Research Article

Analysis of Visual Appearance of Retinal Nerve Fibers in High Resolution Fundus Images: A Study on Normal Subjects

Table 1

Short summarization of papers describing different approaches for the evaluation of RNF in fundus images (DCFI stands for digital colour fundus images).

AuthorMethodDataResults/description

Hoyt et al. (1973), [11]The first subjective attempt to utilize fundus cameras for glaucoma detection by the evaluation of RNFL visual appearance. Comparison with perimetric findings.A few number of black-and-white photographsFunduscopic signs of the RNFL pattern provide the earliest objective evidence of nerve fiber layer atrophy in the retina.

Lundstrom and Eklundh (1980), [12]Subjective visual evaluation of the changes in RNFL pattern intensity using fundus photographs.A few number of black-and-white photographsFindings that consecutive changes in RNFL pattern intensity are connected to progression of glaucoma disease.

Airaksinen et al. (1984), [3]Subjective scoring of visual RNFL appearance in fundus photographs.Black-and-white photographs (84 normals, 58 glaucomatous)Confirmation of the dependence between changes in RNFL pattern and glaucoma progression in fundus photographs.

Peli (1988), [13]Semiautomatic analysis of RNFL texture based on intensity information.Digitized black-and-white photographs (5 normal, 5 glaucomatous, and 5 suspected of glaucoma)Additional confirmation of the changes in RNFL intensity caused by glaucoma atrophy.

Yogesan et al. (1998), [5]Automatic method for texture analysis of RNFL based on gray level run length matrices.Digitized fundus photographs of size 648 × 560 pixels (5 normals, 5 glaucomatous)Promising results for large focal wedge-shaped RNFL losses well outlined by surrounding healthy nerve fiber bundles. Diffuse RNFL loses could not be detected.

Tuulonen et al. (2000), [6]Semiautomatic method using microtexture analysis of the RNFL pattern.Digitized fundus photographs 1280 × 1024 pixels (7 normals, 9 glaucomatous, and 8 suspected of glaucomaShowing that changes in a microtexture of RNFL pattern are related to glaucoma damage. There is a lack of small sample size.

Oliva et al. (2007), [14]Semiautomatic method to texture analysis based on RNFL pattern intensity. Comparison with OCT measurement.DCFI with size of 2256 × 2032 pixels (9 normals, 9 glaucomatous)Correlation was only 0.424 between the intensity related parameters extracted from fundus images and RNFL thickness was measured by OCT.

Kolář and Jan (2008), [7]Automatic method to texture analysis of RNFL based on fractal dimensions.DCFI with size of 3504 × 2336 pixels (14 normal, 16 glaucomatous)Local fractal coefficient was used as a feature for glaucomatous eye detection. There were problems with robust estimation of this coefficient.

Muramatsu, et al. (2010), [10]Automatic approach with Gabor filters to enhance certain regions with RNFL pattern and clustering of these regions aimed to glaucoma detection.DCFI with size of 768 × 768 pixels (81 normals, 81 glaucomatous)The method is suitable only for detection of focal and wider RNFL losses expressed by significant changes in intensity.

Odstrcilik et al. (2010), [8]Automatic method to texture analysis of RNFL based on Markov random fields.DCFI with size of 3504 × 2336 pixels (18 normals, 10 glaucomatous)The features ability to differentiate between healthy and glaucomatous cases is validated using OCT RNFL thickness measurement.

Prageeth et al. (2011), [15]Automatic method to texture analysis using only intensity information about RNFL presence.DCFI with size of 768 × 576 pixels (300 normals, 529 glaucomatous)Intensity criteria were used. Detection of the substantial RNFL atrophy.

Acharya et al. (2011), [16]Automatic analysis of RNFL texture using higher order spectra, run length, and cooccurrence matrices.DCFI with size of 560 × 720 pixels (30 normals, 30 glaucomatous)Specificity to detect glaucomatous eye is over 91%. The article does not explain thoroughly how the features were extracted and in which area of the image were computed.

Jan et al. (2012), [9]Automatic method to RNFL texture analysis based on combination of intensity, edge representation, and Fourier spectral analysis.DCFI with size of 3504 × 2336 pixels (8 normals, 4 glaucomatous)The ability of proposed features to classify RNFL defects has been proven via comparison with OCT. The comparison was done only in a heuristic manner.