Quantification of Retinal Vessel Myogenic Constriction in Response to Blood Pressure Peaks: Implications for Flicker Light-Induced Dilatation

Figures

• 

  FIGURE 1. Examples of arteriolar median curves for DVA protocol I (A) and DVA protocol II (B). DVA protocol I consisted of 50 s baseline recording followed by 20 s flicker light application and 80 s at rest (A). DVA protocol II consisted of 50 s baseline recording, 40 s handgrip strength task at 30% 1RM, 30 s all-out handgrip strength task, 10 s at rest followed by 20 s of flicker light and a rest period of 80 s. DVA, dynamic retinal vessel analysis; aFID, maximal arteriolar flicker light-induced dilatation; aCON, maximal arteriolar vessel constriction after flicker stimulation; aMC, maximal arteriolar myogenic constriction before the flicker; aRA, maximal arteriolar range between arteriolar myogenic constriction and aFID; 1RM, one repetition maximum; BP, blood pressure.

• 

  FIGURE 2. Setup for dynamic retinal vessel analysis (DVA) with the Dynamic Vessel Analyzer (DVA®; Imedos Systems GmbH, Jena, Germany) and a fundus camera (450FF, Carl Zeiss, Jena, Germany). Blood pressure was measured beat-to-beat on the middle finger of the right hand with the Finapres® (Finapres Medical Systems B.V., Enschede, Netherlands). The Leonardo Mechanograph GF® device (Novotec Medical GmbH, Pforzheim, Germany) on the left hand was used to increase the blood pressure of the participants. The produced power was continuously controlled using the Leonardo Mechanography BAS v4.4 software.

• 

  FIGURE 3. Arteriolar and venular median curves for DVA protocol I (A) and DVA protocol II (B) of one representative HA and SR participant. DVA protocol I consisted of 50 s baseline recording followed by 20 s flicker light application and 80 s at rest (A). DVA protocol II consisted of 50 s baseline recording, 40 s handgrip strength task at 30% 1RM, 30 s all-out handgrip strength task, 10 s at rest followed by 20 s of flicker light and a rest period of 80 s. DVA; dynamic retinal vessel analysis; HA, healthy active; SR, sedentary patients with increased cardiovascular risk.

• 

  FIGURE 4. Association of maximal arteriolar range and change in mean arteriolar pressure in healthy active individuals (HA) and sedentary cardiovascular risk patients (SR).

• 

  FIGURE 5. Example for a median time curve of arteriolar diameter and mean arteriolar pressure, calculated from three cycles of DVA protocol II of one participant. DVA; dynamic retinal vessel analysis; MAP, mean arteriolar pressure; 1RM, one repetition maximum.