underst. 98(1), 4–24 (2005).
    [CrossRef]
  5. D. H. Yoo, J. H. Kim, B. R. Lee, M. J. Chung, “Non-contact eye gaze tracking system by mapping of corneal reflections,” in Proc. Internat. Conf. on Automatic Face and Gesture Recognition (2002), pp. 94–99.
  6. D. H. Yoo, M. J. Chung, “A novel non-intrusive eye gaze estimation using cross-ratio under large head motion,” Comput. Vis. Image Underst. 98(1), 25–51 (2005).
    [CrossRef]
  7. D. Beymer, M. Flickner, “Eye gaze tracking using an active stereo head,” in Proc. IEEE Conference on Computer Vision and Pattern Recognition (2003), pp. 451–458.
    [CrossRef]
  8. S. Shih, J. Liu, “A novel approach to 3D gaze tracking using stereo cameras,” IEEE Trans. Syst. Man Cybern. (Part B3), 1–12 (2003).
  9. F. Møller, A. K. Sjølie, T. Bek, “Quantitative assessment of fixational eye movements by scanning laser ophthalmoscopy,” Acta Ophthalmol. Scand. 74(6), 578–583 (1996).
    [CrossRef] [PubMed]
  10. D. X. Hammer, R. D. Ferguson, J. C. Magill, M. A. White, A. E. Elsner, R. H. Webb, “Compact scanning laser ophthalmoscope with high-speed retinal tracker,” Appl. Opt. 42(22), 4621–4632 (2003).
    [CrossRef] [PubMed]
  11. C. K. Sheehy, Q. Yang, D. W. Arathorn, P. Tiruveedhula, J. F. de Boer, A. Roorda, “High-speed, image-based eye tracking with a scanning laser ophthalmoscope,” Biomed. Opt. Express 3(10), 2611–2622 (2012).
    [CrossRef] [PubMed]
  12. Tobii Technology AB, Danderyd, Sweden. www.tobii.se (2013).
  13. SensoMotoric Instruments GmbH (SMI), Teltow, Germany. www.smi.de (2013).
  14. Applied Science Laboratories, Bedford, MA. http://www.cis.rit.edu/people/faculty/pelz/research/manuals/asl_504_manual.pdf
  15. S. K. Schnipke, M. W. Todd, “Trials and tribulations of using an eye-tracking system,” in Proc. ACM SIGCHI – Human Factors in Computing Systems Conference (2000), pp. 273–274.
    [CrossRef]
  16. D. L. Guyton, D. G. Hunter, S. N. Patel, J. C. Sandruck, and R. L. Fry, “Eye fixation monitor and tracker,” U.S. Patent No. 6,027,216 (2000).
  17. D. G. Hunter, S. N. Patel, D. L. Guyton, “Automated detection of foveal fixation by use of retinal birefringence scanning,” Appl. Opt. 38(7), 1273–1279 (1999).
    [CrossRef] [PubMed]
  18. B. I. Gramatikov, “Detecting fixation on a target using time-frequency distributions of a retinal birefringence scanning signal,” Biomed. Eng. Online 12(1), 41 (2013).
    [CrossRef] [PubMed]
  19. B. I. Gramatikov, O. H. Y. Zalloum, Y. K. Wu, D. G. Hunter, D. L. Guyton, “Birefringence-based eye fixation monitor with no moving parts,” J. Biomed. Opt. 11(3), 034025 (2006).
    [CrossRef] [PubMed]
  20. B. I. Gramatikov, O. H. Y. Zalloum, Y. K. Wu, D. G. Hunter, D. L. Guyton, “Directional eye fixation sensor using birefringence-based foveal detection,” Appl. Opt. 46(10), 1809–1818 (2007).
    [CrossRef] [PubMed]
  21. B. Gramatikov, K. Irsch, M. Müllenbroich, N. Frindt, Y. Qu, R. Gutmark, Y. K. Wu, D. Guyton, “A device for continuous monitoring of true central fixation based on foveal birefringence,” Ann. Biomed. Eng. 41(9), 1968–1978 (2013).
    [CrossRef] [PubMed]
  22. D. G. Hunter, A. S. Shah, S. Sau, D. Nassif, D. L. Guyton, “Automated detection of ocular alignment with binocular retinal birefringence scanning,” Appl. Opt. 42(16), 3047–3053 (2003).
    [CrossRef] [PubMed]
  23. D. G. Hunter, D. S. Nassif, N. V. Piskun, R. Winsor, B. I. Gramatikov, D. L. Guyton, “Pediatric Vision Screener 1: Instrument design and operation,” J. Biomed. Opt. 9(6), 1363–1368 (2004).
    [CrossRef] [PubMed]
  24. D. S. Nassif, N. V. Piskun, B. I. Gramatikov, D. L. Guyton, D. G. Hunter, “Pediatric Vision Screener 2: Pilot study in adults,” J. Biomed. Opt. 9(6), 1369–1374 (2004).
    [CrossRef] [PubMed]
  25. D. S. Nassif, N. V. Piskun, D. G. Hunter, “The Pediatric Vision Screener III: Detection of Strabismus in Children,” Arch. Ophthalmol. 124(4), 509–513 (2006).
    [CrossRef] [PubMed]
  26. S. E. Loudon, C. A. Rook, D. S. Nassif, N. V. Piskun, D. G. Hunter, “Rapid, high-accuracy detection of strabismus and amblyopia using the pediatric vision scanner,” Invest. Ophthalmol. Vis. Sci. 52(8), 5043–5048 (2011).
    [CrossRef] [PubMed]
  27. R. W. Knighton, X. R. Huang, “Linear birefringence of the central human cornea,” Invest. Ophthalmol. Vis. Sci. 43(1), 82–86 (2002).
    [PubMed]
  28. R. N. Weinreb, C. Bowd, D. S. Greenfield, L. M. Zangwill, “Measurement of the magnitude and axis of corneal polarization with scanning laser polarimetry,” Arch. Ophthalmol. 120(7), 901–906 (2002).
    [CrossRef] [PubMed]
  29. K. Irsch, A. A. Shah, “Birefringence of the central cornea in children assessed with scanning laser polarimetry,” J. Biomed. Opt. 17(8), 086001 (2012).
    [CrossRef] [PubMed]
  30. G. F. J. Garlick, G. A. Steigmann, and W. E. Lamb, “Differential optical polarization detectors,” U.S. Patent No. 3,992,571 (1976).
  31. J. M. Miller, H. L. Hall, J. E. Greivenkamp, D. L. Guyton, “Quantification of the Brückner Test for Strabismus,” Invest. Ophthalmol. Vis. Sci. 36, 897–905 (1995).
    [PubMed]
  32. K. Irsch, B. Gramatikov, Y.-K. Wu, D. L. Guyton, “Modeling and minimizing interference from corneal birefringence in retinal birefringence scanning for foveal fixation detection,” Biomed. Opt. Express 2(7), 1955–1968 (2011).
    [CrossRef] [PubMed]
  33. A. W. Dreher, K. Reiter, R. N. Weinreb, “Spatially resolved birefringence of the retinal nerve fiber layer assessed with a retinal laser ellipsometer,” Appl. Opt. 31(19), 3730–3735 (1992).
    [CrossRef] [PubMed]
  34. D. G. Hunter, J. C. Sandruck, S. Sau, S. N. Patel, D. L. Guyton, “Mathematical modeling of retinal birefringence scanning,” J. Opt. Soc. Am. A 16(9), 2103–2111 (1999).
    [CrossRef] [PubMed]
  35. H. B. Klein Brink, G. J. Van Blokland, “Birefringence of the human fovea area assessed in vivo with Mueller matrix ellipsometry,” J. Opt. Soc. Am. A 5, 49–57 (1988).
  36. B. C. E. Pelz, C. Weschenmoser, S. Goelz, J. P. Fischer, R. O. W. Burk, J. F. Bille, “In vivo measurement of the retinal birefringence with regard on corneal effects using an electro-optical ellipsometer,” Proc. SPIE 2930, 92–101 (1996).
    [CrossRef]
  37. D. L. Sliney and M. Wolbarsht, Safety with Lasers and Other Optical Sources (Plenum Press, 1980), pp. 261–271.
  38. Q. Zhou, R. N. Weinreb, “Individualized compensation of anterior segment birefringence during scanning laser polarimetry,” Invest. Ophthalmol. Vis. Sci. 43(7), 2221–2228 (2002).
    [PubMed]
  39. Q. Zhou, “System and method for determining birefringence of anterior segment of the patient's eye,” U.S. Patent No. 6,356,036 (2002).
  40. D. G. Hunter, K. J. Nusz, N. K. Gandhi, I. H. Quraishi, B. I. Gramatikov, D. L. Guyton, “Automated detection of ocular focus,” J. Biomed. Opt. 9(5), 1103–1109 (2004).
    [CrossRef] [PubMed]

2013 (2)

B. I. Gramatikov, “Detecting fixation on a target using time-frequency distributions of a retinal birefringence scanning signal,” Biomed. Eng. Online 12(1), 41 (2013).
[CrossRef] [PubMed]

B. Gramatikov, K. Irsch, M. Müllenbroich, N. Frindt, Y. Qu, R. Gutmark, Y. K. Wu, D. Guyton, “A device for continuous monitoring of true central fixation based on foveal birefringence,” Ann. Biomed. Eng. 41(9), 1968–1978 (2013).
[CrossRef] [PubMed]

2012 (2)

2011 (2)

K. Irsch, B. Gramatikov, Y.-K. Wu, D. L. Guyton, “Modeling and minimizing interference from corneal birefringence in retinal birefringence scanning for foveal fixation detection,” Biomed. Opt. Express 2(7), 1955–1968 (2011).
[CrossRef] [PubMed]

S. E. Loudon, C. A. Rook, D. S. Nassif, N. V. Piskun, D. G. Hunter, “Rapid, high-accuracy detection of strabismus and amblyopia using the pediatric vision scanner,” Invest. Ophthalmol. Vis. Sci. 52(8), 5043–5048 (2011).
[CrossRef] [PubMed]

2007 (1)

2006 (2)

D. S. Nassif, N. V. Piskun, D. G. Hunter, “The Pediatric Vision Screener III: Detection of Strabismus in Children,” Arch. Ophthalmol. 124(4), 509–513 (2006).
[CrossRef] [PubMed]

B. I. Gramatikov, O. H. Y. Zalloum, Y. K. Wu, D. G. Hunter, D. L. Guyton, “Birefringence-based eye fixation monitor with no moving parts,” J. Biomed. Opt. 11(3), 034025 (2006).
[CrossRef] [PubMed]

2005 (2)

C. H. Moriomto, M. R. M. Mimica, “Eye gaze tracking techniques for interactive applications,” Comput. Vis. Image Underst. 98(1), 4–24 (2005).
[CrossRef]

D. H. Yoo, M. J. Chung, “A novel non-intrusive eye gaze estimation using cross-ratio under large head motion,” Comput. Vis. Image Underst. 98(1), 25–51 (2005).
[CrossRef]

2004 (3)

D. G. Hunter, D. S. Nassif, N. V. Piskun, R. Winsor, B. I. Gramatikov, D. L. Guyton, “Pediatric Vision Screener 1: Instrument design and operation,” J. Biomed. Opt. 9(6), 1363–1368 (2004).
[CrossRef] [PubMed]

D. S. Nassif, N. V. Piskun, B. I. Gramatikov, D. L. Guyton, D. G. Hunter, “Pediatric Vision Screener 2: Pilot study in adults,” J. Biomed. Opt. 9(6), 1369–1374 (2004).
[CrossRef] [PubMed]

D. G. Hunter, K. J. Nusz, N. K. Gandhi, I. H. Quraishi, B. I. Gramatikov, D. L. Guyton, “Automated detection of ocular focus,” J. Biomed. Opt. 9(5), 1103–1109 (2004).
[CrossRef] [PubMed]

2003 (2)

2002 (4)

Q. Zhou, R. N. Weinreb, “Individualized compensation of anterior segment birefringence during scanning laser polarimetry,” Invest. Ophthalmol. Vis. Sci. 43(7), 2221–2228 (2002).
[PubMed]

R. W. Knighton, X. R. Huang, “Linear birefringence of the central human cornea,” Invest. Ophthalmol. Vis. Sci. 43(1), 82–86 (2002).
[PubMed]

R. N. Weinreb, C. Bowd, D. S. Greenfield, L. M. Zangwill, “Measurement of the magnitude and axis of corneal polarization with scanning laser polarimetry,” Arch. Ophthalmol. 120(7), 901–906 (2002).
[CrossRef] [PubMed]

A. T. Duchowski, “A breadth-first survey of eye-tracking applications,” Behav. Res. Methods Instrum. Comput. 34(4), 455–470 (2002).
[CrossRef] [PubMed]

1999 (2)

1996 (2)

B. C. E. Pelz, C. Weschenmoser, S. Goelz, J. P. Fischer, R. O. W. Burk, J. F. Bille, “In vivo measurement of the retinal birefringence with regard on corneal effects using an electro-optical ellipsometer,” Proc. SPIE 2930, 92–101 (1996).
[CrossRef]

F. Møller, A. K. Sjølie, T. Bek, “Quantitative assessment of fixational eye movements by scanning laser ophthalmoscopy,” Acta Ophthalmol. Scand. 74(6), 578–583 (1996).
[CrossRef] [PubMed]

1995 (1)

J. M. Miller, H. L. Hall, J. E. Greivenkamp, D. L. Guyton, “Quantification of the Brückner Test for Strabismus,” Invest. Ophthalmol. Vis. Sci. 36, 897–905 (1995).
[PubMed]

1992 (1)

1988 (1)

1975 (1)

L. R. Young, D. Sheena, “Survey of eye movement recording methods,” Behav. Res. Meth. Instrum. 7(5), 397–429 (1975).
[CrossRef]

Arathorn, D. W.

Bek, T.

F. Møller, A. K. Sjølie, T. Bek, “Quantitative assessment of fixational eye movements by scanning laser ophthalmoscopy,” Acta Ophthalmol. Scand. 74(6), 578–583 (1996).
[CrossRef] [PubMed]

Beymer, D.

D. Beymer, M. Flickner, “Eye gaze tracking using an active stereo head,” in Proc. IEEE Conference on Computer Vision and Pattern Recognition (2003), pp. 451–458.
[CrossRef]

Bille, J. F.

B. C. E. Pelz, C. Weschenmoser, S. Goelz, J. P. Fischer, R. O. W. Burk, J. F. Bille, “In vivo measurement of the retinal birefringence with regard on corneal effects using an electro-optical ellipsometer,” Proc. SPIE 2930, 92–101 (1996).
[CrossRef]

Bowd, C.

R. N. Weinreb, C. Bowd, D. S. Greenfield, L. M. Zangwill, “Measurement of the magnitude and axis of corneal polarization with scanning laser polarimetry,” Arch. Ophthalmol. 120(7), 901–906 (2002).
[CrossRef] [PubMed]

Burk, R. O. W.

B. C. E. Pelz, C. Weschenmoser, S. Goelz, J. P. Fischer, R. O. W. Burk, J. F. Bille, “In vivo measurement of the retinal birefringence with regard on corneal effects using an electro-optical ellipsometer,” Proc. SPIE 2930, 92–101 (1996).
[CrossRef]

Chung, M. J.

D. H. Yoo, M. J. Chung, “A novel non-intrusive eye gaze estimation using cross-ratio under large head motion,” Comput. Vis. Image Underst. 98(1), 25–51 (2005).
[CrossRef]

D. H. Yoo, J. H. Kim, B. R. Lee, M. J. Chung, “Non-contact eye gaze tracking system by mapping of corneal reflections,” in Proc. Internat. Conf. on Automatic Face and Gesture Recognition (2002), pp. 94–99.

de Boer, J. F.

Dreher, A. W.

Duchowski, A. T.

A. T. Duchowski, “A breadth-first survey of eye-tracking applications,” Behav. Res. Methods Instrum. Comput. 34(4), 455–470 (2002).
[CrossRef] [PubMed]

Elsner, A. E.

Ferguson, R. D.

Fischer, J. P.

B. C. E. Pelz, C. Weschenmoser, S. Goelz, J. P. Fischer, R. O. W. Burk, J. F. Bille, “In vivo measurement of the retinal birefringence with regard on corneal effects using an electro-optical ellipsometer,” Proc. SPIE 2930, 92–101 (1996).
[CrossRef]

Flickner, M.

D. Beymer, M. Flickner, “Eye gaze tracking using an active stereo head,” in Proc. IEEE Conference on Computer Vision and Pattern Recognition (2003), pp. 451–458.
[CrossRef]

Frindt, N.

B. Gramatikov, K. Irsch, M. Müllenbroich, N. Frindt, Y. Qu, R. Gutmark, Y. K. Wu, D. Guyton, “A device for continuous monitoring of true central fixation based on foveal birefringence,” Ann. Biomed. Eng. 41(9), 1968–1978 (2013).
[CrossRef] [PubMed]

Gandhi, N. K.

D. G. Hunter, K. J. Nusz, N. K. Gandhi, I. H. Quraishi, B. I. Gramatikov, D. L. Guyton, “Automated detection of ocular focus,” J. Biomed. Opt. 9(5), 1103–1109 (2004).
[CrossRef] [PubMed]

Goelz, S.

B. C. E. Pelz, C. Weschenmoser, S. Goelz, J. P. Fischer, R. O. W. Burk, J. F. Bille, “In vivo measurement of the retinal birefringence with regard on corneal effects using an electro-optical ellipsometer,” Proc. SPIE 2930, 92–101 (1996).
[CrossRef]

Gramatikov, B.

B. Gramatikov, K. Irsch, M. Müllenbroich, N. Frindt, Y. Qu, R. Gutmark, Y. K. Wu, D. Guyton, “A device for continuous monitoring of true central fixation based on foveal birefringence,” Ann. Biomed. Eng. 41(9), 1968–1978 (2013).
[CrossRef] [PubMed]

K. Irsch, B. Gramatikov, Y.-K. Wu, D. L. Guyton, “Modeling and minimizing interference from corneal birefringence in retinal birefringence scanning for foveal fixation detection,” Biomed. Opt. Express 2(7), 1955–1968 (2011).
[CrossRef] [PubMed]

Gramatikov, B. I.

B. I. Gramatikov, “Detecting fixation on a target using time-frequency distributions of a retinal birefringence scanning signal,” Biomed. Eng. Online 12(1), 41 (2013).
[CrossRef] [PubMed]

B. I. Gramatikov, O. H. Y. Zalloum, Y. K. Wu, D. G. Hunter, D. L. Guyton, “Directional eye fixation sensor using birefringence-based foveal detection,” Appl. Opt. 46(10), 1809–1818 (2007).
[CrossRef] [PubMed]

B. I. Gramatikov, O. H. Y. Zalloum, Y. K. Wu, D. G. Hunter, D. L. Guyton, “Birefringence-based eye fixation monitor with no moving parts,” J. Biomed. Opt. 11(3), 034025 (2006).
[CrossRef] [PubMed]

D. G. Hunter, K. J. Nusz, N. K. Gandhi, I. H. Quraishi, B. I. Gramatikov, D. L. Guyton, “Automated detection of ocular focus,” J. Biomed. Opt. 9(5), 1103–1109 (2004).
[CrossRef] [PubMed]

D. G. Hunter, D. S. Nassif, N. V. Piskun, R. Winsor, B. I. Gramatikov, D. L. Guyton, “Pediatric Vision Screener 1: Instrument design and operation,” J. Biomed. Opt. 9(6), 1363–1368 (2004).
[CrossRef] [PubMed]

D. S. Nassif, N. V. Piskun, B. I. Gramatikov, D. L. Guyton, D. G. Hunter, “Pediatric Vision Screener 2: Pilot study in adults,” J. Biomed. Opt. 9(6), 1369–1374 (2004).
[CrossRef] [PubMed]

Greenfield, D. S.

R. N. Weinreb, C. Bowd, D. S. Greenfield, L. M. Zangwill, “Measurement of the magnitude and axis of corneal polarization with scanning laser polarimetry,” Arch. Ophthalmol. 120(7), 901–906 (2002).
[CrossRef] [PubMed]

Greivenkamp, J. E.

J. M. Miller, H. L. Hall, J. E. Greivenkamp, D. L. Guyton, “Quantification of the Brückner Test for Strabismus,” Invest. Ophthalmol. Vis. Sci. 36, 897–905 (1995).
[PubMed]

Gutmark, R.

B. Gramatikov, K. Irsch, M. Müllenbroich, N. Frindt, Y. Qu, R. Gutmark, Y. K. Wu, D. Guyton, “A device for continuous monitoring of true central fixation based on foveal birefringence,” Ann. Biomed. Eng. 41(9), 1968–1978 (2013).
[CrossRef] [PubMed]

Guyton, D.

B. Gramatikov, K. Irsch, M. Müllenbroich, N. Frindt, Y. Qu, R. Gutmark, Y. K. Wu, D. Guyton, “A device for continuous monitoring of true central fixation based on foveal birefringence,” Ann. Biomed. Eng. 41(9), 1968–1978 (2013).
[CrossRef] [PubMed]

Guyton, D. L.

K. Irsch, B. Gramatikov, Y.-K. Wu, D. L. Guyton, “Modeling and minimizing interference from corneal birefringence in retinal birefringence scanning for foveal fixation detection,” Biomed. Opt. Express 2(7), 1955–1968 (2011).
[CrossRef] [PubMed]

B. I. Gramatikov, O. H. Y. Zalloum, Y. K. Wu, D. G. Hunter, D. L. Guyton, “Directional eye fixation sensor using birefringence-based foveal detection,” Appl. Opt. 46(10), 1809–1818 (2007).
[CrossRef] [PubMed]

B. I. Gramatikov, O. H. Y. Zalloum, Y. K. Wu, D. G. Hunter, D. L. Guyton, “Birefringence-based eye fixation monitor with no moving parts,” J. Biomed. Opt. 11(3), 034025 (2006).
[CrossRef] [PubMed]

D. G. Hunter, K. J. Nusz, N. K. Gandhi, I. H. Quraishi, B. I. Gramatikov, D. L. Guyton, “Automated detection of ocular focus,” J. Biomed. Opt. 9(5), 1103–1109 (2004).
[CrossRef] [PubMed]

D. S. Nassif, N. V. Piskun, B. I. Gramatikov, D. L. Guyton, D. G. Hunter, “Pediatric Vision Screener 2: Pilot study in adults,” J. Biomed. Opt. 9(6), 1369–1374 (2004).
[CrossRef] [PubMed]

D. G. Hunter, D. S. Nassif, N. V. Piskun, R. Winsor, B. I. Gramatikov, D. L. Guyton, “Pediatric Vision Screener 1: Instrument design and operation,” J. Biomed. Opt. 9(6), 1363–1368 (2004).
[CrossRef] [PubMed]

D. G. Hunter, A. S. Shah, S. Sau, D. Nassif, D. L. Guyton, “Automated detection of ocular alignment with binocular retinal birefringence scanning,” Appl. Opt. 42(16), 3047–3053 (2003).
[CrossRef] [PubMed]

D. G. Hunter, S. N. Patel, D. L. Guyton, “Automated detection of foveal fixation by use of retinal birefringence scanning,” Appl. Opt. 38(7), 1273–1279 (1999).
[CrossRef] [PubMed]

D. G. Hunter, J. C. Sandruck, S. Sau, S. N. Patel, D. L. Guyton, “Mathematical modeling of retinal birefringence scanning,” J. Opt. Soc. Am. A 16(9), 2103–2111 (1999).
[CrossRef] [PubMed]

J. M. Miller, H. L. Hall, J. E. Greivenkamp, D. L. Guyton, “Quantification of the Brückner Test for Strabismus,” Invest. Ophthalmol. Vis. Sci. 36, 897–905 (1995).
[PubMed]

Hall, H. L.

J. M. Miller, H. L. Hall, J. E. Greivenkamp, D. L. Guyton, “Quantification of the Brückner Test for Strabismus,” Invest. Ophthalmol. Vis. Sci. 36, 897–905 (1995).
[PubMed]

Hammer, D. X.

Huang, X. R.

R. W. Knighton, X. R. Huang, “Linear birefringence of the central human cornea,” Invest. Ophthalmol. Vis. Sci. 43(1), 82–86 (2002).
[PubMed]

Hunter, D. G.

S. E. Loudon, C. A. Rook, D. S. Nassif, N. V. Piskun, D. G. Hunter, “Rapid, high-accuracy detection of strabismus and amblyopia using the pediatric vision scanner,” Invest. Ophthalmol. Vis. Sci. 52(8), 5043–5048 (2011).
[CrossRef] [PubMed]

B. I. Gramatikov, O. H. Y. Zalloum, Y. K. Wu, D. G. Hunter, D. L. Guyton, “Directional eye fixation sensor using birefringence-based foveal detection,” Appl. Opt. 46(10), 1809–1818 (2007).
[CrossRef] [PubMed]

B. I. Gramatikov, O. H. Y. Zalloum, Y. K. Wu, D. G. Hunter, D. L. Guyton, “Birefringence-based eye fixation monitor with no moving parts,” J. Biomed. Opt. 11(3), 034025 (2006).
[CrossRef] [PubMed]

D. S. Nassif, N. V. Piskun, D. G. Hunter, “The Pediatric Vision Screener III: Detection of Strabismus in Children,” Arch. Ophthalmol. 124(4), 509–513 (2006).
[CrossRef] [PubMed]

D. G. Hunter, K. J. Nusz, N. K. Gandhi, I. H. Quraishi, B. I. Gramatikov, D. L. Guyton, “Automated detection of ocular focus,” J. Biomed. Opt. 9(5), 1103–1109 (2004).
[CrossRef] [PubMed]

D. G. Hunter, D. S. Nassif, N. V. Piskun, R. Winsor, B. I. Gramatikov, D. L. Guyton, “Pediatric Vision Screener 1: Instrument design and operation,” J. Biomed. Opt. 9(6), 1363–1368 (2004).
[CrossRef] [PubMed]

D. S. Nassif, N. V. Piskun, B. I. Gramatikov, D. L. Guyton, D. G. Hunter, “Pediatric Vision Screener 2: Pilot study in adults,” J. Biomed. Opt. 9(6), 1369–1374 (2004).
[CrossRef] [PubMed]

D. G. Hunter, A. S. Shah, S. Sau, D. Nassif, D. L. Guyton, “Automated detection of ocular alignment with binocular retinal birefringence scanning,” Appl. Opt. 42(16), 3047–3053 (2003).
[CrossRef] [PubMed]

D. G. Hunter, S. N. Patel, D. L. Guyton, “Automated detection of foveal fixation by use of retinal birefringence scanning,” Appl. Opt. 38(7), 1273–1279 (1999).
[CrossRef] [PubMed]

D. G. Hunter, J. C. Sandruck, S. Sau, S. N. Patel, D. L. Guyton, “Mathematical modeling of retinal birefringence scanning,” J. Opt. Soc. Am. A 16(9), 2103–2111 (1999).
[CrossRef] [PubMed]

Irsch, K.

B. Gramatikov, K. Irsch, M. Müllenbroich, N. Frindt, Y. Qu, R. Gutmark, Y. K. Wu, D. Guyton, “A device for continuous monitoring of true central fixation based on foveal birefringence,” Ann. Biomed. Eng. 41(9), 1968–1978 (2013).
[CrossRef] [PubMed]

K. Irsch, A. A. Shah, “Birefringence of the central cornea in children assessed with scanning laser polarimetry,” J. Biomed. Opt. 17(8), 086001 (2012).
[CrossRef] [PubMed]

K. Irsch, B. Gramatikov, Y.-K. Wu, D. L. Guyton, “Modeling and minimizing interference from corneal birefringence in retinal birefringence scanning for foveal fixation detection,” Biomed. Opt. Express 2(7), 1955–1968 (2011).
[CrossRef] [PubMed]

Kim, J. H.

D. H. Yoo, J. H. Kim, B. R. Lee, M. J. Chung, “Non-contact eye gaze tracking system by mapping of corneal reflections,” in Proc. Internat. Conf. on Automatic Face and Gesture Recognition (2002), pp. 94–99.

Klein Brink, H. B.

Knighton, R. W.

R. W. Knighton, X. R. Huang, “Linear birefringence of the central human cornea,” Invest. Ophthalmol. Vis. Sci. 43(1), 82–86 (2002).
[PubMed]

Lee, B. R.

D. H. Yoo, J. H. Kim, B. R. Lee, M. J. Chung, “Non-contact eye gaze tracking system by mapping of corneal reflections,” in Proc. Internat. Conf. on Automatic Face and Gesture Recognition (2002), pp. 94–99.

Liu, J.

S. Shih, J. Liu, “A novel approach to 3D gaze tracking using stereo cameras,” IEEE Trans. Syst. Man Cybern. (Part B3), 1–12 (2003).

Loudon, S. E.

S. E. Loudon, C. A. Rook, D. S. Nassif, N. V. Piskun, D. G. Hunter, “Rapid, high-accuracy detection of strabismus and amblyopia using the pediatric vision scanner,” Invest. Ophthalmol. Vis. Sci. 52(8), 5043–5048 (2011).
[CrossRef] [PubMed]

Magill, J. C.

Miller, J. M.

J. M. Miller, H. L. Hall, J. E. Greivenkamp, D. L. Guyton, “Quantification of the Brückner Test for Strabismus,” Invest. Ophthalmol. Vis. Sci. 36, 897–905 (1995).
[PubMed]

Mimica, M. R. M.

C. H. Moriomto, M. R. M. Mimica, “Eye gaze tracking techniques for interactive applications,” Comput. Vis. Image Underst. 98(1), 4–24 (2005).
[CrossRef]

Møller, F.

F. Møller, A. K. Sjølie, T. Bek, “Quantitative assessment of fixational eye movements by scanning laser ophthalmoscopy,” Acta Ophthalmol. Scand. 74(6), 578–583 (1996).
[CrossRef] [PubMed]

Moriomto, C. H.

C. H. Moriomto, M. R. M. Mimica, “Eye gaze tracking techniques for interactive applications,” Comput. Vis. Image Underst. 98(1), 4–24 (2005).
[CrossRef]

Müllenbroich, M.

B. Gramatikov, K. Irsch, M. Müllenbroich, N. Frindt, Y. Qu, R. Gutmark, Y. K. Wu, D. Guyton, “A device for continuous monitoring of true central fixation based on foveal birefringence,” Ann. Biomed. Eng. 41(9), 1968–1978 (2013).
[CrossRef] [PubMed]

Nassif, D.

Nassif, D. S.

S. E. Loudon, C. A. Rook, D. S. Nassif, N. V. Piskun, D. G. Hunter, “Rapid, high-accuracy detection of strabismus and amblyopia using the pediatric vision scanner,” Invest. Ophthalmol. Vis. Sci. 52(8), 5043–5048 (2011).
[CrossRef] [PubMed]

D. S. Nassif, N. V. Piskun, D. G. Hunter, “The Pediatric Vision Screener III: Detection of Strabismus in Children,” Arch. Ophthalmol. 124(4), 509–513 (2006).
[CrossRef] [PubMed]

D. G. Hunter, D. S. Nassif, N. V. Piskun, R. Winsor, B. I. Gramatikov, D. L. Guyton, “Pediatric Vision Screener 1: Instrument design and operation,” J. Biomed. Opt. 9(6), 1363–1368 (2004).
[CrossRef] [PubMed]

D. S. Nassif, N. V. Piskun, B. I. Gramatikov, D. L. Guyton, D. G. Hunter, “Pediatric Vision Screener 2: Pilot study in adults,” J. Biomed. Opt. 9(6), 1369–1374 (2004).
[CrossRef] [PubMed]

Nusz, K. J.

D. G. Hunter, K. J. Nusz, N. K. Gandhi, I. H. Quraishi, B. I. Gramatikov, D. L. Guyton, “Automated detection of ocular focus,” J. Biomed. Opt. 9(5), 1103–1109 (2004).
[CrossRef] [PubMed]

Patel, S. N.

Pelz, B. C. E.

B. C. E. Pelz, C. Weschenmoser, S. Goelz, J. P. Fischer, R. O. W. Burk, J. F. Bille, “In vivo measurement of the retinal birefringence with regard on corneal effects using an electro-optical ellipsometer,” Proc. SPIE 2930, 92–101 (1996).
[CrossRef]

Piskun, N. V.

S. E. Loudon, C. A. Rook, D. S. Nassif, N. V. Piskun, D. G. Hunter, “Rapid, high-accuracy detection of strabismus and amblyopia using the pediatric vision scanner,” Invest. Ophthalmol. Vis. Sci. 52(8), 5043–5048 (2011).
[CrossRef] [PubMed]

D. S. Nassif, N. V. Piskun, D. G. Hunter, “The Pediatric Vision Screener III: Detection of Strabismus in Children,” Arch. Ophthalmol. 124(4), 509–513 (2006).
[CrossRef] [PubMed]

D. S. Nassif, N. V. Piskun, B. I. Gramatikov, D. L. Guyton, D. G. Hunter, “Pediatric Vision Screener 2: Pilot study in adults,” J. Biomed. Opt. 9(6), 1369–1374 (2004).
[CrossRef] [PubMed]

D. G. Hunter, D. S. Nassif, N. V. Piskun, R. Winsor, B. I. Gramatikov, D. L. Guyton, “Pediatric Vision Screener 1: Instrument design and operation,” J. Biomed. Opt. 9(6), 1363–1368 (2004).
[CrossRef] [PubMed]

Qu, Y.

B. Gramatikov, K. Irsch, M. Müllenbroich, N. Frindt, Y. Qu, R. Gutmark, Y. K. Wu, D. Guyton, “A device for continuous monitoring of true central fixation based on foveal birefringence,” Ann. Biomed. Eng. 41(9), 1968–1978 (2013).
[CrossRef] [PubMed]

Quraishi, I. H.

D. G. Hunter, K. J. Nusz, N. K. Gandhi, I. H. Quraishi, B. I. Gramatikov, D. L. Guyton, “Automated detection of ocular focus,” J. Biomed. Opt. 9(5), 1103–1109 (2004).
[CrossRef] [PubMed]

Reiter, K.

Rook, C. A.

S. E. Loudon, C. A. Rook, D. S. Nassif, N. V. Piskun, D. G. Hunter, “Rapid, high-accuracy detection of strabismus and amblyopia using the pediatric vision scanner,” Invest. Ophthalmol. Vis. Sci. 52(8), 5043–5048 (2011).
[CrossRef] [PubMed]

Roorda, A.

Sandruck, J. C.

Sau, S.

Schnipke, S. K.

S. K. Schnipke, M. W. Todd, “Trials and tribulations of using an eye-tracking system,” in Proc. ACM SIGCHI – Human Factors in Computing Systems Conference (2000), pp. 273–274.
[CrossRef]

Shah, A. A.

K. Irsch, A. A. Shah, “Birefringence of the central cornea in children assessed with scanning laser polarimetry,” J. Biomed. Opt. 17(8), 086001 (2012).
[CrossRef] [PubMed]

Shah, A. S.

Sheehy, C. K.

Sheena, D.

L. R. Young, D. Sheena, “Survey of eye movement recording methods,” Behav. Res. Meth. Instrum. 7(5), 397–429 (1975).
[CrossRef]

Shih, S.

S. Shih, J. Liu, “A novel approach to 3D gaze tracking using stereo cameras,” IEEE Trans. Syst. Man Cybern. (Part B3), 1–12 (2003).

Sjølie, A. K.

F. Møller, A. K. Sjølie, T. Bek, “Quantitative assessment of fixational eye movements by scanning laser ophthalmoscopy,” Acta Ophthalmol. Scand. 74(6), 578–583 (1996).
[CrossRef] [PubMed]

Tiruveedhula, P.

Todd, M. W.

S. K. Schnipke, M. W. Todd, “Trials and tribulations of using an eye-tracking system,” in Proc. ACM SIGCHI – Human Factors in Computing Systems Conference (2000), pp. 273–274.
[CrossRef]

Van Blokland, G. J.

Webb, R. H.

Weinreb, R. N.

Q. Zhou, R. N. Weinreb, “Individualized compensation of anterior segment birefringence during scanning laser polarimetry,” Invest. Ophthalmol. Vis. Sci. 43(7), 2221–2228 (2002).
[PubMed]

R. N. Weinreb, C. Bowd, D. S. Greenfield, L. M. Zangwill, “Measurement of the magnitude and axis of corneal polarization with scanning laser polarimetry,” Arch. Ophthalmol. 120(7), 901–906 (2002).
[CrossRef] [PubMed]

A. W. Dreher, K. Reiter, R. N. Weinreb, “Spatially resolved birefringence of the retinal nerve fiber layer assessed with a retinal laser ellipsometer,” Appl. Opt. 31(19), 3730–3735 (1992).
[CrossRef] [PubMed]

Weschenmoser, C.

B. C. E. Pelz, C. Weschenmoser, S. Goelz, J. P. Fischer, R. O. W. Burk, J. F. Bille, “In vivo measurement of the retinal birefringence with regard on corneal effects using an electro-optical ellipsometer,” Proc. SPIE 2930, 92–101 (1996).
[CrossRef]

White, M. A.

Winsor, R.

D. G. Hunter, D. S. Nassif, N. V. Piskun, R. Winsor, B. I. Gramatikov, D. L. Guyton, “Pediatric Vision Screener 1: Instrument design and operation,” J. Biomed. Opt. 9(6), 1363–1368 (2004).
[CrossRef] [PubMed]

Wu, Y. K.

B. Gramatikov, K. Irsch, M. Müllenbroich, N. Frindt, Y. Qu, R. Gutmark, Y. K. Wu, D. Guyton, “A device for continuous monitoring of true central fixation based on foveal birefringence,” Ann. Biomed. Eng. 41(9), 1968–1978 (2013).
[CrossRef] [PubMed]

B. I. Gramatikov, O. H. Y. Zalloum, Y. K. Wu, D. G. Hunter, D. L. Guyton, “Directional eye fixation sensor using birefringence-based foveal detection,” Appl. Opt. 46(10), 1809–1818 (2007).
[CrossRef] [PubMed]

B. I. Gramatikov, O. H. Y. Zalloum, Y. K. Wu, D. G. Hunter, D. L. Guyton, “Birefringence-based eye fixation monitor with no moving parts,” J. Biomed. Opt. 11(3), 034025 (2006).
[CrossRef] [PubMed]

Wu, Y.-K.

Yang, Q.

Yoo, D. H.

D. H. Yoo, M. J. Chung, “A novel non-intrusive eye gaze estimation using cross-ratio under large head motion,” Comput. Vis. Image Underst. 98(1), 25–51 (2005).
[CrossRef]

D. H. Yoo, J. H. Kim, B. R. Lee, M. J. Chung, “Non-contact eye gaze tracking system by mapping of corneal reflections,” in Proc. Internat. Conf. on Automatic Face and Gesture Recognition (2002), pp. 94–99.

Young, L. R.

L. R. Young, D. Sheena, “Survey of eye movement recording methods,” Behav. Res. Meth. Instrum. 7(5), 397–429 (1975).
[CrossRef]

Zalloum, O. H. Y.

B. I. Gramatikov, O. H. Y. Zalloum, Y. K. Wu, D. G. Hunter, D. L. Guyton, “Directional eye fixation sensor using birefringence-based foveal detection,” Appl. Opt. 46(10), 1809–1818 (2007).
[CrossRef] [PubMed]

B. I. Gramatikov, O. H. Y. Zalloum, Y. K. Wu, D. G. Hunter, D. L. Guyton, “Birefringence-based eye fixation monitor with no moving parts,” J. Biomed. Opt. 11(3), 034025 (2006).
[CrossRef] [PubMed]

Zangwill, L. M.

R. N. Weinreb, C. Bowd, D. S. Greenfield, L. M. Zangwill, “Measurement of the magnitude and axis of corneal polarization with scanning laser polarimetry,” Arch. Ophthalmol. 120(7), 901–906 (2002).
[CrossRef] [PubMed]

Zhou, Q.

Q. Zhou, R. N. Weinreb, “Individualized compensation of anterior segment birefringence during scanning laser polarimetry,” Invest. Ophthalmol. Vis. Sci. 43(7), 2221–2228 (2002).
[PubMed]

Acta Ophthalmol. Scand. (1)

F. Møller, A. K. Sjølie, T. Bek, “Quantitative assessment of fixational eye movements by scanning laser ophthalmoscopy,” Acta Ophthalmol. Scand. 74(6), 578–583 (1996).
[CrossRef] [PubMed]

Ann. Biomed. Eng. (1)

B. Gramatikov, K. Irsch, M. Müllenbroich, N. Frindt, Y. Qu, R. Gutmark, Y. K. Wu, D. Guyton, “A device for continuous monitoring of true central fixation based on foveal birefringence,” Ann. Biomed. Eng. 41(9), 1968–1978 (2013).
[CrossRef] [PubMed]

Appl. Opt. (5)

Arch. Ophthalmol. (2)

R. N. Weinreb, C. Bowd, D. S. Greenfield, L. M. Zangwill, “Measurement of the magnitude and axis of corneal polarization with scanning laser polarimetry,” Arch. Ophthalmol. 120(7), 901–906 (2002).
[CrossRef] [PubMed]

D. S. Nassif, N. V. Piskun, D. G. Hunter, “The Pediatric Vision Screener III: Detection of Strabismus in Children,” Arch. Ophthalmol. 124(4), 509–513 (2006).
[CrossRef] [PubMed]

Behav. Res. Meth. Instrum. (1)

L. R. Young, D. Sheena, “Survey of eye movement recording methods,” Behav. Res. Meth. Instrum. 7(5), 397–429 (1975).
[CrossRef]

Behav. Res. Methods Instrum. Comput. (1)

A. T. Duchowski, “A breadth-first survey of eye-tracking applications,” Behav. Res. Methods Instrum. Comput. 34(4), 455–470 (2002).
[CrossRef] [PubMed]

Biomed. Eng. Online (1)

B. I. Gramatikov, “Detecting fixation on a target using time-frequency distributions of a retinal birefringence scanning signal,” Biomed. Eng. Online 12(1), 41 (2013).
[CrossRef] [PubMed]

Biomed. Opt. Express (2)

Comput. Vis. Image Underst. (2)

D. H. Yoo, M. J. Chung, “A novel non-intrusive eye gaze estimation using cross-ratio under large head motion,” Comput. Vis. Image Underst. 98(1), 25–51 (2005).
[CrossRef]

C. H. Moriomto, M. R. M. Mimica, “Eye gaze tracking techniques for interactive applications,” Comput. Vis. Image Underst. 98(1), 4–24 (2005).
[CrossRef]

Invest. Ophthalmol. Vis. Sci. (4)

S. E. Loudon, C. A. Rook, D. S. Nassif, N. V. Piskun, D. G. Hunter, “Rapid, high-accuracy detection of strabismus and amblyopia using the pediatric vision scanner,” Invest. Ophthalmol. Vis. Sci. 52(8), 5043–5048 (2011).
[CrossRef] [PubMed]

R. W. Knighton, X. R. Huang, “Linear birefringence of the central human cornea,” Invest. Ophthalmol. Vis. Sci. 43(1), 82–86 (2002).
[PubMed]

J. M. Miller, H. L. Hall, J. E. Greivenkamp, D. L. Guyton, “Quantification of the Brückner Test for Strabismus,” Invest. Ophthalmol. Vis. Sci. 36, 897–905 (1995).
[PubMed]

Q. Zhou, R. N. Weinreb, “Individualized compensation of anterior segment birefringence during scanning laser polarimetry,” Invest. Ophthalmol. Vis. Sci. 43(7), 2221–2228 (2002).
[PubMed]

J. Biomed. Opt. (5)

D. G. Hunter, K. J. Nusz, N. K. Gandhi, I. H. Quraishi, B. I. Gramatikov, D. L. Guyton, “Automated detection of ocular focus,” J. Biomed. Opt. 9(5), 1103–1109 (2004).
[CrossRef] [PubMed]

K. Irsch, A. A. Shah, “Birefringence of the central cornea in children assessed with scanning laser polarimetry,” J. Biomed. Opt. 17(8), 086001 (2012).
[CrossRef] [PubMed]

D. G. Hunter, D. S. Nassif, N. V. Piskun, R. Winsor, B. I. Gramatikov, D. L. Guyton, “Pediatric Vision Screener 1: Instrument design and operation,” J. Biomed. Opt. 9(6), 1363–1368 (2004).
[CrossRef] [PubMed]

D. S. Nassif, N. V. Piskun, B. I. Gramatikov, D. L. Guyton, D. G. Hunter, “Pediatric Vision Screener 2: Pilot study in adults,” J. Biomed. Opt. 9(6), 1369–1374 (2004).
[CrossRef] [PubMed]

B. I. Gramatikov, O. H. Y. Zalloum, Y. K. Wu, D. G. Hunter, D. L. Guyton, “Birefringence-based eye fixation monitor with no moving parts,” J. Biomed. Opt. 11(3), 034025 (2006).
[CrossRef] [PubMed]

J. Opt. Soc. Am. A (2)

Proc. SPIE (1)

B. C. E. Pelz, C. Weschenmoser, S. Goelz, J. P. Fischer, R. O. W. Burk, J. F. Bille, “In vivo measurement of the retinal birefringence with regard on corneal effects using an electro-optical ellipsometer,” Proc. SPIE 2930, 92–101 (1996).
[CrossRef]

Other (12)

D. L. Sliney and M. Wolbarsht, Safety with Lasers and Other Optical Sources (Plenum Press, 1980), pp. 261–271.

G. F. J. Garlick, G. A. Steigmann, and W. E. Lamb, “Differential optical polarization detectors,” U.S. Patent No. 3,992,571 (1976).

Q. Zhou, “System and method for determining birefringence of anterior segment of the patient's eye,” U.S. Patent No. 6,356,036 (2002).

D. Beymer, M. Flickner, “Eye gaze tracking using an active stereo head,” in Proc. IEEE Conference on Computer Vision and Pattern Recognition (2003), pp. 451–458.
[CrossRef]

S. Shih, J. Liu, “A novel approach to 3D gaze tracking using stereo cameras,” IEEE Trans. Syst. Man Cybern. (Part B3), 1–12 (2003).

D. H. Yoo, J. H. Kim, B. R. Lee, M. J. Chung, “Non-contact eye gaze tracking system by mapping of corneal reflections,” in Proc. Internat. Conf. on Automatic Face and Gesture Recognition (2002), pp. 94–99.

A. T. Duchowski, Eye Tracking Methodology: Theory and Practice, 2nd ed. (Springer, 2007).

Tobii Technology AB, Danderyd, Sweden. www.tobii.se (2013).

SensoMotoric Instruments GmbH (SMI), Teltow, Germany. www.smi.de (2013).

Applied Science Laboratories, Bedford, MA. http://www.cis.rit.edu/people/faculty/pelz/research/manuals/asl_504_manual.pdf

S. K. Schnipke, M. W. Todd, “Trials and tribulations of using an eye-tracking system,” in Proc. ACM SIGCHI – Human Factors in Computing Systems Conference (2000), pp. 273–274.
[CrossRef]

D. L. Guyton, D. G. Hunter, S. N. Patel, J. C. Sandruck, and R. L. Fry, “Eye fixation monitor and tracker,” U.S. Patent No. 6,027,216 (2000).

Cited By

OSA participates in CrossRef's Cited-By Linking service. Citing articles from OSA journals and other participating publishers are listed here.

Alert me when this article is cited.


Figures (8)

Fig. 1
Fig. 1

Conventional RBS approach to eye-fixation detection. a, Schematic illustration of RBS, showing circular scan of polarized light and its centration on the fovea, and on the radially arrayed birefringent Henle fibers surrounding the fovea, with the eye fixating at the center of the scan. b, Conventional dual-photodetector RBS system for differential polarization detection. Linearly polarized light is emitted by a laser diode (LD), then 50% is reflected by a non-polarizing beam splitter (NPBS) towards the scanner, which consists of two plane mirrors that are spun about the optical axis by a motor (not shown) to create a circular scan on the subject’s retina. On the return pass, 50% of the polarization-altered light passes towards the differential polarization detection unit consisting of a polarizing beam splitter (PBS) and two photodetectors. The polarization component in the plane of the diagram is transmitted to the upper detector (#2), whereas the polarization component perpendicular to the plane of the diagram is reflected to the lower detector (#1). The lower signal is subtracted from the upper signal, yielding the differential polarization signal. c, Circular scan of the retina during central fixation (corneal birefringence neglected). The 360° scan in this figure begins at the 9-o’clock position (black curved arrow). RBS signal maxima occur whenever the azimuth of the linearly-polarized incident light (double-ended arrows) is 45° to the orientation of the nerve fibers (at locations 1, 2, 3 and 4). RBS signal minima occur when the axis of polarization is perpendicular or parallel to the orientation of the nerve fibers. Thus, the polarization-related changes arising from the retina occur at a characteristic frequency component that is 4 times the frequency of the scan.

Fig. 2
Fig. 2

Polarization-modulated RBS approach to eye-fixation detection. a, Circular scan of the retina during central fixation (corneal birefringence neglected). With the HWP spinning 1/16th as fast as the circular scan, the azimuth of linear polarization (double-ended arrows) incident on the radially-arrayed retinal Henle fibers changes continuously as the scan progresses. The 360° scan in this figure begins at the 9-o’clock position (black curved arrow). During one revolution of the scan, the fast axis of the HWP rotates 1/16th of 360° from 0° to 22.5°, causing the incident polarization axis to rotate at twice the angle of HWP rotation (that is, a total of 45°). RBS signal maxima occur whenever the azimuth of the linearly-polarized incident light is 45° to the orientation of the nerve fibers (at locations 1, 2, 3 and 4). RBS signal minima occur when the axis of polarization is perpendicular or parallel to the orientation of the nerve fibers. Thus, by spinning the HWP 1/16th as fast as the scan, the polarization-related changes arising from the retina occur at a characteristic half-multiple frequency component that is 3.5f. b, Our single-photodetector RBS approach that employs a spinning HWP. The non-polarizing beam splitter (NPBS) and one of the two detectors present in Fig. 1(b) have been eliminated. Linearly-polarized light emitted by the laser diode (LD) has its axis of polarization perpendicular to the plane of the diagram and is reflected towards the eye by the polarizing beam splitter (PBS). After the PBS, the beam passes through the spinning HWP and enters the scanner, which creates a circular scan on the subject’s retina. On the return pass, the PBS separates the polarization-altered light into two orthogonally-polarized components. The polarization component in the plane of the diagram is transmitted to the detector, and the polarization component perpendicular to the plane of the diagram is reflected back to the LD.

Fig. 3
Fig. 3

Simulated results using a single-photodetector RBS system with an HWP spinning at (9/16)f. Differential RBS-signal strength at 2.5f (with a minor contribution at 6.5f for eyes with high corneal retardance) is shown in relative power units as a function of CR and CA during simulated central fixation. For demonstration purposes, the RBS-signal strengths at the two center frequencies are added (FFT2.5f + FFT6.5f). The right and left eyes from the available data set are shown as black dots on the surface of the 3D-plot.

Fig. 4
Fig. 4

Optimization results. Contour plot of the normalized standard deviation of RBS-signal strengths at the central fixation frequencies times that of the spin-generated frequency, (SD/mean)[2.5f + 6.5f] x (SD/mean)[4.5f], for the 644 “eyes” in the data set, shown as a function of retardance and azimuth (fast-axis orientation) of the double-pass wave plate, with contours plotted only below a level of 0.1. The wave plate properties were varied with an incremental resolution of 10°.

Fig. 5
Fig. 5

Simulated results using the polarization-modulated technique; HWP spinning at (9/16)f and fixed 74° wave plate at 90°. a-d, RBS-signal strength as a function of CR in nm and CA in degrees during simulated central fixation. The differential RBS-signal strength is plotted (in relative power units) at the two frequencies that indicate central fixation: 2.5f (a; predominant for the majority of people, who have lower relative CR) and 6.5f (b; predominant for a minority of people, who have higher relative CR). The behavior at these individual frequencies reverses when a 106° wave plate at 0° is used instead, such that the data in a and b would then represent the RBS-signal strengths at 6.5f and 2.5f, respectively. c, For demonstration purposes, the RBS-signal strengths at the two central fixation frequencies are added (FFT2.5f + FFT6.5f) to show that by considering both frequencies in the analysis, excellent coverage is obtained of all the varying CR and CA values that occur in the population. d, Differential RBS-signal strength (in relative power units) at 4.5f (the spin-generated frequency). The black dots superimposed on the 3D-plots represent the signal strengths for specific CR and CA values for the eyes from the data set. e-f, Spatial dependency of RBS-signal strength. The differential RBS-signal strength for a typical right eye (CR = 39 nm, CA = 70°) is plotted e, at the frequencies indicating foveal fixation (FFT2.5f + FFT6.5f) and f, at the 4.5f spin-generated frequency in relative power units. Signal strength is plotted as a function of the horizontal and vertical distance from the foveal center, where distance is expressed in degrees of visual angle. g, The differential RBS-signal strength during simulated paracentral fixation (1.5° away from the foveal center) is plotted at the two paracentral fixation frequencies (FFT3.5f + FFT5.5f) in relative power units. The signal strength is plotted as a function of CR and CA.

Fig. 6
Fig. 6

Experimental validation set-up, implementing the polarization-modulated technique; HWP spinning at (9/16)f and fixed 106° wave plate at 0°. LD1, main 785-nm laser diode; PBS, polarizing beam splitter; HWP, half wave plate; M1 and M2, two gold-plated mirrors constituting the scanning unit; WP, 106° retarder with its fast axis oriented horizontally (0° azimuth); LD2, 690-nm laser diode used as a fixation target; P, knife-edge reflecting prism; PD1 and PD2, two photodetectors, one for each eye, constituting the photodetector assembly. Note that the eyes and the photodetector assembly have been rotated 90° about the optical axis for clarity of illustration.

Fig. 7
Fig. 7

Experimental results from human eyes: Proof-of-concept in emmetropic eyes (with no refractive error). a, FFT power spectrum of a 29-year-old’s emmetropic left eye (CR = 37 nm, CA = 104°) during central fixation on the blinking light and during paracentral fixation 1.5° away from the center on the edge of the red scanning circle. b, FFT power spectrum with and without 360°-phase-shift subtraction. c, FFT power specta showing very low noise levels with eyes closed and with no subject in front of the system. d-e, Spatial distribution of (FFT2.5f + FFT6.5f)/FFT4.5f from the 29-year-old’s emmetropic right eye (CR = 34 nm, CA = 77°).

Fig. 8
Fig. 8

Experimental results from human eyes: Robustness demonstration in sub-optimal eyes. FFT power spectrum from a 67-year-old presbyopic individual (right eye: CR = 22 nm, CA = 61°; left eye: CR = 33 nm, CA = 129°) with essentially no focusing ability and mild bilateral nuclear sclerotic cataracts, measured through corrective lenses, during central fixation.

Equations (6)

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

θ HWP =(2n+1) θ r 16 =(2n+1) ω r t 16 =(2n+1) 2πft 16
S out = M HWP(out) ( δ HWP , θ HWP ) M cornea(out) (CR,CA) M retina(out) ( δ r , θ r ) M fundus ... M retina(in) ( δ r , θ r ) M cornea(in) (CR,CA) M HWP(in) ( δ HWP , θ HWP ) S in
S out = M HWP(out) ( δ HWP , θ HWP ) M WP(out) ( δ WP , θ WP ) M cornea(out) (CR,CA)... M retina(out) ( δ r , θ r ) M fundus M retina(in) ( δ r , θ r ) M cornea(in) (CR,CA)... M WP(in) ( δ WP , θ WP ) M HWP(in) ( δ HWP , θ HWP ) S in
Min[ SD mean [ FF T 2.5f +FF T 6.5f ] SD mean [ FFT 4.5f ] ]
δ r =( i=1 2 e r τ i )( i=3 5 ( 1 e r τ i ) )
θ r = tan 1 ( Rsin(φ)+ y ret Rcos(φ)+ x ret )+90°

Metrics