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What is Corneal Edema (Bullous Keratopathy)?

Bullous keratopathy is a condition that occurs when the cornea, the clear front window of the eye, swells and becomes cloudy. The cornea's inner layer of cells, known as the endothelium, is responsible for pumping fluid out of the cornea to keep it clear. When these cells are damaged or die, fluid builds up, causing the cornea to become swollen and form tiny blisters (bullae). As these blisters break, it can lead to pain and discomfort. This condition typically affects only one eye and is a major cause of corneal edema.

Symptoms of Bullous Keratopathy

The symptoms of bullous keratopathy can range from mild discomfort to severe pain and vision loss. They typically worsen over time and may include:

  • Blurred or hazy vision: Often worse in the morning and can fluctuate throughout the day.

  • A feeling of a foreign object in the eye.

  • Pain and discomfort: Caused by the blisters on the cornea breaking.

  • Light sensitivity (photophobia).

  • Halos or glare around lights.

  • A cloudy or grayish appearance to the cornea.

Causes of Bullous Keratopathy

The primary cause of bullous keratopathy is damage to the corneal endothelial cells. The most common cause is:

  • Corneal trauma from previous surgery: This is a major cause of bullous keratopathy. It can occur after cataract surgery, glaucoma surgery, or any other intraocular surgery that damages the endothelial cells. The risk is higher in patients who have had a complicated surgery.

  • Fuchs' Endothelial Dystrophy: This is a genetic condition that causes the gradual death of corneal endothelial cells. It often affects both eyes and can lead to bullous keratopathy in its advanced stages.

  • Advanced Glaucoma: High intraocular pressure can also damage the endothelial cells, leading to corneal swelling.

Diagnosis of Bullous Keratopathy

An ophthalmologist can diagnose bullous keratopathy during a comprehensive eye examination. The diagnosis typically involves:

  • A slit-lamp examination: The doctor will use a special microscope to examine the cornea and look for swelling and blisters.

  • Pachymetry: This test measures the thickness of the cornea. An increased corneal thickness is a key sign of bullous keratopathy.

  • Specular Microscopy: A device that takes a photograph of the corneal endothelial cells, allowing the doctor to count the number of healthy cells. This is a crucial test to determine the severity of the condition.

Management

Treatment of Bullous Keratopathy

The goal of treatment is to reduce the swelling, relieve pain, and restore clear vision. While non-surgical options can help manage the symptoms, the only definitive treatment for advanced bullous keratopathy is a corneal transplant.

  • Non-Surgical Treatment (Symptom Management)

    • Hypertonic saline drops or ointment: These can help draw excess fluid out of the cornea, reducing swelling.

    • Bandage contact lenses: These can help relieve pain by protecting the corneal surface.

  • Surgical Treatment (Corneal Transplant)

    • For a severe or advanced bullous keratopathy, a corneal transplant is the most effective treatment. The surgeon removes the damaged part of the cornea and replaces it with healthy donor tissue. There are two main types of corneal transplants used for bullous keratopathy:

      • DSAEK (Descemet's Stripping Automated Endothelial Keratoplasty): A minimally invasive procedure where only the damaged inner layer of the cornea is removed and replaced with a thin sheet of donor tissue. This is the most common and preferred procedure for bullous keratopathy.

      • PKP (Penetrating Keratoplasty): A traditional full-thickness corneal transplant where the entire damaged cornea is removed and replaced with a full-thickness donor cornea. This procedure is more complex and has a longer recovery period than DSAEK.

Surgery
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