Reproducibility of topographic measures of the glaucomatous optic nerve head

Abstract

Aims/background-Laser scanning tomography provides an assessment of three dimensional optic disc topography. For the clinical purpose of follow up of glaucoma patients, the repeatability of the various measured variables is essential. In the present study, the reproducibility of morphometric variables calculated by the topographic scanning system, TopSS (Laser Diagnostic Technology, San Diego, CA) was investigated. Methods-Two independent measurements (30 minutes apart) each consisting of three complete images of the optic disc were performed on 16 eyes of 16 glaucoma patients using a TopSS. The instrument calculates 14 morphometric variables for the characterisation of the optic disc. Results-From the two tailed paired tests, all variables were seen to have good reproducibility. However, correlation and regression analyses showed that only the three variables, volume below, half depth area, and average cup depth, are acceptably reproducible. Conclusion-The TopSS provides three variables which describe the physiological shape of the optic disc that have high reproducibility. These three variables might be useful for following the progression of optic disc changes in glaucoma patients.

The influence of age, gender, refractive error, and optic disc size on the optic disc configuration in Japanese normal eyes

“…It has been reported that the results obtained from this system are highly reproducible (Geyer et al 1998). In the current study, one author drew the contour of the optic disc without any patient information, which eliminated intra-observer variation affecting the results.…”

“…Of the 12 variables that can be investigated by TopSS, we focused on the volume below, the half-depth area and the average cup depth, as it has been indicated by Geyer et al that these three variables show a high level of reproducibility and are reliable parameters for detecting small changes (Geyer et al 1998). Although TopSS A can access the disc every 30 degrees, we decided that it would be adequate to sum up the raw data for every quadrant portion.…”

Estimating the clinical usefulness of optic disc biometry for detecting glaucomatous change over time

“…So far, SLO-studies have mainly evaluated the usefulness of optic disc parameters for glaucoma detection, their reproducibility of measurements and any correlations with visual field defects. [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] However, relatively little attention has been paid to the possible value of SLO optic disc biometry for improvement of glaucoma follow-up. [20][21][22] To reliably detect development or progression of disease with a certain measurement parameter, it is necessary to know the absolute difference between follow-up measurements that must be exceeded to detect a statistically significant change over time.…”

Correlação entre o topógrafo de disco óptico (TOPSS) e índices do campo visual

“…Entre esses novos métodos de imagem, destacam-se a análise da camada de fibras nervosas da retina por meio da Polarimetria de Varredura a Laser (GDx, Laser Diagnostic Technologies, San Diego, CA, USA) (6)(7) , e a topografia de disco óptico, realizada pelo Tomógrafo Retiniano de Heidelberg (HRT, Heidelberg Engineering, Heidelberg, Germany) (8)(9) ou o Topógrafo de Disco Óptico (TOPSS, Laser Diagnostic Technologies, San Diego, CA, USA) (10)(11) . As informações estruturais provenientes dos instrumentos relacionados acima podem ser validadas através da comparação com métodos diagnósticos considerados como "gold standard" em glaucoma.…”

“…Apesar do TOPSS e HRT usarem o mesmo princípio na aquisição das imagens (Sistema de Varredura Confocal), existem diferenças quanto às variáveis testadas em cada aparelho (11,18) , e na forma de delinear o disco óptico para proceder a análise. Portanto, as informações obtidas com o HRT não podem ser extrapoladas e utilizadas como premissas para o TOPSS.…”