Analysis of Blood Flow in the Macula and Optic Nerve Head in Healthy Young Volunteers Using Laser Speckle Flowgraphy

Abstract

Purpose To assess optic nerve head (ONH) and macular blood flow in young healthy volunteers using laser speckle flowgraphy (LSFG).

Methods This is a prospective single-center study conducted at the Department of Ophthalmology, University Hospital Zurich from May to November 2021. Young, healthy men aged ≥ 18 years without ocular or systemic diseases were included. A corrected visual acuity (VA) of 0.0 logMAR or better in both eyes and an intraocular pressure (IOP) of 21 mmHg or lower were required for inclusion. Subjects exceeding a spherical equivalent (SE) of ± 6 diopters (dpt) were excluded. Blood flow in the macula and the ONH was recorded using the Nidek LSFG RetFlow device (Nidek Company, Ltd., Hirioshi-cho, Japan). Laser power was set to 0.5 Millivolts (mV). Mean blur rate (MBR) was recorded as a parameter for blood flow. MBR is a calculated parameter that represents relative blood flow velocity correlated with the real anatomical blood flow rate. Colored heat maps of the recorded retinal area were generated automatically by the RetFlow device.

Results Final analyses included 83 eyes of 43 male volunteers. Mean age was 21.9 years (SD ± 1.5, range: 20 to 29). Mean corrected VA was − 0.1 logMAR (SD ± 0.05, range: − 0.2 to 0.0), mean IOP was 15.4 mmHg (SD ± 2.5, range: 8.5 to 18.5), and mean SE was − 0.3 dpt (SD ± 1.2, range: − 5.0 to 1.2). Mean ONH MBR was 37.44 (SD ± 7.9, range: 22.5 to 53.5) and mean macular MBR was 27.8 (SD ± 9.7, range: 6.4 to 57.7). Pearsonʼs Test showed a strong correlation between macular and papillary blood flow (p < 0.05, coefficient: 0.647).

Conclusion This study provides both ONH and macular blood flow data in a healthy young male population, showing a strong correlation between ONH and macular blood flow in the examined eyes. Further investigations are required to assess the validity of MBR as a parameter for the combined evaluation of retinal blood flow at the macula and ONH in healthy volunteers and patients with various diseases.

Zusammenfassung

Ziel Untersuchung und Vergleich des papillären und makulären Blutfluss in jungen, gesunden Probanden mittels Laser Speckle Flowgraphy (LSFG).

Methodenn Diese prospektive Single-Center-Studie wurde an der Augenklinik des Universitätsspitals Zürich, Schweiz, von Mai bis November 2021 durchgeführt. Junge, gesunde Männer ohne okuläre oder systemische Vorerkrankungen mit einem Alter von ≥ 18 Jahren wurden eingeschlossen. Die Teilnehmer mussten einen Visus von 0.0 logMAR oder besser an beiden Augen und einen Augendruck (IOD) von 8 – 21 mmHg aufweisen. Teilnehmer mit einem sphärischen Äquivalent (SE) außerhalb ± 6 Dioptrien (dpt) wurden ausgeschlossen. Blutfluss in der makulären und papillären Region wurde mittels des LSFG-RetFlow-Geräts von Nidek aufgenommen (Nidek Company, Ltd., Hirioshi-cho, Japan). Die Laserleistung (Power) betrug bei den Aufnahmen 0.5 Millivolts (mV). Die Mean Blur Rate (MBR) wurde als Parameter des Blutflusses gemessen. Die MBR ist ein berechneter Parameter, welcher die relative Blutflussgeschwindigkeit mit dem anatomischen Blutfluss korreliert. Heat Mapʼs wurden automatisch aus den Aufnahmen des RetFlow-Geräts erstellt.

Resultate In der finalen Analyse konnten 83 Augen von 43 männlichen Probanden eingeschlossen werden. Das mittlere Alter betrug 21,9 Jahre (SD ± 1,5, Spanne: 20 bis 29). Der mittlerer korrigierte Visus betrug logMAR (± 0,05, Spanne: − 0,2 bis 0,0), der mittlere IOD betrug 15,4 mmHg (SD ± 2,5, Spanne: 8,5 bis 18,5), mittleres SE war − 0,3 dpt (± 1,2, Spanne: − 5,0 bis 1,2). Die mittlere papilläre MBR betrug 37,44 (± 7,9, Spanne: 22,5 bis 53,5) und die mittlere makuläre MBR betrug 27,8 (± 9,7, Spanne: 6,4 bis 57,7). Der Pearsonʼs Test zeigte eine starke Korrelation zwischen makulärem und papillärem Blutfluss (p < 0,05, Koeffizient: 0,647).

Schlussfolgerung Diese Studie gibt Daten über den papillären sowie makulären Blutfluss in einer Kohorte junger, gesunder Männer an, wobei papillärer und makulärer Blutfluss in den untersuchten Augen stark korrelieren. Weitere Studien zur Untersuchung beider Parameter werden benötigt, um die kombinierte Analyse der Parameter durchführen zu können.

Conclusion Box

Already known:

• Retinal and choroidal blood flow can be altered in patients with retinal and systemic vascular diseases.

Newly described:

• Optic Nerve Head (ONH) and macular retinal blood flow strongly correlated in this cohort of young, healthy, male probands.

Key words

laser speckle flowgraphy - retina - bloodflow - noninvasive - retinal imaging

Schlüsselwörter

Netzhaut - Blutfluss der Netzhaut - nichtinvasive Messmethode - Bildgebung der Netzhaut

Publication History

Received: 15 October 2022

Accepted: 29 January 2023

Article published online:
25 April 2023

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