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Simulate choroideremia — a rare X-linked recessive progressive chorioretinal degeneration caused by loss-of-function mutations in the CHM gene (chromosome Xq21.2), which encodes Rab escort protein-1 (REP-1). REP-1 is essential for the prenylation of Rab GTPases (particularly Rab27a) — the molecular machinery that governs intracellular vesicle trafficking and membrane fusion in the retinal pigment epithelium and photoreceptors. Without functional REP-1, unprenylated Rab27a accumulates and RPE melanosome transport fails, triggering progressive degeneration of the choroid, RPE, and photoreceptors in a characteristic centripetal (periphery-to-centre) pattern. Affected males develop severe nyctalopia in childhood, expanding ring-shaped visual field scotoma in adolescence and early adulthood, and progressive peripheral visual field constriction ultimately leaving only a small central island of vision in the 4th-6th decade. Carrier females (heterozygous) typically have a normal or near-normal phenotype but may show mosaic RPE/choroidal changes on fundus examination. Model three disease stages: early peripheral rod degeneration (scotopic loss, ring scotoma), mid-stage progressive chorioretinal atrophy (expanding field constriction), and advanced choroidal atrophy (residual central island). Inspect ΔE colour shift, CIE xy chromaticity, and image-level visual field simulation. Advanced retinal genetics, gene therapy, and vision science research tool.

Choroideremia colour science simulation by Auric Artisan.

Base color
Disease stage & settings
Severity / degeneration progression 50%
Image simulation
Upload JPG/PNG (max 1200 × 1200). See how a scene appears through early ring scotoma, progressive constriction, or advanced choroidal atrophy with residual central island.
Research notes
Choroideremia was first described by Mauthner in 1872 as a bilateral condition causing diffuse choroidal atrophy. The CHM gene was identified in 1990 by Cremers et al. and REP-1 protein function characterised by Seabra & Mules in 1992. REP-1 uniquely escorts newly synthesised Rab GTPases to the cytosol membrane-targeting machinery (geranylgeranyltransferase-II, GGTase-II) for double geranylgeranylation — a critical lipid modification that anchors Rab proteins to intracellular membranes and vesicles. In the RPE, Rab27a-dependent melanosomes fail to transport to apical processes, disrupting daily photoreceptor outer segment phagocytosis. This leads to lipofuscin accumulation, RPE oxidative stress, and progressive degeneration of all three layers of the posterior retina (choroid, RPE, photoreceptors) in a centripetal wave. The disease is currently the subject of active gene therapy trials using AAV2/8 vectors carrying the CHM cDNA.
Swatches
Normal
HEX: — • RGB: — • xy: —
CHM affected
HEX: — • RGB: — • xy: —
ΔE (CIE76)
—
ΔE (CIEDE2000)
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Deep preview
Normal
CHM (deep)
Chromaticity (CIE xy)
Chorioretinal atrophy chromaticity shift
D65 white point: 0.313, 0.329
Image simulation

Choroideremia simulations model centripetal photoreceptor and choroidal degeneration using a progressive rod-first, then rod+cone channel reduction in the sRGB colour space. The characteristic visual field constriction (ring scotoma → concentric narrowing → central island) is a spatial deficit not fully representable as a uniform colour shift — this tool provides colour science approximations of the photoreceptor sensitivity reduction and desaturation component for educational and research purposes. ΔE2000 per Sharma et al. (2005). Not for clinical diagnosis — choroideremia requires genetic testing (CHM), ERG, goldmann visual field, and OCT. New peripheral vision loss requires urgent ophthalmic assessment.

Multi-condition comparison
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Compare early, progressive, and advanced choroideremia stages across severity grades. Image simulation applies a visual field constriction + photoreceptor degeneration profile to uploaded scenes.