Ethnicity, CVD, CKD influence retinal emboli prevalence in Singapore
The prevalence of retinal emboli among Singaporeans, while low, varies widely by ethnicity, and is also associated with cardiovascular risk factors and chronic kidney disease (CKD), according to results of the SEED* study.
In this population-based cross-sectional study conducted between 2004 and 2011, researchers used retinal photographs of both eyes of 10,033 participants aged 40–80 years to assess the prevalence of retinal emboli in the Singaporean general population, of which 99.5 percent (n=9,978) had gradable retinal photographs. Retinal emboli was present in 88 patients (0.9 percent, mean age 65.1 years, 51 percent male).
Person-specific, age-standardized prevalence of retinal emboli was 0.75 percent, with prevalence highest in participants of Indian descent, followed by those of Chinese and Malay descent (0.98, 0.73, and 0.44 percent, respectively; p=0.02). [JAMA Ophthalmol 2017;doi:10.1001/jamaophthalmol.2017.2972]
The prevalence of retinal emboli was higher among individuals of older age (odds ratio [OR], 1.22, 95 percent confidence interval [CI], 1.05–1.41 per 5-year increase; p=0.009) and in individuals of Indian descent (OR, 3.58, 95 percent CI, 1.95–6.60 compared with those of Malay descent; p<0.001).
Retinal emboli was also more prevalent among current smokers (OR, 2.25, 95 percent CI, 1.08–4.70; p=0.03) and individuals with hypertension (OR, 1.95, 95 percent CI, 1.03–3.70; p=0.04) or a history of stroke (OR, 3.45, 95 percent CI, 1.70–6.99; p<0.001), as well as those with CKD (OR, 2.05, 95 percent CI, 1.15–3.64; p=0.02) as measured by elevated creatinine level (OR, 1.13, 95 percent CI, 1.05–1.21 per SD increase; p=0.003) or lower glomerular filtration rate (GFR; OR, 0.67, 95 percent CI, 0.51–0.86 per SD increase; p<0.001).
“By virtue of its anatomic orientation, the central retinal artery represents an end artery of the cerebral circulation,” said the researchers. “Emboli seen in the retina may therefore reflect thromboembolic events that occurred in the brain or elsewhere in the body.”
“[T]he association between retinal emboli and lower GFR [ie, renal function] remained similar, even in participants without hypertension or diabetes. In view of our findings, patients with asymptomatic retinal emboli may benefit from not only general cardiovascular workup but also assessment of renal function to detect this potentially fatal complication,” they said, suggesting that longitudinal studies may help ascertain if retinal emboli could predict renal disease risk and prognosis.
The association between retinal emboli and certain risk factors also differed by ethnicity, where the association between smoking and retinal emboli was most evident among participants of Malay descent, while the association between CKD and retinal emboli was only evident in participants of Indian and Chinese descent.
The researchers acknowledged study limitations including the potential underestimation of retinal emboli prevalence due to the “transient nature of emboli” or inadequate images used in the assessment (two images per eye). The associations between the risk factors and retinal emboli may also be chance findings, they said.