Bullous keratopathy is a painful eye condition in which the cornea fills with excess fluid and develops small blisters, called bullae, on its surface. It happens when the thin layer of cells lining the back of the cornea, the endothelium, stops working well enough to keep the cornea clear. The most common trigger is damage during cataract surgery, but inherited conditions like Fuchs corneal dystrophy can also lead to it. Treatment ranges from eye drops and bandage contact lenses for symptom relief all the way to corneal transplantation, and a handful of newer therapies are beginning to change the outlook for people who develop it.
What the Corneal Endothelium Does and Why It Matters
Your cornea is the clear, dome-shaped window at the front of your eye. To stay transparent, it needs to maintain a very specific water content. Too much fluid and the cornea swells, scatters light, and becomes hazy. The endothelium, a single-cell-thick layer on the cornea’s inner surface, is what keeps that water balance in check. It works through what researchers call a “pump-leak” system: the stroma (the thick middle layer of the cornea) naturally draws water in because of its sponge-like molecules, and the endothelium actively pumps that water back out into the front chamber of the eye.1PubMed Central. Molecular mechanisms underlying the corneal endothelial pump At the same time, tight junctions between endothelial cells act as a barrier, slowing down how fast fluid leaks in.2PubMed Central. Dynamic regulation of barrier integrity of the corneal endothelium
In a healthy eye, the leak and the pump are roughly equal, and your cornea stays thin, compact, and crystal clear. When enough endothelial cells are lost or damaged, the pump can no longer keep up. Fluid accumulates in the stroma first, then pushes forward into the epithelium on the cornea’s outer surface, forming the painful, blister-like bullae that give the condition its name.
What Causes Bullous Keratopathy
By far the most recognized cause is cataract surgery. When an artificial lens is placed inside the eye, surgical instruments, fluid turbulence, or the lens itself can injure endothelial cells. Because human endothelial cells barely divide in adulthood, the lost cells are not replaced. This post-surgical form is called pseudophakic bullous keratopathy (PBK), and it has been one of the leading reasons people need corneal transplants.3PubMed Central. An analysis of corneal endothelial and graft survival in pseudophakic bullous keratopathy A key detail from older research is that it wasn’t simply how many cells a patient started with before surgery that predicted trouble. Instead, variation in cell size, a sign of an endothelium already under stress, correlated more strongly with developing corneal swelling afterward.4PubMed. Pseudophakic bullous keratopathy. Relationship to preoperative corneal endothelial status
The other major cause is Fuchs corneal dystrophy, a hereditary condition in which tiny wart-like bumps called guttae form on the membrane behind the endothelium. Over years, these growths crowd out endothelial cells, and the cornea gradually decompensates. In its late stages, Fuchs dystrophy produces the same stromal edema and epithelial bullae seen in PBK.5PubMed. Fuchs Corneal Dystrophy Other, less common routes to bullous keratopathy include glaucoma (especially after certain glaucoma surgeries or prolonged high eye pressure), herpes simplex infections of the cornea, and blunt trauma to the eye. In all cases the underlying story is the same: enough endothelial cells are lost that the pump fails.
Symptoms and How It Is Diagnosed
Early on, people often notice that their vision is worse in the morning and clears somewhat as the day goes on. That happens because the cornea swells slightly overnight when the eyelids are closed and evaporation drops; once the eye is open again, some fluid evaporates and the cornea thins a bit. As the disease progresses, vision stays blurry all day, and the bullae that form on the corneal surface can rupture, exposing nerve endings underneath. That rupture is what makes bullous keratopathy genuinely painful: patients describe a sharp, stinging sensation that can come and go unpredictably.
Diagnosis usually combines a slit-lamp exam (where your ophthalmologist can see the swelling and bullae directly) with a few measurements. A pachymeter or anterior-segment optical coherence tomography scan measures corneal thickness, which is elevated well beyond the normal range in affected eyes.6PLOS ONE. Bullous keratopathy associated with a shallow anterior chamber: An anatomical risk phenotype for corneal endothelial decompensation Specular microscopy, which photographs the endothelial cell layer, can show how many cells remain and whether guttae are present. These tests together help the doctor figure out how far along the disease is and which treatment makes sense.
Nonsurgical Ways to Manage It
Not everyone with bullous keratopathy heads straight to the operating room. For milder cases or for people who aren’t good candidates for surgery, several measures can reduce discomfort and sometimes improve vision modestly.
- Hypertonic saline drops: Concentrated salt solutions (typically 5% sodium chloride) draw water out of the swollen cornea by osmosis. They can help with stromal edema, but a review of the published studies found limited benefit once the disease involves the epithelium, which is exactly the stage that defines bullous keratopathy.7PubMed. Review on the Use of Topical Ocular Hypertonic Saline in Corneal Edema Still, many clinicians prescribe them early on for whatever incremental relief they offer.
- Bandage contact lenses: A soft lens placed on the cornea shields exposed nerve endings from the mechanical scraping of the eyelid. This does not fix the underlying problem, but it can dramatically reduce pain when bullae rupture.8Asia-Pacific Journal of Ophthalmology. Therapeutic Contact Lenses in the Treatment of Corneal and Ocular Surface Diseases—A Review Silicone hydrogel lenses, which allow more oxygen to reach the cornea, have proven to be a safe and effective alternative to older conventional lenses for this purpose.9Eye & Contact Lens: Science & Clinical Practice. Comparison of Conventional and Silicone Hydrogel Contact Lenses for Bullous Keratoplasty
- Anterior stromal puncture: A procedure in which a fine needle makes tiny holes in the front of the cornea, encouraging scar tissue that tacks the epithelium down and prevents bullae from reforming. One study reported that symptom severity scores dropped roughly in half within two weeks when stromal puncture was combined with a bandage lens.10PubMed Central. Efficacy of Anterior Stromal Puncture Surgery with Corneal Bandage Lens for Bullous Keratopathy
These options are palliative. They manage symptoms but do not restore the endothelial cell population. When pain is controlled and vision is acceptable in the other eye, some patients live with these measures for years without pursuing surgery.
Collagen Cross-Linking as a Middle Ground
Corneal collagen cross-linking (CXL), better known as a treatment for keratoconus, has been tried in bullous keratopathy on the theory that stiffening the stroma might reduce how much fluid it absorbs. The results have been mixed. A systematic review of the available evidence found that while corneal thickness decreased in the first month after CXL, the reduction was not sustained over six months in the randomized trials, and most studies reported no meaningful improvement in vision.11PubMed Central. Role of corneal collagen cross-linking in bullous keratopathy: A systematic review
Where CXL may have a clearer role is pain control. One study tracked patients for a year after the procedure and found that pain intensity scores dropped from about 5.6 out of 10 before treatment to around 1.5 at one year, with the frequency of painful episodes also falling significantly by six months.12Asia-Pacific Journal of Ophthalmology. Sustainability of Pain Relief After Corneal Collagen Cross-Linking in Eyes With Bullous Keratopathy Vision, corneal thickness, and eye pressure did not change in that study. So CXL appears to be a reasonable pain-relief option for patients who cannot or do not want surgery, even though it does not restore clarity.
Corneal Transplant Surgery
For most people with significant vision loss from bullous keratopathy, some form of corneal transplant is the definitive treatment. The field has shifted substantially over the past couple of decades. Older full-thickness transplants, known as penetrating keratoplasty, replaced every layer of the cornea. They worked, but recovery was slow and the risk of rejection was higher. Endothelial keratoplasty techniques, which replace only the diseased back layers of the cornea, have become the standard of care.13PubMed Central. Descemet’s membrane endothelial keratoplasty (DMEK) versus Descemet’s stripping automated endothelial keratoplasty (DSAEK) for corneal endothelial failure
The two main endothelial techniques are DSAEK (Descemet stripping automated endothelial keratoplasty) and DMEK (Descemet membrane endothelial keratoplasty). DMEK transplants an even thinner tissue layer than DSAEK, which tends to give slightly sharper vision but is technically harder to perform. Single-center data comparing both approaches with older penetrating keratoplasty found that endothelial keratoplasty produced superior overall clinical outcomes in both Fuchs dystrophy and bullous keratopathy, even when including early learning-curve cases.14PubMed. Outcomes of Descemet membrane endothelial keratoplasty, Descemet stripping automated endothelial keratoplasty and penetrating keratoplasty from a single centre study
DMEK is not without complications. A large series documented visually significant graft detachment in about 7% of eyes and graft failure in roughly 2%. Elevated eye pressure or worsening glaucoma occurred in close to 10%, and cataract formation affected about 9% of patients who still had their natural lens.15Cornea. Prevention and Management of Descemet Membrane Endothelial Keratoplasty Complications Most detachments can be managed with a rebubbling procedure (injecting an air or gas bubble to push the graft back into place), but the numbers underscore that even the best current surgery carries real risks.
For patients whose donor grafts have failed repeatedly, an artificial cornea called the Boston Type 1 keratoprosthesis is an option. A retrospective comparison found that it produced less frequent graft failure, greater visual improvement, and a better chance of maintaining that improvement than repeat donor transplants.16PubMed Central. Donor Corneal Transplantation vs Boston Type 1 Keratoprosthesis in Patients with Previous Graft Failures: A Retrospective Single Center Study The keratoprosthesis requires lifelong daily antibiotic drops and regular monitoring, so it is generally reserved for cases where conventional grafts have failed.
ROCK Inhibitor Eye Drops
One of the more exciting recent developments is the use of Rho-kinase (ROCK) inhibitor eye drops, originally developed for glaucoma. These drugs encourage endothelial cells to multiply, migrate, and stick together, which are things human endothelial cells normally do very reluctantly in adults. They also reduce cell death and help the endothelium pump more efficiently.17PubMed Central. RhoKinase (ROCK) Inhibition as a Therapeutic Strategy for Pseudophakic Bullous Keratopathy: A Comprehensive Review Side effects of the topical drops are minimal and tend to resolve on their own.18PubMed. Rho-kinase inhibitors: Role in corneal endothelial disorders
A small case series using ripasudil (one of the commercially available ROCK inhibitors) in pseudophakic bullous keratopathy found reductions in corneal thickness and improvements in visual acuity across all three treated eyes. The researchers noted, however, that endothelial cell counts did not change much, suggesting the drug improved how the remaining cells functioned rather than generating a new population of cells.19PubMed Central. Managing pseudophakic bullous keratopathy with a topical rho kinase inhibitor: a case series That distinction matters: ROCK inhibitors may buy time and delay the need for transplant, but whether they can serve as a stand-alone cure in advanced disease remains unproven. Larger trials are underway.
Cultured Endothelial Cell Injection
Perhaps the most forward-looking therapy is the injection of lab-grown human corneal endothelial cells directly into the eye. Instead of transplanting a whole disc of donor tissue, a surgeon harvests cells from a single donor cornea, expands them in culture to produce enough for multiple patients, and then injects the cell suspension into the front chamber of the recipient’s eye combined with a ROCK inhibitor to help the cells attach.
Long-term follow-up data from the pioneering Japanese trial are striking. Corneal transparency was maintained in about 98% of eyes at six months, roughly 93% at five years, and about 84% at ten years. Around 80% of treated eyes achieved an endothelial cell density above the critical threshold of 1,000 cells per square millimeter at five years, and about 86% had improved vision. No severe adverse reactions occurred.20PubMed. Long-term Corneal Rejuvenation after Transplantation of Cultured Human Corneal Endothelial Cells The approach has also been tested in eyes where a previous DSAEK graft had failed, with results showing dramatic improvements in corneal thickness and visual acuity within three months and measurable endothelial cell density where none could be detected before.21PubMed Central. Cultured Human Corneal Endothelial Cell Injection for Endothelial Graft Failure After DSAEK
Early work in eyes that still have their natural lens (phakic eyes) has been promising as well, suggesting the technique could be a lens-preserving option for younger patients who develop bullous keratopathy from causes other than cataract surgery.22PubMed. Cultured Human Corneal Endothelial Cell Injection Therapy in Phakic Eyes with Bullous Keratopathy Quality-of-life assessments after cultured-cell transplant showed significant improvements in vision-related scores, including pain, social function, mental health, and ability to carry out daily tasks.23PubMed. Quality of life after cultured corneal endothelial cell transplant in patients with bullous keratopathy
Cell injection therapy is not yet widely available outside of clinical trials. Regulatory approval is still pending in most countries, and the infrastructure for producing clinical-grade cell cultures at scale does not exist everywhere. But because one donor cornea can potentially treat dozens of recipients, the approach could eventually ease the global shortage of donor tissue, which remains a major bottleneck for conventional transplant surgery.24PubMed. Alternatives to endokeratoplasty: an attempt towards reducing global demand of human donor corneas
Infection Risk in Bullous Keratopathy
A cornea covered in fluid-filled blisters that periodically rupture is essentially a cornea with a broken barrier. That makes it vulnerable to infections that a healthy eye would shrug off. A study examining risk factors for corneal ulcers in people with bullous keratopathy identified steroid use as the strongest individual predictor of ulcer development, followed by bandage contact lens wear. Using both at the same time carried the greatest risk.25Ophthalmology (Rochester, Minn.). Ulcerative keratitis in bullous keratopathy This creates an awkward treatment dilemma: steroids calm inflammation and bandage lenses ease pain, but together they raise the odds of a secondary infection.
The organisms involved are not always the usual suspects. A case report documented an infection with Beauveria bassiana, a fungus more commonly known as an insect pathogen, in a patient with aphakic bullous keratopathy. The infection resisted standard antifungal treatment and ultimately required a full-thickness transplant to resolve.26PubMed. Beauveria bassiana keratitis in bullous keratopathy: antifungal sensitivity testing and management While exotic infections like that one are rare, the broader point is practical: anyone managing bullous keratopathy with a bandage lens or topical steroids needs careful follow-up to catch infections early.
The Donor Cornea Shortage and What It Means for Access
All of the transplant options described above depend on donor corneal tissue, and globally there is not nearly enough to go around. Many countries have no eye bank infrastructure at all, and even in well-resourced health systems, wait lists can stretch for months. The supply-demand gap is a major reason that cell-injection therapies and tissue-engineering approaches have attracted so much research attention: they could multiply the number of patients treated from each donated cornea.27PubMed. Alternatives to endokeratoplasty: an attempt towards reducing global demand of human donor corneas Innovations in corneal storage, transport, and eye-bank networking have also improved the situation in some regions, though the gap between supply and demand remains wide worldwide.28PubMed Central. Innovations in Corneal Transplantation: The Role of Eye Banks, Donor Corneas, and Artificial Alternatives in Combating Worldwide Corneal Blindness
For someone living in an area with limited tissue availability, this reality can shape which treatment pathway is realistic. Palliative measures like bandage lenses, ROCK inhibitor drops, or collagen cross-linking for pain control may need to serve as a bridge for months or longer while a donor cornea or a trial enrollment becomes available. Understanding the full spectrum of options, from the simplest to the most cutting-edge, helps patients and their doctors make the best use of whatever resources are at hand.