Utility of high-resolution anterior segment optical coherence tomography in the diagnosis and management of sub-clinical ocular surface squamous neoplasia

Background:To evaluate the frequency and characteristics of sub-clinical ocular surface squamous neoplasia(OSSN)detected by high-resolution anterior segment tomography(HR-OCT)in patients with clinically unapparent disease following topical treatment.Methods:A retrospective chart review of patients with OSSN identified through a pharmacy database at the Bascom Palmer Eye Institute from January 2013 to December 2018 was conducted.Patients undergoing primary therapy with topical 5-fluorouracil 1%(5-FU)(4 times a day for 7 days with a 21-day break)or interferon-alpha-2b(IFN)(4 times a day)were reviewed.Patients were separated into two groups.Group 1 included individuals whose clinical resolution of OSSN aligned with complete resolution on HR-OCT.Group 2(sub-clinical OSSN group)included individuals with clinical OSSN resolution but with features of persistent disease on HR-OCT.Patients excluded included those treated at an outside institution and those who used topical therapy as a surgical adjunct.Results:A total of 95 patients(95 eyes)were reviewed.Sub-clinical OSSN was detected at a frequency of 17%in our study patients(n=16 patients,9 treated with 5-FU and 7 treated with IFN).In the 16 individuals,the mean time to clinical resolution was 3.6±1.0 cycles for 5-FU and 4.0±0.0 months for IFN.An additional 2.1±0.8 cycles for 5-FU and 1.2±0.4 months for IFN were needed to achieve HR-OCT resolution of OSSN.Recurrence in Group 1 was noted in 10 patients(12%)while no recurrences occurred in Group 2,the cohort with subclinical disease that received the extended medical therapy.The mean follow-up was 24.0±17.9 months.Conclusion:We found that at least 17%of individuals with apparent clinical resolution of OSSN have sub-clinical disease detected on HR-OCT.This information can be used to optimize treatment and extend therapy past the point of clinical resolution.