Lattice corneal dystrophy type I

What it is, symptoms and effects

From: MedlinePlus Genetics, National Library of Medicine

Lattice corneal dystrophy type I is an eye disorder that affects the clear, outer covering of the eye called the cornea. The cornea must remain clear for an individual to see properly; however, in lattice corneal dystrophy type I, protein clumps known as amyloid deposits cloud the cornea, which leads to vision impairment. The cornea is made up of several layers of tissue, and in lattice corneal dystrophy type I, the deposits form in the stromal layer. The amyloid deposits form as delicate, branching fibers that create a lattice pattern.

Affected individuals often have recurrent corneal erosions, which are caused by separation of particular layers of the cornea from one another. Corneal erosions are very painful and can cause sensitivity to bright light (photophobia). Lattice corneal dystrophy type I is usually bilateral, which means it affects both eyes. The condition becomes apparent in childhood or adolescence and leads to vision problems by early adulthood.

Causes and biological mechanisms

From: MedlinePlus Genetics, National Library of Medicine

Lattice corneal dystrophy type I is caused by mutations in the TGFBI gene. This gene provides instructions for making a protein that is found in many tissues throughout the body, including the cornea. The TGFBI protein is part of the extracellular matrix, an intricate network that forms in the spaces between cells and provides structural support to tissues. The protein is thought to play a role in the attachment of cells to one another (cell adhesion) and cell movement (migration).

The TGFBI gene mutations involved in lattice corneal dystrophy type I change single protein building blocks (amino acids) in the TGFBI protein. Mutated TGFBI proteins abnormally clump together and form amyloid deposits. However, it is unclear how the changes caused by the gene mutations induce the protein to form deposits.

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 has one parent with the condition.

How common is it?

From: MedlinePlus Genetics, National Library of Medicine

Lattice corneal dystrophy type I is one of the most common disorders in a group of conditions that are characterized by protein deposits in the cornea (corneal dystrophies); however, it is still a rare condition. The prevalence of lattice corneal dystrophy type I is unknown.

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.

Abnormal cornea morphology · Very frequent (99-80%)

Any abnormality of the cornea, which is the transparent tissue at the front of the eye that covers the iris, pupil, and anterior chamber.

Central opacification of the cornea · Very frequent (99-80%)

Reduced transparency of the central portion of the corneal stroma.

Corneal opacity · Very frequent (99-80%)

A reduction of corneal clarity.

Lattice corneal dystrophy · Very frequent (99-80%)

The presence of fine, branching linear opacities in Bowman's layer in the central area that may spread to the periphery in the clinical course. The deep corneal stroma may be involved but the process does not reach Descemet's membrane. Recurrent corneal erosion may occur. Histologic examination reveals amyloid deposits in the collagen fibers of the cornea.

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).

Corneal scarring · Very frequent (99-80%)

Astigmatism · Frequent (79-30%)

A type of refraction error associated with abnormal curvatures on the anterior and/or posterior surface of the cornea.

Corneal stromal edema · Frequent (79-30%)

Abnormal accumulation of fluid and swelling of the stroma of cornea.

Ocular pain · Frequent (79-30%)

An unpleasant sensation characterized by physical discomfort (such as pricking, throbbing, or aching) localized to the eye.

Photophobia · Frequent (79-30%)

Excessive sensitivity to light with the sensation of discomfort or pain in the eyes due to exposure to bright light.

Recurrent corneal erosions · Frequent (79-30%)

The presence of recurrent corneal epithelial erosions. Although most corneal epithelial defects heal quickly, some may show recurrent ulcerations.

Red eye · Frequent (79-30%)

A reddish appearance over the white part (sclera) of the eye ranging from a few enlarged blood vessels appearing as wiggly lines over the sclera to a bright red color completely covering to sclera.

Subepithelial corneal opacities · Frequent (79-30%)

Central posterior corneal opacity · Occasional (29-5%)

Reduced transparency of the central posterior portion of the corneal stroma.

Other findings in the same source

From: Orphanet

Additional reported features include Decreased corneal sensation (Occasional (29-5%)); High myopia (Occasional (29-5%)); Slow decrease in visual acuity (Occasional (29-5%)). This is a selected summary, not a complete description of the condition.

Which doctor should you see?

The suggested department for discussing Lattice corneal dystrophy type I 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 Lattice corneal dystrophy type I. 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.