This section describes safety outcomes from the published literature that the Committee considered as part of the evidence about these procedures. This safety evidence is not subdivided by procedure variant because similar adverse events were reported for each. For more detailed information on the evidence, see the systematic review and the addendum to the systematic review.
5.1 Infections were reported in 8 single case reports. In 4 of these patients there was no major long-term adverse impact, visual acuity was reduced in 1 patient and no further details were reported in 3 patients.
5.2 Sterile keratitis associated with scarring or loss of vision or needing keratoplasty was reported in 3% (4/117) of patients in a case series of 117 patients. This was treated with high-dose topical or subconjunctival corticosteroids and 2 patients had a persistent decrease in BCVA. Deep stromal infiltrates with scarring at 2 months despite treatment with antibiotics was reported in a single case report.
5.3 Stromal scar developed in 4 patients (3 cases in 1 study); in 3 patients, the UCVA increased significantly despite scars, and in the other patient visual acuity was corrected with a lens.
5.4 Corneal oedema within 24 hours after CXL and inflammation for 2–3 weeks, iris atrophy and pigment dispersion were reported in a case series of 10 patients. These resolved in 1 patient and improved in 4 patients after treatment. Corneal oedema that developed in a single case report resolved after 6 months' treatment but scarring and poor visual acuity remained.
5.5 Corneal melting was reported in 1 single case report. This patient was initially treated with tissue glue and bandage contact lens application but needed penetrating keratoplasty on day 12. Perforation due to corneal melting was reported in 2 single case reports. These patients were treated by penetrating keratoplasty and antibiotics with no long-term adverse impact.
5.6 Corneal burn and ulcer were reported in 3 single case reports; 1 patient was treated by phototherapeutic keratectomy (CVA improved from 20/69 to 20/20 at 28 months) and treatment details were not reported for the other 2 patients.
5.7 Corneal haze with diffuse subepithelial opacification and paracentral corneal thinning associated with scarring was reported in a single case report. This disappeared only gradually despite intensive therapy.
5.8 Stromal haze was reported in all eyes in a randomised controlled trial of 10 patients comparing same-day ICRS and CXL with ICRS and CXL 6 months later. This resolved eventually in both groups (the time period was not reported). Mild posterior linear stromal haze at 1 month after CXL with PRK was reported in 46% of eyes (13/28) in a case series of 28 eyes (23 patients). At 12 months follow-up, this had decreased in density but had not completely disappeared.
5.9 The specialist advisers listed anecdotal adverse events as delayed epithelial healing, bilateral corneal infection and transient recurrent erosion syndrome. In addition, a specialist provided information about a single occurrence of corneal perforation after the procedure.