June 2013
Volume 54, Issue 15
Free
ARVO Annual Meeting Abstract  |   June 2013
Retinal oximetry using stereo retinal fundus camera with band-pass filter
Author Affiliations & Notes
  • Toshiaki Nakagawa
    Development Department, Life Science Division, Kowa Company, Ltd., Hamamatsu City, Japan
  • Atsushi Kakuuchi
    Development Department, Life Science Division, Kowa Company, Ltd., Hamamatsu City, Japan
  • Takayoshi Suzuki
    Development Department, Life Science Division, Kowa Company, Ltd., Hamamatsu City, Japan
  • Shinji Toyoda
    Development Department, Life Science Division, Kowa Company, Ltd., Hamamatsu City, Japan
Investigative Ophthalmology & Visual Science June 2013, Vol.54, 45. doi:
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    • Get Citation

      Toshiaki Nakagawa, Atsushi Kakuuchi, Takayoshi Suzuki, Shinji Toyoda; Retinal oximetry using stereo retinal fundus camera with band-pass filter. Invest. Ophthalmol. Vis. Sci. 2013;54(15):45.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract
 
Purpose
 

To measure hemoglobin oxygen saturation (SO2) in the retinal blood vessels by use of a stereo fundus camera with two narrow band-pass filters.

 
Methods
 

Stereo retinal fundus image pairs were taken simultaneously using a prototype stereo fundus camera with two narrow band-pass filters, which was modified from a commercially available stereo fundus camera (nonmydWX, Kowa Company, Ltd., Japan). The two different filters were inserted into the left and right of light paths, respectively. The center wavelengths of the filters were 570 nm and 600 nm and the half-bandwidth was 10 nm. Namely, the stereo retinal fundus image pair consists of a left image and a right image of the same area with 570-nm and 600-nm light. This was able to be generated by taking a single shot using a single sensor, the images were acquired with a digital camera (D90, Nikon Corporation, Japan) attached to the stereo fundus camera. Images were 4288 × 2848 pixels in size with a 27° field of view. SO2 of the individual blood vessel was measured using specially developed software were obtained with the two-wavelength algorithm proposed by Beach et al. (J Appl Physiol., 1999). The blood vessels were extracted by using the black-top-hat transformation, which is a type of grayscale morphological operation, from the 570-nm image of the stereo retinal fundus image pairs. Optical density ratio (ODR) for each blood vessel was calculated and SO2 was calculated as SO2 = 1.96 − 6.00 × ODR. Six stereo fundus images were taken from both eyes of 3 healthy volunteers (age 41 ± 7.2 y) without mydriasis. Mean SO2 was measured in 71 artery and 67 vein segments.

 
Results
 

SO2 was 97.2 ± 16.0 % (mean ± SD) in arterioles and 58.5 ± 13.9 % in venules. There was a significant variation of the SO2 of the individual arteriolar and venular vessels (p<0.0001).

 
Conclusions
 

Experimental results show that the proposed technique could be useful for the SO2 measurements in the retina.

 
 
An example of stereo retinal fundus image taken by the stereo fundus camera with two narrow band-pass filters.
 
An example of stereo retinal fundus image taken by the stereo fundus camera with two narrow band-pass filters.
 
 
Pseudocolor SO2 map generated automatically by our proposed procedure.
 
Pseudocolor SO2 map generated automatically by our proposed procedure.
 
Keywords: 549 image processing • 635 oxygen • 688 retina  
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