Abstract
Purpose Proof of concept of ex vivo retinal vessel diameter measurements in human postmortem eyes.
Methods En face near-infrared (IR) images and optical coherence tomography (OCT) of the optic nerve head (ONH) were captured ex vivo with a Heidelberg Engineering Spectralis (Spectralis, version 7.0.4, Image Capture Module, version 1.2.4, Heidelberg Heidelberg, Germany) device, using a custom-made eye chamber holding and positioning the eyes during the image process. Thirty-two formaldehyde-fixated eyes of 16 patients were imaged. In the IR images, two independent graders measured retinal vessel diameters at the intersection of a drawn circle centered on the ONH with diameters of 2.0 mm and 3.4 mm, respectively. The anatomically corresponding measurements between both graders were statistically analyzed using a Wilcoxon signed-rank test.
Results A total of 246 matched measurements of both graders were analyzed across all 32 imaged eyes. Statistically significant differences between the graders were found for arterioles at 2 mm from the ONH. The other measurements did not show statistically significant intergrader differences. The mean values for arteriole diameters were 72.2 µm at 2.0 mm and 61.5 µm at 3.4 mm for grader 1, and 66.4 µm at 2.0 mm and 63.2 µm at 3.4 mm for grader 2. The mean diameter for venules were 75.5 µm at 2.0 mm and 79.3 µm at 3.4 mm for grader 1, and 67.4 µm at 2 mm and 79.1 µm at 3.4 mm for grader 2.
Conclusion To the best of our knowledge, this is the first study to present IR image-based retinal vessel diameters in ex vivo postmortem eyes. Retinal IR/OCT imaging is possible, and measurements are reproducible in formaldehyde-fixated human eyes. Fixation artefacts result in lower image quality, and this can impose challenges in correctly detecting, classifying, and measuring retinal vessels.
Zusammenfassung
Messung retinaler Gefäßdurchmesser in menschlichen postmortalen Augen durch zwei unabhängige Personen. Die Studie zeigt, dass die ex vivo IR-/OCT-Bildgebung der Netzhaut möglich ist und Messungen an formaldehydfixierten Augen reproduzierbar sind, wobei Fixierungsartefakte eine Herausforderungen bei der korrekten Erkennung, Klassifizierung und Messung retinaler Gefässe darstellen können.
Keywords
ex vivo imaging - postmortem - retinal vessel diameter - optical coherence tomography - OCT - infrared
Schlüsselwörter
Ex-vivo-Bildgebung - postmortal - Gefäßdurchmesser in der Netzhaut - optische Kohärenztomografie - OCT - Infrarot
