Bullous Keratopathy: Symptoms and Treatment
What Is Bullous Keratopathy
Bullous keratopathy is a painful corneal condition that occurs when the inner layer of the cornea loses its ability to pump fluid properly, leading to swelling, blister formation, and progressive vision loss. The corneal endothelium is responsible for maintaining corneal clarity by actively pumping excess fluid out of the corneal stroma, which is the thickest middle layer of the cornea. Healthy endothelial cells keep the cornea thin and transparent, and this balance is essential for clear vision. Unlike many other cells in the body, corneal endothelial cells do not regenerate significantly in adults, so once a critical number of cells are lost, the remaining cells cannot compensate.
When the endothelium can no longer regulate fluid balance, water seeps into the corneal stroma and eventually reaches the outermost epithelial layer. This fluid accumulation causes the cornea to swell and become cloudy. As fluid collects beneath and within the epithelium, small blisters called bullae develop on the corneal surface. These bullae can rupture spontaneously, exposing sensitive corneal nerve endings and causing significant pain. According to the EBAA 2024 Statistical Report, endothelial disease including bullous keratopathy remains the leading indication for corneal transplant surgery in the United States, accounting for the majority of the more than 51,000 annual keratoplasty procedures.
Some patients develop bullous keratopathy suddenly following eye surgery or trauma, while others experience a gradual onset related to progressive endothelial cell loss. In acute cases, corneal swelling can develop within days or weeks. Chronic bullous keratopathy tends to worsen over months to years as endothelial function continues to decline, often resulting in persistent corneal scarring if left untreated.
Symptoms of Bullous Keratopathy
Corneal edema (swelling of the cornea) causes light to scatter as it passes through the swollen tissue, resulting in blurred or hazy vision. Many patients notice that their vision is worse in the morning because fluid accumulates overnight when the eyes are closed, and it may improve slightly throughout the day as some fluid evaporates from the corneal surface. As the condition progresses, vision can become persistently cloudy regardless of the time of day.
Pain is one of the hallmark symptoms of bullous keratopathy and can be quite severe. When the epithelial bullae rupture, the exposed nerve endings create a sharp, stinging sensation. Patients often describe a foreign body feeling, as though something is stuck in the eye. Between episodes of bullae rupture, a dull ache or pressure sensation may persist.
Excessive tearing is a common reflex response to the corneal irritation caused by ruptured bullae. Light sensitivity, or photophobia, often accompanies the tearing because the irregular corneal surface scatters incoming light. These symptoms can make everyday activities like reading, driving, and spending time outdoors uncomfortable.
The chronic irritation from bullae formation and rupture can lead to redness and inflammation of the eye. In some cases, the repeated breakdown of the corneal epithelium resembles recurrent corneal erosion, where the surface layer fails to adhere properly to the underlying tissue. This cycle of breakdown and healing can increase the risk of infection and corneal scarring over time.
What Causes Bullous Keratopathy
The most frequent cause of bullous keratopathy is endothelial damage following intraocular surgery, particularly cataract surgery. This form, known as pseudophakic bullous keratopathy, can develop when surgical instruments, irrigation fluid, or the intraocular lens itself causes trauma to the delicate endothelial cells. While advances in surgical technique have significantly reduced this risk, pseudophakic bullous keratopathy remains one of the leading indications for corneal transplantation.
Fuchs endothelial dystrophy is a progressive, inherited condition in which endothelial cells gradually deteriorate and develop abnormal deposits called guttae on the inner corneal surface. Over time, the endothelial cell count drops below the level needed to maintain corneal clarity, resulting in edema and bullous keratopathy. Fuchs dystrophy is one of the most common underlying conditions associated with endothelial failure.
Direct injury to the eye, chemical burns, or severe intraocular inflammation can damage the endothelium and lead to bullous keratopathy. Viral infections such as herpes simplex keratitis or herpes zoster can also affect the endothelium, especially after repeated episodes. Inflammatory conditions that raise intraocular pressure or cause prolonged swelling within the eye pose additional risk to the endothelial cell layer.
How Bullous Keratopathy Is Diagnosed
Our cornea specialists use a slit-lamp microscope to examine the cornea at high magnification. During this evaluation, visible signs of corneal edema, epithelial bullae, and endothelial changes such as guttae can be identified. The slit-lamp also helps rule out other conditions that may cause similar symptoms, such as infectious keratitis or other corneal dystrophies.
Pachymetry measures the thickness of the cornea using ultrasound or optical technology. A cornea affected by bullous keratopathy is typically much thicker than normal due to fluid retention. Serial pachymetry measurements can help track how the condition is progressing and guide treatment decisions over time.
Specular microscopy provides a detailed image of the corneal endothelial cells, allowing our cornea specialists to count the number of remaining cells and assess their size and shape. A healthy cornea typically has an endothelial cell density above 2,000 cells per square millimeter. In bullous keratopathy, the cell count is usually well below this threshold, confirming that endothelial failure is the underlying cause of corneal swelling.
Treatment Options for Bullous Keratopathy
In mild or early cases, non-surgical treatments can help manage symptoms. Hypertonic saline drops and ointments (typically 5 percent sodium chloride) draw excess fluid from the cornea and can temporarily reduce swelling and improve clarity. Bandage contact lenses may be placed over the cornea to protect exposed nerve endings when bullae rupture, providing significant pain relief. While these measures help control discomfort, they do not address the underlying endothelial dysfunction.
The primary surgical treatment is endothelial keratoplasty, which replaces only the damaged endothelial layer rather than the full thickness of the cornea. The two most common techniques are DSEK (Descemet stripping endothelial keratoplasty) and DMEK (Descemet membrane endothelial keratoplasty). DMEK transplants only the thin Descemet membrane and endothelial layer, which typically results in faster visual recovery and lower rejection rates. DSEK includes a thin layer of stromal tissue along with the endothelium and may be preferred in certain clinical situations.
In cases where the cornea has developed significant scarring throughout its full thickness, a penetrating keratoplasty may be necessary. This procedure replaces the entire cornea with healthy donor tissue. Our cornea specialists evaluate each patient individually to determine which approach offers the best outcome based on the extent of corneal damage and other eye health factors.
Frequently Asked Questions
In mild or early cases, non-surgical treatments can help manage symptoms. Hypertonic saline drops and bandage contact lenses provide temporary relief by reducing swelling and protecting the corneal surface. However, these measures do not address the underlying endothelial dysfunction, so most patients with progressive bullous keratopathy eventually require surgical treatment.
Both DSEK and DMEK work by replacing the dysfunctional endothelial cells with healthy donor tissue. Both techniques are performed through a small incision, and the donor tissue is held in place by an air bubble while it adheres to the patient's cornea. Most patients experience significant improvement in corneal clarity and reduction in pain following successful endothelial keratoplasty.
The prognosis depends on the severity of the condition and the chosen treatment approach. Patients who undergo endothelial keratoplasty before significant corneal scarring develops generally achieve good visual outcomes, with many regaining functional vision within several months after surgery. Without treatment, bullous keratopathy tends to progress, leading to chronic pain and permanent vision loss.
Yes, pseudophakic bullous keratopathy is one of the most common forms of this condition and develops when the corneal endothelium sustains damage during cataract surgery. Improvements in surgical instruments, techniques, and viscoelastic protective agents have made this complication less frequent than in earlier decades. Patients who already have a low endothelial cell count or an underlying condition like Fuchs dystrophy may have a higher risk.
Prevention focuses on protecting the corneal endothelium during eye surgery and monitoring patients who are at elevated risk. Surgeons use viscoelastic substances to cushion the endothelium during intraocular procedures, and careful surgical technique helps minimize cell loss. For patients with Fuchs dystrophy or other conditions that affect endothelial health, regular monitoring with specular microscopy allows early detection of declining cell counts.
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