A major complication of hypertension is microvascular damage and capillary rarefaction is a known complication of hypertensive end-organ damage which confers a higher risk of systemic disease such as stroke and cardiovascular events. Our aim was to study the effect of hypertension on the retinal microvasculature using non-invasive optical coherence tomography angiography (octA). We performed a case-control study of 94 eyes of 94 participants with systemic hypertension and 46 normal control eyes from the Singapore chinese eye Study using a standardized protocol to collect data on past medical history of hypertension, including the number and type of hypertensive medications and assessed mean arterial pressure. Retinal vascular parameters were measured in all eyes using octA. in the multivariate analysis adjusting for confounders, compared to controls, eyes of hypertensive patients showed a decrease in the macular vessel density at the level of the superficial [OR 0.02; 95% CI, 0 to 0.64; P 0.027] and deep venous plexuses [OR 0.03; 95% CI, 0 to 0.41; P 0.009] and an increase in the deep foveal avascular zone. this shows that hypertension is associated with reduced retinal vessel density and an increased foveal avascular zone, especially in the deep venous plexus, as seen on octA and there is a potential role in using octA as a clinical tool to monitor hypertensive damage and identifying at risk patients Hypertension is a major cause of morbidity and mortality globally 1,2 , affecting 29.2% men and 24.8% women in 2012 3. A major complication of hypertension is microvascular damage, related partly to abnormal vasomotor tone and increased wall-to-lumen ratio in relation to higher blood pressure 4,5. It has also been suggested that vascular rarefaction may due to either functional alterations such as microvessel constriction resulting in non-perfusion or anatomical alterations resulting in actual non-perfusion and vessel loss 4. There have been many previous studies on the association between hypertension and retinal vasculature. Retinal fundus photo changes seen in response to hypertension include classic hypertensive retinopathy signs such as arteriovenous (AV) nicking, generalized or focal arteriolar narrowing, microaneurysms, intraretinal hemorrhages, cotton wool spots and papilloedema 6. These changes have been shown to confer a higher risk of systemic disease such as stroke and cardiovascular events 6-9. Other studies have also looked at larger retinal vessels (200-300 µm) using color fundus photos and demonstrated a correlation between narrower arteriolar diameter in hypertension 10-13. The impact of hypertension on capillary microvasculature is less clear. Historically, invasive fundus fluorescein angiography (FFA) was needed to evaluate perfusion and the structure of capillary microvasculature. Previous studies using FFA have shown that in patients with hypertension, there is an increase in perifoveal inter-capillary area and decrease in capillary blood velocity 14. However, FFA is not suitable for use in larg...

Background/AimsTo compensate the retinal nerve fibre layer (RNFL) thickness assessed by spectral-domain optical coherence tomography (SD-OCT) for anatomical confounders.MethodsThe Singapore Epidemiology of Eye Diseases is a population-based study, where 2698 eyes (1076 Chinese, 704 Malays and 918 Indians) with high-quality SD-OCT images from individuals without eye diseases were identified. Optic disc and macular cube scans were registered to determine the distance between fovea and optic disc centres (fovea distance) and their respective angle (fovea angle). Retinal vessels were segmented in the projection images and used to calculate the circumpapillary retinal vessel density profile. Compensated RNFL thickness was generated based on optic disc (ratio, orientation and area), fovea (distance and angle), retinal vessel density, refractive error and age. Linear regression models were used to investigate the effects of clinical factors on RNFL thickness.ResultsRetinal vessel density reduced significantly with increasing age (1487±214 µm in 40–49, 1458±208 µm in 50–59, 1429±223 µm in 60–69 and 1415±233 µm in ≥70). Compensation reduced the variability of RNFL thickness, where the effect was greatest for Chinese (10.9%; p<0.001), followed by Malays (6.6%; p=0.075) and then Indians (4.3%; p=0.192). Compensation reduced the age-related RNFL decline by 55% in all participants (β=−3.32 µm vs β=−1.50 µm/10 years; p<0.001). Nearly 62% of the individuals who were initially classified as having abnormally thin RNFL (outside the 99% normal limits) were later reclassified as having normal RNFL.ConclusionsRNFL thickness compensated for anatomical parameters reduced the variability of measurements and may improve glaucoma detection, which needs to be confirmed in future studies.

We quantified the effect of unreliable responses on the MD and PSD in SAP. Our study may allow clinicians to estimate how VF results are affected by varying degrees of unreliability, instead of relying on cutoff values for reliability indices.

There are interethnic differences in MT profile among Asians, particularly between Chinese and Indians. Ocular and systemic factors affect MT measurements as well. This Asian-specific information may be incorporated into existing clinical interpretation of macular OCT scans to aid in improving the diagnostic and monitoring accuracy of macular diseases among Asians.