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Akira Obana, Yuko Gohto, Takahiko Seto, Tokio Ueno, Mohsen Sharifzadeh, Werner Gellermann; Autofluorescence-Based Macular Pigment Measurements before and after Cataract Surgery in a Large Subject Population. Invest. Ophthalmol. Vis. Sci. 2014;55(13):5869.
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© ARVO (1962-2015); The Authors (2016-present)
We explore the impact of cataracts on autofluorescence-imaging (AFI) measurements of macular pigment (MP) optical densities (ODs) and their spatial distributions in a large subject population. This will allow us to determine cataract associated image degradation limits for accurate MPOD assessment.
Our method for the measurement of MP is based on a fundus camera platform, implementing near-IR, video-assisted alignment of the macula, blue-filtered Xenon flash lamp exposure of the retina for 10 milliseconds, and synchronized CCD camera detection of lipofuscin (“auto”-) fluorescence. Two-dimensional pixel fluorescence intensity maps (“AFI images”) are obtained in which the MP is visible as a region of attenuated fluorescence, and MPOD levels are derived from a comparison of pixel fluorescence intensities between the peripheral retina and macular region. For each subject, AFI images were recorded and evaluated pre and post cataract surgery. Parameters such as cataract LOCS III scores, contrast of suitable retinal blood vessels in the AFI images, peak MPOD levels, and general image contrast were quantified and evaluated for respective correlations. All patients provided informed consent based on institutional review board approval and the tenets of the Declaration of Helsinki prior to surgery.
The clinical trial involved 93 subjects aged 22 to 87 years (34 males; 59 females; mean age of 72.0±11.6 yrs). AFI images could be obtained for 140 eyes. MPOD levels ranged from 0.10 to 0.25 pre surgery, and from 0.25 to 0.90 post surgery. Mean LOCS III scores were as follows; nuclear color: 2.8; cortical: 2.8; posterior subcapsular: 2.3. Retinal blood vessel contrast ranged from 0.01 to 0.20 pre surgery, and from 0.1 to 0.4 post surgery.
Cataracts can cause severe AFI image degradation and can strongly confound the accurate determination of MPOD levels. LOCS III scores are a weak predictor of AFI image quality obtainable pre surgery. Image contrast of retinal blood vessels and/or spatially integrated general retinal image contrast can serve as an objective quantitative measure for acceptable AFI image quality and corresponding limit for accurate determination of MPOD results.
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