Complications of retinal vein occlusion (RVO) that are strongly related to visual function include macular edema and macular ischemia. Anti-vascular endothelial growth factor (anti-VEGF) therapy, the current mainstream treatment for macular edema accompanying RVO, results in significant improvement in visual acuity. However, several factors, such as the type of cases that are susceptible to more severe photoreceptor damage and retinal ischemia, remain unclear.
We investigated the pathological mechanisms and visual acuity prognosis of photoreceptor damage resulting from macular edema, findings that could predict the presence of macular ischemia, and features of patients who are resistant to anti-VEGF therapy. First, we reported that the presence of the foveal bulge of the ellipsoid zone of the central fovea observed on optical coherence tomography (OCT) scans indicates healthy photoreceptor cells, which therefore correlates with good visual prognosis. Second, our investigation of OCT images revealed that lipoproteins etc. in effusion flow through the disrupted external limiting membrane and deposit, consequently cause photoreceptor damage. Third, we found that in eyes with macular edema that exhibit low reflective spaces in the retinal nerve fiber layer on OCT images, a retinal non-perfusion region was formed later at the corresponding site. Therefore, this finding could be used for early prediction of macular ischemia. Finally, we demonstrated that cases of macular edema caused by microaneurysms tend to be resistant to anti-VEGF therapy. Thus, the utilization of fundus imaging, such as OCT, could facilitate further understanding of RVO pathology and lead to the development of appropriate treatment strategies.
Nippon Ganka Gakkai Zasshi (J Jpn Ophthalmol Soc) 123: 1038-1053, 2019.