Originally published in NKCF Update (May 2023).

While all medical procedures carry potential risk, it is up to patients, along with their doctor to decide if the benefits of a procedure outweigh the risks.

Numerous studies have shown that FDA-approved crosslinking (CXL) has a success rate greater than 95%. Knowing that the procedure is successful in halting the progression of keratoconus, doctors at Kaiser Permanente in Northern California were interested in learning more about the safety profile. How much risk was associated with the procedure?

Kaiser Permanente is a comprehensive health care system with over 4 million members in Northern California as of 2018. Fifteen different eye surgeons perform CXL at 15 locations.

The study identified 878 eyes (654 patients) that underwent CXL between 2016-2018. Kaiser only performs the FDA-approved epithelium-off (epi-off) protocol. Dr. Naveen Chandra MD, the study’s senior author noted that “removing the epithelium is not a complicated process. It ensures the UV light reaches the proper layers” and increases the chances of success. After 30-minute exposure to UV light, patients are sent home with eyedrops or ointment, and a bandage contact lens to assist with healing and to control discomfort.

Patients are normally examined 1 day, 1 week, and 2 weeks after CXL. The researchers hypothesized that any patient who had more than 3 post-operative visits in the 31 days following CXL may have experienced a side-effect or post-operative complication and those charts were reviewed in detail.

34 of 878 (3.9%) eyes had delayed healing. Instead of the usual 5-8 days it takes for the epithelium to heal, there was a group of patients that took between 9-35 days to heal. The average for this “late” group was 18 days and the epithelium for all patients eventually healed.

Dr. Chandra noted the chart review was conducted on patients crosslinked in the two years immediately after FDA-approval. “We have learned more about optimum post-operative care after treating thousands of patients. Now, we remove the bandage contact lens after 5 days, even if the epithelium is not completely healed. In a small number of cases, the bandage rubs against the apex (the tip of the cone) and this is the most common cause of delayed healing.”

Thirteen (1.4%) of 878 eyes exhibited signs of redness, inflammation, or infection within the first postoperative month and were treated successfully with antibacterial eye drops or ointment. All patients are cautioned to avoid putting water in the eye which could introduce infection while the surface is healing.

Visual outcomes for patients who experienced complications was good. Of the 878 eyes that underwent CXL, only 9 patients (1%) who experienced either a delayed in epithelial healing or inflammation developed a corneal scar.

This study of US-based patients who underwent epi-off CXL between 2016 and 2018 showed the overwhelming majority had no adverse events, and the post-op complications that did occur were infrequent and temporary. While other studies have confirmed that CXL slows or stops disease progression, this study validates that the procedure itself is safe, with a low occurrence of post-operative complications.

Reference: Ang MJ, Darbinian JA, et al, The Safety Profile of FDA-Approved Epithelium-Off Corneal Cross-Linking in a US Community Based Healthcare System, Clin
Ophthal, 16:1117-1125, 2022

Dr. Naveen Chandra MD is a graduate of the Univ. of Michigan School of Medicine and completed his ophthalmology training at Univ. of Florida in
Gainesville and a cornea fellowship at UCLA-Jules Stein Eye Institute. He has been a member of the Kaiser Permanente team since 2001, treating
patients at their Walnut Creek office.