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Oulun yliopiston väitöskirjat

STEREOMETRIC PARAMETERS OF THE HEIDELBERG RETINA TOMOGRAPH IN THE FOLLOW-UP OF GLAUCOMA, ACTA UNIVERSITATIS OULUENSIS D Medica 1076

ISBN-13:	978-951-42-6327-9
Kieli:	englanti
Kustantaja:	Oulun yliopisto
Oppiaine:	Lääketiede, farmasia
Painosvuosi:	2010
Sidosasu:	pehmeäkantinen
Sijainti:	Print Tietotalo
Sivumäärä:	128
Tekijät:	SAARELA VILLE

20.00 €

Glaucoma is a progressive neuropathy of the optic nerve. It causes degeneration of ganglion cellaxons resulting in defects in the retinal nerve fibre layer (RNFL) and characteristic changes in theoptic nerve head (ONH). The Heidelberg Retina Tomograph (HRT) is a confocal scanning laserimaging device, which measures the topography of the ONH and the adjacent RNFL. To quantifythe measurements of the ONH topography, various stereometric parameters are calculated. The change in the stereometric parameters of the HRT was studied in 34 eyes withglaucomatous progression in RNFL photographs and 34 eyes without progression. The change inonly one stereometric parameter, the cup shape measure, showed a statistically significantcorrelation with the progression of the RNFL defect. An optimised change in the best three-parameter combination had 77% sensitivity and 79% specificity for progression. The change in the stereometric parameters was compared in 51 eyes with glaucomatousprogression in stereoscopic ONH photographs and 425 eyes without progression. The parametershaving the best correlation with progression include cup:disc area ratio, vertical cup:disc ratio, cupvolume and rim area. The parameter with the largest area under the receiver operatingcharacteristics curve (0.726) was the vertical cup:disc ratio. A change of 0.007 in the verticalcup:disc ratio had a sensitivity of 80% and a specificity of 65% for progression. The factors having the most significant effect on the sensitivity and specificity of thestereometric parameters for progression were the reference height difference and the meantopography standard deviation, indicating image quality. The change in image quality and age alsoshowed a consistent, but variably significant influence on all parameters tested. Exercise was associated with an increase in variance in 17 of the 18 stereometric parameters. In conclusion, the change in the stereometric parameters provides useful information on ONHtopography, especially when image quality is excellent. However, the evaluation of glaucomatousprogression should not rely solely on the stereometric parameters of the HRT.

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