What is Lattice Corneal Dystrophy?
Dr. H Janhavi
Kalyan nagar, Bengaluru May 4, 2019
Lattice Dystrophy or Lattice Corneal Dystrophy (LCD) is an autosomal-dominant condition in which there is an accumulation of abnormal protein fibers, or amyloid deposits, throughout the anterior and middle stroma of the cornea. It is a slowly progressive disease and involves both eyes equally that results in a decrease in vision and recurrent corneal erosions.
While examining, the amyloid deposits in the stroma of the cornea appear as a comma-shaped, clear overlapping dots and branching filaments that creates a lattice effect. Over time, they make your cornea cloudy, lattice lines grow opaque, and reduce your vision. The abnormality of the protein fibers accumulates under the epithelium (outer layer of the cornea) causing it to erode, which is also known as recurrent epithelial erosion. This can happen at any age, but it usually occurs in children between the ages of 2 and 7.
Types of Lattice Corneal Dystrophy
There are generally two types of lattice corneal dystrophy – lattice corneal dystrophy type I and lattice corneal dystrophy type II.
Lattice Corneal Dystrophy Type I
LCD1 is an eye disease that affects the outer lining of the eye, or cornea. When your cornea is clear, it gives you a clear vision. In LCD1, the formation of a protein (amyloid) takes place in the layer of the cornea, known as stroma resulting in vision loss, a decrease in vision, eye pain, separation of cornea layers (corneal erosions), and photosensitivity.
Lattice Corneal Dystrophy Type I is a genetic disorder which is caused by the mutations in the TGFB1 (Transforming Growth Factor Beta 1) gene. TGFB1 is responsible for providing instructions to your eyes for making a TGFB1 protein, which is available in many tissues of your body, including the cornea. It also plays an essential role in attaching one cell to another cell (cell adhesion) and the movement of cells (migration).
The symptoms of LCD Type 1 differ from patient to patient. The people with lattice corneal dystrophy type 1 may have
- Autosomal dominant inheritance
- Progressive loss of vision
- Lattice corneal dystrophy
- Recurrent corneal erosions
The treatment of Lattice corneal dystrophy type 1 (LCD1) involves,
- Patching and soft contact lenses (if you have episodes of corneal erosion)
- Phototherapeutic keratectomy
- Cornea transplant (penetrating keratoplasty)
Lattice Corneal Dystrophy Type II
LCD Type 2 occurs when there is an accumulation of amyloid deposits (protein clumps) in the tissues throughout your body. These deposits occur in basement membranes and blood vessel walls. Amyloid deposits lead to signs and symptoms that include age-disturbed eyes, nerves, and skin. Over time, the amyloid deposits disrupt the never function in the face and head and cause paralysis of facial muscles (facial palsy), difficulty speaking, swallowing, and chewing, and decreased sensations in the face (cranial nerves).
The dysfunction of the nerves that binds the brain and the spinal cord to the muscles and sensory cells that detect a feeling of pain, touch, and heat (peripheral nerves) can cause weakness in the limb (peripheral neuropathy) and loss of sensitivity.
The LCD2 is caused by the mutations in the GSN gene, which provides instructions for making gelsolin. The formation of the protein filament network is regulated by gelsolin which gives structure to cells. Mutations that cause LCD2 covert a single protein building block in the gelsolin protein, resulting in an abnormal protein fragment. These irregular protein fragments clump together to form protein clumps and lead to lattice corneal dystrophy type 2.
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