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Padmaja Sankaridurg, Arthur Ho, thomas naduvilath, Xiang Chen, Earl L Smith; Astigmatism and effect on progression of myopia. Invest. Ophthalmol. Vis. Sci. 2016;57(12):2476.
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© ARVO (1962-2015); The Authors (2016-present)
To determine if baseline ocular astigmatism influences the progression of myopia in Chinese children with myopia
Children with myopia (n=141; 9.8 ± 1.5 yrs, range 6 to 12 yrs) enrolled in Vision CRC and BHVI myopia control studies conducted at Guangzhou, China. Only those wearing single vision spectacles, with spherical equivalent refractive error (SEQ) from -0.50 to -4.50D and astigmatism <2.00D were considered for the analysis. All children were fitted with single vision spectacles that corrected for baseline astigmatism (3.5D base curve). At baseline and 6 monthly intervals thereafter, measurements of cycloplegic (2 drops of 1% tropicamide) autorefraction and axial length were conducted on both eyes. To analyse astigmatism including magnitude and type, astigmatic components J, J0 and J45 were used. Relation if any between baseline astigmatism (type and magnitude) to change in sphere (D), SEQ (D) and axial length (mm) from baseline to 12 months was determined using linear mixed model. Statistical significance was defined as p<0.05.
At baseline, mean SEQ was -2.39 ± 0.80D (range -0.43 to -4.31D). Astigmatism (J, J0 and J45) was 0.58 ± 0.38D, 0.10 ± 0.25D and 0.00± 0.22D, respectively. There was no correlation between baseline cylinder power to baseline sphere power (R2=0.0007). 94% of eyes had astigmatism. Of those, WTR astigmatism was the most frequent (48.5%) followed by oblique (27.1%) and ATR (24.4%). Change from baseline to 12 months for SEQ, sphere, J, J0 and J45 were -0.75 ± 0.43D, -0.71 ± 0.42D, -0.09 ±0.28D, 0.07 ± 0.26D and -0.01 ± 0.23D, respectively. There was no relation between baseline astigmatism (magnitude or type) to change in sphere, spherical equivalent or axial length from baseline to 12 months (p>0.05).
Previous studies found that certain types of inherent ocular astigmatism resulted in altered growth patterns and myopia thus suggesting that astigmatic defocus may influence myopia development and/or progression. In this limited sample of myopic eyes, a significant number of eyes had baseline astigmatism and mostly WTR but baseline ocular astigmatism was not related to progression of myopia. Also, shift in astigmatism was slight over 12 months.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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