Understanding Pseudophakic Bullous Keratopathy (PBK): Corneal Swelling After Cataract Surgery

Cataract surgery is one of the most common and successful surgical procedures performed worldwide, restoring clear vision for millions. However, in a small percentage of cases, a complication known as Pseudophakic Bullous Keratopathy (PBK) can arise, leading to persistent corneal swelling and blurred vision after the surgery.

The term “pseudophakic” refers to an eye that has an artificial intraocular lens (IOL) implanted, which is standard practice in modern cataract surgery. “Bullous keratopathy” describes a condition where the cornea becomes swollen (edematous) and may develop blisters (bullae) on its surface due to the failure of its innermost layer, the endothelium.

The Root of the Problem: Endothelial Cell Damage

The cornea’s clarity is critically dependent on its endothelial cells. This single layer of cells on the back surface of the cornea functions like a pump, constantly removing fluid from the cornea to keep it thin and transparent. Humans are born with a finite number of these cells, and they do not regenerate effectively if damaged or lost.

Any intraocular surgery, including cataract surgery, inevitably causes some stress and a degree of loss to these delicate endothelial cells. In most individuals, the remaining cells are more than sufficient to maintain corneal clarity. However, PBK can develop if:

1. Pre-existing Endothelial Weakness: The patient already had a low endothelial cell count or a pre-existing condition like early Fuchs’ Dystrophy before cataract surgery. In such cases, even a routine surgery might push the endothelium beyond its capacity to compensate.

2. Surgical Complexity or Complications: A particularly challenging cataract surgery (e.g., a very dense cataract, prolonged surgical time, or intraoperative complications like vitreous loss or damage from instruments) can lead to a greater-than-average loss of endothelial cells.

3. Post-operative Inflammation: Significant or prolonged inflammation after surgery can also damage endothelial cells.

When the endothelial cell density drops below a critical threshold, the pump mechanism fails, fluid accumulates within the cornea (corneal edema), and the cornea loses its transparency, leading to PBK.

Symptoms of Pseudophakic Bullous Keratopathy:

The onset of symptoms can vary, sometimes appearing weeks or months, or even years, after cataract surgery. Common signs include:

• Persistently blurry or hazy vision that does not clear after the initial post-operative period.

• Fluctuating vision, often worse in the morning.

• Glare and sensitivity to light (photophobia).

• Seeing halos around lights.

• In more advanced cases, eye pain, a gritty sensation, or excessive tearing, especially if surface blisters (bullae) form and rupture.

Diagnosis of PBK

Diagnosis is typically made based on:

• Patient History: A key factor is a history of previous cataract surgery.

• Slit-Lamp Examination: This allows the ophthalmologist to observe corneal edema (swelling and haziness), and potentially bullae. The presence of an IOL confirms the “pseudophakic” status. Signs of pre-existing conditions like guttae (from Fuchs’ Dystrophy) might also be noted.

• Pachymetry: This test measures corneal thickness. An increased thickness is indicative of corneal edema.

• Specular Microscopy: This specialized imaging technique can visualize and count the endothelial cells, assessing their density and health. A significantly low cell count is a hallmark of PBK.

Treatment Approaches for PBK

Treatment aims to reduce corneal swelling and improve vision.

• Medical Management (Often Temporary or Palliative):

  • Hypertonic Saline Solutions: Eye drops or ointments (e.g., 5% sodium chloride) can help draw fluid out of the cornea, providing temporary relief from swelling and improving vision, especially for mild edema.

  • Bandage Contact Lenses: If painful bullae are present, a soft bandage contact lens can protect the cornea and relieve discomfort.

  • Intraocular Pressure Lowering Medications: Reducing eye pressure can sometimes help lessen corneal edema.

• Surgical Management (Definitive Treatment): For persistent and visually significant PBK, corneal transplantation is usually necessary.

  • DMEK (Descemet’s Membrane Endothelial Keratoplasty): This is often the preferred surgical procedure. It involves selectively replacing only the damaged Descemet’s membrane and endothelium with healthy donor tissue. DMEK offers rapid visual recovery and excellent outcomes for PBK.

  • DSAEK/DSEK (Descemet’s Stripping Automated Endothelial Keratoplasty): Another effective endothelial keratoplasty technique that replaces the posterior layers of the cornea.

  • PKP (Penetrating Keratoplasty): A full-thickness corneal transplant may be considered if there is extensive corneal scarring in addition to the endothelial failure, or if endothelial keratoplasty is not suitable.

While PBK can be a concerning complication after cataract surgery, advancements in endothelial keratoplasty techniques like DMEK have dramatically improved the prognosis. Careful pre-operative assessment of corneal health and meticulous surgical technique during cataract surgery are important in minimizing the risk. For those who do develop PBK, effective treatments are available to restore clear vision.