Study limitations
retinal microvascular anatomy, failure, diabetes, cardio-vascular disease, hypertension, SDB
HYPERTENSION, HYPERCHOLESTEROLAEMIA, DIABETES
The study has a number of strengths and limitations. Firstly, it is essentially descriptive and exploratory in nature, consequently, its results should be interpreted accordingly. In addition, given the number of relationships explored, p-values provided should be regarded as only a guide to any potential relationships.Inclusion/exclusion criteria eliminated a major cardiovascular risk factor, diabetes, and controlled for others, eg treatment of hypertension and hypercholesterolaemia, but allowed for major anthropometric influences, e.g. age and body size. This approach aimed to avoid effects of known cardio-vascular disease confounders that typically occur in large community recruited cohorts, while simultaneously avoiding the limitations of very small groups, often produced by protocols that attempt to eliminate all known risk factors. In addition, the majority of the subjects had retinal microvasculature diameters that were within ranges seen in healthy subjects. The failure to identify any major change following treatment may be a consequence of a floor effect, where vessels are unable to change any further. Despite our efforts, classic risk factors were still present in the group and in the process, we have also restricted our ability to examine interactions between SDB and retinal microvascular anatomy when uncontrolled classic risk factors such as diabetes are fully present. The lack of a demonstrated association between SDB metrics and retinal vessel diameters needs to be interpreted with this latter point in mind. It is possible that SDB may have had an additive or even multiplicative effect on uncontrolled classic cardiovascular risk factors. However, such an interaction would have been missed by our current study design.