Fundus albipunctatus

What it is, symptoms and effects

From: MedlinePlus Genetics, National Library of Medicine

Fundus albipunctatus is an eye disorder characterized by an impaired ability to see in low light (night blindness) and the presence of whitish-yellow flecks in the retina, which is the specialized light-sensitive tissue in the inner lining of the back of the eye (the fundus). The flecks are detected during an eye examination.

Individuals with fundus albipunctatus experience night blindness from an early age. In particular, they have delayed dark adaptation, which means they have trouble adapting from bright light to dark conditions, such as when driving into a dark tunnel on a sunny day. It often takes hours for adaptation to occur. Their vision in bright light is usually normal.

The flecks are especially abundant near the outer edge (the periphery) of the retina. Their density varies among affected individuals; some people have numerous flecks that overlap, while others have fewer. For unknown reasons, the flecks get smaller or fade with age in some affected individuals, although night vision does not improve.

While fundus albipunctatus typically does not worsen (progress) over time, some individuals with the condition develop other eye conditions, such as breakdown of the central region of the retina known as the macula (macular degeneration) with loss of specialized light receptor cells called cones, which can affect vision in bright light.

Causes and biological mechanisms

From: MedlinePlus Genetics, National Library of Medicine

Fundus albipunctatus is primarily caused by mutations in the RDH5 gene. This gene is involved in a multi-step process called the visual cycle, by which light entering the eye is converted into electrical signals that are interpreted as vision. In rare cases, fundus albipunctatus is caused by mutations in other genes that play roles in the visual cycle.

An integral operation of the visual cycle is the recycling of a molecule called 11-cis retinal, which is a form of vitamin A that is needed for the conversion of light to electrical signals. The RDH5 gene provides instructions for making an enzyme called 11-cis retinol dehydrogenase 5, which performs one step in this recycling process. This enzyme converts a molecule called 11-cis retinol to 11-cis retinal.

RDH5 gene mutations are thought to reduce or eliminate the function of the 11-cis retinol dehydrogenase 5 enzyme, which results in a shortage of 11-cis retinal. Without this important molecule, electrical signals integral for vision are not stimulated, and vision is impaired.

For vision in low-light conditions, the eyes primarily use 11-cis retinol dehydrogenase 5 to generate 11-cis retinal, which is why a shortage of this enzyme's function impairs night vision.

Researchers speculate that impairment of 11-cis retinol dehydrogenase 5 also leads to the accumulation of 11-cis retinol and related molecules, forming the flecks characteristic of fundus albipunctatus.

Inheritance and family implications

From: MedlinePlus Genetics, National Library of Medicine

This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.

How common is it?

From: MedlinePlus Genetics, National Library of Medicine

Fundus albipunctatus is a rare disorder. Its prevalence is unknown.

Understanding terms used in the source

These definitions explain medical words used above. A definition is not evidence that another condition is present, and it does not predict how a symptom will develop. Ask the clinician which terms apply to the actual examination or test result.

Macular degeneration

A nonspecific term denoting degeneration of the retinal pigment epithelium and/or retinal photoreceptor cells of the macula lutea.

Blindness

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.

Affected

This term applies to a family member who is diagnosed with the same condition as the individual who is the primary focus of investigation (the proband).

Central

Applies to an abnormality that is located close to the median plane or midline of the body or of the referenced structure.

Which doctor should you see?

The suggested department for discussing Fundus albipunctatus 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 Fundus albipunctatus. 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.