| Objective: Vascular features and fractal structures of periphery and posterior retina in Familial exudative vitreoretinopathy(FEVR)will be studied in this research to offer new ideas and methods for screening and diagnosis of FEVR.Method: A retrospective observational study.73 eyes of 42 FEVR patients and 73 eyes of 41 controls were enrolled who visited The First Affiliated Hospital of Anhui Medical University from December 2017 to October 2020.The FEVR patients all underwent fundus imaging and fundus fluorescein angiography for clinical diagnosis.Features of fundus vessels were described in both 45°fundus imaging and ultra-wide field scanning laser ophthalmoscopy of FEVR patients.Additionally,retinal vessels in 45°fundus imaging of FEVR patients and the controls were semiautomatically segmented by VAMPIRE(Vascular Assessment and Measurement Platform for Images of the Retina)software(https://vampire.computing.dunde e.ac.uk/)into binary pictures,fractal dimension of which was calculated using Image J software(https://imagej.nih.gov/ij/)as well as Frac Lac plugin(http://rsb.inf o.nih.gov/ij/plugins/fraclac/FLHelp/Introduction.htm).And fractal structures of retinal vessels in the two groups were then compared.Result: Of 42 FEVR patients,there are 25 males and 17 females,the mean age of which is 28.93±11.85 years old,and of 41 controls,27 males and 14 females,the mean age is 32.88±14.70 years old,with no significant difference in gender or age of the two groups(P>0.05).Among 73 eyes of 42 FEVR patients,straightened retinal vessels,reduced vessel curvature and narrower angle between posterior vascular arch were found in 45 cases(45/73,61.64%),as well as the traction-like change of small vessels from optic disc to the temporal,while none of them in the control group.Among 36 eyes of 22 FEVR patients who underwent ultra-wide field scanning laser ophthalmoscopy,avascular area of temporal retina can be seen in 33 eyes(33/36,91.67%),demarcation line between avascular and normal retina in 14 eyes(14/36,38.89%),periphery retinal vascular abnormalities including brush-like increasing vascular branches,abrupt termination,expansion and tortuosity,and aberrant anastomosis of periphery vessels in 29 eyes(29/36,80.56%),periphery degeneration area in 11 eyes(11/36,30.56%).FD of retinal vessels in 45° fundus images of FEVR patients and the control group was 1.553±0.026,1.544±0.021(P<0.05),FD of veins 1.405±0.031,1.384±0.028(P<0.05),FD of arteries 1.369±0.039,1.362±0.030(P>0.05)respectively.In the circular area with midpoint of optic disc and macular as center and their distance as diameter,FD of vessels was 1.351±0.040 and 1.298±0.044(P<0.05)respectively.Conclusion: Fundus changes in FEVR patients,like avascular zone,increasing vascular branches,aberrant anastomosis,can be seen in the periphery retina as well as posterior and other areas.The branching and bifurcation of human retinal vessels has fractal tree-like features,so that it can be identified or analyzed through quantative parameters including FD.FD can apply to estimate the fractal structure of retinal vessels.Difference in FD of retinal vessels was found in FEVR patients and the controls,with a higher FD in FEVR patients indicating that the structure of retina vessels was more complex than normal.Basing on this,it will be of great benefit to set out studies of artificial intelligence assisting fractal features analysis in FEVR patients in order to provide a new efficient way for the screening and diagnosis of FEVR. |
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