Analysis of HRT images: comparison of reference planes.

PURPOSE The values of Heidelberg Retinal Tomograph (HRT; Heidelberg Engineering, Heidelberg, Germany) stereometric parameters depend on the reference plane (RP), the instability of which results in parameter variability. Identification of change depends on RP stability. This study was undertaken to evaluate the influence of various RPs on rim areas (RAs) in a longitudinal image series. METHODS A longitudinal image series of 31 subjects with ocular hypertension who had reproducible visual field loss and 19 normal subjects was analyzed using five different RPs: the standard RP (HRT software version 3.1.2.0), two 320-mum RPs (software ver. 3.1.2.0 and 1.7.0), a previously described experimental RP, and a new Moorfields RP. The Moorfields RP takes the standard RP at baseline and then is fixed relative to the reference ring for subsequent images. Linear regression of RA over time was performed, and the slope and residual SD (RSD) were calculated for each RP. Comparisons between RPs were made by paired t-tests. RESULTS In eyes with progressing disease, application of the standard RP resulted in significantly greater variability (as measured by the RSD) compared with other RPs (mean 0.057 mm(2) vs. 0.035-0.038 mm(2)). There was a trend toward faster RA change/time (mean, -0.0123 mm(2)/y) for the standard RP and slower (-0.0095 mm(2)/y) for the experimental RP. There was a trend for the Moorfields RP to result in the best signal-to-noise ratio (speed of RA change/variability): mean RA slope -0.0118 mm(2)/y and mean global RSD 0.037mm(2). CONCLUSIONS Compared to the standard RP, the Moorfields RP has significantly lower variability and probably provides a greater facility for discriminating RA change from measurement variability in a longitudinal HRT image series.

[1]  D. Garway-Heath,et al.  Measurement variability in Heidelberg Retina Tomograph imaging of neuroretinal rim area. , 2006, Investigative ophthalmology & visual science.

[2]  G. Nahler.  randomized controlled clinical trial , 2009 .

[3]  Nicholas G Strouthidis,et al.  Optic disc and visual field progression in ocular hypertensive subjects: detection rates, specificity, and agreement. , 2006, Investigative ophthalmology & visual science.

[4]  Thinning of the Papillomacular Bundle in the Glaucomatous Eye and its Influence on the Reference Plane of the Heidelberg Retinal Tomography , 2001, Journal of glaucoma.

[5]  David P Crabb,et al.  A new statistical approach for quantifying change in series of retinal and optic nerve head topography images. , 2005, Investigative ophthalmology & visual science.

[6]  A C Viswanathan,et al.  Detection of optic disc change with the Heidelberg retina tomograph before confirmed visual field change in ocular hypertensives converting to early glaucoma , 1999, The British journal of ophthalmology.

[7]  J. Tan,et al.  Variability across the optic nerve head in scanning laser tomography , 2003, The British journal of ophthalmology.

[8]  P J Airaksinen,et al.  Initial glaucomatous optic disk and retinal nerve fiber layer abnormalities and their progression. , 1991, American journal of ophthalmology.

[9]  D. Garway-Heath,et al.  Improving the repeatability of Heidelberg retina tomograph and Heidelberg retina tomograph II rim area measurements , 2005, British Journal of Ophthalmology.

[10]  A. Coleman,et al.  Comparison of optic nerve imaging methods to distinguish normal eyes from those with glaucoma. , 2002, Investigative ophthalmology & visual science.

[11]  Reference plane definition and reproducibility in optic nerve head images. , 2003, Investigative ophthalmology & visual science.

[12]  B. Chauhan,et al.  Longitudinal changes in the visual field and optic disc in glaucoma , 2005, Progress in Retinal and Eye Research.

[13]  B C Chauhan,et al.  Technique for detecting serial topographic changes in the optic disc and peripapillary retina using scanning laser tomography. , 2000, Investigative ophthalmology & visual science.

[14]  K Rohrschneider,et al.  Reproducibility of the optic nerve head topography with a new laser tomographic scanning device. , 1994, Ophthalmology.

[15]  Stefano Miglior,et al.  Reproducibility of evaluation of optic disc change for glaucoma with stereo optic disc photographs. , 2003, Ophthalmology.

[16]  Augusto Azuara-Blanco,et al.  Clinical agreement among glaucoma experts in the detection of glaucomatous changes of the optic disk using simultaneous stereoscopic photographs. , 2003, American journal of ophthalmology.

[17]  F W Fitzke,et al.  Use of sequential Heidelberg retina tomograph images to identify changes at the optic disc in ocular hypertensive patients at risk of developing glaucoma , 2000, The British journal of ophthalmology.

[18]  D. Garway-Heath,et al.  Reasons for rim area variability in scanning laser tomography. , 2003, Investigative ophthalmology & visual science.

[19]  Standardizing Diagnostic Procedures , 1975 .

[20]  S M Drance,et al.  Features of the optic disc in preglaucomatous eyes. , 1981, Archives of ophthalmology.

[21]  R N Weinreb,et al.  Reproducibility of topographic measurements of the normal and glaucomatous optic nerve head with the laser tomographic scanner. , 1991, American journal of ophthalmology.

[22]  Roger A Hitchings,et al.  Approach for identifying glaucomatous optic nerve progression by scanning laser tomography. , 2003, Investigative ophthalmology & visual science.

[23]  J. Caprioli,et al.  An optimal reference plane to detect glaucomatous nerve fiber layer abnormalities with computerized image analysis , 1992, Graefe's Archive for Clinical and Experimental Ophthalmology.

[24]  Roger A Hitchings,et al.  Optimizing and validating an approach for identifying glaucomatous change in optic nerve topography. , 2004, Investigative ophthalmology & visual science.

[25]  A E Maumenee,et al.  Optic disc parameters and onset of glaucomatous field loss. I. Methods and progressive changes in disc morphology. , 1979, Archives of ophthalmology.

[26]  D. R. Anderson,et al.  The mode of progressive disc cupping in ocular hypertension and glaucoma. , 1980, Archives of ophthalmology.

[27]  P. Lichter.  Variability of expert observers in evaluating the optic disc. , 1976, Transactions of the American Ophthalmological Society.

[28]  G. Wollstein,et al.  Identification of early glaucoma cases with the scanning laser ophthalmoscope. , 1998, Ophthalmology.

[29]  I. Scott,et al.  Expert agreement in evaluating the optic disc for glaucoma. , 1992, Ophthalmology.

[30]  Anja Tuulonen,et al.  Development of the standard reference plane for the Heidelberg retina tomograph , 2000, Graefe's Archive for Clinical and Experimental Ophthalmology.

[31]  David Garway-Heath,et al.  Results of the betaxolol versus placebo treatment trial in ocular hypertension , 2003, Graefe's Archive for Clinical and Experimental Ophthalmology.

[32]  D. Garway-Heath,et al.  Factors affecting the test-retest variability of Heidelberg retina tomograph and Heidelberg retina tomograph II measurements , 2005, British Journal of Ophthalmology.