The goal of this observational study is to to assess the ocular microvascular status of SLE patients with inactive disease and without ocular involvement. The main questions it aims to answer are:

• the choroidal vascular status and thickness in SLE
• the retinal macular microvascular status and structure in SLE

Participants will be assessed with Spectral Domain Optical Coherence Tomography (SD-OCT). Researchers will compare SLE patients with healthy controls matched for age and sex.

The investigators will perform a cross-sectional evaluation of 25 SLE patients and 25 healthy controls matched for sex and age, using a Spectral Domain Optical Coherence Tomography (SD-OCT) with Enhanced Depth Imaging for choroidal assessment and with Angiography module to assess the retinal and choriocapillaris vasculature. Processing of image with external software will be performed to calculate the main outcomes: retinal vessel density, foveal avascular zone parameters and the choroidal vascular index.

Systemic inclusion criteria for SLE patients:

• fulfill the 2019 European League Against Rheumatism (EULAR) / American College of Rheumatology (ACR) classification criteria for the diagnosis of SLE
• age between 18 and 80 years
• no disease activity (SLEDAI <3)
• no risk factors for drug toxicity

Systemic inclusion criteria for control group:

• no systemic diseases
• age between 18 and 80 years

Systemic exclusion criteria:

• arterial hypertension (defined as systolic blood pressure higher than 140 mm Hg or diastolic blood pressure higher than 90 mm Hg) or medically treatment for hypertension
• diabetes mellitus
• nephropathy or other documented microvascular complications
• secondary Sjögren syndrome
• local or systemic inflammatory diseases (other than SLE)
• smokers of more than 20 cigarettes a day
• pregnancy.

Ophthalmological inclusion criteria:

• best-corrected visual acuity ≤ 0.3 LogMAR
• intra-ocular pressure <21 mm Hg on diurnal testing with measurements using Goldmann applanation tonometry
• spherical equivalent refractive error between -6.0 and +4.0 diopters
• open anterior chamber angle on slit lamp examination.

Ophthalmic exclusion criteria:

• established primary ocular diseases including a history of any retinal or optic nerve disease
• presence of significant lens opacities (Lens Opacities Classification System III equal to or more stage 2)
• retinopathy
• high refractive error
• ocular hypertension
• previous intraocular surgery or trauma.

Patients fulfilling the 2019 European League Against Rheumatism (EULAR) / American College of Rheumatology (ACR) classification criteria for the diagnosis of SLE and aged between 18 and 80 years old and an age and sex-matched group of healthy controls.