What is Corneal Dystrophy?
Corneal dystrophy is a group of rare, genetic eye disorders that affect the cornea, the clear front window of the eye. These conditions are typically inherited and can cause a buildup of abnormal material in one or more of the cornea's layers. This can lead to a loss of clarity, causing vision to become cloudy, hazy, or blurred. The effects of corneal dystrophy are generally not caused by external factors like injury or diet, and they are typically progressive, slowly worsening over time.
Types of Corneal Dystrophy
Corneal dystrophies are categorized by the layer of the cornea they affect. Here are some of the most common types:
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Fuchs' Endothelial Dystrophy: This is a corneal dystrophy that affects the innermost layer of the cornea, the endothelium. This layer is responsible for pumping fluid out of the cornea to keep it clear. In Fuchs', the endothelial cells gradually die off, causing fluid to build up, which leads to corneal swelling and blurred vision.
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Lattice Dystrophy: This type of dystrophy affects the middle and outer layers of the cornea. It is characterized by the formation of tiny, lattice-like lines or deposits within the corneal tissue. These deposits can cause a loss of clarity and may lead to recurrent, painful corneal erosions.
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Granular Dystrophy: This condition causes small, white, granular-like deposits to form in the middle layer of the cornea. These deposits can eventually become dense enough to interfere with vision.
Symptoms of Corneal Dystrophy
The symptoms of corneal dystrophy often depend on the specific type and severity of the condition. In the early stages, many people experience no symptoms at all. As the condition progresses, symptoms may include:
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Blurred or hazy vision, often worse in the morning.
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Pain and discomfort from recurrent corneal erosions.
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Light sensitivity (photophobia).
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A cloudy or hazy appearance to the cornea.
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Halos or glare around lights.
Causes of Corneal Dystrophy
Corneal dystrophies are caused by genetic variants that are passed down through families. While the specific gene variants vary between different types of dystrophies, the underlying cause is an inherited defect that leads to the abnormal accumulation of material in the cornea.
Diagnosis of Corneal Dystrophy
An ophthalmologist can diagnose corneal dystrophy during a comprehensive eye examination. The diagnosis typically involves:
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A slit-lamp examination: A special microscope is used to examine the cornea in detail and identify any characteristic deposits, irregularities, or swelling.
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Pachymetry: This test measures the thickness of the cornea. An increased corneal thickness can be a key sign of Fuchs' endothelial dystrophy.
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Specular Microscopy: This device takes a photograph of the corneal endothelial cells, allowing the doctor to count the number of healthy cells and determine the severity of Fuchs' dystrophy.
Treatment of Corneal Dystrophy
The goal of treatment is to manage symptoms, reduce corneal swelling, and, when necessary, restore clear vision.
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Non-Surgical Treatment (Symptom Management)
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Hypertonic saline drops or ointment: These can help draw excess fluid out of the cornea, reducing swelling in conditions like Fuchs' dystrophy.
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Bandage contact lenses: These can help relieve pain by protecting the corneal surface in cases of recurrent erosions.
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Surgical Treatment (Corneal Transplant)
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For a severe or advanced corneal dystrophy, a corneal transplant is the most effective treatment. The surgeon removes the damaged part of the cornea and replaces it with healthy donor tissue. The type of transplant depends on the specific dystrophy:
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DSAEK: These are preferred for dystrophies that primarily affect the inner layer of the cornea, such as Fuchs' dystrophy. Only the damaged inner layer is removed and replaced with a thin sheet of donor tissue.
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PKP: This traditional full-thickness corneal transplant is used for dystrophies that affect the full thickness of the cornea.
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