Information for the public
Benefits and risks
Benefits and risks
When NICE looked at the evidence, it found that most of the evidence was on the epithelium‑off procedure, and this showed that it worked well enough and was safe enough to use in the NHS. Because the epithelium‑on procedure is a more recent technique, there was not as much good evidence on how safe it is or how well it works. There was also not much good evidence for combining either the epithelium‑on or epithelium‑off procedure with other procedures.
The studies that NICE looked at involved about 2500 patients in studies of the epithelium‑off procedure, about 700 patients in studies of the epithelium‑off procedure combined with other procedures, and about 170 patients in studies of the epithelium‑on procedure either on its own or combined with other procedures.
Generally, they showed the following benefits:
-
Epithelium‑off: improved keratoconus, eyesight, and astigmatism (a condition in which the front of the cornea does not curve normally, which can affect eyesight if it is severe).
-
Epithelium‑off combined with other procedures: clearer eyesight and improved keratoconus.
-
Epithelium‑on: clearer eyesight and improved keratoconus.
-
Epithelium‑on combined with other procedures: improved keratoconus and clearer eyesight.
The studies showed that the risks of the procedures included:
-
infection
-
inflammation (redness, swelling, heat and pain), which in a small number of cases led to scarring or loss of eyesight and the need for a corneal transplant
-
scarring
-
fluid build‑up causing swelling in the eye
-
problems with the size, shape and colour of the iris (the coloured part of the eye)
-
the cornea breaking down
-
the UV light burning the cornea
-
ulcers
-
clouding of the cornea.
NICE was also told about 1 patient who had a tear in their cornea after the procedure.
If you want to know more about the studies see the guidance. Ask your health professional to explain anything you don't understand.