OCT Angiography of the Central Macular Capillary Network in Glaucoma Patients and Healthy Controls

Abstract

Purpose We aimed to investigate central macular microvasculature by optical coherence tomography angiography (OCTA) and to analyse its relation to alterations in classical parameters of optical coherence tomography (OCT) in glaucoma patients.

Methods Using OCTA (Avanti incl. AngioVue; Optovue, Inc., Fremont, CA), the superficial flow (SF) and the superficial non-flow (SNF) area of the macula, as well as the S-ETDRS (based on Early Treatment Diabetic Retinopathy charts). and S-grid vessel density (zones 1 – 9) of the macula, were evaluated in 27 glaucoma patients (49 eyes) and compared to those of 27 age-matched healthy controls (50 eyes; p = 0.253). The interactions between OCTA parameters representing macular microvasculature and classical OCT measurements of the circumpapillary retinal nerve fibre layer (RNFL) and macular ganglion cells (mGCC) were analysed within groups (linear mixed-effects model).

Results SF, SNF, and S-ETDRS vessel density exhibited no significant difference between the glaucoma and control groups (all p ≥ 0.158). However, within the glaucoma group, decreased RNFL and mGCC thickness correlated significantly with decreased S-ETDRS density (zones 1; 2 – 9, p ≤ 0.033). The same held true for the interactions between the RNFL and mGCC thickness with S-grid density (zones 1 – 3; 6 – 9; p ≤ 0.033). For perimetric glaucoma patients, subgroup analyses demonstrated significantly reduced density maps of superficial foveal flow as well as significant interactions between OCT and OCTA parameters; this was not the case within the preperimetric group.

Conclusions Even if the central macular microvasculature, as measured by SF and SNF, is found preserved in glaucoma, the strong positive relation between the central microvascular and structural changes in OCTA and OCT indicates that there are alterations in central macular microvasculature in subclinical glaucoma.

Zusammenfassung

Hintergrund Ziel der Studie war die Untersuchung der zentralen makulären Gefäßversorgung mittels optischer Kohärenztomografie-Angiografie (OCTA) bei Glaukompatienten und die Korrelation dieser OCTA-Parameter mit klassischen OCT- und klinischen Befunden.

Patienten und Methoden Für die Studie wurden 27 Glaukompatienten und 27 alterskorrelierte, gesunde Probanden gewonnen. Mit der OCTA (Avanti incl. AngioVue; Fa. Optovue, Inc, Fremont, CA) wurden verschiedene Parameter der oberflächlichen kapillaren Blutversorgung der Makula gemessen: das oberflächliche Flussareal (Superficial Flow = SF) und das kapillar nicht durchblutete Areal (Non-Flow Area = SNF) der Makula sowie zusätzlich die Messung der kapillaren Gefäßdichte unter zonaler Aufteilung der Makularegion nach 2 Mustern (S-ETDRS- und S-Grid-Muster mit jeweils 9 Zonen). Neben den klinischen Befunden wurden klassische OCT-Parameter der Glaukomdiagnostik (zirkularpapillare retinale Nervenfaserschicht = RNFL, makulärer Ganglienzellkomplex = mGCC) erhoben und eine Analyse der OCT- und OCTA-Parameter vorgenommen (Linear Mixed-Effects Model).

Ergebnisse Verschiedene OCTA-Parameter (SF, SNF und S-ETDRS-Gefäßdichte) zeigten keinen signifikanten Unterschied zwischen Glaukomgruppe und Kontrollgruppe (alle p = 0,158). Jedoch ergab sich innerhalb der Glaukomgruppe eine starke Korrelation zwischen reduzierter RNFL-Dicke und mGCC-Dicke einerseits und reduzierten S-ETDRS-Gefäßdichtezonen (Zonen 1; 2 – 9; p = 0,033) und S-Grid-Gefäßdichtezonen (Zonen 1 – 3; 6 – 9; p = 0,033) andererseits. In einer Subgruppenanalyse zeigten Glaukomaugen mit manifesten Gesichtsfeldausfällen signifikante Veränderungen der kapillaren Gefäßversorgung, die bei einem präperimetrischen Glaukomstatus nicht sichtbar waren.

Schlussfolgerung Veränderungen der zentralen mikrovakulären Gefäßversorgung der Makula sind zumindest auf subklinischer Ebene mittels OCTA bei Glaukompatienten darstellbar und zeigen eine Korrelation zu Veränderungen klassischer OCT-Parameter und dem Gesichtsfeldstatus.

Key words

glaucoma - optical coherence tomography angiography - optical coherence tomography - microvasculature - optic nerve - macula

Schlüsselwörter

Glaukom - optische Kohärenztomografie - OCT-Angiografie - Makula - mikrovaskuläre Gefäßversorgung - Sehnerv

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