Aqueous Deficient Dry Eye Syndrome Post Orbital Radiotherapy: A 10-Year Retrospective Study.

PURPOSE: Despite advances in orbital radiotherapy (XRT), a significant proportion of patients develop ophthalmic complication like dry eye syndrome (DES). The study evaluates the prevalence of aqueous deficient DES (ADDE) and lacrimal gland (LG) changes through histologic evaluation and ex-vivo expansion potential postorbital XRT.

METHODS: With the approval of the institutional review board, medical records of patients who underwent orbital XRT as management protocol were reviewed for evidence of ADDE using DEWS (Dry Eye Workshop) 2007 criteria (n = 51). HuLG was harvested from three of these patients who underwent subsequent orbital exenteration and used for histological studies/ex-vivo culture.

RESULTS: ADDE was noted in 47.07% of the patients, status postorbital XRT, with a prediction of nearly 50% developing it within 0.5 to 2.9 years. ADDE severity was grade 2 (18%), grade 3 (14%), and grade 4 (17%). Other comorbidities were radiation retinopathy (33.4%), radiation-induced cataract (24.9%), and radiation keratopathy (20.8%). Multivariate and univariate analysis showed that fraction of radiation and dose of radiation/fraction were significant risk factors; male gender and young age were protective factors. The post-XRT exenterated HuLG showed near-total effacement of histoarchitecture with intra/periductal and intra/interlobular fibrosis, loss of acini, and reduced secretory activity. The potential of the LG to expand and grow in culture was impaired with loss of stem cells as compared to normal HuLG.

CONCLUSION: This study documents that orbital-XRT is associated with morphological and functional loss of lacrimal function in nearly 50% of the patients with a prediction of two-third developing ADDE by the end of 5 years.

TRANSLATIONAL RELEVANCE: The study provides objective clinical evidence for DES development due to architectural/functional damage to the LG postorbital XRT. Based on recent findings that the LG can be cultured in-vitro, with preservation of stem cells and secretory potential, it would be logical to harvest a portion of LG before radiation, and expand and transplant it to rescue the damaged gland if indicated.