Biometry Of Ocular Refractive Components In Myopic College Students:IOL-Master Study

Purpose:(1)To measure axial length(AL),horizontal corneal refractive power(K1),vertical corneal refractive power(K2), anterior chamber depth(ACD) and corneal diameter(white to white) in myopic college students by IOL-Master (Zeiss Humphrey Systems);(2) To explore the difference of axial length,horizontal corneal refractive power,vertical corneal refractive power, anterior chamber depth and corneal diameter(white to white) among low myopia, middle myopia and high myopia.(3)To detect the correlation between diopter and all above ocular refractive components.and detect the main cause of myopia in college students.(4)To detect the correlation between axial length and horizontal corneal refractive power(K1),vettical corneal refractive power(K2) in low myopia, middle myopia and high myopia. Methods:The subjects of this study were medical undergraduate students in Lanzhou University.In the first place,examine all subjects through the routine eye examination, exclude organic eye diseases, without wear contact lens in72hours.The diopter were measured by the automatic computer refractor (TOPCON RM.8800).In the second place.the number of standard subject is1059myopic college students(2118eyes),the average age is (21.06±2.41) years old.They were divided into three groups according to different the mean spherical equivalent diopters:A group: low myopia<-3.00D (738eyes);B group:middle myopia-3.00D～-6.00D(989eyes);C group:high myopia:>-6.00D(391eyes).Finally AL, Kl, K2, ACD and W-W(white to white) of all eyes were measured with the Optical coherence biometry (Zeiss. IOL-Master) in1059(2118eyes) subjects,and calculate AL/CR.The SPSS18.0was used for the statistical analysis.Results:(1)A group:low myopia the average of AL is (24.28±0.83) mm. the average of K1,K2are (42.68±1.33) D、(43.69±1.49)D respectively, the average of ACD is (3.61±0.25) mm, the average of W-W is (12.02±0.38) mm.B group:middle myopia the average of AL is(25.29±0.82)mm, the average of K1.K2are(42.82±1.30) D,(43.91±1.52) D respectively, the average of ACD is (3.71±0.23) mm, the average of W-W is (12.02±0.37)mm.C group:high myopia the average of AL is (26.25±1.00) mm, the average of K1,K2are (43.02±1.40) D、(44.29±1.55) D respectively, the average of ACD is (3.73±0.23) mm, the average of W-W is (11.99±0.35) mm.(2) There are statistically significant differences for AL classified with refractive degree(P<0.01) in three group;there are significant differences between low myopia and high myopia(P<0.05), also between middle myopia and high myopia(P<0.05) in Kl;there are significant differences in K2among three groups(P<0.05);there are significant differences between low myopia and high myopia(P<0.05), also between low myopia and high myopia(P<0.05) in ACD;There are no significant differences of white to white among three groups(P>0.05).(3)With the development of diopter, the AL was increased, and there is significant correlation between diopter and AL in three group(P<0.01);there is significant correlation between diopter and K1,K2in middle myopia(P<0.05);there is significant correlation between diopter and ACD in low myopia (P<0.05);there are no significant correlation between W-W and refractive degree in three groups(P>0.05).(4)AL/CR is3.183±0.132, the AL/CR ratio is negatively correlated with diopter of myopia(r=-0.761, p=0.000), AL is negatively correlated with K1and K2(P<0.01).Conclusions:(1)The development of axial length is the main reason in myopic college students, and corneal refractive power is a secondary factor,The axial myopia is main type of myopic college students.(2) Low myopia is induced by axial length, anterior chamber depth deepened maybe a main reasons of axial growth.Middle myopia is induced by development of both axial length and corneal refractive power.High myopia is induced by axial length.(3)White to white has no effect on diopter in myopic college students. Purpose:To measure axial length(AL),horizontal corneal refractive power(K1),vertical corneal refractive power(K2), anterior chamber depth(ACD) and corneal diameter(white to white) in male and female myopic college students by IOL-Master (Zeiss Humphrey Systems);To analysis the differences of all above ocular refractive component between male and female.Methods:The subjects of this study are medical undergraduate students in Lanzhou University.In the first place,examine all subjects through the routine eye examination, exclude organic eye diseases, without wear contact lens in72hours.The diopter were measured by the automatic computer refractor (TOPCON RM.8800).In the second place,the number of standard subject is1059myopic college students(2118eyes),the average age is (21.06±2.41) years old.They were divided into six groups according to different the mean spherical equivalent diopters and gender:A group:low myopia:<-3.00D (738eyes), male(318eyes),female(420eyes);B group: middle myopia-3.00D～-6.00D(989eyes),male(419eyes),female(570eyes):C group: high myopia>-6.00D(391eyes),male(135eyes),female(256eyes).Finally AL, K1, K2. ACD and W-W(white to white) of all eyes were measured with the Optical coherence biometry (Zeiss IOL-Master) in all subjects.The SPSS18.0was used for the statistical analysis.Results:(1)A group:low myopia comparison of ocular refractive component in female and male:①there is statistically significant differences in axial length between male and female (t=-7.73, P<0.05);②there are statistically significant differences in K1,K2between male and female K1(t=5.22, P<0.05), K2(t=4.2, P<0.05);②there is statistically significant differences in ACD between male and female (t=-4.78, P<0.05);④there is statistically significant differences in W-W between male and female (t=-3.53, P<0.05);(2)B group:middle myopia comparison of ocular refractive component in female and male:①there is statistically significant differences in axial length between male and female (t=-11.97, P<0.05);②there are statistically significant differences in K1,K2between male and female K1(t=5.7, P<0.05), K2(t=6.05, P<0.05);③there is statistically significant differences in ACD between male and female (t=-8.28, P<0.05);④there is statistically significant differences in W-W between male and female (t=-3.99, P<0.05);(3)C group:high myopia comparison of ocular refractive component in female and male:①there is statistically significant differences in axial length between male and female (t=-7.31, P<0.05)②there are statistically significant differences in K1,K2between male and female K1(t=4.18, P<0.05), K2(t=4.45, P<0.05);③there is statistically significant differences in ACD between male and female(t=-3.84,P<0.05);②there is statistically significant differences in W-W between male and female (t=0.22, P<0.05).Conclusions:The ocular refractive components differ between male and female in myopic college students.As for axial length,anterior chamber depth and corneal diameter(white to white),there are bigger in male than female.And as for horizontal and vertical corneal refractive power(K1, K2),there is bigger in female than male.