@inbook {1047,
	title = {Appearance-based Approach to Extract an Age-related Biomarker from Retinal Images},
	booktitle = {3rd Russian-Bavarian Conference on Bio-Medical Engineering, Proceedings},
	volume = {1},
	year = {2007},
	month = {2007},
	pages = {127 - 131},
	publisher = {Friedrich-Alexander University Erlangen-Nuremberg},
	organization = {Friedrich-Alexander University Erlangen-Nuremberg},
	type = {Conference paper},
	address = {Erlangen},
	abstract = {<p>We present an appearance-based method that extracts a new age-related biomarker from retina images. The Principal Component Analysis is applied on intensity values of the illumination corrected green channel of fundus images. The algorithm does not use segmentation, is robust and shows a high range of reliability. It identified an age-related feature with a strong influence of the temporal parapapillary area and the optic nerve head. The feature correlates with chronological age of the participants and is significantly influenced by the appearance of cardiovascular risk factors such as smoking and hypertension, and thus it can be designated a biomarker. We extract and validate a medical parameter from retina images applying a purely data-driven approach without using any prior knowledge.</p>},
	author = {Rudriger Bock and J{\"o}rg Meier and L{\'a}szl{\'o} G{\'a}bor Ny{\'u}l and Simone W{\"a}rntges and Georg Michelson and Joachim Hornegger},
	editor = {Joachim Hornegger and Ernst W Mayr and Sergey Schookin and Hubertus Feu{\ss}ner and Nassir Navab and Yuri V. Gulyaev and Kurt H{\"o}ller and Victor Ganzha}
}
@article {1085,
	title = {Extraction of an Age-Related Biomarker From Retinal Images Using Appearance Based Approach},
	journal = {INVESTIGATIVE OPHTHALMOLOGY \& VISUAL SCIENCE},
	volume = {48},
	year = {2007},
	note = {ARVO Meeting Abstracts},
	month = {2007},
	pages = {2167},
	type = {Journal article},
	abstract = {<p>Purpose:To develop an appropriate algorithm from retina imagesusing an appearance-based version of the Principal Component Analysis and to test the age-related biomarker{\textquoteright}s significance for patients at cardiovascular risk. Methods:Sixty-five men (age, 44.2 {\textpm} 11.4 years) and 60 women (age, 48.8 {\textpm} 12.6 years) without cardiovascular risk factors and without pathologic eye diagnosis were acquired during a clinical non-experimental cross-sectional survey and represented the control group. Forty-four hypertensive men (age, 45.5 {\textpm} 9.4 years; hypertensive for 5.9 {\textpm} 6.7 years) and 26 hypertensive women (age, 51.2 {\textpm} 7.3 years; hypertensive for 7.9 {\textpm} 7.1 years) as well as 57 male smokers (age, 41.8 {\textpm} 8.5 years; smoking for 20.6 {\textpm} 9.8 years; 15.3 {\textpm} 8.6 cigarettes per day) and 60 female smokers (age, 43.2 {\textpm} 9.5 years; smoking for 20.1 {\textpm} 10.7 years; 13.5 {\textpm} 8.1 cigarettes per day) were matched for age and sex to the respective number of control subjects. Results:The reliability of the algorithm was 0.958. The retinal biomarker correlated with age (men, -0.284, p = 0.017; women, -0.374, p = 0.001). Smokers showed a lower biomarker value (male, -0.16 {\textpm} 1.29; female, -0.12 {\textpm} 0.11) than age-matched control subjects (male, 0.72 {\textpm} 0.92, p \&lt; 0.001; female, 0.24 {\textpm} 0.98, p = 0.048). Hypertension had a similar influence to the biomarker in men (0.10 {\textpm} 0.84), but not in women (-0.46 {\textpm} 1.23) as compared to age-matched controls (male, 0.57 {\textpm} 0.95, p = 0.01; female, 0.06 {\textpm} 0.99, p = 0.09). Conclusions:The algorithm of the appearance-based version of the Principal Component Analysis identified an age-related image feature dependent on light intensity with a strong influence to the temporal parapapillary area. It may be used to identify patients at cardiovascular risk.</p>},
	isbn = {0146-0404},
	author = {Georg Michelson and Simone W{\"a}rntges and Rudriger Bock and L{\'a}szl{\'o} G{\'a}bor Ny{\'u}l and Joachim Hornegger}
}
