Early-onset glaucoma

What it is, symptoms and effects

From: MedlinePlus Genetics, National Library of Medicine

Glaucoma is a group of eye disorders in which the optic nerves connecting the eyes and the brain are progressively damaged. This damage can lead to reduction in side (peripheral) vision and eventual blindness. Other signs and symptoms may include bulging eyes, excessive tearing, and abnormal sensitivity to light (photophobia). The term "early-onset glaucoma" may be used when the disorder appears before the age of 40.

In most people with glaucoma, the damage to the optic nerves is caused by increased pressure within the eyes (intraocular pressure). Intraocular pressure depends on a balance between fluid entering and leaving the eyes.

Usually glaucoma develops in older adults, in whom the risk of developing the disorder may be affected by a variety of medical conditions including high blood pressure (hypertension) and diabetes mellitus, as well as family history. The risk of early-onset glaucoma depends mainly on heredity.

Structural abnormalities that impede fluid drainage in the eye increase ocular pressure. These abnormalities may be present at birth and usually become apparent during the first year of life. Such structural abnormalities may be part of a genetic disorder that affects many body systems, called a syndrome. If glaucoma appears before the age of 3 without other associated abnormalities, it is called primary congenital glaucoma.

Other individuals experience early onset of primary open-angle glaucoma, the most common adult form of glaucoma. If primary open-angle glaucoma develops during childhood or early adulthood, it is called juvenile open-angle glaucoma.

Causes and biological mechanisms

From: MedlinePlus Genetics, National Library of Medicine

Approximately 10 percent to 33 percent of people with juvenile open-angle glaucoma have variants (also known as mutations) in the MYOC gene. MYOC gene variants have also been detected in some people with primary congenital glaucoma. The MYOC gene provides instructions for producing a protein called myocilin. Myocilin is found in certain structures of the eye, called the trabecular meshwork and the ciliary body, that regulate the intraocular pressure.

Researchers believe that myocilin functions together with other proteins in the eye as part of the extracellular matrix, which is an intricate lattice that forms in the space between cells and provides structural support. Variants may alter the protein in such a way that the protein is not part of the extracellular matrix. Defective myocilin that does not get incorporated in the extracellular matrix remains inside the cell. The defective protein may damage the cell, causing insufficient flow of fluid from the eye, resulting in increased intraocular pressure and causing the signs and symptoms of early-onset glaucoma.

Between 20 percent and 40 percent of people with primary congenital glaucoma have variants in the CYP1B1 gene. CYP1B1 gene variants have also been detected in some people with juvenile open-angle glaucoma. The CYP1B1 gene provides instructions for producing a form of the cytochrome P450 protein. Like myocilin, this protein is found in the trabecular meshwork, ciliary body, and other structures of the eye.

It is not well understood how defects in the CYP1B1 protein cause signs and symptoms of glaucoma. Recent studies suggest that the defects may interfere with the early development of the trabecular meshwork, the tissue that regulates the secretion of fluid inside the eye.

Unknown variants in other genes may also be involved in early-onset glaucoma.

Inheritance and family implications

From: MedlinePlus Genetics, National Library of Medicine

Early-onset glaucoma can have different inheritance patterns. Primary congenital glaucoma is usually inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have variants. Most often, the parents of an individual with an autosomal recessive condition each carry one copy of the altered gene, but do not show signs and symptoms of the condition.

Juvenile open-angle glaucoma 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 some families, primary congenital glaucoma may also be inherited in an autosomal dominant pattern.

How common is it?

From: MedlinePlus Genetics, National Library of Medicine

Primary congenital glaucoma affects approximately 1 in 10,000 people. Its frequency is higher in the Middle East. Juvenile open-angle glaucoma affects about 1 in 50,000 people. Primary open-angle glaucoma is much more common after the age of 40, affecting about 1 to 2 percent of the population worldwide.

Which doctor should you see?

The suggested department for discussing Early-onset glaucoma 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 Early-onset glaucoma. 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.