Study On Choroidal Thickness(CT) In Patients Of Adolescent Myopia

Background People's lifestyles have changed along with the progress of science and technology,and their lives have become increasingly abundant owning to a variety of electronic products,but problems arise also,China now is known as the country with the largest number of myopia patients,in which the number of myopia patients accounts for one-third of the total population.In recent years,due to the bad habits of using the eyes,“Smart-phone Addict” is no longer the exclusive words for adults.The number of adolescents who suffer from myopia has been on the increase,the occurrence and development of myopia,especially high myopia,would result in a series of changes in the eye tissue,such as elongation of axial length,vitreous opacities,appearance of posterior scleral staphyloma,atrophy of epithelial layer of retinal pigment and chorioid,changes of choroidal thickness of macula lutea,and so on.The changes of choroidal thickness have something to do with the occurrence of various eye diseases,such as retinal detachment,myopic choroidal neovascularization,these diseases would lead to an irreversible decline in eyesight or blindness.Over the years,due to the limitations of medical technology and device,people's understanding of the occurrence and development of myopia is still in the stage of exploration,but the clinical application of advanced equipment allows people to clearly observe adolescent myopia's posterior segment changes,quantitative choroidal thickness,which provides a deeper level of theory for the formation and development of myopia.Objectives To measure the choroidal thickness of adolescent myopia by applying Optical Coherence Tomography(OCT)observe the differences in the choroidal thickness between adolescent myopia and normal adolescent,carry out study on the characteristic of changes of choroidal thickness in different directions of adolescents who suffer from low,medium,and high myopia,conduct further analysis of correlation between the changes of choroidal thickness in macula lutea of adolescent myopia and diopter,axial length and intraocular pressure.Methods This is a controlled clinical study.It selects 60 adolescents(120 eyes),at the age of 12 to 17,with an average age of(14.57±1.63),who visited and carried out examination in the Optometry Clinic of our hospital from September 2015 to September 2016.The objects of study are divided into four groups according to spherical equivalent,visual acuity and best corrected visual acuity.The normal group consists of 15 adolescents(30 eyes,visual acuity ?1.0).The group of low myopia consists of 15 adolescents(30 eyes,-0.50D? spherical equivalent<-3.00 D,best corrected visual acuity?1.0).The group of medium myopia consists of 15 adolescents(30 eyes,-3.00D? spherical equivalent<-6.00 D,best corrected visual acuity?1.0).The group of high myopia consists of 30 adolescents(30 eyes,-6.00D? spherical equivalent <-10.00 D,best corrected visual acuity?0.8).Based on the application of Cirrus HD OCT,by taking advantage of five line HD grating and scanning line with a length of 9.00 mm,this study carries out enhanced depth imaging regarding to the azimuth of 0° and 90°,so as to obtain the subfoveal horizontal and vertical cross-sectional images.Then it also conducts manual measurement in terms of the foveal and choroidal thickness value of the 9 sites of temporal,nasal,superior,inferior that are 1000?m,3000?m away from the foveal.All measurements are completely by two experienced doctors independently,3 times of measurement respectively,a total of 6 times,and then it gets their average value for the final reference.Results A total number of 60 adolescent myopias(120 eyes)are taken as the object of this study.The differences in the age and gender of myopia patients in each group are not significant,and there is no statistical significance(P>0.05).The SFCT of the normal group,the group of low myopia,the group of medium myopia and the group of high myopia are(347.62±6.00)?m,(300.14±13.85)?m,(234.49±18.71)?m,(183.39±25.12)?m respectively.The differences in the choroidal thickness of different sites in each group have statistical significance(P<0.05).Among different groups,The temporal of low myopia group is 1000?m,and its average chorioid thickness is 1000?m more than that of the normal group.the temporal of normal group,low myopia group are 3000?m.The superior of normal group and low myopia group are 3000?m,the inferior of normal group and low myopia group are 3000?m,and the nasal of normal group and low myopia group are 3000?m,the differences show no statistical significance(P>0.05).The differences in the choroidal thickness of the rest groups are statistically significant(P<0.05).The choroidal thickness of the rest sites becomes thinner along with the increase of the absolute value of spherical equivalent.The choroidal thicknesses of central fovea of macula are significantly positively correlated with spherical equivalent,significantly negatively correlated with the axial length,and negatively correlated with intraocular pressure.Conclusion The macular choroidal thickness of adolescent myopia becomes thinner with the decline of spherical equivalent,and the change of central fovea of macula is the most significant.Choroidal thickness is positively associated with diopter,and negatively related to axial length and intraocular pressure.