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F. Lu, J. Wu, Q. Wang, C. Xu, S. Chen, J. Qu, J. He; Corneal Higher Order Aberration and Its Association With Intraocular Pressure in the Myopic Eyes . Invest. Ophthalmol. Vis. Sci. 2006;47(13):1176.
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© ARVO (1962-2015); The Authors (2016-present)
To investigate the relationship between intraocular pressure (IOP), central corneal thickness (CCT) and corneal higher order aberrations for myopes.
Subjects participated in this study included 174 myopes (aged from 18 to 38 yrs, mean =25.5yr) from three refractive groups: 14 low myopes (Rx: –1.13 to –2.88 D, mean=–2.05D), 91 moderate myopes (Rx: –3.00 to –5.88D, mean=–4.36D) and 69 high myopes (Rx: –6.00 to –11.38D, mean=–7.70D). Wave–front aberrations in the anterior corneal surface for the right eye were measured using a Humphrey corneal topographer (Carl Zeiss Medtec, Inc), and 7 orders (35 terms) of Zernike aberrations within a 6mm diameter pupil area were derived. IOP and CCT were measured with a non–contact Canon Tonometer (Canon Tonometer X–10, Japan) and a TOMEY Pachymeter (Pachymeter SP–3000,TOMEY corp. Japan) respectively.
For all of the 174 eyes, IOP was significantly correlated with spherical aberration (r=0.23, p<0.005), trefoil (Z6, r=0.21, p<0.01), and on the significant margin with y–axis coma (r=0.13, p=0.076). When low myopes were excluded for analysis, correlation coefficients were increased for spherical aberration (r=0.26, p<0.001), trefoil (Z6, r=0.24, p<0.002) and y–axis coma (r=0.18, p<0.025). For high myopes only, the correlation coefficient for y–axis coma reached 0.30 (p<0.02). The CCT for our subjects was significantly correlated with IOP (r=0.44, p<0.0001), and the mean CCT of low myopes (556.7 micron) was significantly greater than that for either the moderate (540.6 micron, t=1.79, p<0.05) or the high myopes (538.7 micron, t=1.94, p<0.05).
The results suggest that intraocular pressure has influences on corneal higher order aberrations including the trefoil, the coma and the spherical aberration. The effect of IOP on corneal aberrations is very likely dependent on refractive error and/or central corneal thickness. The increase in y–axis coma with the IOP for the high myopes could be due to an effect from a combination of both the IOP and the gravity.
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