散光为一种常见的屈光不正,占所有屈光不正的13%。[2]Porter J, Guirao A, Cox IG, et al. Monochromatic aberrations of the human eye in a large population. J Opt Soc Am A Opt Image Sci Vis. 2001 Aug;18(8):1793-1803.http://www.ncbi.nlm.nih.gov/pubmed/11488483?tool=bestpractice.com 不同年龄间散光的发生率不同,人出生后的前几个月角膜曲率大,散光的发生率高(大约为20%)。[3]Howland HC, Sayles N. Photokeratometric and photorefractive measurements of astigmatism in infants and young children. Vision Res. 1985;25(1):73-81.http://www.ncbi.nlm.nih.gov/pubmed/3984220?tool=bestpractice.com 一些研究发现,婴儿期的散光主要为顺规散光,而其他一些研究报道婴儿以逆规散光为主。[3]Howland HC, Sayles N. Photokeratometric and photorefractive measurements of astigmatism in infants and young children. Vision Res. 1985;25(1):73-81.http://www.ncbi.nlm.nih.gov/pubmed/3984220?tool=bestpractice.com[4]Friling R, Weinberger D, Kremer I, et al. Keratometry measurements in preterm and full term newborn infants. Br J Ophthalmol 2004 Jan;88(1):8-10.http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1771931/http://www.ncbi.nlm.nih.gov/pubmed/14693760?tool=bestpractice.com 随着婴儿年龄的增长,角膜逐渐变平,高度散光(>1D)发生率逐渐降低。 学龄前儿童高度散光的发生率为4.8%,以逆规散光为主。[5]Atkinson J, Braddick O, French J. Infant astigmatism: its disappearance with age. Vision Res. 1980;20(11):891-3.http://www.ncbi.nlm.nih.gov/pubmed/7210516?tool=bestpractice.com[6]Gwiazda J, Scheinman M, Mohindra I, et al. Astigmatism in children: changes in axis and amount from birth to six years. Invest Ophthalmol Vis Sci. 1984 Jan;25(1):88-92.http://www.iovs.org/cgi/reprint/25/1/88http://www.ncbi.nlm.nih.gov/pubmed/6698734?tool=bestpractice.com 在20~30岁的年轻人中,63%有≥0.25D的散光,少数有>1D的散光。[7]Satterfield DS. Prevalence and variation of astigmatism in a military population. J Am Optom Assoc. 1989 Jan;60(1):14-8.http://www.ncbi.nlm.nih.gov/pubmed/2783696?tool=bestpractice.com 另一项研究报道,>0.5D的角膜源性散光者占全部人口的46%,而>1.5D的散光仅占4.7%,以顺规散光为主。40岁或以上的人口中,散光轴向发生变化,从以顺规散光为主变为以逆规散光为主,可能是由于角膜曲率的变化所致。[8]Fledelius HC, Stubgaard M. Changes in refraction and corneal curvature during growth and adult life. A cross sectional study. Acta Ophthalmol (Copenh). 1986 Oct;64(5):487-91.http://www.ncbi.nlm.nih.gov/pubmed/3492854?tool=bestpractice.com
一些种族的散光发生率高,如东亚人种散光发生率相对高,可能与亚洲人眼睑更紧、睑裂更窄有关。 一项前瞻性队列研究发现,19.3%的新加坡儿童有1D或以上的散光。[9]Tong L, Saw SM, Lin Y, et al. Incidence and progression of astigmatism in Singaporean children. Invest Ophthalmol Vis Sci. 2004 Nov;45(11):3914-8.http://www.iovs.org/cgi/content/full/45/11/3914http://www.ncbi.nlm.nih.gov/pubmed/15505036?tool=bestpractice.com 中国学龄前儿童散光的发生率为21.1%,对一部分患有散光的儿童随访观察发现,大部分儿童散光稳定甚至增加。[10]Fan DS, Rao SK, Cheung EY, et al. Astigmatism in Chinese preschool children: prevalence, change, and effect on refractive development. Br J Ophthalmol. 2004 Jul;88(7):938-41.http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1772230/http://www.ncbi.nlm.nih.gov/pubmed/15205242?tool=bestpractice.com 美国印第安人种高度散光(>1D)的发生率高, 推测主要与遗传和营养有关。 其他散光发生风险高的种族包括西班牙裔和本土巴西人。[11]Harvey EM, Dobson V, Miller JM. Prevalence of high astigmatism, eyeglass wear, and poor visual acuity among Native American grade school children. Optom Vis Sci. 2006 Apr;83(4):206-12.http://www.ncbi.nlm.nih.gov/pubmed/16614575?tool=bestpractice.com[12]Kleinstein RN, Jones LA, Hullett S, et al. Refractive error and ethnicity in children. Arch Ophthalmol. 2003 Aug;121(8):1141-7.http://www.ncbi.nlm.nih.gov/pubmed/12912692?tool=bestpractice.com