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Achromatopsia 2 is a condition that affects the color vision. Most people have complete achromatopsia which is characterized by a total absence of color vision (only able to see black, white and shades of gray). Rarely, affected people may have incomplete achromatopsia which is associated with some color discrimination. Other common signs and symptoms include reduced visual acuity, involuntary back-and-forth eye movements, increased sensitivity to light (photophobia), and hyperopia (farsightedness). Achromatopsia 2 is caused by changes (mutations) in the CNGA3 gene and is inherited in an autosomal recessive manner. Although color discrimination cannot be improved, treatments are available to address some of the other associated symptoms.
Data assembled from 7 of 12 sources · Last updated Sep 19, 2026, 12:48 AM UTC
Online Mendelian Inheritance in Man
Genetic and Rare Diseases Info Center
Common questions about achromatopsia 2
Features include always present findings: Undetectable light-adapted electroretinogram, Myopic astigmatism, Hemeralopia, and Nystagmus and others; and very common findings: Achromatopsia. 14 total HPO annotations.
Organ System | Phenotype Count | Example Features |
|---|---|---|
Eyes | 3 | Retinal thinning on OCT, Nystagmus, Pendular nystagmus |
Muscles | 1 | Peripapillary atrophy |
Achromatopsia is characterized by reduced visual acuity, pendular nystagmus, increased sensitivity to light (photophobia), a small central scotoma (which is often difficult to demonstrate), eccentric fixation, and reduced or complete lack of color discrimination. Hyperopia is common. Nystagmus develops during the first few weeks after birth and is followed by increased sensitivity to bright light. Best visual acuity varies with severity of the disease; it is 20/200 or less in complete achromatopsia and may be as high as 20/80 in incomplete achromatopsia. Visual acuity is usually stable over time, but both nystagmus and sensitivity to bright light may improve slightly.
Source: GeneReviews — "Achromatopsia"
CNGA3 encodes cyclic nucleotide gated channel subunit alpha 3 (694 aa). Pore-forming subunit of the cone cyclic nucleotide-gated channel. Mediates cone photoresponses at bright light converting transient changes in intracellular cGMP levels into electrical signals. Highest expression in Pituitary (20.1 TPM) and Colon Sigmoid (6.2 TPM).
Achromatopsia 2 is associated with mutations in the CNGA3 gene on chromosome 2.
CNGA3 is classified as a druggable target (Druggable Genome, Ion Channel, and Transporter categories) with score 0.0.
Achromatopsia should be suspected in individuals with the following typical clinical findings, additional testing, and family history.
Clinical findings
Pendular nystagmus
Increased sensitivity to light (photophobia)
Eccentric fixation
Reduced visual acuity
Reduced or complete lack of color discrimination
Small central scotoma
Fundus appearance: normal in many affected individuals, but can show subtle bilateral macular changes such as absence of the foveal reflex, pigment mottling, or narrowing of the retinal vessels. Frank atrophy of the retinal pigment epithelium (RPE) in the fovea can occur in older individuals.
Additional testing
Source: GeneReviews — "Achromatopsia"
Achromatopsia is readily recognized by its characteristic features . Conditions to consider in the differential diagnosis are congenital nystagmus (as nystagmus is usually one of the first manifestations) and cerebral achromatopsia or dyschromatopsia, which is associated with severe or total color vision deficits and can arise adventitiously after brain fever, cortical trauma, or cerebral infarction, especially involving lesions to the ventral occipital cortex . Inherited retinal dystrophies that may be confused with achromatopsia are summarized in . Table 3. Inherited Retinal Dystrophies to Consider in the Differential Diagnosis of Achromatopsia
Disorder | Gene(s) | MOI | Overlapping Clinical Features | Distinguishing Clinical Features | Comments |
|---|---|---|---|---|---|
Genetic testing for CNGA3 is available. Testing is considered confirmatory for diagnosis.
Biomarker and diagnostic research for achromatopsia 2 has been reported in the published literature.
No approved treatments are currently available for achromatopsia 2. The disease remains an area of unmet medical need.
To establish the extent of disease and needs in an individual diagnosed with achromatopsia, the evaluations summarized in this section (if not performed as part of the evaluation that led to the diagnosis) are recommended:
Standard clinical ophthalmologic evaluation and testing with attention to visual acuity and use of spectacles and/or contact lenses to achieve the best possible corrected visual acuity
Color vision evaluation
Consultation with a clinical geneticist and/or genetic counselor as treatment could be possible in the near future (See .)
Dark or special filter glasses or red-tinted contact lenses reduce photophobia and may improve visual acuity. Low vision aids include high-powered magnifiers for reading as well as digital/electronic devices. Children with achromatopsia should have preferential seating in the classroom (i.e., in the front to benefit maximally from magnifying devices and away from windows to reduce the effects of glare on vision). Extensive information about learning and occupational aids is available from the Achromatopsia Network (www.achromat.info).
Ophthalmologic examination is indicated:
Every six to 12 months in children to monitor changes in refraction in order to achieve the best possible corrected visual acuity;
Every two to three years in adults.
To avoid additional light damage to the retina, it is recommended that individuals wear approp...
Source: GeneReviews — "Achromatopsia"
To avoid additional light damage to the retina, it is recommended that individuals wear appropriate protective (dark) glasses in bright light.
Source: GeneReviews — "Achromatopsia"
In July 2012 a Phase I/II clinical trial (NCT01846052) investigating the therapeutic effects and safety of an intraocular implant releasing ciliary neurotrophic factor (CNTF) in individuals with CNGB3-related achromatopsia was started. No objectively measurable enhancement of cone function was found by assessments of visual acuity, mesopic increment sensitivity threshold, photopic electroretinogram, or color hue discrimination. Subjectively, individuals reported beneficial changes of visual function in the treated eyes, including reduced light sensitivity and aversion to bright light, but slowed adaptation to darkness, consistent with CNTF action on rod photoreceptors .
Source: GeneReviews — "Achromatopsia"
1 trial found
Ophthalmologic examination is indicated:
Every six to 12 months in children to monitor changes in refraction in order to achieve the best possible corrected visual acuity;
Every two to three years in adults.
Source: GeneReviews — "Achromatopsia"
Phenotype severity distribution: 6 always present features, 1 very common feature, 4 common features.
1 clinical trial registered. Interventions under study include biologic therapy. Pipeline includes 1 PHASE1. Research is primarily industry-sponsored.
15 publications have been identified in PubMed for achromatopsia 2. Research spans Epidemiology / Natural History (33%), Basic Science / Preclinical (27%), and Diagnostic / Biomarker (13%).
Research Type | Count | % of Total |
|---|---|---|
Disease patterns and progression | 5 | 33% |
Laboratory research | 4 | 27% |
Testing and diagnosis research | 2 | 13% |
New treatment approaches | 2 | 13% |
Research summaries | 1 | 7% |
Clinical study results | 1 | 7% |
Inooka T (2026). [PMID: 41666299](https://pubmed.ncbi.nlm.nih.gov/41666299/). *Retina (Philadelphia, Pa.)*. [Gene Therapy / Novel Therapeutics]
Sonehra (2026). [PMID: 42099125](https://pubmed.ncbi.nlm.nih.gov/42099125/). *Ophthalmic Genet*. [Epidemiology / Natural History]
Warszawer Y (2026). [PMID: 41317340](https://pubmed.ncbi.nlm.nih.gov/41317340/). *Eur Neurol*. [Basic Science / Preclinical]
Lai Y (2025). [PMID: 40241905](https://pubmed.ncbi.nlm.nih.gov/40241905/). *Frontiers in medicine*. [Gene Therapy / Novel Therapeutics]
Jeong YD (2025). [PMID: 40769301](https://pubmed.ncbi.nlm.nih.gov/40769301/). *Ophthalmology*. [Epidemiology / Natural History]
Abramovitch H (2025). [PMID: 39908132](https://pubmed.ncbi.nlm.nih.gov/39908132/). *Translational vision science & technology*. [Clinical Trial Publication]
Tareen JK (2025). [PMID: 40737315](https://pubmed.ncbi.nlm.nih.gov/40737315/). *PloS one*. [Basic Science / Preclinical]
Owusu-Afriyie B (2025). [PMID: 40690734](https://pubmed.ncbi.nlm.nih.gov/40690734/). *Optometry and vision science : official publication of the American Academy of Optometry*. [Diagnostic / Biomarker]
Manav Yigit Z (2025). [PMID: 40699246](https://pubmed.ncbi.nlm.nih.gov/40699246/). *International ophthalmology*. [Basic Science / Preclinical]
Mutalib HA (2025). [PMID: 40103958](https://pubmed.ncbi.nlm.nih.gov/40103958/). *International journal of ophthalmology*. [Diagnostic / Biomarker]
Blue-cone monochromatism1 (OMIM 303700)
OPN1LW; OPN1MW2 |
XL3 |
Severely visual acuity; Eccentric fixation; ± Infantile nystagmus; No obvious fundus abnormalities; Poor or no color discrimination4; Peak of photopic luminosity function is near 440 nm (the peak sensitivity of the S cones), not 507 nm (the peak sensitivity of the rods). |
A special 4-color plate test or a 2-color filter test can clinically distinguish blue-cone monochromats from achromats (rod monochromats).; Cone ERG responses can be elicited by presenting blue flashes on a yellow background (because the S cones are functioning in addition to the rods). |
— |
Hereditary red-green color vision defects (OMIM 303800, 303900) | OPN1LW, OPN1MW | XL | Color vision defects5 | In hereditary red-green color vision defects:; Most individuals w/protanomalous deuteranomalous color vision defects (i.e., anomalous trichromats) have no major problems in naming colors. | Clinical chart tests widely used to detect red-green color vision defects include Ishihara plates the American Optical HRR pseudoisochromatic plates. |
OPN1SW | AD | Color confusion | Other non-congenital yellow-blue deficits (similar in some ways to tritan defects) may result from aging or disorders of choroid, pigment epithelium, retina, or optic nerve (e.g., optic atrophy type 1; OMIM 165500); they are usually progressive have other related signs; e.g. | — | — |
Source: GeneReviews — "Achromatopsia"
AI-curated news mentioning achromatopsia 2
Updated Jul 29, 2026
A study highlights progressive cone dystrophy linked to PDE6C-associated achromatopsia, identifying a likely pathogenic variant and a variant of uncertain significance. This research contributes to understanding the genetic underpinnings of visual disorders.
Blue Gen Therapeutics Foundation is advancing BGTF-027, a gene therapy for achromatopsia, to a phase 1 clinical trial within the next 18 months. This investigational therapy encodes a functional CNGB3 gene, aiming to address the vision impairment associated with this rare eye disease.