30

Simulate branch retinal vein occlusion (BRVO) — the most common retinal vascular occlusion, with an estimated prevalence of 4.4 per 1,000 adults over age 40 worldwide (the Beijing Eye Study, Blue Mountains Eye Study, and Beaver Dam Eye Study report lifetime cumulative incidence of 1.6–3.7%). BRVO occurs when a retinal arteriole compresses the underlying venule at an arteriovenous (AV) crossing point — the arteriole and venule share a common adventitial sheath at these crossings, and arteriosclerotic thickening of the arteriolar wall (from systemic hypertension, diabetes, hyperlipidaemia, or age-related vascular remodelling) narrows the venous lumen, producing turbulent flow, endothelial damage, and thrombotic occlusion. The resulting venous congestion produces a characteristic sectoral distribution of pathology: flame-shaped and dot-blot haemorrhages, cotton-wool spots (focal retinal nerve fibre layer infarcts from capillary non-perfusion), retinal oedema, and — critically for visual prognosis — macular oedema. Macular oedema is the primary cause of vision loss in BRVO, present in approximately 60% of BRVO eyes at diagnosis. The superotemporal branch is affected in approximately 63% of cases (the highest density of AV crossings), inferotemporal in ~29%, and nasal branches in ~8%. Simulate three clinical presentations: major BRVO (large branch, extensive sectoral haemorrhage), macular BRVO (small tributaries draining the foveal region), and hemiretinal vein occlusion (HRVO — half of the retinal venous drainage occluded at or near the disc). ΔE colour shift, CIE xy chromaticity, and image simulation.

Branch retinal vein occlusion colour science simulation by Auric Artisan.

Base color
BRVO subtype & settings
Venous congestion / macular oedema severity 50%
Image simulation
Upload JPG/PNG (max 1200 × 1200). See how a scene appears through major BRVO (sectoral haemorrhage with macular oedema — blurred central vision with scotoma in the affected sector), macular BRVO (localised foveal oedema causing central blur with relative field preservation), or hemiretinal vein occlusion (extensive half-retinal haemorrhage with severe macular oedema and neovascularisation risk).
Research notes
Arteriovenous crossing — the anatomical bottleneck: At retinal AV crossings, the arteriole and venule share a common adventitial sheath (Ruskell, 1961). In 97% of AV crossings, the arteriole lies anterior to (on top of) the venule. When the arteriolar wall thickens from hypertension or arteriosclerosis, it compresses the underlying venule against the rigid adventitial sheath — producing a "nipping" effect visible on fundoscopy as AV nicking (Gunn's sign). This compression causes turbulent venous flow → endothelial damage → thrombus formation → venous occlusion. The superotemporal arcade has the highest density of AV crossings, explaining its predominance in BRVO (63% of cases).
Swatches
Normal
HEX: — • RGB: — • xy: —
BRVO affected
HEX: — • RGB: — • xy: —
ΔE (CIE76)
—
ΔE (CIEDE2000)
—
Deep preview
Normal
BRVO (deep)
Chromaticity (CIE xy)
Venous congestion chromaticity shift
D65 white point: 0.313, 0.329
Image simulation

BRVO simulations model the retinal oedema and haemorrhagic attenuation from venous congestion in the sRGB colour space. Major BRVO: models extensive sectoral macular oedema as central cone signal degradation with intraretinal fluid causing contrast loss and desaturation — the haemorrhagic component produces a warm reddish-brown chromaticity bias from haemoglobin absorption (Soret band ~415 nm, Q-bands ~540/575 nm). Macular BRVO: models localised foveal oedema as centralised blur with moderate L/M-cone signal disruption. Hemiretinal vein occlusion: models half-retinal congestion with severe macular oedema and ischaemic retinal damage. Anti-VEGF treatment reduces VEGF-driven vascular permeability → resolves macular oedema → improves vision. ΔE2000 per Sharma et al. (2005). Not for clinical diagnosis — BRVO requires dilated fundoscopy, FFA, SD-OCT, and systemic risk factor assessment.

Multi-condition comparison
5
Compare major BRVO (extensive sectoral haemorrhage), macular BRVO (localised foveal tributary), and hemiretinal vein occlusion (half-retinal drainage, ischaemic risk).