title: Autofluorescence imaging of macular pigment: influence and correction of ocular media opacities.
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 lightinduced 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.
authors.affiliation: University of Utah, Department of Physics and Astronomy, Salt Lake City, Utah 84112, United States.
authors.forename: Mohsen
authors.initials: M
authors.lastname: Sharifzadeh
authors.affiliation: Seirei Hamamatsu General Hospital, Department of Ophthalmology, Hamamatsu, Shizuoka 430-0906, JapancHamamatsu University, School of Medicine, Department of Medical Spectroscopy, Medical Photonics Research Center, Hamamatsu, Shizuoka 430-3192, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Obana
authors.affiliation: Seirei Hamamatsu General Hospital, Department of Ophthalmology, Hamamatsu, Shizuoka 430-0906, Japan.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Gohto
authors.affiliation: Seirei Hamamatsu General Hospital, Department of Ophthalmology, Hamamatsu, Shizuoka 430-0906, Japan.
authors.forename: Takahiko
authors.initials: T
authors.lastname: Seto
authors.affiliation: University of Utah, Department of Physics and Astronomy, Salt Lake City, Utah 84112, United States.
authors.forename: Werner
authors.initials: W
authors.lastname: Gellermann
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002386:Cataract / Q000378:metabolism*; D002387:Cataract Extraction; D005654:Fundus Oculi; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D065348:Macular Pigment / Q000737:chemistry*; D008297:Male; D008875:Middle Aged; D061848:Optical Imaging / Q000379:methods*; D055815:Young Adult
chemical_list: D065348:Macular Pigment