Optical Coherence Tomography Angiography after External Beam Irradiation
Janelle Fassbender Adeniran; Raafay Sophie; Mehreen Adhi; Aparna Ramasubramanian
University of Louisville
Introduction: It is estimated that 0.1% of individuals 20 years of age are survivors of childhood cancer and many of them have been treated with cranial or whole body radiation. Detection of subtle radiation retinopathy (RR) in the pediatric population is challenging but can have significant long term visual consequences. Optical coherence tomography angiography (OCT-A) effectively detects subtle vascular changes in the retina.
Methods: OCT-A images (3×3 mm foveal scans, Cirrus Angioplex) were obtained for healthy patients 18 years and under and those pediatric patients with prior cranial irradiation (CI) or total body irradiation (TBI). Foveal avascular zone (FAZ) area and circularity were obtained using Image J and parafoveal capillary density using Photoshop. High-definition OCT through the fovea was used to measure choroidal thickness.
Results: Nine patients, CI (n=5) and TBI (n=4), were included. Three patients had RR on clinical exam and OCT-A. Four patients had vascular abnormalities detected on OCT-A that were not present on clinical exam or other imaging. The mean FAZ area in superficial (radiation: 0.31 ± 0.13 vs normal: 0.18 ± 0.10) and deep (radiation: 0.85 ± 0.46 versus normal: 0.53 ± 0.15) capillary plexi were significantly different (p<0.05). The parafoveal capillary density was significantly less in the superficial (radiation: 40.66 ± 6.08 vs normal: 45.41 ± 5.23; p<0.05) but not the deep (radiation: 20.84 ± 5.54 vs normal: 22.67 ± 5.30; p>0.05) capillary plexi. Circularity of the foveal avascular zone was not different between conditions but choroidal thickness was significantly less in the radiation group (224.15 ± 54.36 vs 276.91 ± 38.18; p<0.05).
Discussion: OCT-A can detect early radiation retinopathy before clinical features appear and it would aid in close monitoring and early treatment of macular edema and preserve long term vision.
Conclusion: Non-invasive OCT-A may aid in the early detection of RR.
References: Cindy L. Schwartz. Long-Term Survivors of Childhood Cancer: The Late Effects of Therapy. The Oncologist (1999); 45-54.