New software analyses increase the reliability of measurements of retinal arterioles morphology by scanning laser Doppler flowmetry in humans.

OBJECTIVE: The investigation of the retinal arterioles offers the unique opportunity to analyze in vivo arteriolar remodeling in arterial hypertension in humans. We analyzed the reliability of assessing retinal arteriolar morphology with our new version of the software analyses for scanning laser Doppler flowmetry.
METHOD: In the test-retest reliability study, 10 eyes of 10 healthy persons were measured during 5 days under routine laboratory conditions with the Heidelberg Retinal Flowmetry. In a second study, interobserver and intraobserver reliability was analyzed from retinal images of 18 patients with three types of arterial hypertension by three readers and the most experienced reader analyzed all images twice on two different days. Images were analyzed by the old and the newly developed software versions. To characterize the reliability, the coefficients of variation were calculated.
RESULTS: The test-retest study analyzed with the new program showed that the variation coefficients of vessel and lumen diameter, wall thickness, wall/lumen ratio and new calculated parameter: lumen/vessel diameter ratio of retinal arterioles were significantly less than 10%, with the exception of the wall cross-sectional area (12.5%). The interobserver and intraobserver reliability showed in nearly all circumstances coefficients of variations of less than 10% and did not differ across various readers and patient groups.
CONCLUSION: The new software 'SLDF version 4.0' clearly improved the reliability of assessing the structural parameters of the retinal arterioles. The application delivers reliable measurements of the retinal arteriolar structure in vivo in humans.