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S. N. Mathur, S. S. Huang, M. Harrod, B. A. Benetz; Spectral Light Characteristics of the Crystalline Lens as a Function of Age. Invest. Ophthalmol. Vis. Sci. 2009;50(13):6129.
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© ARVO (1962-2015); The Authors (2016-present)
To analyze the spectral light characteristics of the crystalline lens as a function of age. Phakic and pseudophakic patients’ digital fundus images were analyzed for spectral differences which could serve as quantitative markers for progressive lens opacification.
A retrospective analysis of phakic and pseudophakic patients free from any other media opacity with digital fundus images were randomly selected. No phakic eyes had sectoral or PSC-type opacities. Digital fundus images were captured by the same Topcon TRC 50 VT fundus camera/Nikon D1X digital camera back. Images were analyzed with Adobe Photoshop® CS2. Standardized pixel regions free from vasculature or other ocular abnormality within the optic cup and disc were analyzed within Hue/Saturation/Brightness, Red/Green/Blue, Cyan/Magenta/Yellow/Key(Black), and Lightness/a/b color parameters. Retina, macula, and blood vasculature were also analyzed. Patients with dysmorphic, abnormally pigmented, and pathologic optic nerves were excluded from analysis.
Pseudophakic cup and disc analysis showed differences from phakic cup and discs when comparing saturation, green, blue, and yellow. Saturation in cup and discs expressed as a ratio between phakic:pseudophakic were cup 77:53 (145%) and disc 92:59 (156%). Green revealed 158:169 (94%) in the cup and 137:168 (82%) in the disc. Blue values between phakic and pseudophakic eyes were cup 59:117 (50%) and disc 21:99 (21%). Yellow demonstrated 79:59 (134%) in the cup and disc 94:69 (136%) in the disc. Images of the retina in the papillomacular bundle and macula produced inconsistent spectral analysis due to variations in retinal pigment epithelium and macular pigmentation.
Current systems of cataract grading are highly subjective. Variability of imaging environments and observer sensitivity make quantification of small changes in cataract progression especially difficult. Our analysis reveals that there are quantifiable differences in spectral light characteristics between phakic and pseudophakic eyes. Large increases in saturation and decreases in blue light transmittance occur in phakic eyes. The efficacy in eyes with other types of cataract requires further study. Blue light absorption may be valuable as a quantifiable clinical measure of cataract progression. Furthermore, this technique may assist clinical evaluation of the amount of harmful visible light reaching the retina.
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