A Comparative Study Of Choroidal Thickness And Blood Flow In Patients With Myopia With Different Diopters

Objective:By comparing the choroidal thickness and blood flow in patients with myopia with different diopters,the changes of choroid in the development of myopia were preliminarily discussed,which lays a foundation for the pathological changes of eye tissue caused by myopia and provides a theoretical basis for the prevention and control of myopia.Methods:A cross-sectional study.A total of 82 patients were randomly collectedwho underwent preoperative myopia examination in the Ophthalmology Excimer Laser treatment Center of Dazhou Central Hospital from January to August 2020 were divided into low myopia group(0.50D～-3.00D),moderate myopia group(-3.25D～-6.00D)and high myopia group(≥-6.25D)according to equivalent spherical lenses.Using ultra-wide-angle scanning swept-source optical coherence tomography angiography of SVision Imaging,to measure the choroid thickness of the circular area with the center of fovea is 1mm in diameter,and the choroidal thickness of superior,temporal,inferior and nasal parts of the examinee with the macular fovea as the center of the circle with diameters of 3mm,6mm,9mm,and 12mm.and the choroidal vascular index(Refers to the ratio of the volume of the large and medium choroidal vessels to the volume of the choroid),choroidal vascular vessels,and choriocapillaris flow density in the circular area with macular fovea as the center of the circle with diameters of 1mm,3mm,6mm,9mm and 12mm were measured.In order to make the data comparable,the right eye was selected for statistical analysis.Results:with the increase of the degree of myopia,the choroidal thickness became thinner in patients with low,moderate and high myopia(P<0.05),and the thickness of nasal choroid was the thinnest in different myopic groups,and compared in different areas.the nasal side changes first,followed by the inferior side.There were significant differences in choroidal vascular index and choroidal vascular vessels in the circular area from the macular fovea to 3～6mm,6～9mm and 9～12mm(P<0.05).With the increase of myopia,the blood flow of large and medium vessels in the above areas decreased.There was no significant difference in diopter choriocapillaris flow density among the three groups(P>0.05).Conclusion:As the degree of myopia increases,the choroidal thickness becomes thinner,and the direction of the thinning of the choroidal thickness of myopic patients is inconsistent,which is different from the normal choroidal thickness distribution.The thickness of the choroid in the eyes with high myopia becomes the most significant,and the thickness of the choroid on the nasal side changes first.With the increase of myopia,the blood flow index of the large and medium choroidal vessels decreased,the volume of the large and medium choroidal vessels decreased,and the blood flow density of the choroidal capillaries did not change significantly.The large and medium choroidal blood vessels may change before the choroidal capillaries,which needs further study.It suggests that changes in choroidal thickness and blood flow are closely related to the development of myopia.