Purpose
Vitamin D has been shown to have anti-fibrotic properties and deficient levels of circulating 25-hydroxyvitamin D have been associated with fibrogenesis in several extra-ocular tissues. Evidence linking vitamin D deficiency to age-related macular degeneration (AMD) is inconsistent. Thus, we sought to investigate 25-hydroxyvitamin D levels across clinical subgroups of AMD and whether the presence of subretinal fibrosis in neovascular AMD at diagnosis is associated with lower levels of circulating vitamin D.
Methods
Plasma samples were collected from 202 participants across 4 groups: controls (n=73), early AMD (n=22), geographic atrophy (n=12) and neovascular AMD (n=95). All participants were subjected to a structured interview and retinal examination was performed using stereoscopic funduscopy on mydriatic eyes, digital color fundoscopy, autofluorescence imaging, spectral-domain optical coherence tomography and fluorescein and indocyanin green angiography in patients suspected of having neovascular age-related macular degeneration. Clinical grading was performed using the Clinical Age-Related Maculopathy Grading System. Venous blood was obtained for measurement of 25-hydroxyvitamin D2 and D3 in plasma using liquid chromatography-tandem mass spectrometry. Genomic DNA was extracted from leukocytes and genotyping was performed for single nucleotide polymorphisms in the vitamin D metabolism.
Results
Patients with subretinal fibrosis in addition to neovascular AMD had significantly lower levels of circulating 25-hydroxyvitamin D compared to patients without subretinal fibrosis (47.2 versus 75.6 nmol/L, p<0.001). Multiple regression analysis demonstrated that the differences observed were independent of other predictors for vitamin D status ((age, body mass index, physical activity, smoking habits, and genetic polymorphisms in the 1α-hydroxylase (rs10877012), vitamin D receptor (rs2228570) and vitamin D binding proteins (rs4588, rs7041)). No differences in 25-hydroxyvitamin D levels were found across the clinical subgroups when patients with or without subretinal fibrosis were not differentiated from each other (p=0.81).
Conclusions
Lower plasma levels of 25-hydroxyvitamin D in patients diagnosed with neovascular AMD are associated with subretinal fibrosis.
Keywords: 618 nutritional factors •
412 age-related macular degeneration •
688 retina