Quantitative Analysis Of Microvascular And Morphological Changes In Fellow Eyes Of Patients With Retinal Vein Occlusion

Purpose: Retinal vein Occlusion（RVO）is the second most common retinal vasculopathy after diabetic retinopathy（DR）.Its main symptom is the sudden and painless vision decrease monocularly accompanied by typical changes in the fundus:such as the hemorrhage of different degrees from optic disc to peripheral retina,peripapillary or macular ischemia.The vessel density of macular microvasculature and choriocapillary plexus,the flow and morphology changes of the fovea avascular zone（FAZ）in the fellow eyes of unilateral RVO patients were quantitatively compared with the RVO eyes and normal controls respectively using optical coherence tomography angiography（OCTA）.Furthermore,to clarify the application value of OCTA in early pathological and physiological changes and the process of RVO,and explore the potential influence of systemic risk factors on the occurrence and development of RVO disease.Methods: This is an observational retrospective study.72 unilateral RVO patients（72RVO eyes and 72 RVO fellow eyes）and 72 healthy controls（72 eyes）were recruited from the ophthalmology department of the First Affiliated Hospital of Anhui Medical University.All subjects were underwent best-corrected visual acuity examination,the anterior and fundus slit-lamp examination and fundus photographic examination.Furthermore,quantitative parameters were acquired by OCTA,which was conducted with the 3 × 3mm scan pattern centered on the macular fovea,including the vessel density of superficial capillary plexus（SCP）,deep capillary plexus（DCP）and choriocapillary plexus（CCP）,fovea density 300 μ m（FD-300）,FAZ area and perimeter（PERIM）and A-circularity index（AI）.RVO eyes,RVO fellow eyes and normal controls were compared between groups,and the difference of relevant OCTA parameters between CRVO patients and BRVO patients were analyzed.Results: Both the RVO eyes compared to their fellow eyes and the fellow eyes compared to the normal controls,showed a significantly lower macular vessel density of the whole image and parafovea（P<0.05）in both the SCP and DCP,except for the fovea region（P>0.05）,and the same change for the vessel density of CCP.The FAZ area and PERIM（P>0.05）were observed that had no significant differences between the RVO eyes and the fellow eyes,while AI in the RVO eyes was significantly higher than the fellow eyes（P<0.05）and the FD-300 in the RVO eyes was significantly lower than their fellow eyes（P<0.05）.BCVA in the RVO eyes was significantly lower than in the fellow eyes（P < 0.05）,while there was no significant difference between the RVO fellow eyes and the normal controls（P > 0.05）.There were no significant differences in OCTA relevant parameters between CRVO fellow eyes and BRVO fellow eyes（P>0.05）.Conclusion: Both the RVO eyes and the fellow eyes in unilateral RVO patients presented ischemia in the SCP,DCP and CCP,indicating that early flow and morphological changes in retina and choroid had occurred in the RVO fellow eyes even without the clinical symptoms of RVO.All these results revealed that systemic risk factors may have a great influence on RVO,also could provide evidence for the early prevention of lesion in RVO fellow eyes.Furthermore,OCTA may play an important role in the judgment of early pathophysiological changes and disease progression of RVO.