Rare diseases · Sign or symptom
Blindness
HP:0000618
What it means
Blindness is the condition of lacking visual perception defined as a profound reduction in visual perception. On the 6m visual acuity scale, blindness is defined as less than 3/60. On the 20ft visual acuity scale, blindness is defined as less than 20/400. On the decimal visual acuity scale, blindness is defined as less than 0.05. Blindness is typically characterized by a visual field of no greater than 10 degrees in radius around central fixation.
Various scales have been developed to describe the extent of vision loss and define blindness. Total blindness is the complete lack of form and visual light perception and is clinically recorded as NLP (no light perception). Blindness is frequently used to describe severe visual impairment with residual vision. Those described as having only light perception have no more sight than the ability to tell light from dark and the general direction of a light source.
Rare diseases that can present with this92
Very common80–99%
18- Alpha-N-acetylgalactosaminidase deficiency
- Alström syndrome
- Blindness-scoliosis-arachnodactyly syndrome
- Cerebrooculonasal syndrome
- Combined hamartoma of the retina and retinal pigment epithelium
- Ectodermal dysplasia-blindness syndrome
- Fraser syndrome
- GM1 gangliosidosis type 1
- Hydranencephaly
- Hypotrichosis with juvenile macular degeneration
- Lethal ataxia with deafness and optic atrophy
- Microphthalmia-brain atrophy syndrome
- Norrie disease
- Ophthalmomandibulomelic dysplasia
- Retinitis pigmentosa
- Sandhoff disease
- Usher syndrome
- X-linked neurodegenerative syndrome, Hamel type
Common30–79%
11- Autosomal recessive spinocerebellar ataxia-blindness-deafness syndrome
- Bardet-Biedl syndrome
- Canavan disease
- Developmental malformations-deafness-dystonia syndrome
- Gyrate atrophy of choroid and retina
- HSD10 disease, infantile type
- Hyposmia-nasal and ocular hypoplasia-hypogonadotropic hypogonadism syndrome
- Joubert syndrome with oculorenal defect
- NARP syndrome
- Non-24-hour sleep-wake syndrome
- Severe X-linked intellectual disability, Gustavson type
The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions. A sign on this page is a conversation to have with a clinician, not a conclusion.
Part of the broader category
Also called: Legal blindness · Total vision loss
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Start free with EleplanThis page uses the Human Phenotype Ontology (2026-06-23) — Human Phenotype Ontology Consortium, hpo.jax.org. Disease associations from Orphanet (INSERM), CC BY 4.0. Content is educational and is not medical advice.