Mutti Donald O, Hayes John R, Mitchell G Lynn, Jones Lisa A, Moeschberger Melvin L, Cotter Susan A, Kleinstein Robert N, Manny Ruth E, Twelker J Daniel, Zadnik Karla
Ohio State University College of Optometry, Columbus, Ohio 43210-1240, USA.
Invest Ophthalmol Vis Sci. 2007 Jun;48(6):2510-9. doi: 10.1167/iovs.06-0562.
To evaluate refractive error, axial length, and relative peripheral refractive error before, during the year of, and after the onset of myopia in children who became myopic compared with emmetropes.
Subjects were 605 children 6 to 14 years of age who became myopic (at least -0.75 D in each meridian) and 374 emmetropic (between -0.25 D and +1.00 D in each meridian at all visits) children participating between 1995 and 2003 in the Collaborative Longitudinal Evaluation of Ethnicity and Refractive Error (CLEERE) Study. Axial length was measured annually by A-scan ultrasonography. Relative peripheral refractive error (the difference between the spherical equivalent cycloplegic autorefraction 30 degrees in the nasal visual field and in primary gaze) was measured using either of two autorefractors (R-1; Canon, Lake Success, NY [no longer manufactured] or WR 5100-K; Grand Seiko, Hiroshima, Japan). Refractive error was measured with the same autorefractor with the subjects under cycloplegia. Each variable in children who became myopic was compared to age-, gender-, and ethnicity-matched model estimates of emmetrope values for each annual visit from 5 years before through 5 years after the onset of myopia.
In the sample as a whole, children who became myopic had less hyperopia and longer axial lengths than did emmetropes before and after the onset of myopia (4 years before through 5 years after for refractive error and 3 years before through 5 years after for axial length; P < 0.0001 for each year). Children who became myopic had more hyperopic relative peripheral refractive errors than did emmetropes from 2 years before onset through 5 years after onset of myopia (P < 0.002 for each year). The fastest rate of change in refractive error, axial length, and relative peripheral refractive error occurred during the year before onset rather than in any year after onset. Relative peripheral refractive error remained at a consistent level of hyperopia each year after onset, whereas axial length and myopic refractive error continued to elongate and to progress, respectively, although at slower rates compared with the rate at onset.
A more negative refractive error, longer axial length, and more hyperopic relative peripheral refractive error in addition to faster rates of change in these variables may be useful for predicting the onset of myopia, but only within a span of 2 to 4 years before onset. Becoming myopic does not appear to be characterized by a consistent rate of increase in refractive error and expansion of the globe. Acceleration in myopia progression, axial elongation, and peripheral hyperopia in the year prior to onset followed by relatively slower, more stable rates of change after onset suggests that more than one factor may influence ocular expansion during myopia onset and progression.
评估近视儿童在近视发生前、发生当年及发生后与正视儿童相比的屈光不正、眼轴长度和相对周边屈光不正情况。
研究对象为605名6至14岁的近视儿童（每条子午线至少-0.75 D）和374名正视儿童（每次检查时每条子午线在-0.25 D至+1.00 D之间），这些儿童于1995年至2003年参与了种族与屈光不正协作纵向评估（CLEERE）研究。每年通过A超超声测量眼轴长度。使用两种自动验光仪中的一种（R-1；佳能，Lake Success，纽约[已停产]或WR 5100-K；日本广岛精工）测量相对周边屈光不正（鼻侧视野30度处与第一眼位的等效球镜睫状肌麻痹自动验光值之差）。屈光不正通过同一种自动验光仪在睫状肌麻痹下测量。将近视儿童的每个变量与近视发生前5年至发生后5年每年年龄、性别和种族匹配的正视眼值模型估计值进行比较。
在整个样本中，近视儿童在近视发生前和发生后（屈光不正为发生前4年至发生后5年，眼轴长度为发生前3年至发生后5年）比正视儿童有更少的远视和更长的眼轴长度（每年P<0.0001）。从近视发生前2年至发生后5年，近视儿童比正视儿童有更多的远视性相对周边屈光不正（每年P<0.002）。屈光不正、眼轴长度和相对周边屈光不正变化最快的时期发生在近视发生前一年，而不是发生后的任何一年。近视发生后每年相对周边屈光不正保持在一致的远视水平，而眼轴长度和近视性屈光不正则分别继续延长和进展，尽管与发生时的速度相比有所减慢。
屈光不正更负、眼轴长度更长、相对周边屈光不正更远视，以及这些变量更快的变化速度可能有助于预测近视的发生，但仅在近视发生前2至4年的时间段内。近视似乎并非以屈光不正一致的增加率和眼球扩张为特征。近视发生前一年近视进展、眼轴伸长和周边远视加速，随后发生后相对较慢、更稳定的变化速度，这表明在近视发生和进展过程中可能有多个因素影响眼球扩张。
