Bullous keratopathy occurs due to damage of the endothelial layer of cornea, leaving too few cells to keep the cornea clear. This results in dehydration and swelling of cornea and patient complains of gradual loss of vision. The condition is characterized by the presence of corneal epithelial bullae.
Pseudophakic bullous keratopathy (PBK) is the irreversible corneal edema that develops as a complication of cataract surgery. Usually a cataract surgery damages only 10% of the endothelial layer of the cornea, leaving behind enough endothelial cells to keep the cornea clear. But in case of complicated cataract surgery, there is more than usual damage of the endothelial layer of the cornea that leaves few cells to keep cornea clear. This result in swelling of cornea and is associated with the development of bullae, hence named as pseudophakic bullous keratopathy.
With improved surgical techniques and lens used for cataract surgery, the incidence of this complication has decreased dramatically.
Risk factors of PBK:
PBK can occur in any complicated case of cataract surgery. But certain pre-operative factors can predispose the patient to develop PBK even after a smooth and successful surgery. These risk factors may include:
- Old age
- High intraocular pressure
- Corneal dystrophies, trauma or inflammation
- Implant of anterior chamber intraocular lenses
Cause of PBK
During the surgical procedure to remove cataract and implant a lens, following causative factors can cause excessive damage to the corneal epithelium:
- Complicated cataract or intraocular surgery
- Placement of a poorly designed or mal-positioned intraocular lens implant
- Fuchs corneal endothelial dystrophy
- Corneal endothelial trauma
- Inadequate irrigation
- Oedema of the cornea
- Corneal transplant rejection
Symptoms of PBK
PBK may manifest immediately after surgery or symptoms may not present for many years.
- Decreased or complete loss of vision
- Hazy vision that is worse in the mornings
- Increased tearing
- Light sensitivity
- Eye discomfort
- Loss of contrast
- Eye pain
- Eye irritation
- Foreign body sensation in the eye
- Occasional infectious keratitis
- Corneal ulceration may occur due to infection
Diagnosis of PBK
The swelling of the corneal stroma can be seen on slit-lamp examination and dilated fundus examination. In addition to this, following non-invasive techniques are also used to evaluate PBK:
- Corneal pachymetry will confirm a thicker cornea
- Specular microscopy demonstrates reduced endothelial cell density and abnormal morphology.
- Clinical confocal microscopy to study corneal cell layers.
Treatment of PBK
Most of the cases of PBK need corneal transplantation as damaged cells do not regenerate and cornea needs to be replaced. But before opting for corneal transplantation, some other measures may prevent the need of transplantation:
- Topical dehydrating agents (e.g., hypertonic saline)
- Intraocular pressure–lowering agents
- Occasional short-term use of therapeutic soft contact lens
- Treatment of any secondary microbial infection
- Phototherapeutic keratectomy
- Anterior stromal micropuncture
- Gundersen conjunctival flap or amniotic membrane graft
- Penetrating keratoplasty
- Corneal Transplantation