Abstract

This paper presents optical coherence tomography (OCT) signal intensity variation based segmentation algorithms for retinal layer identification. Its main ambition is to reduce the calculation time required by layer identification algorithms. Two algorithms, one for the identification of the internal limiting membrane (ILM) and the other for retinal pigment epithelium (RPE) identification are implemented to evaluate structural features of the retina. Using a 830 nm spectral domain OCT device, this paper demonstrates a segmentation method for the study of healthy and diseased eyes.

© 2009 Optical Society of America

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  1. D. Koozekanani, K. Boyer, and C. Roberts, "Retinal thickness measurements from optical coherence tomography using a Markov boundary model," IEEE Trans. Med. Imaging 20,900-916 (2001).
    [PubMed]
  2. H. Ishikawa, D.M. Stein, G. Wollstein, S. Beaton, J.G. Fujimoto, and J.S. Schuman, "Macular segmentation with optical coherence tomography," Investigative Ophthalmol. Visual Scie. 46,2012-2017 (2005).
  3. M. Mujat, R. C. Chan, B. Cense, B. H. Park, C. Joo, T. Akkin, T. C. Chen, and J. F. de Boer, "Retinal nerve fiber layer thickness map determined from optical coherence tomography images," Opt. Express 13,9480-9491 (2005).
    [PubMed]
  4. M. Szkulmowski, M. Wojtkowski, B. Sikorski, T. Bajraszewski, V. J. Srinivasan, A. Szkulmowska, J. J. Kaluzny, J. G. Fujimoto, and A. Kowalczyk, "Analysis of posterior retinal layers in spectral optical coherence tomography images of the normal retina and retinal pathologies," J. Biomed. Opt. 12, (2007).
    [PubMed]
  5. D. C. Fernandez, H. M. Salinas, and C. A. Puliafito, "Automated detection of retinal layer structures on optical coherence tomography images," Opt. Express 13,200-216 (2005).
  6. M. Baroni, P. Fortunato, and A. L. Torre, "Towards quantitative analysis of retinal features in optical coherence tomography," Med. Engin. Phys. 29,432-441 (2007).
  7. E. G¨otzinger, M. Pircher, W. Geitzenauer, C. Ahlers, B. Baumann, S. Michels, U. Schmidt-Erfurth, and C. K. Hitzenberger, "Retinal pigment epithelium segmentation by polarization sensitive optical coherence tomography," Opt. Express 16,16410-16422 (2008).
    [PubMed]
  8. M. Zeng, J. Li and P. Zhang "The design of Top-Hat morphological filter and application to infrared target detection," Infr. Phys. Technol. 48,67-76 (2006).
  9. N. Otsu "A threshold selection method from gray-level histograms," IEEE Trans. Syst. Man Cyber. 9,62-66 (1979).
  10. S. Makita, Y.J. Hong, M. Yamanari, T. Yatagai, and Y. Yasuno, "Optical coherence angiography," Opt. Express 17,7821-7840 (2006).
  11. A. Misota, T. Sakuma, O. Miyauchi,M. Honda, and M. Tanaka, "Measurement of retinal thickness fromthe threedimensional images obtained from C scan images from the optical coherence tomography ophthalmoscope," Clinical and Experimental Ophthalmology 35,220-224 (2007).
  12. S. H. M. Liew, C. E. Gilbert, T. D. Spector, J. Mellerio, F. J. Van Kuijk, S. Beatty, F. Fitzke, J. Marshall, and C. J. Hammond, "Central retinal thickness is positively correlated with macular pigment optical density," Experimental Eye Research 82,915-920 (2006).

2008

2007

M. Szkulmowski, M. Wojtkowski, B. Sikorski, T. Bajraszewski, V. J. Srinivasan, A. Szkulmowska, J. J. Kaluzny, J. G. Fujimoto, and A. Kowalczyk, "Analysis of posterior retinal layers in spectral optical coherence tomography images of the normal retina and retinal pathologies," J. Biomed. Opt. 12, (2007).
[PubMed]

M. Baroni, P. Fortunato, and A. L. Torre, "Towards quantitative analysis of retinal features in optical coherence tomography," Med. Engin. Phys. 29,432-441 (2007).

A. Misota, T. Sakuma, O. Miyauchi,M. Honda, and M. Tanaka, "Measurement of retinal thickness fromthe threedimensional images obtained from C scan images from the optical coherence tomography ophthalmoscope," Clinical and Experimental Ophthalmology 35,220-224 (2007).

2006

S. H. M. Liew, C. E. Gilbert, T. D. Spector, J. Mellerio, F. J. Van Kuijk, S. Beatty, F. Fitzke, J. Marshall, and C. J. Hammond, "Central retinal thickness is positively correlated with macular pigment optical density," Experimental Eye Research 82,915-920 (2006).

M. Zeng, J. Li and P. Zhang "The design of Top-Hat morphological filter and application to infrared target detection," Infr. Phys. Technol. 48,67-76 (2006).

S. Makita, Y.J. Hong, M. Yamanari, T. Yatagai, and Y. Yasuno, "Optical coherence angiography," Opt. Express 17,7821-7840 (2006).

2005

D. C. Fernandez, H. M. Salinas, and C. A. Puliafito, "Automated detection of retinal layer structures on optical coherence tomography images," Opt. Express 13,200-216 (2005).

H. Ishikawa, D.M. Stein, G. Wollstein, S. Beaton, J.G. Fujimoto, and J.S. Schuman, "Macular segmentation with optical coherence tomography," Investigative Ophthalmol. Visual Scie. 46,2012-2017 (2005).

M. Mujat, R. C. Chan, B. Cense, B. H. Park, C. Joo, T. Akkin, T. C. Chen, and J. F. de Boer, "Retinal nerve fiber layer thickness map determined from optical coherence tomography images," Opt. Express 13,9480-9491 (2005).
[PubMed]

2001

D. Koozekanani, K. Boyer, and C. Roberts, "Retinal thickness measurements from optical coherence tomography using a Markov boundary model," IEEE Trans. Med. Imaging 20,900-916 (2001).
[PubMed]

1979

N. Otsu "A threshold selection method from gray-level histograms," IEEE Trans. Syst. Man Cyber. 9,62-66 (1979).

Ahlers, C.

Akkin, T.

Bajraszewski, T.

M. Szkulmowski, M. Wojtkowski, B. Sikorski, T. Bajraszewski, V. J. Srinivasan, A. Szkulmowska, J. J. Kaluzny, J. G. Fujimoto, and A. Kowalczyk, "Analysis of posterior retinal layers in spectral optical coherence tomography images of the normal retina and retinal pathologies," J. Biomed. Opt. 12, (2007).
[PubMed]

Baroni, M.

M. Baroni, P. Fortunato, and A. L. Torre, "Towards quantitative analysis of retinal features in optical coherence tomography," Med. Engin. Phys. 29,432-441 (2007).

Baumann, B.

Beaton, S.

H. Ishikawa, D.M. Stein, G. Wollstein, S. Beaton, J.G. Fujimoto, and J.S. Schuman, "Macular segmentation with optical coherence tomography," Investigative Ophthalmol. Visual Scie. 46,2012-2017 (2005).

Beatty, S.

S. H. M. Liew, C. E. Gilbert, T. D. Spector, J. Mellerio, F. J. Van Kuijk, S. Beatty, F. Fitzke, J. Marshall, and C. J. Hammond, "Central retinal thickness is positively correlated with macular pigment optical density," Experimental Eye Research 82,915-920 (2006).

Boyer, K.

D. Koozekanani, K. Boyer, and C. Roberts, "Retinal thickness measurements from optical coherence tomography using a Markov boundary model," IEEE Trans. Med. Imaging 20,900-916 (2001).
[PubMed]

Cense, B.

Chan, R. C.

Chen, T. C.

de Boer, J. F.

Fernandez, D. C.

D. C. Fernandez, H. M. Salinas, and C. A. Puliafito, "Automated detection of retinal layer structures on optical coherence tomography images," Opt. Express 13,200-216 (2005).

Fitzke, F.

S. H. M. Liew, C. E. Gilbert, T. D. Spector, J. Mellerio, F. J. Van Kuijk, S. Beatty, F. Fitzke, J. Marshall, and C. J. Hammond, "Central retinal thickness is positively correlated with macular pigment optical density," Experimental Eye Research 82,915-920 (2006).

Fortunato, P.

M. Baroni, P. Fortunato, and A. L. Torre, "Towards quantitative analysis of retinal features in optical coherence tomography," Med. Engin. Phys. 29,432-441 (2007).

Fujimoto, J. G.

M. Szkulmowski, M. Wojtkowski, B. Sikorski, T. Bajraszewski, V. J. Srinivasan, A. Szkulmowska, J. J. Kaluzny, J. G. Fujimoto, and A. Kowalczyk, "Analysis of posterior retinal layers in spectral optical coherence tomography images of the normal retina and retinal pathologies," J. Biomed. Opt. 12, (2007).
[PubMed]

Fujimoto, J.G.

H. Ishikawa, D.M. Stein, G. Wollstein, S. Beaton, J.G. Fujimoto, and J.S. Schuman, "Macular segmentation with optical coherence tomography," Investigative Ophthalmol. Visual Scie. 46,2012-2017 (2005).

G¨otzinger, E.

Geitzenauer, W.

Gilbert, C. E.

S. H. M. Liew, C. E. Gilbert, T. D. Spector, J. Mellerio, F. J. Van Kuijk, S. Beatty, F. Fitzke, J. Marshall, and C. J. Hammond, "Central retinal thickness is positively correlated with macular pigment optical density," Experimental Eye Research 82,915-920 (2006).

Hammond, C. J.

S. H. M. Liew, C. E. Gilbert, T. D. Spector, J. Mellerio, F. J. Van Kuijk, S. Beatty, F. Fitzke, J. Marshall, and C. J. Hammond, "Central retinal thickness is positively correlated with macular pigment optical density," Experimental Eye Research 82,915-920 (2006).

Hitzenberger, C. K.

Honda, M.

A. Misota, T. Sakuma, O. Miyauchi,M. Honda, and M. Tanaka, "Measurement of retinal thickness fromthe threedimensional images obtained from C scan images from the optical coherence tomography ophthalmoscope," Clinical and Experimental Ophthalmology 35,220-224 (2007).

Hong, Y.J.

S. Makita, Y.J. Hong, M. Yamanari, T. Yatagai, and Y. Yasuno, "Optical coherence angiography," Opt. Express 17,7821-7840 (2006).

Ishikawa, H.

H. Ishikawa, D.M. Stein, G. Wollstein, S. Beaton, J.G. Fujimoto, and J.S. Schuman, "Macular segmentation with optical coherence tomography," Investigative Ophthalmol. Visual Scie. 46,2012-2017 (2005).

Joo, C.

Kaluzny, J. J.

M. Szkulmowski, M. Wojtkowski, B. Sikorski, T. Bajraszewski, V. J. Srinivasan, A. Szkulmowska, J. J. Kaluzny, J. G. Fujimoto, and A. Kowalczyk, "Analysis of posterior retinal layers in spectral optical coherence tomography images of the normal retina and retinal pathologies," J. Biomed. Opt. 12, (2007).
[PubMed]

Koozekanani, D.

D. Koozekanani, K. Boyer, and C. Roberts, "Retinal thickness measurements from optical coherence tomography using a Markov boundary model," IEEE Trans. Med. Imaging 20,900-916 (2001).
[PubMed]

Kowalczyk, A.

M. Szkulmowski, M. Wojtkowski, B. Sikorski, T. Bajraszewski, V. J. Srinivasan, A. Szkulmowska, J. J. Kaluzny, J. G. Fujimoto, and A. Kowalczyk, "Analysis of posterior retinal layers in spectral optical coherence tomography images of the normal retina and retinal pathologies," J. Biomed. Opt. 12, (2007).
[PubMed]

Li, J.

M. Zeng, J. Li and P. Zhang "The design of Top-Hat morphological filter and application to infrared target detection," Infr. Phys. Technol. 48,67-76 (2006).

Liew, S. H. M.

S. H. M. Liew, C. E. Gilbert, T. D. Spector, J. Mellerio, F. J. Van Kuijk, S. Beatty, F. Fitzke, J. Marshall, and C. J. Hammond, "Central retinal thickness is positively correlated with macular pigment optical density," Experimental Eye Research 82,915-920 (2006).

Makita, S.

S. Makita, Y.J. Hong, M. Yamanari, T. Yatagai, and Y. Yasuno, "Optical coherence angiography," Opt. Express 17,7821-7840 (2006).

Marshall, J.

S. H. M. Liew, C. E. Gilbert, T. D. Spector, J. Mellerio, F. J. Van Kuijk, S. Beatty, F. Fitzke, J. Marshall, and C. J. Hammond, "Central retinal thickness is positively correlated with macular pigment optical density," Experimental Eye Research 82,915-920 (2006).

Mellerio, J.

S. H. M. Liew, C. E. Gilbert, T. D. Spector, J. Mellerio, F. J. Van Kuijk, S. Beatty, F. Fitzke, J. Marshall, and C. J. Hammond, "Central retinal thickness is positively correlated with macular pigment optical density," Experimental Eye Research 82,915-920 (2006).

Michels, S.

Misota, A.

A. Misota, T. Sakuma, O. Miyauchi,M. Honda, and M. Tanaka, "Measurement of retinal thickness fromthe threedimensional images obtained from C scan images from the optical coherence tomography ophthalmoscope," Clinical and Experimental Ophthalmology 35,220-224 (2007).

Miyauchi, O.

A. Misota, T. Sakuma, O. Miyauchi,M. Honda, and M. Tanaka, "Measurement of retinal thickness fromthe threedimensional images obtained from C scan images from the optical coherence tomography ophthalmoscope," Clinical and Experimental Ophthalmology 35,220-224 (2007).

Mujat, M.

Otsu, N.

N. Otsu "A threshold selection method from gray-level histograms," IEEE Trans. Syst. Man Cyber. 9,62-66 (1979).

Park, B. H.

Pircher, M.

Puliafito, C. A.

D. C. Fernandez, H. M. Salinas, and C. A. Puliafito, "Automated detection of retinal layer structures on optical coherence tomography images," Opt. Express 13,200-216 (2005).

Roberts, C.

D. Koozekanani, K. Boyer, and C. Roberts, "Retinal thickness measurements from optical coherence tomography using a Markov boundary model," IEEE Trans. Med. Imaging 20,900-916 (2001).
[PubMed]

Sakuma, T.

A. Misota, T. Sakuma, O. Miyauchi,M. Honda, and M. Tanaka, "Measurement of retinal thickness fromthe threedimensional images obtained from C scan images from the optical coherence tomography ophthalmoscope," Clinical and Experimental Ophthalmology 35,220-224 (2007).

Salinas, H. M.

D. C. Fernandez, H. M. Salinas, and C. A. Puliafito, "Automated detection of retinal layer structures on optical coherence tomography images," Opt. Express 13,200-216 (2005).

Schmidt-Erfurth, U.

Schuman, J.S.

H. Ishikawa, D.M. Stein, G. Wollstein, S. Beaton, J.G. Fujimoto, and J.S. Schuman, "Macular segmentation with optical coherence tomography," Investigative Ophthalmol. Visual Scie. 46,2012-2017 (2005).

Sikorski, B.

M. Szkulmowski, M. Wojtkowski, B. Sikorski, T. Bajraszewski, V. J. Srinivasan, A. Szkulmowska, J. J. Kaluzny, J. G. Fujimoto, and A. Kowalczyk, "Analysis of posterior retinal layers in spectral optical coherence tomography images of the normal retina and retinal pathologies," J. Biomed. Opt. 12, (2007).
[PubMed]

Spector, T. D.

S. H. M. Liew, C. E. Gilbert, T. D. Spector, J. Mellerio, F. J. Van Kuijk, S. Beatty, F. Fitzke, J. Marshall, and C. J. Hammond, "Central retinal thickness is positively correlated with macular pigment optical density," Experimental Eye Research 82,915-920 (2006).

Srinivasan, V. J.

M. Szkulmowski, M. Wojtkowski, B. Sikorski, T. Bajraszewski, V. J. Srinivasan, A. Szkulmowska, J. J. Kaluzny, J. G. Fujimoto, and A. Kowalczyk, "Analysis of posterior retinal layers in spectral optical coherence tomography images of the normal retina and retinal pathologies," J. Biomed. Opt. 12, (2007).
[PubMed]

Stein, D.M.

H. Ishikawa, D.M. Stein, G. Wollstein, S. Beaton, J.G. Fujimoto, and J.S. Schuman, "Macular segmentation with optical coherence tomography," Investigative Ophthalmol. Visual Scie. 46,2012-2017 (2005).

Szkulmowska, A.

M. Szkulmowski, M. Wojtkowski, B. Sikorski, T. Bajraszewski, V. J. Srinivasan, A. Szkulmowska, J. J. Kaluzny, J. G. Fujimoto, and A. Kowalczyk, "Analysis of posterior retinal layers in spectral optical coherence tomography images of the normal retina and retinal pathologies," J. Biomed. Opt. 12, (2007).
[PubMed]

Szkulmowski, M.

M. Szkulmowski, M. Wojtkowski, B. Sikorski, T. Bajraszewski, V. J. Srinivasan, A. Szkulmowska, J. J. Kaluzny, J. G. Fujimoto, and A. Kowalczyk, "Analysis of posterior retinal layers in spectral optical coherence tomography images of the normal retina and retinal pathologies," J. Biomed. Opt. 12, (2007).
[PubMed]

Tanaka, M.

A. Misota, T. Sakuma, O. Miyauchi,M. Honda, and M. Tanaka, "Measurement of retinal thickness fromthe threedimensional images obtained from C scan images from the optical coherence tomography ophthalmoscope," Clinical and Experimental Ophthalmology 35,220-224 (2007).

Torre, A. L.

M. Baroni, P. Fortunato, and A. L. Torre, "Towards quantitative analysis of retinal features in optical coherence tomography," Med. Engin. Phys. 29,432-441 (2007).

Van Kuijk, F. J.

S. H. M. Liew, C. E. Gilbert, T. D. Spector, J. Mellerio, F. J. Van Kuijk, S. Beatty, F. Fitzke, J. Marshall, and C. J. Hammond, "Central retinal thickness is positively correlated with macular pigment optical density," Experimental Eye Research 82,915-920 (2006).

Wojtkowski, M.

M. Szkulmowski, M. Wojtkowski, B. Sikorski, T. Bajraszewski, V. J. Srinivasan, A. Szkulmowska, J. J. Kaluzny, J. G. Fujimoto, and A. Kowalczyk, "Analysis of posterior retinal layers in spectral optical coherence tomography images of the normal retina and retinal pathologies," J. Biomed. Opt. 12, (2007).
[PubMed]

Wollstein, G.

H. Ishikawa, D.M. Stein, G. Wollstein, S. Beaton, J.G. Fujimoto, and J.S. Schuman, "Macular segmentation with optical coherence tomography," Investigative Ophthalmol. Visual Scie. 46,2012-2017 (2005).

Yamanari, M.

S. Makita, Y.J. Hong, M. Yamanari, T. Yatagai, and Y. Yasuno, "Optical coherence angiography," Opt. Express 17,7821-7840 (2006).

Yasuno, Y.

S. Makita, Y.J. Hong, M. Yamanari, T. Yatagai, and Y. Yasuno, "Optical coherence angiography," Opt. Express 17,7821-7840 (2006).

Yatagai, T.

S. Makita, Y.J. Hong, M. Yamanari, T. Yatagai, and Y. Yasuno, "Optical coherence angiography," Opt. Express 17,7821-7840 (2006).

Zeng, M.

M. Zeng, J. Li and P. Zhang "The design of Top-Hat morphological filter and application to infrared target detection," Infr. Phys. Technol. 48,67-76 (2006).

Zhang, P.

M. Zeng, J. Li and P. Zhang "The design of Top-Hat morphological filter and application to infrared target detection," Infr. Phys. Technol. 48,67-76 (2006).

Clinical and Experimental Ophthalmology

A. Misota, T. Sakuma, O. Miyauchi,M. Honda, and M. Tanaka, "Measurement of retinal thickness fromthe threedimensional images obtained from C scan images from the optical coherence tomography ophthalmoscope," Clinical and Experimental Ophthalmology 35,220-224 (2007).

Experimental Eye Research

S. H. M. Liew, C. E. Gilbert, T. D. Spector, J. Mellerio, F. J. Van Kuijk, S. Beatty, F. Fitzke, J. Marshall, and C. J. Hammond, "Central retinal thickness is positively correlated with macular pigment optical density," Experimental Eye Research 82,915-920 (2006).

IEEE Trans. Med. Imaging

D. Koozekanani, K. Boyer, and C. Roberts, "Retinal thickness measurements from optical coherence tomography using a Markov boundary model," IEEE Trans. Med. Imaging 20,900-916 (2001).
[PubMed]

IEEE Trans. Syst. Man Cyber.

N. Otsu "A threshold selection method from gray-level histograms," IEEE Trans. Syst. Man Cyber. 9,62-66 (1979).

Infr. Phys. Technol.

M. Zeng, J. Li and P. Zhang "The design of Top-Hat morphological filter and application to infrared target detection," Infr. Phys. Technol. 48,67-76 (2006).

Investigative Ophthalmol. Visual Scie.

H. Ishikawa, D.M. Stein, G. Wollstein, S. Beaton, J.G. Fujimoto, and J.S. Schuman, "Macular segmentation with optical coherence tomography," Investigative Ophthalmol. Visual Scie. 46,2012-2017 (2005).

J. Biomed. Opt.

M. Szkulmowski, M. Wojtkowski, B. Sikorski, T. Bajraszewski, V. J. Srinivasan, A. Szkulmowska, J. J. Kaluzny, J. G. Fujimoto, and A. Kowalczyk, "Analysis of posterior retinal layers in spectral optical coherence tomography images of the normal retina and retinal pathologies," J. Biomed. Opt. 12, (2007).
[PubMed]

Med. Engin. Phys.

M. Baroni, P. Fortunato, and A. L. Torre, "Towards quantitative analysis of retinal features in optical coherence tomography," Med. Engin. Phys. 29,432-441 (2007).

Opt. Express

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Figures (9)

Fig. 1.
Fig. 1.

Steps in RPE identification. (i) The positions of maximum intensity pixels are determined and a 2D RPE position matrix is obtained, (ii) Automated binarization is performed to obtain a mask to identify erroneous pixels in the RPE position matrix (iii) Erroneous pixels are removed and replaced with new numerical values based on information on neighbouring pixels, (iv) 30 pixels around the RPE estimation are extracted from the original volume data, (v) the position of the RPE is redetermined on the basis of maximum intensity determination. The thus obtained RPE position map can be further improved by repeating steps (iv-vi) using a reduced amount of pixels around the estimated RPE.

Fig. 2.
Fig. 2.

Steps in ILM identification. (i) A threshold value is calculated automatically and each slice of volume data is binarized; (ii) the depth position of the first zero value of each binarized A-scan is determined to get a first estimation of the ILM position; (iii) to remove erroneous ILM position pixels, 45 pixels around the estimated ILM are extracted and reprocessed; (iv) intensity-based binarization is performed again with same threshold value as the first time; (v) the depth position of the ILM is re-estimated based on determining the position of the first zero value pixels of A-scans; (vi) to improve the reliability of the obtained ILM position matrix, steps (iii–v) are repeated with a smaller amount of pixels around the estimated ILM.

Fig. 3.
Fig. 3.

RPE and ILM layer segmentation results in a healthy volunteers macula. En-face projection image and ten cross-section images with identified RPE (green line) and ILM (red line). The position of each cross-section image is pointed by a number and a line in the en-face image. The projection image covers an area of 5×5 mm2 and the vertical dimension of each cross-section image is 1.37 mm. (in air)

Fig. 4.
Fig. 4.

Healthy volunteers macula. (a) Position map of the ILM; (b) position map of the RPE; (c) retinal thickness map. The position of the ILM and RPE are given by the depth from the top of the cross-section image. The effect of the refractive index of the tissue is not taken into account.

Fig. 5.
Fig. 5.

Macula of the left eye with ARMD. An en-face projection image and ten cross-section images showing the identified RPE (green line) and ILM (red line). The position of each cross-section image is pointed by a number and a line in the en-face image. The projection image covers an area of 5×5 mm2 and the vertical dimension of each crosssection image is 1.72 mm.

Fig. 6.
Fig. 6.

Macula of a patient with ARMD. (a) Position map of the ILM; (b) position map of the RPE; (c) retinal thickness map. The positions of the ILM and RPE are given by the depth from the top of cross-section image. The effect of refractive index is ignored.

Fig. 7.
Fig. 7.

Macula of the right eye with PCV. An en-face projection image and ten cross-section images showing the identified RPE (green line) and ILM (red line). The position of each cross-section image is pointed by a number and a line in the en-face image. The projection image covers an area of 5×5 mm2, and the vertical dimension of each cross-section image is 1.64 mm. Images 4 and 7 are magnified to see segmentation results in more details. White arrows are used to indicate the location of errors.

Fig. 8.
Fig. 8.

Macula of a patient with PCV. (a) Position map of the ILM; (b) position map of the RPE;(c) retinal thickness map. The position of the ILM and the RPE are given by the depth from the top of the cross-section image. The effect of refractive index is ignored.

Fig. 9.
Fig. 9.

The effect of iterations on segmentation result (a) RPE estimation based on maximum intensity search (red dots). The green line stands for final segmentation result; (b) RPE position estimate after masking the erroneous pixels (yellow dots); (c) representative cross-section image (healthy eye) with the red line showing the result of the first iteration, while the yellow and green lines stand for the second and third iteration, respectively; (d) magnified image of the region of interest with the white arrows showing the position where the second iteration fails; (e) representative cross-section image (ARMD eye) with the red line showing the result of the first iteration, while the yellow, blue and green lines stand for the second, third and forth iteration, respectively; (f) magnified image of the region of interest with the white arrows showing the position where the two first iterations fail.

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