Evaluation of Retinal and Optic Disc Vascular Changes and Retinal Nerve Fiber Layer Thickness in Patients with Nasopharyngeal Carcinoma Following Image Guided Intensity-Modulated Radiation Therapy Using Optical Coherence Tomography Angiography.

Background: Radiation-induced optic neuropathy (RION) is one of the most important late complications during head and neck radiotherapy and is recognized usually between 2-9 years after RT. Our study aims to prospectively without baseline measurement evaluate retinal and optic disc vascular changes and retinal nerve fiber layer thickness (RNFL) using optical coherence tomography angiography (OCTA) in nasopharyngeal cancer (NPC) patients previously treated with intensity-modulated radiation therapy (IMRT) and with optic nerve doses are above 45 Gy.

Methods: Fourteen NPC patients and sixteen age-matched healthy control subjects were included in our study. A complete ophthalmological examination including the best-corrected visual acuity (BCVA), intraocular pressure, slit-lamp biomicroscopic, fundoscopic examination and OCTA were performed for all patients and healthy volunteers. OCTA findings of RT and control groups were compared and correlation analysis was performed to find the association between the radiation-related factors and OCTA findings.

Results: Inferior hemi disc, parafovea and perifovea superficial/deep vessel densities were were statistically significantly lower in RT patients. Negative correlations were found between Dmax of optic tract and both RNFL and vessel densities. Furthermore, there were negative correlations found between the Dmean of glob and vessel densities.

Conclusion: Although none of the patients in our study had marked vision loss and retinal abnormalities with the examination, OCTA findings showed that perifoveal and parafoveal vascularity were statistically significantly affected due to the RT.