McVeigh Laboratory
Epidemiological studies show changes in the retinal microcirculation (decreased retinal arteriolar diameter, increased venular diameter) can predict future development of risk factors for cardiovascular disease (e.g. hypertension) and cardiovascular outcome. These data indicate the microcirculation may be involved not only in the pathogenesis or earliest stages of disease development but that endothelial activation in the microcirculation may act as a driver for plaque development and rupture in conduit vessels.
Our work has focussed the study of Doppler flow velocity envelopes, recorded in the central retinal and ophthalmic arteries, in relation to changes in architecture of the retinal circulation in different patient groups, including type 1 and type 2 diabetes mellitus. We developed novel Eigenvector and wavelet methodologies that capture the altered signatures of pulse wave reflection from the downstream microvascular bed. These signatures sensitively identified altered structure and function in the retinal microvascular bed in diabetic patients who had no evidence of retinopathy detected by retinal photography.
We have also developed software to accurately map diameters of the retinal vascular network in order to study the relationship between changes in retinal arteriolar calibre in response to 100% 02 and pharmacological interventions and associated change in the flow velocity waveforms. In the patient studies, pulse wave morphology and microvascular architecture in the ocular network are assessed in relation to:-
1. measures of nitric oxide bioactivity and microvascular function using the technique of forearm mediated dilation (FMD)
2. free radical chemistry (nitric oxide, nitric oxide synthase activity, superoxide production, peroxinitrite and NAD(P)H activity) using the platelet as an ex-vivo tissue model.
The ability to detect altered microvascular structure and function at an early pre-clinical stage holds potential to identify those individuals at greatest risk for future complications and intervene at an earlier stage to help prevent or delay the development of vascular pathology that is responsible for the majority of morbid and mortal events in patients with diabetes mellitus.
MEMBERS OF THE RESEARCH GROUP
Dr Mark Harbinson
Dr Rick Plumb
Dr Paul Hamilton
Dr Auleen Millar
Dr Stephen Wright
Dr Cathy Quinn
Dr Chris Lockhart
Dr Canice McGivern
Dr Aaron McCann
Miss Christina Agnew
Mr Adrian Devine
Mr William Leahey