Sorsby fundus dystrophy

What it is

From: Orphanet

Sorsby's fundus dystrophy is a rare progressive autosomal dominant macular dystrophy, presenting between the third and sixth decades of life, characterized by retinal atrophy and retinal detachment and leading to loss of central vision, then peripheral vision, and eventually blindness.

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.

Macular dystrophy · Very frequent (99-80%)

Macular dystrophy is a nonspecific term for retinal degeneration, generally confined to the macula, usually presumed of genetic origin.

Subretinal deposits · Very frequent (99-80%)

Deposits accumulating between the outer retina and the retinal pigment epithelium.

Visual loss · Very frequent (99-80%)

Loss of visual acuity (implying that vision was better at a certain time point in life). Otherwise the term reduced visual acuity should be used (or a subclass of that).

Yellow/white lesions of the macula · Very frequent (99-80%)

A type of white and/or yellow lesion located anywhere within the macula. These lesions can be flat or raised and can vary in size from very small to bigger.

Abnormal choroid morphology · Frequent (79-30%)

Any structural abnormality of the choroid (the posterior part of the uvea, the middle tunic of the eye, consisting mainly of blood vessels).

Abnormal fundus autofluorescence imaging · Frequent (79-30%)

Fundus autofluorescence (FAF) is a non-invasive retinal imaging modality used in clinical practice to provide a density map of lipofuscin, the predominant ocular fluorophore, in the retinal pigment epithelium. Autofluorescent patterns result from the complex interaction of fluorophores such a lipofuscin, which release an autofluorescent signal, and elements such as melanin and rhodopsin, which absorb the excitation beam and attenuate autofluorescence. Other structures such as retinal vessels and the crystalline lens may also influence autofluorescence through blocking and interference.

Choriocapillaris atrophy · Frequent (79-30%)

Atrophy of the capillary lamina of choroid.

Choroidal neovascularization · Frequent (79-30%)

Choroidal neovascularization (CNV) is the inward growth of new blood vessels arising from the choriocapillaris. Depending on the stage of development, they can be external (type 1 NV) or internal (type 2 NV) to the retinal pigment epithelium.

Nyctalopia · Frequent (79-30%)

Inability to see well at night or in poor light.

Hyporeflective spaces on macular OCT · Frequent (79-30%)

Large central visual field defect · Frequent (79-30%)

Blindness · Occasional (29-5%)

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.

Chorioretinal atrophy · Occasional (29-5%)

Atrophy (wasting) of the choroid and retinal layers of the fundus.

Pigmentary retinopathy · Occasional (29-5%)

An abnormality of the retina characterized by pigment deposition. It is typically associated with migration and proliferation of macrophages or retinal pigment epithelial cells into the retina; melanin from these cells causes the pigmentary changes. Pigmentary retinopathy is a common final pathway of many retinal conditions and is often associated with visual loss.

Other findings in the same source

From: Orphanet

Additional reported features include Retinal atrophy (Occasional (29-5%)); Retinal pigment epithelial atrophy (Occasional (29-5%)); Severely reduced visual acuity (Occasional (29-5%)). This is a selected summary, not a complete description of the condition.

When it may begin

From: Orphanet

Adult

Inheritance in the source

From: Orphanet

Autosomal dominant

Understanding the inheritance label

From: MedlinePlus Genetics

An autosomal dominant pattern means that one altered copy of a relevant gene can be sufficient for the condition. Some affected people inherit the change; others have a new change without an affected parent. The precise finding, family history and condition determine what this means for relatives.

Which doctor should you see?

The suggested department for discussing Sorsby fundus dystrophy 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 Sorsby fundus dystrophy. 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.