Introduction and Overview
The term keratopathy refers to a disease or degeneration of the cornea, the clear, dome-shaped structure at the very front of the eye where light first enters the eye.
This particular corneal degeneration is produced when calcium deposits on the cornea, usually in the area between the eyelids when the eye is in the open position. This is probably because this is the area of the cornea most exposed to the normal atmosphere, where the calcium is more likely to drop out of the tears because it is more concentrated.
(Figure 1 shows the structure of the cornea and its layers. Band keratopathy calcium deposits are located beneath the epithelium and above Bowman's Layer.)
There is usually an underlying cause for the calcium to build up in the tears and deposit on the cornea. Some of these conditions include:
- Excessive vitamin D intake
- Kidney failure
- Paget's Disease
In addition, some ocular conditions that are also associated with band keratopathy are chronic uveitis (also known as iridocyclitis or iritis), juvenile rheumatoid arthritis and end-stage glaucoma. There also seems to be a connection between the use of ocular medications or contact lens solutions containing mercury-based preservatives, as well as exposure to mercury vapor.
Symptoms and Signs
The band of calcium deposits can cause a disruption in vision due to its position across the front of the eye. There is usually a foreign body sensation, more or less severe, depending on the size and quantity of depositing, occasional redness and the band may be visible to others and cause a problem with cosmetic appearance of the eye.
The calcium deposits may be very fine or quite thick and plaque-like; when it is thick, it may flake off and cause scratching of the corneal surface and associated pain.
Treatment of band keratopathy is usually successful, by the physical removal of the deposits from the surface of the cornea, followed, if necessary, by the use of an excimer laser to smooth out any remaining irregularity in the corneal surface. There is risk of complications from corneal debridement therapy, including corneal scarring and vision loss, but the incidence of such adverse events is quite low.
After treatment, a bandage soft contact lens is usually applied to the eye for a period of about one to two weeks.
Patients with band keratopathy should have serum blood tests for calcium and phosphate levels, as well as have their renal function tested.
When this condition causes obstruction of the vision, significant foreign-body irritation or a cosmetic problem, treatment is usually successful. Manually removing the deposits under corneal anesthetic followed by polishing the surface with the excimer laser are usually effective, but the keratopathy will probably recur unless the underlying cause is diagnosed and treated as well.