Introduction
Uveitis, characterised by eye inflammation, can result from infection, injury, autoimmune disorders or inflammatory conditions. This condition involves inflammation of the uvea tract, encompassing the iris, ciliary body and choroid, as well as adjacent eye structures like the vitreous, retina, optic nerve and sclera.1 Uveitis is classified anatomically into four types: anterior uveitis, intermediate uveitis, posterior uveitis and panuveitis. Additionally, based on aetiology, it can be categorised into three types: infectious, non-infectious and masquerade.2 Non-infectious uveitis (NIU) can be the manifestation of systemic autoimmune disease. In China, the most common types of NIU include Behçet’s disease (BD), Vogt-Koyanagi-Harada (VKH) disease and idiopathic panuveitis. Idiopathic panuveitis is an inflammation of all layers of the uvea with an unknown cause. VKH disease causes inflammation in the eyes, skin, hair and ears due to an autoimmune response. Symptoms include vision changes, eye pain, hearing loss, headaches and skin colour changes. BD is a chronic autoimmune disease causing recurrent inflammation in blood vessels throughout the body, affecting organs like the eyes, skin, joints and gut. Ocular BD presents as uveitis. Uveitis can be severe, potentially leading to permanent vision loss. Therefore, early diagnosis and treatment are essential for preventing complications and preserving vision.
Lipid profiles have been observed to undergo changes in numerous chronic inflammatory diseases.3 Abnormal lipid metabolism and variations in the content and composition of membrane phospholipids have been identified in the blood of systemic lupus erythematosus patients when compared with individuals without the condition. Furthermore, investigations have revealed alterations in lipid content and composition among patients diagnosed with rheumatoid arthritis, inflammatory bowel disease, multiple sclerosis and type 1 diabetes mellitus.4 Dyslipidaemia, as a significant contributing factor, can also expedite inflammation and atherosclerosis in autoimmune diseases.
Abnormalities in lipid parameters have also been reported in BD. Lessof et al discovered that BD-associated uveitis was correlated with serum high-density lipoprotein-cholesterol (HDLc) levels when compared with healthy controls.5 Interestingly, it has also been reported that there were no significant differences in the concentrations of low-density lipoprotein-cholesterol (LDLc), total cholesterol (TC) and triglyceride (TG) between patients with BD and controls.6 These lipid parameter abnormalities may elevate the risk of cardiovascular events in BD patients.7 However, the proportion of BD-associated uveitis cases within the total uveitis population is very small, and more than 60% being idiopathic uveitis. The impact of uveitis on lipid metabolism remains unclear.
Optical coherence tomography angiography (OCTA) is an innovative, non-invasive imaging technique capable of visualising the 3D vasculature of the retina and choroid. This technology can identify both physiological and pathological blood flow abnormalities, which are particularly relevant in uveitis cases.8 OCTA has demonstrated its advantage in diagnosing and monitoring choroidal involvement in uveitis, including conditions such as acute posterior multifocal placoid pigment epitheliopathy,9 multifocal choroiditis,10 birdshot chorioretinopathy,11 acute macular neuroretinopathy.12 Furthermore, OCTA allows for the quantification of microvascular changes in the retinal capillary network, in addition to detecting classical uveitis features. Some studies have reported that OCTA can provide quantitative analysis for VKH disease.13 While previous retinal studies have shown associations between serum lipid profiles, dyslipidaemia and retinal microvascular changes,14 the assessment of retinal and choroidal microvasculature in NIU and its correlation with systemic biomarkers, such as lipid profiles, remains unexplored.
The aim of this study was to evaluate the lipid profile in NIU and provide guidance for its treatment. This study involved the assessment of serum lipids in NIU, including BD-associated uveitis, VKH disease and idiopathic uveitis cases. OCTA was used to measure vascular density (VD) in the superficial capillary plexus (SCP), deep capillary plexus (DCP), outer retinal circulation and choriocapillaris. The relationship between serum lipids and OCTA parameters was examined.