Optic atrophy type 1

What it is, symptoms and effects

From: MedlinePlus Genetics, National Library of Medicine

Optic atrophy type 1 is a condition that often causes slowly worsening vision, usually beginning in childhood. People with optic atrophy type 1 typically experience a narrowing of their field of vision (tunnel vision). Affected individuals gradually lose their sight as their field of vision becomes smaller. Both eyes are usually affected equally, but the severity of the vision loss varies widely, even among affected members of the same family, ranging from nearly normal vision to complete blindness.

In addition to vision loss, people with optic atrophy type 1 frequently have problems with color vision (color vision deficiency) that make it difficult or impossible to distinguish between shades of blue and green.

In the early stages of the condition, individuals with optic atrophy type 1 experience a progressive loss of certain cells within the retina, which is a specialized light-sensitive tissue that lines the back of the eye. The loss of these cells (known as retinal ganglion cells) is followed by the degeneration (atrophy) of the nerves that relay visual information from the eye to the brain (optic nerves), which results in further vision loss. Atrophy causes these nerves to have an abnormally pale appearance (pallor), which can be seen during an eye examination.

Causes and biological mechanisms

From: MedlinePlus Genetics, National Library of Medicine

Optic atrophy type 1 is caused by mutations in the OPA1 gene. The protein produced from this gene is made in cells and tissues throughout the body. The OPA1 protein is found within mitochondria, which are the energy-producing centers of cells. The protein plays a key role in the organization of the shape and structure of the mitochondria and in controlled cell death (apoptosis). The OPA1 protein is also involved in a process called oxidative phosphorylation, from which cells derive much of their energy. Additionally, the protein plays a role in the maintenance of the DNA within mitochondria, called mitochondrial DNA (mtDNA).

Mutations in the OPA1 gene lead to problems with mitochondrial function. The mitochondria become misshapen and disorganized and have reduced energy-producing capabilities. The maintenance of mtDNA may also be impaired, resulting in mtDNA mutations that further interfere with mitochondrial energy production. Cells that contain these poorly functioning mitochondria are more susceptible to apoptosis. In particular, cells that have high energy demands, such as retinal ganglion cells, die over time. Specialized extensions of retinal ganglion cells, called axons, form the optic nerves, so when retinal ganglion cells die, the optic nerves atrophy and cannot transmit visual information to the brain.

Inheritance and family implications

From: MedlinePlus Genetics, National Library of Medicine

This condition is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder.

In most cases, an affected person inherits the mutation from one affected parent. Other cases result from new mutations in the gene and occur in people with no history of the disorder in their family.

In rare cases, people who have an OPA1 gene mutation do not develop optic atrophy type 1, a situation known as reduced penetrance.

How common is it?

From: MedlinePlus Genetics, National Library of Medicine

Optic atrophy type 1 is estimated to affect 1 in 35,000 people worldwide. This condition is more common in Denmark, where it affects approximately 1 in 10,000 people.

Reported clinical features and what the terms mean

The following findings are associated with this condition in Orphanet. They are not a checklist for diagnosing yourself, and they do not all occur in every affected person. Some are examination, imaging or laboratory findings that cannot be recognised at home.

The frequency labels describe how often a finding was reported among people with the condition in the source. They do not give the chance that a person with that symptom has the condition. Definitions below reproduce HPO terminology; they explain the term, not the likely severity in an individual.

Optic atrophy · Very frequent (99-80%)

Atrophy of the optic nerve. Optic atrophy results from the death of the retinal ganglion cell axons that comprise the optic nerve and manifesting as a pale optic nerve on fundoscopy.

Visual impairment · Very frequent (99-80%)

Visual impairment (or vision impairment) is vision loss (of a person) to such a degree as to qualify as an additional support need through a significant limitation of visual capability resulting from either disease, trauma, or congenital or degenerative conditions that cannot be corrected by conventional means, such as refractive correction, medication, or surgery.

Color vision defect · Frequent (79-30%)

An anomaly in the ability to discriminate between or recognize colors.

Moderately reduced visual acuity · Frequent (79-30%)

Moderate reduction of the ability to see. On the 6m visual acuity scale, moderate reduction is defined as less than 6/18 but at least 6/60. On the 20ft visual acuity scale, moderate reduction is defined as less than 20/70 but at least 20/200. On the decimal visual acuity scale, moderate reduction is defined as less than 0.3 but at least 0.1.

Morning glory anomaly · Frequent (79-30%)

An abnormality of the optic nerve in which the optic nerve is large and funneled and displays a conical excavation of the optic disc. The optic disc appears dysplastic.

Ophthalmoplegia · Frequent (79-30%)

Paralysis of one or more extraocular muscles that are responsible for eye movements.

Sensorineural hearing impairment · Frequent (79-30%)

A type of hearing impairment in one or both ears related to an abnormal functionality of the cochlear nerve.

Temporal optic disc pallor · Frequent (79-30%)

A pale yellow discoloration of the temporal (lateral) portion of the optic disc.

Other findings in the same source

From: Orphanet

Additional reported features include Sensorimotor neuropathy (Frequent (79-30%)); Ataxia (Occasional (29-5%)); Central scotoma (Occasional (29-5%)); Gait disturbance (Occasional (29-5%)); Myopathy (Occasional (29-5%)); Ptosis (Occasional (29-5%)); Abnormal periventricular white matter morphology (Very rare (<4-1%)); Areflexia (Very rare (<4-1%)); Basal ganglia calcification (Very rare (<4-1%)); Cataract (Very rare (<4-1%)). This is a selected summary, not a complete description of the condition.

Which doctor should you see?

The suggested department for discussing Optic atrophy type 1 is Ophthalmology, with a ophthalmologist as the relevant type of clinician. Ophthalmologist; paediatric services for children as appropriate.

Additional services that may be relevant, depending on the findings, include: Clinical Genetics.

This is an editorial referral starting point. The appropriate clinic depends on the person’s age, symptoms, previous diagnosis and local services. The first clinician can decide whether another specialty or a team is needed; a department label does not confirm the diagnosis.

How to prepare for an assessment

Bring a short timeline of the main symptoms: when they first appeared, whether they are constant or episodic, what seems to change them, and how they affect daily activities. Include previous reports, discharge summaries, current medicines and supplements, allergies, and any relevant family history. A dated record is more useful than trying to match every feature in an online article.

Ask the clinician what is already established and what remains uncertain. If a test is suggested, ask what question it answers, what its limitations are and how the result would change the next step. The information here is not an instruction to arrange every possible test. In children, bring growth, developmental and school information if it is relevant to the concern.

• Which part of the eye or visual pathway is affected?
• What change in vision requires immediate contact with the eye service?
• What are the aims and alternatives of any proposed eye treatment?

Treatment discussions and follow-up

The material gathered for this draft does not provide a complete condition-specific treatment pathway for Optic atrophy type 1. That gap does not mean that treatment is unavailable. A clinician needs to establish the diagnosis and review current guidance before recommending medicines, procedures, rehabilitation or other support.

Before leaving the appointment, clarify the next review date, who will communicate results, and whom to contact if the situation changes. Discuss difficulties with sleep, work, school, mobility, eating or emotional wellbeing when these are relevant. Practical support may require coordination between the treating clinician and other services.

The collected references do not establish a complete prevention or long-term outlook section for this entry. Missing information should not be interpreted as proof that prevention is impossible or that a particular outcome is inevitable. Ask what is known for the exact subtype, stage and personal circumstances, and which uncertainties remain.

When to seek emergency help

Severe breathing difficulty, collapse, new stroke-like symptoms, a seizure that is prolonged or repeated without recovery, uncontrolled major bleeding, or an immediate risk of self-harm require emergency help. In India, call 112 or reach the nearest emergency department. This is a general, non-exhaustive warning list; it is not a condition-specific triage tool.