Static retinal vessel analysis is a noninvasive ophthalmic diagnostic procedure that can be used to detect and evaluate structural changes in retinal vessels (microvessels). Using a fundus camera (camera for the creation of images of the ocular fundus), the vessel diameters of both the arterial and venous vessel sections are determined from individual images or image sequences. The diameter of the vessels is assessed on the basis of defined measuring points. However, functional assessment can be performed exclusively during dynamic vascular analysis of retinal microvessels.
Indications (areas of application)
- Risk assessment for apoplexy (stroke)-vascular (vascular) changes in the retina correlate with the incidence (occurrence) of cardiovascular disease (CVD), which includes apoplexy. Of critical diagnostic importance for risk assessment is the determination of the retinal artery/vein diameter ratio, which is associated with both the presence of hypertension (high blood pressure) and stroke risk. This allows the use of non-invasive diagnostics for the evaluation (assessment) of cardiovascular risk factors. Comparing the vascular structure and physiology of the retinal vessels and the small vessels of the central nervous system, there is a clear homology (close relationship), so that the informative value of the test method can be considered very good.
- Risk assessment for dementia (decrease of the mind, accompanied by a deficit in cognitive, emotional and social skills) – dementia can have various causes. Vascular changes represent an important factor in the pathogenesis (disease development) of dementia.
- Risk assessment for myocardial infarction (heart attack) – a crucial risk factor for the occurrence of a heart attack is the vascular status. Hypertension not only damages the vessels, but also causes microscopic and macroscopic changes in the myocardium (heart muscle). The VSL Analyzer can be used as a non-invasive additional diagnostics to determine risk.
Contraindications
There are no contraindications to the use of static retinal vascular analysis for risk assessment. However, the application should not be used in acute cardiovascular events.
Before the examination
In addition to the retinal vessels, other vascular systems must be examined to assess the risk of a cardiovascular event. Sonography of the carotid artery is useful as an additional noninvasive diagnostic tool, especially for assessing the risk of apoplexy, because it also has a high degree of association with stroke risk.
The procedure
To perform static retinal vascular analysis, pupil dilation (mydriasis) is usually necessary to improve examination results. For example, tropicamide eye drops are used as mydriaticum (drug-induced pupil dilation). For optimal examination, an angle setting of 30° and positioning of the optic disc (optic nerve exit) in the center of the image are necessary. In order to use the procedure to draw conclusions about the systemic vascular status, the fundus images obtained are subsequently analyzed using a computer-assisted semi-automatic image analysis method. To perform the procedure, it is necessary, among other things, to define a measurement zone located approximately one optic disc diameter from the optic disc margin. Subsequently, the existing retinal arterioles and venules (arterial and venular microvessels) are localized within this measurement zone, so that the vessel diameter can be calculated with a mathematical formula from the sum of the individual automatically determined arteriolar and venular vessel diameters. This yields the arteriolar-venular quotient (AVR), which can be used to draw conclusions about systemic vascular status.
After the examination
The combination of a blood pressure measurement, an assessment of the risk factors present, and static and dynamic retinal vascular analysis allows reproducible findings on systemic vascular status. The results can be further refined by the application of additional diagnostic procedures.
Possible complications
Static retinal vascular analysis is a noninvasive diagnostic procedure with no risk for the occurrence of a complication.
