Characteristics of highly myopic choroidal neovascularization by optical coherence tomography angiography and analysis of macular choriocapillaris density / 中华眼底病杂志

ABSTRACT

Objective:To observe the imaging characteristics of optical coherence tomography angiography (OCTA) and the changes of choroidal capillary density (CCD) in the eyes of patients with high myopia choroidal neovascularization (mCNV).Methods:A case-control study. From January 2018 to October 2020, 50 cases of mCNV patients with 50 eyes (mCNV group) were included in the study. There were 18 males and 32 females; their age was 42.11±11.66 years old. Fifty eyes of 50 patients with normal fundus with matching myopia refractive power (≥6.00 D) were selected as the simple high myopia group, and 50 normal volunteers (refractive power -0.25-0.25 D) while 50 eyes were selected as the normal control group. There was no statistically significant difference in age ( F=0.028) and gender composition ratio ( χ2=0.136) among the three groups of patients ( P>0.05); the difference in best corrected visual acuity was statistically significant ( F=14.762, P=0.004). Compared with mCNV group and pure high myopia group, the refractive index ( t=-0.273) and axial length ( t=0.312) of the examined eyes were not statistically significant ( P>0.05). OCTA instrument was used to measure the CCD in the macular area of the examined eye. Analysis of variance was used for comparison of measurement data among the three groups; χ2 test was used for comparison of categorical variables. The paired t test was performed to compare the CCD of the mCNV patient's eye and the contralateral eye. Results:Among the 50 eyes in the mCNV group, Ⅰ , Ⅱ, and mixed choroidal neovascularization (CNV) were 12 (24%, 12/50), 34 (68%, 34/50), and 4 (8%, 4/50) eyes, respectively. Corresponding to the OCTA cross-sectional image of the lesion, there was a clear "flower cluster" -like strong blood flow signal. Among them, the focal shape, the filament shape, and the group net shape were 6 (12%, 6/50), 8 (11%, 8/50), and 36 (72%, 36/50) eyes, respectively. The CCD of the eyes in the mCNV group, the pure high myopia group, and the normal control group were (57.39±3.24)%, (59.33±2.23)%, and (61.87±1.62)%, respectively. The CCD of the eyes in the mCNV group was significantly lower than that of the simple high myopia group ( P=0.030) and the normal control group ( P<0.001). The CCD of the affected eye and the contralateral eye in the mCNV group were (57.39±3.24)% and (59.82±3.94)%, respectively; there was no statistically significant difference between the CCD of the affected eye and the contralateral eye ( t=-0.496, P=0.100). The CCDs of eyes with Ⅰ, Ⅱ and mixed CNV were (57.38±3.31)%, (57.39±2.83)%, and (57.36±4.21)%, respectively. There were no statistically significant differences in CCD ( F=1.476), age ( F=0.274), sex ratio ( χ2=0.825), and diopter ( F=0.348) in different CNV types ( P>0.05). Conclusion:The mCNV is mostly type Ⅱ, and OCTA has a "bloom" appearance of abnormal reticular blood vessels; the CCD is significantly reduced, and it is bilateral.