Research Papers: Imaging

Autofluorescence imaging of macular pigment: influence and correction of ocular media opacities

[+] Author Affiliations
Mohsen Sharifzadeh, Werner Gellermann

University of Utah, Department of Physics and Astronomy, Salt Lake City, Utah 84112, United States

Akira Obana

Seirei Hamamatsu General Hospital, Department of Ophthalmology, Hamamatsu, Shizuoka 430-0906, Japan

Hamamatsu University, School of Medicine, Department of Medical Spectroscopy, Medical Photonics Research Center, Hamamatsu, Shizuoka 430-3192, Japan

Yuko Gohto, Takahiko Seto

Seirei Hamamatsu General Hospital, Department of Ophthalmology, Hamamatsu, Shizuoka 430-0906, Japan

J. Biomed. Opt. 19(9), 096010 (Sep 15, 2014). doi:10.1117/1.JBO.19.9.096010
History: Received May 2, 2014; Revised August 22, 2014; Accepted August 25, 2014
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Abstract.  The healthy adult human retina contains in its macular region a high concentration of blue-light absorbing carotenoid compounds, known as macular pigment (MP). Consisting of the carotenoids lutein, zeaxanthin, and meso-zeaxanthin, the MP is thought to shield the vulnerable tissue layers in the retina from light-induced damage through its function as an optical attenuator and to protect the tissue cells within its immediate vicinity through its function as a potent antioxidant. Autofluorescence imaging (AFI) is emerging as a viable optical method for MP screening of large subject populations, for tracking of MP changes over time, and for monitoring MP uptake in response to dietary supplementation. To investigate the influence of ocular media opacities on AFI-based MP measurements, in particular, the influence of lens cataracts, we conducted a clinical trial with a large subject population (93 subjects) measured before and after cataract surgery. General AFI image contrast, retinal blood vessel contrast, and presurgery lens opacity scores [Lens Opacities Classification System III (LOCS III)] were investigated as potential predictors for image degradation. These clinical results show that lens cataracts can severely degrade the achievable pixel contrasts in the AFI images, which results in nominal MP optical density levels that are artifactually reduced. While LOCS III scores and blood vessel contrast are found to be only a weak predictor for this effect, a strong correlation exists between the reduction factor and the image contrast, which can be quantified via pixel intensity histogram parameters. Choosing the base width of the histogram, the presence or absence of ocular media opacities can be determined and, if needed, the nominal MP levels can be corrected with factors depending on the strength of the opacity.

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© 2014 Society of Photo-Optical Instrumentation Engineers

Citation

Mohsen Sharifzadeh ; Akira Obana ; Yuko Gohto ; Takahiko Seto and Werner Gellermann
"Autofluorescence imaging of macular pigment: influence and correction of ocular media opacities", J. Biomed. Opt. 19(9), 096010 (Sep 15, 2014). ; http://dx.doi.org/10.1117/1.JBO.19.9.096010


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