The Study Of Ocluar Refraction Components Measurement With Optic Coherence Biometry In Ametropic Children

[Objective] To study the variation of ocular refractive components measurementwith optic coherence biometry before and after cycloplegia respectively in ametropic children. To analyze the influence of accommodation on ametropia.[Methods] Nine hundreds and fifty eyes of 529 children at the age 3 to 12 wereenrolled in this study. The degree of refraction was measured by auto-refractomer and retinoscopy after instillation of one drop of 1% atropine in each eye thrice every day for 3 days. The axial length (AL), refraction Power of cornea (K1,K2) and anterior chamber depth (ACD) were measured by optic coherence biometry (Zeiss IOL Master) before and after cycloplegia. The data was statistical analyzed.[Results] Hyperopic children (1) Axial length is 21.59±1.03mm beforecycloplegia and 21.58 ± 0.99mm after cycloplegia, with significant difference (t=-2.55 P=0.01) (2) Refraction Power of cornea is 42.21 ±1.54D for K1, 44.06 ±1.73D for K2 before cycloplegia and 42.18 ±1.55D for K1, 44.03±1.72D for K2 after cycloplegia, with significant difference (K1 t=-2.75 P=0.01; K2 t=-236 P=0.04). (3) Axis of astigmatism showed no significant difference before and after cycloplegia (t=-1.59 P=0.11) . (4) Anterior chamber depth is 3.20± 0.28mm before cycloplegia and 3.50 ± 0.22mm after cycloplegia, with significant difference (t=33.63 P=0.00). (5) Refraction degree of hyperopia positively correlated with the difference of ACD(r=0.134 P=0.001) . There were no correlation between refraction degree of hyperopia and the difference of AL (r=-0.059 P=0.133) . There were no correlation between refraction degree of hyperopia and the difference of refraction power of cornea(k1 r=-0.023 P=0.561; k2 r=-0.041 P=0.293). (6)Age of hyperopic children negtaively correlated with the difference of AL (r=-0.089 P=0.023 ), the difference of ACD (r=-0.129 P=0.001). Age of hyperopic children positively correlated with the difference of refraction power of cornea (k1 r=0.084 P=0.033; k2 r=0.095 P=0.040). Myopic children (1) Axial length is 24.06 ± 0.93mm before cycloplegia and24.06 ±0.91mm after cycloplegia, without significant difference (t=0.08 P=0.93) .(2) Refraction power of cornea (K1 t=0.23 P=0.82; K2 t=0.06 P=0.95) and axis of astigmatism (t=1.40 P=0.16) showed no significant difference before and after cycloplegia. (3)Anterior chamber depth was 3.61±0.26mm before cycloplegia and 3.70±0.27mm after cycloplegia, with significant difference (t=6.68 P=0.00) .(4) There were no correlation between refraction degree of myopia and the difference of AL(r=0.104 P=0.126). There were no correlation between refraction degree of myopia and the difference of refraction power of cornea (k1 r=0.007 P=0.917; k2 r=-0.004 P=0.949) .There were no correlation between refraction degree of myopia and the difference of ACD (r=0.093 P=0.169) .(5) There were no correlation between age and the difference of AL (r=-0.078 P=0.251) .There were no correlation between age and the difference of refraction power of cornea (k1 r=-0.010 P=0.888 k2 r=-0.022 P=0.746) .There were no correlation between age and the difference of ACD (r=-0.071 P=0.291) .[ Conclusion ] Axial length get shorter, refraction power of cornea get smaller andanterior chamber depth get deeper after cycloplegia in hyperopic children. The greater refraction degree of hyperopia, the greater variation of anterior chamber depth before and after cycloplegia. The variation of axial length and anterior chamber depth before and after cycloplegia decrease for hyperopic children aged 3 to 12. Anterior chamber depth get deeper, axial length and refraction power of cornea remain steady after cycloplegia for myopic children. [Objective] To study the ocular refractive components measurement with opticcoherence biometry for hyperopic children and myopic children as well as the relation between refractive components and gender, age and the degree of refraction.[Methods] Nine hundreds and sixty seven eyes of 531 children aged 3 to 12 wereenrolled. The degree of refraction was measured by autorefraction and refractionist performing retinoscopy after instillation of 1 drop of 1% atropine in each eye thrice every day for 3 days, then axial length (AL), refraction power of cornea (K1,K2) and anterior chamber depth (ACD) were measured by optic coherence biometry (Zeiss IOL Master) . The data was statistical analyzed.[Results](1) Hyperopic children ①The average AL is 21.58± 1.00mm (ranged 18.14 to 24.44 mm). ②The average K1 is 42.17±1.57D (ranged 36.61 to 47.01D). ③The average K2 is 44.00±1.74D (ranged 39.52 to 49.85D).④ The average AX is 85.13±80.19°(ranged 0 to 179°).④The average ACD is 3.50±0.22mm (ranged 1.94 to 4.17mm).(2) Myopic children ①The average AL is 24.06± 0.92mm (ranged 21.46 to 26.74 mm). ②The average K1 is 43.24±1.44D (ranged 39.80 to 47.07 D). ③ The average K2 is 44.76±1.79D (ranged 41.11 to 50.75 D).④ The average AX is 90.63±81.40°(ranged 0 to 179°). ⑤ The average ACD is 3.70±0.27mm (ranged 2.98 to 4.94 mm).(3) Both the degree of refraction and age showed no significant difference in gender. AL was significantly longer (hyperopia t= 6.38 P=0.00; myopia t= 4.83 P=0.00) of boys than that of girls. Boys also had deeper ACD (hyperopia t=5.48 P=0.00; myopia t=2.22 P=0.02) and smaller refraction Power of corneas (hyperopia K1 t=-4.74 P=0.00 K2 t=-6.14 P=0.00; myopia K1 t=-4.06 P=0.00 K2 t=-3.80 P=0.00). (4)Hyperopic children had significantly shorter AL (t=-32.58 P=0.00) , smallerrefraction Power of corneas (K1 t=-9.06 P=0.00; K2 t=-5.59 P=0.00)and shallower ACD (t=-11.50 P=0.00) than myopic children.(5)Axial length (r=-0.775 P=0.000), refraction Power of corneas (K1 r=-0.226 P=0.000; K2 r=-0.141 P=0.000) and anterior chamber depth (r=-0.153 P=0.000) negatively correlated with refraction degree for hyperoPic children. Both axial length(r=-0.539 P=0.000) and refraction Power of corneas (K1 r=-0.146 P=0.029; K2 r=-0.203 P=0.002) negatively correlated with refraction degree for myopic children. (6)Both axial length (hyperopia r=0.362 P=0.000; myopia r=0.353 P=0.000) and anterior chamber depth (hyperopia r=0.231 P=0.000; myopia r=0.244 P=0.001) correlated with age Positively.(7)The AL/CR ratio is 2.75±0.13 in hyperopic children, 3.13 ± 0.11 in myopic children. There was negative correlation between refraction degree and AL/CR ratio ( hyperopia r=-0.899 P=0.000; myopia r=-0.732 P=0.000). AL/CR showed significant difference between hyperopic children and myopic children (t=-39.655 P=0.000) .[Conclusions](1)Both the degree of refraction and age showed no significant difference betweengenders. Boys had longer AL, deeper ACD and smaller refraction power of corneasthan girls.(2)Ocular refractive components showed significant difference between hyperopia andmyopia. Hyperopic children had significantly shorter AL, smaller refraction power ofcorneas and shallower ACD than myopic children.(3) Hyperopia and myopia are predominantly both axial and refraction Power ofcorneas in children.There is inverse correlation between the degree of refraction and axial length, anterior chamber depth, refraction power of corneas in hyperopia children, while no obvious correlation is observed between the degree of refraction and astigmatic axis of corneas. There is inverse correlation between the degree of refraction and axial length, refraction power of corneas in myopia children, while no obvious correlation is observed between the degree of refraction and astigmatic axis of corneas, anterior chamber depth. It illustrate that both hyperopia and myopia in children are resulted from the co-effect of axial length and refraction power of corneas.(4) Axial length and anterior chamber depth increase with age, while the refractionpower of cornea remains steady for ametropic children aged 3 —12. (5)There was negative correlation between refraction degree and AL/CR ratio. AL/CR ratio is higher in myopia than hyperopia.