Relationship Between The Structure Of Eyeball And The Visual Acuity In Young Persons With Severe Myopia

Objective: To investigate the regularity of the change of eyeball structure and the level of myopia in the mid-age and youth,and to explore the relationship between eyeball structure and visual acuity in high myopia,then to select the parameters of eyeball structure which have a close correlation with the visual acuity,finally to establish the method which can be utilized to deduce the objective visual acuity according to the eyeball structure in high myopia and to assure the accurate and scientific assessment of eye injury.Methods: Visual acuity,corneal radius ,anterior chamber depth,axial length ,fundus and total macula thickness in six millimeter diameter of 152 myopic subjects (283 eyes) were tested successively, and the ratio of the comus'area and optic disc's area in the fundus images was calculated. All subjects were classified into different groups according to their diopter,axial length and fundus indexes.Then the data was analyzed by SAS8.1 and SPSS15.0 statistical software. The correlation and the multiple regression between age,diopter,axial length,corneal radius,anterior chamber depth, ratio of comus'area and optic disc's area, fundus class,total macula thickness,total macula volume and visual acuity were analyzed.To explore the relationship between diopter,axial length,fundus and visual acuity.Finally the mathematical models with visual acuity and eyeball structure parameters were established.Results:①The visual acuity had moderate correlation with age,fundus class, comus'area,axial length and dioper(｜r｜>0.4,p<0.0001).The visual acuity had low correlation with macula thickness and total macula volume(｜r｜close to 0.4, p<0.0001).The visual acuity had no significant correlation with corneal radius,anterior chamber depth.②There was no significant influence to visual acuity by the change of eyeball structure in a certain myopia degree, but the visual acuity decreased with the aggravation of eyeball structure change when the diopter increase to a special degree, for example the visual acuity was in normal range mostly (about 1.0 ) when the axial length was shorter than 28.5mm, the diopter was lower than -10.00D and the fundus was beneath second class. And the visual acuity was below 0.5 mostly when the axial length was longer than 30.00mm, the diopter was more than -20.00D and the fundus was fourth class.③The mathematical models which can be used to infer the visual acuity by eyeball structure parameters in high myopia had been established, the accuracy was more than 75% when the error was±0.1,and the accuracy was more than 90% when the error was±0.15 in back substitution test.Conclusions:①The more severity change in age,axial length, diopter and fundus, the lower visual acuity of high myopia people.The visual acuity mainly depended on the type and degree of pathologic change of the fundus posterior pole, especially the macula.②With the test of eyeball structure , the objective acuity can be well judged and evaluated in high myopia by the mathematical models established with eyeball structure parameters .