What is Pseudophakic Bullous Keratopathy?
Pseudophakic bullous keratopathy (PBK) is a condition where the cornea, the front part of your eye, swells up permanently after a cataract surgery. The initial damage happens to the innermost part of the cornea, the corneal endothelium. Following that, the swelling can progressively move to the stroma, the thickest layer of the cornea.
This swelling can then potentially proceed to the subepithelial and epithelial layers, the topmost layers of the cornea, causing the formation of fluid-filled blisters, which is why it’s termed bullous keratopathy. Damage to the inner layer of the cornea can happen during any eye surgery but the reports of PBK are most frequent after phacoemulsification, a type of cataract surgery.
PBK has also been reported following excessive or incorrect use of ultrasound energy during phacoemulsification, complex cataract surgery, removal of the vitreous humor (the clear gel that fills the space between the lens and the retina) in the front part of the eye, rubbing of the nucleus (the central part of the eye’s lens) to the corneal endothelium during manual small incision cataract surgery, Fuch’s endothelial dystrophy (a genetic eye condition that causes gradual loss of vision), and other diseases that affect the corneal endothelium.
With the advancement in surgical techniques and introduction of newer designs for the intraocular lens (IOL), which is the artificial lens implanted during cataract surgery, the chances of getting PBK have decreased a lot. Nonetheless, it still remains a significant cause for decreased vision following common and complex cataract surgeries.
What Causes Pseudophakic Bullous Keratopathy?
Pseudophakic bullous keratopathy (PBK) is usually caused by a loss of cells from the inner layer of the cornea (endothelial cells) after eye surgery, especially cataract surgery in older patients. There could be other reasons too such as using high energy levels during eye surgery, or high fluid outputs and suction during the cataract operation. This might result in damage to endothelial cells causing clear, blister-like areas on your cornea after cataract surgery.
In some cases, PBK can be seen with various diseases that affect the endothelial cells of the cornea, like:
* Fuchs endothelial dystrophy, a condition that causes gradual loss of vision
* Posterior polymorphous endothelial dystrophy, a rare condition causing clouding of the cornea
* Congenital hereditary endothelial dystrophy, a condition present at birth causing poor vision
* Iridocorneal endothelial (ICE) syndrome-Chandler syndrome, a group of three related conditions that cause swelling in the cornea
* Essential/progressive iris atrophy, a rare eye disorder that results in the thinning and eventual loss of the iris
* Iris nevus / Cogan-Reese syndrome, a rare condition that can cause a build-up of pressure in the eye
* Herpetic disciform keratitis, a condition caused by the herpes simplex virus that results in inflammation and vision loss.
Other conditions like diabetes, narrow-angle glaucoma, or a history of eye trauma could be associated with PBK. Endothelial cell damage could also occur during any eye surgery, or due to a reaction to toxic substances in the eye. Sometimes, silicone oil used in certain eye surgeries, or the presence of a collagen lens in the eye could contribute to PBK.
During an operation, using specific types of intraocular lenses (manmade lenses that replace the eye’s natural lens) could also contribute to PBK. After routine eye surgery, there’s usually a 10% loss of endothelial cells, and a 1% natural loss every year. Certain eye conditions post-surgery like vitreous touch syndrome (a condition where the vitreous -gel-like substance in the eye-, touches the cornea), vitreous wick syndrome, and flat anterior chamber post-surgery intermittent intraocular lens touch could be linked to PBK.
Risk Factors and Frequency for Pseudophakic Bullous Keratopathy
Pseudophakic bullous keratopathy (PBK) is a medical condition that isn’t easy to quantify, but in the USA, it’s reported at a rate of 0.1%. From the years 1978 to 1982, studies approved by the US FDA highlighted an incidence of 0.06% after intraocular lens implantation, 1.2% following anterior chamber lenses, and 1.5% following iris-fixated lenses. The long-term reported incidence of PBK is much higher at 15%.
The degree to which eye endothelial cells are lost during cataract surgery shows a link with the rate of PBK. Evidence suggests that the rate is around 4.72% following extracapsular cataract extraction, 4.21% after small incision cataract surgery, and 5.41% after phacoemulsification.
PBK isn’t known to impact any particular gender, sex, or race more than another. However, certain risk factors make it more likely. Fuchs dystrophy, for example, is three times more common in women and it’s a significant risk factor for PBK. Increasing age is another contributing risk because eye endothelial cells decrease as we age.
Signs and Symptoms of Pseudophakic Bullous Keratopathy
Pseudophakic bullous keratopathy (PBK) is a condition that typically happens after cataract surgery. The diagnosis is made based on the patient’s medical history and observation of their symptoms.
Medical History
People diagnosed with PBK typically report a slowly worsening vision after having cataract surgery. They might mention a long or complicated surgical procedure. Another common experience is blurred vision in the morning due to fluid build-up and swelling in the cornea overnight.
Symptoms
At first, a person with PBK might not have any symptoms. But as the condition progresses, they may start to notice blurred vision. This can eventually develop into severe vision loss. Other symptoms might include pain, redness, sensitivity to light, irritation, a feeling of something in the eye, and seeing halos around lights.
Signs
- A detailed examination with a tool called a slit lamp can show problems in different layers of the cornea, including:
- in the epithelium (the outer layer), like an epithelial defect, swelling, tiny cysts, and blisters
- in the subepithelial layer, such as scarring or clouding,
- in the stromal layer, signs like swelling, scarring, and clouding
- In the Descemet membrane (a thin layer deep in the cornea), there might be folds and scarring.
- and in the endothelium (the innermost layer), there could be swelling and inability to function properly.
- Other indicators are:
- The location of the surgical incision
- abnormal blood vessels in the cornea
- an unusually shallow anterior chamber (the space in the eye just above the pupil)
- damage to the iris
- IOL (intraocular lens) location
- Other signs linked to a vitreous prolapse (a complication after cataract surgery where the jelly-like substance in the eyeball protrudes into the anterior chamber)
- Lastly, the health of the other eye should also be checked, particularly for a condition called guttae (bumps on the inner surface of the cornea) and other endothelial pathologies (diseases that affect the innermost layer of the cornea).
Testing for Pseudophakic Bullous Keratopathy
Certain imaging techniques allow doctors to examine parts of your body in a non-invasive way. Two such techniques are Specular Microscopy, which involves capturing images of the corneal endothelium – a thin layer at the back of your cornea, and Ultrasound Pachymetry, which measures the thickness of your cornea.
With Specular Microscopy, light rays are used to create images of the corneal endothelium. These images help doctors count the cells present within this layer of your eye. Young individuals normally have 3000 to 3500 cells per square millimeter, while older adults typically have 2000 to 2500 cells per square millimeter. If a person has fewer than 1000 cells per square millimeter, they are at a high risk of developing problems with their cornea. Additionally, cells of different sizes and shapes can be a sign of stress within these regions.
In Ultrasound Pachymetry, sound waves are used to measure the thickness of your cornea. Usually, in a healthy state, your central cornea is 0.55 mm thick, which can increase up to 0.80 mm towards the periphery. However, if your cornea is more than 0.60 mm thick, then this could be an indicator of a condition known as corneal edema, which leads to swelling of the cornea. Doctors use Ultrasound Pachymetry to monitor changes in your cornea over time in case of conditions such as Fuch’s endothelial dystrophy, or to check the response of the cornea to certain treatments such as a steroid regimen after a corneal graft.
There is another technique, called Optical Pachymetry, which helps doctors evaluate the depth of a corneal defect, particularly if it is not fully penetrating the thickness of the cornea. This information can assist the doctor in planning treatments such as a laser procedure.
Treatment Options for Pseudophakic Bullous Keratopathy
One way to treat eye swelling and discomfort caused by a medical condition known as pseudophakic bullous keratopathy (PBK) is the application of a solution called topical sodium chloride which is either in form of 2% drops or 5% ointment. It works by drawing water out of the cornea, the clear front surface of your eye, leading to a decrease in swelling. This treatment is typically applied four times a day and the ointment is added at bedtime to counter any morning discomfort due to excessive fluid accumulation in your eye while you sleep.
Another method of managing this condition is through drugs that are usually used to treat glaucoma which help to lower the pressure within your eyes, thus relieving the swelling and thickness of the cornea especially after an operation. However, avoid certain types of drugs such as miotics, prostaglandins, and carbonic anhydrase inhibitors as they may cause further inflammation.
Steroids can also be used to decrease any sudden inflammation, especially after cataract surgery. But it is essential to ensure that your cornea is free of any epithelial defect or infectious inflammation by staining it with a substance called fluorescein before applying the steroids.
To prevent irritation and dryness of your eyes, lubricants can be applied to smoothen the surface of your cornea. Additionally, wearing soft contact lenses for an extended period can alleviate pain, protect against infections, improve visual clarity when used in conjunction with the hypertonic saline and prevent new fluid-filled blisters from forming due to its barrier effect.
In certain cases, surgical methods can be applied to bring relief. With the Gunderson Conjunctival Flap technique, a thin flap of the conjunctiva (the clear tissue covering the white part of your eye) is brought over the surface of the cornea. This helps in healing, by meeting the metabolic needs of the cornea, increasing the local blood supply, and replacing any dead or damaged surface cells.
Another surgical technique is the Amniotic Membrane Grafting (AMG) where a specific membrane is applied over the cornea after any loose cells have been removed. This can help in healing and a special type of contact lens could also be applied over the grafted membrane if required.
There are other surgical techniques to alleviate pain like Bowman’s Membrane Cautery which prevents fluid from moving into the outer layer of the cornea by creating a strong barrier or Anterior Stromal Puncture which induces healing by making multiple small punctures in the cornea. There is also the Annular Keratotomy technique which reduces pain by cutting the nerve supply to the cornea or Basement Membrane Polishing which smoothen the basement membrane in order to promote healing.
Cornea Transplantation is another method where either the whole cornea is replaced with donor tissue or the inner lining of the cornea and sometimes a part of the inner layer of the cornea is replaced. After the operation, some of the advantages include quicker recovery of vision, less chance of your body rejecting the transplant and a lower risk of complications related to wound healing. However, these surgical techniques also have their disadvantages and may require a lot of skill and experience in order for you to get the desired result.
What else can Pseudophakic Bullous Keratopathy be?
Some conditions that may affect your eyes include:
- Fuch’s endothelial dystrophy – a condition where the innermost layer of the cornea progressively deteriorates
- Congenital hereditary endothelial dystrophy (CHED) – it’s a rare genetic disorder that affects the back part of the cornea
- Posterior polymorphous corneal dystrophy (PPMD) – a rare genetic condition that alters the cornea’s appearance and function
- Iridocorneal endothelial syndrome (ICE) – this involves changes in the cornea and iris, which can lead to an increased eye pressure
- Herpetic stromal keratitis (HSK) – it’s an inflammatory disease caused by the herpes simplex virus
- Recurrent corneal erosion syndrome (RCES) – a disorder where the outermost layer of corneal cells does not adhere properly to the underlying ones, causing episodic pain
What to expect with Pseudophakic Bullous Keratopathy
Performing an optical penetrating keratoplasty or Descemet stripping endothelial keratoplasty (DSEK) – both of which are types of cornea transplantation surgery – in a careful and timely manner, generally has good outcomes for those with pseudophakic bullous keratopathy, a condition where the cornea swells and blisters after cataract surgery.
However, if only medical treatments are used to manage the symptoms, the overall outlook of the condition is usually not as successful. It’s important to remember that these medical treatments primarily aim to provide relief from symptoms rather than curing the condition.
Possible Complications When Diagnosed with Pseudophakic Bullous Keratopathy
Medical issues can include:
- Permanent swelling of the cornea
- Dryness in the eyes
- Poisoning from medication
Potential problems from surgery can include:
- The graft not taking hold
- Injury caused by the surgery itself
- Infection in the graft
- Secondary glaucoma – a type of eye disease
- Sudden, significant bleeding in the back of the eye
- Bulging of the jelly-like substance in the eye
- Swelling in the macula, the part of the retina responsible for central vision
Recovery from Pseudophakic Bullous Keratopathy
Proper after-surgery care is crucial after keratoplasty (a corneal graft surgery) to ensure the best results for the patient’s sight and the survival of the graft. After the surgery, the patient should start using a 1% prednisolone or 0.1% dexamethasone eye drops every 2 hours for three days. After that, they should be used six times daily for 15 days, followed by a gradual reduction to 4, 3, 2, and then 1 time per day, each for three months. Afterwards, it’s recommended to use them once during the night as a maintenance dose to ensure graft survival.
Additionally, other medications should be used such as 2% homatropine two times daily for 15 days, 0.5% timolol eye drops two times daily along with steroids to prevent a condition called secondary glaucoma (increased pressure in the eye that can lead to vision loss), and oral anti-inflammatory drugs for pain relief.
Moreover, it’s crucial for the patient to understand the importance of taking their medications regularly, keeping up with their doctor’s appointments, and reporting any sudden symptoms like pain, redness, or blurred vision immediately to prevent the loss of the graft. Patients should also understand that full vision clarity usually returns around three to four months after the surgery.
Preventing Pseudophakic Bullous Keratopathy
Teaching patients is critical when dealing with PBK, a condition where the cornea (the front surface of the eye) becomes swollen. It’s important for patients to understand the nature of this eye issue and the reason behind the swelling in the cornea. Patients also need to know about the possible course of treatment, which could include a cornea transplant in the future.
To ensure the other eye is not also affected, it will be carefully checked to rule out any existing problems with the endothelium – the thin layer at the back of the cornea. Patients should be made aware of this examination.
If the cornea swells and blisters break, a bandage contact lens may be needed. In this case, patients need to be educated on how to keep the lens clean and maintain it properly. Regular use of certain medicines, like steroids, is also crucial, as it helps control the swelling within the eye. Patients should be taught how to effectively manage their medication usage, including understanding when to reduce their steroid dose, to avoid any complications leading to potentially irreversible vision damage.
Getting regular check-ups and taking medicines on time is critical for patients with PBK. Understanding their condition and its management can help them ensure their vision doesn’t deteriorate further.
