Topical 1% 5-fluorouracil eye drops as primary treatment for ocular surface squamous neoplasia: Long-term follow-up study

To determine the efficacy and safety of topical 1% 5-fluorouracil (5FU) eye drops as primary treatment of ocular surface squamous neoplasia (OSSN).Patients were diagnosed with OSSN based on slit-lamp examination and anterior segment optical coherence tomography (AS-OCT). In ambiguous cases an incisional biopsy was performed. All were treated with 5FU eye drops as primary therapy and retrospectively reviewed. Data on demographics, tumor characteristics, treatment outcome, and side effects were collected. The primary outcome measures were resolution frequency and recurrence rate of OSSN. Secondary outcomes were risk factors for resolution and recurrence, and side effects of treatment.The mean age of 251 subjects (258 eyes) was 67.5 ± 11.7 years, 182 were male. Patients were followed up on average for 752 ± 580 days. Overall, 87% of patients experienced complete tumor resolution. Multivariable analysis revealed that superior tumor location (HR: 0.62, 95% CI: 0.41-0.93, p = 0.02) and leukoplakia (HR: 0.65, 95% CI: 0.41-0.93, p = 0.02), decreased the likelihood of tumor resolution. The recurrence rate was 4% at six months, 8% at one year, and 19% at two years. Larger tumor area increased chances of tumor recurrence (HR: 1.01, 95% CI: 1.00-1.02 p = 0.03). The most common side effects of 5-FU were mild hyperemia and pain, which occurred in 26% and 23% of patients, respectively. Among the sight-threatening side effects, limbal stem cell deficiency occurred in only 3% of patients.Topical 1% 5FU eye drops are a safe and effective medication for OSSN. Superior tumor location and leukoplakia decreased the chance of tumor resolution.