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Simulate cone-rod dystrophy (CRD) — a heterogeneous group of progressive inherited retinal dystrophies in which cone photoreceptors degenerate before, or proportionally faster than, rod photoreceptors. CRD is distinguished from retinitis pigmentosa (rod-first degeneration) by its clinical signature: visual acuity loss, photophobia, and colour vision failure appearing before or alongside nyctalopia and peripheral field constriction. As the disease advances, both photopic and scotopic ERG become severely impaired, leading to confluent loss of central and peripheral vision. Causal mutations span diverse genes: ABCA4 encodes the ATP-binding cassette transporter A4 that exports N-retinylidene-PE from cone and rod outer-segment discs — severe ABCA4 alleles cause CRD phenotypes (whereas milder alleles cause Stargardt disease or late-onset ARMD). RPGR ORF15 mutations disrupt ciliary photoreceptor transport in both cone and rod cells. CRX mutations impair the transcription factor governing >50 photoreceptor-specific genes. CNNM4 mutations cause Jalili syndrome — autosomal recessive CRD combined with amelogenesis imperfecta. Model three disease stages: cone-predominant early CRD (colour and acuity failure ahead of rod loss), mixed progressive stage (combined photopic and scotopic degeneration with peripheral field constriction), and advanced panretinal degeneration (profound combined photoreceptor failure). Inspect ΔE colour shift, CIE xy chromaticity, and image-level simulation.

Cone-rod dystrophy colour science simulation by Auric Artisan.

Base color
Disease stage & settings
Severity / combined photoreceptor degeneration 50%
Image simulation
Upload JPG/PNG (max 1200 × 1200). See how a scene appears through cone-predominant colour failure, progressive mixed cone-rod loss, or advanced panretinal degeneration with combined central and peripheral vision loss.
Research notes
Cone-rod dystrophy is distinguished from pure cone dystrophy by the eventual involvement of rod photoreceptors, and from retinitis pigmentosa by the cone-first temporal sequence. In ABCA4-related CRD — the most studied molecular pathway — the ABCA4 transporter normally flips N-retinylidene-PE from the luminal to the cytoplasmic leaflet of outer-segment disc membranes. Without ABCA4, this retinoid intermediate spontaneously condenses with a second retinaldehyde molecule to form A2E (di-retinoid pyridinium ethanolamine) — a potent bisretinoid that accumulates in RPE lysosomes, inhibits lysosomal hydrolases, generates reactive oxygen species under blue-light irradiation, and ultimately drives RPE apoptosis. Given that ABCA4 is expressed in both cone and rod outer-segment discs but at higher density in cones (and that A2E accumulation is RPE-dependent, which overlies dense macular cones first), cone photoreceptors are the primary casualty before peripheral rods are affected.
Swatches
Normal
HEX: — • RGB: — • xy: —
CRD affected
HEX: — • RGB: — • xy: —
ΔE (CIE76)
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ΔE (CIEDE2000)
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Deep preview
Normal
CRD (deep)
Chromaticity (CIE xy)
Combined photoreceptor degeneration chromaticity shift
D65 white point: 0.313, 0.329
Image simulation

Cone-rod dystrophy simulations model progressive combined photoreceptor degeneration using a stage-dependent differential cone-then-rod channel reduction in the sRGB colour space. The early stage weights cone channels (L, M, S) more aggressively than rod; the mixed stage adds rod-luminance reduction reflecting scotopic ERG involvement; the advanced stage applies near-total pan-photoreceptor depletion. Central scotoma and peripheral field constriction are spatial deficits approximated in image simulation only. ΔE2000 per Sharma et al. (2005). Not for clinical diagnosis — cone-rod dystrophy requires combined photopic and scotopic ERG, colour vision testing, OCT, FAF, and genetic panel. New colour vision loss, photophobia, or progressive peripheral field loss requires urgent ophthalmic assessment.

Multi-condition comparison
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Compare cone-predominant, mixed, and advanced CRD stages across severity grades. Image simulation applies a cone-first then combined photoreceptor degradation profile, including peripheral field approximation in advanced stages.