A keratocele, or descemetocele, is a herniation (perforation) of the Descemet membrane through the overlying corneal epithelium and supporting stroma. This usually happens as a result of a disruption to the cornea, such as in the presence of a corneal ulcer or perforation.
Descemet’s membrane is the membrane that underlies the stroma of the cornea (transparent bit of the cornea), separating it from the innermost or endothelial layer of the cornea.
Symptoms of a keratocele can include a sudden drop in visual acuity (clarity), ocular pain and excessive tear production.
What causes a keratocele?
A keratocele can be caused by a wide variety of factors ranging from infections to trauma. The most common viral infections include Herpes simplex and Herpes zoster. Bacterial infections may be caused by Pseudomonas aeruginosa, as well as a range of Streptococcus species. Some fungal infections causing keratocele include Fusarium solani (a common cause of keratitis) and Aspergillus fumigatus.
Other conditions that can lead to a keratocele include exposure keratitis, dry eye and xerosis. Several inflammatory conditions are also incriminated, such as the collagen vascular disorders like rheumatoid arthritis, systemic lupus erythematosus, and inflammatory bowel disease.
Possible causes of dry eye syndrome may include Sjogren’s syndrome/Mikulicz syndrome and vitamin A deficiency. Disruption of the corneal membrane could also occur because of penetrating injury, surgical trauma or chemical injuries.
How is a keratocele treated?
Treatments should be tailored to treating the underlying cause in addition to management of the herniation itself. It is also important to take the visual impact into consideration.
if bacterial or fungal infection is present, topical applications of antibiotics or antifungals may be used to treat the cause. Furthermore, anti-inflammatory medications are successfully used to treat corneal ulcers that have produced inflammation.
Anti-collagenase medications have been successfully used to treat corneal ulceration (keratocele). These work by inhibiting matrix metalloproteinase (MMP) enzymes that are synthesised by immune cells (neutrophils), as well as scavenging reactive oxygen species that could otherwise exacerbate corneal breakdown.
Surgical methods may also be employed to treat keratocele. A common method for treating small perforations with certain specific features is through the application of glue. This is also used to slow down the spread of infections and allow time for antibiotics to act. Other surgical methods include a partial or full corneal transplant, if the cornea is severely damaged, with little chance of natural or medicated recovery.
The outlook for keratocele is often favourable, and in uncomplicated cases its management may succeed with simple procedures and medications. If the keratocele is associated with trauma, surgical techniques are more suitable, as also for those perforations that are very small or which do not heal despite medication. However, there is a high rate of re-treatment, and keratoplasty is often essential to ensure useful vision is retained.
Treating the cause of the keratocele is important to prevent further deterioration of the cornea, in case of infection or inflammation.