Retinal Vasculature Reactivity During Flicker Light Provocation, Cardiac Stress and Stroke Risk in Africans: The SABPA Study


Structural and functional similarities exist between the retinal, cerebral and, as previously suggested, the coronary microvasculature. Retinal microvascular structure and functionality (in response to flicker-light-induced-provocation (FLIP)) may relate to coronary artery disease risk and possible stroke risk. We investigated associations between retinal vessel structure, functionality and cardiac stress markers (cardiac troponin T [cTnT], amino-terminal B-type natriuretic peptide [NT-proBNP]) to translate these retina–heart relationships to stroke risk. We included 317 African and Caucasian teachers’ (aged 23–68 years), who participated in the Sympathetic Activity and Ambulatory Blood Pressure in Africans (SABPA) study. Fasting plasma and serum samples for cTnT and NT-proBNP were collected. Retinal vascular calibres were quantified from fundus images and dynamic retinal vessel calibre responses during FLIP. The University of California stroke risk score was applied to assess sub-clinical 10-year stroke risk. cTnT levels were similar in Africans and Caucasians, whereas NT-proBNP levels were lower in Africans. In Africans, a reduced arteriolar calibre and attenuated arteriolar dilation during FLIP was associated with higher cTnT (p < 0.01). Their larger retinal–venular calibre (p < 0.02) and attenuated arteriolar dilation during FLIP (p < 0.05) were associated with lower NT-proBNP. Again, exclusively in Africans, increased cardiac stress, wider venular calibres and retinal arteriovenous nicking predicted an increased 10-year stroke risk with odds ratios of 1.57 (95% CI, 1.34; 1.68, p = 0.031), 1.51 (95% CI, 1.26; 1.59, p = 0.002), 1.10 (95% CI, 0.94; 2.85, p = 0.002) and 1.06 (95% CI 0.83; 1.56, p = 0.052), respectively. None of these associations were evident in the Caucasian group. Investigating the retinal vasculature may serve as a tool to approximate sub-clinical coronary and cerebral microvasculature damage or dysfunction. These cardiac stress–retinal associations additionally predicted a greater stroke risk in the SABPA African cohort. Observable changes in the retinal vasculature may serve as markers for the identification and prediction of cardio-systemic and cerebral vascular morbidities and risks, thereby establishing a brain-heart link.

Proposed series of events during which sustained high pressure and increased cardiac stress may alter retinal reactivity and link to increased stroke risk

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Fig. 1



Area under the curve


Dynamic vessel analyses


Cardiac troponin T


Maximum constriction


Maximum dilation


Amino-terminal pro-B-type natriuretic peptide


Odds ratio


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The present study was partially funded by the National Research Foundation, South African Medical Research Council, ROCHE Diagnostics, North-West University (Potchefstroom Campus), North-West Department of Education South Africa as well as the Metabolic Syndrome institute, France.

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Correspondence to Leoné Malan.

Ethics declarations

The SABPA study obtained ethical approval from the Health Research Ethics Committee (HREC) of the NWU and extended approval was granted for the second phase (ethics number: NWU-00036-07-S6). Written informed consent was obtained from all volunteers prior to participation. All procedures and objectives were explained to the participants prior to their recruitment and adhered to the applicable institutional guidelines and terms, as stated by the Declaration of Helsinki (2004). Please also refer to uploaded SABPA Protocol article.

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The authors declare that they have no conflict of interest.



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Any opinion, findings and conclusions or recommendations expressed in this material are those of the authors; therefore, funders do not accept any liability regarding this study.

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Wentzel, A., Malan, L., Smith, W. et al. Retinal Vasculature Reactivity During Flicker Light Provocation, Cardiac Stress and Stroke Risk in Africans: The SABPA Study. Transl. Stroke Res. 10, 485–494 (2019).

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  • Retina
  • Dynamic retinal vessel responses
  • Flicker-light-induced-provocation (FLIP)
  • NT-proBNP
  • cTnT
  • Stroke
  • Ethnicity