SIGNIFICANCE 

The ratios of diopters of change in refractive error produced per millimeter of eye elongation (D/mm) are rarely those predicted from geometric optics because of changes in other ocular components. Quantifying this optical compensation in millimeters instead of ratios reveals some important principles about eye growth and refractive error.

PURPOSE 

The study purpose was to sort total vitreous chamber elongation into millimeters that either contributed (uncompensated) or did not contribute to change in refractive error (compensated).

METHODS 

Participants were infants in the Berkeley Infant Biometry Study (n = 271, ages 3 months to 6 years) or schoolchildren in the Collaborative Longitudinal Evaluation of Ethnicity and Refractive Error (n = 456 emmetropes and 522 myopes, ages 6 to 14 years). Refractive error was measured using cycloplegic retinoscopy in infants (cyclopentolate 1%) and cycloplegic autorefraction in schoolchildren (tropicamide 1% or combined with cyclopentolate 1%). Axial dimensions were assessed using A-scan ultrasonography. Uncompensated millimeters were estimated from ratios of change in refractive error per millimeter of elongation using Gullstrand eye models. Compensated millimeters were the difference between measured elongation and uncompensated millimeters.

RESULTS 

Compensated millimeters exceeded uncompensated millimeters in emmetropic children across ages, but uncompensated millimeters exceeded compensated millimeters in myopic children. Compensated millimeters were highest in infancy and decreased with age, reaching less than 0.10 mm per year by age 10 years in both myopic and emmetropic children. There were no statistically significant differences in compensated millimeters between myopic and emmetropic children between ages 8 and 14 years (P values from .17 to .73).

CONCLUSIONS 

The ability of the ocular components, primarily crystalline lens, to compensate for vitreous elongation is independent of the higher demands of myopic eye growth. The limited compensation after age 10 years suggests the target for elongation in myopia control needed to arrest myopia progression may be that seen in emmetropes or less.

中文翻译：

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婴儿期和儿童期玻璃体腔伸长的代偿

 意义

由于其他眼部成分的变化，每毫米眼睛伸长产生的屈光不正变化的屈光度比率（D/mm）很少是通过几何光学预测的。以毫米而不是比率来量化这种光学补偿揭示了有关眼睛生长和屈光不正的一些重要原理。

 目的

研究目的是将玻璃体腔总伸长率分类为毫米，这些伸长率对屈光不正的变化有贡献（未代偿）或无贡献（已代偿）。

 方法

参与者是伯克利婴儿生物测量研究中的婴儿（n = 271，年龄 3 个月至 6 岁）或种族和屈光不正协作纵向评估中的学童（n = 456 名正视眼和 522 名近视眼，年龄 6 至 14 岁）。婴儿屈光不正采用散瞳检影（环喷托酯 1%）进行测量，学童则采用散瞳验光（托吡卡胺 1% 或联合环喷托酯 1%）进行测量。使用 A 扫描超声检查评估轴向尺寸。使用 Gullstrand 眼模型根据每毫米伸长的屈光不正变化率来估计未补偿的毫米数。补偿毫米数是测量的伸长率与未补偿毫米数之间的差值。

 结果

各个年龄段的正视儿童的代偿毫米数均超过未代偿毫米数，但近视儿童的未代偿毫米数超过了代偿毫米数。代偿毫米数在婴儿期最高，并随着年龄的增长而减少，到 10 岁时，近视儿童和正视儿童的代偿毫米数都达到每年不到 0.10 毫米。 8 岁至 14 岁之间的近视儿童和正视儿童的补偿毫米数没有统计学上的显着差异（ P值从 0.17 到 0.73）。

 结论

眼部组件（主要是晶状体）补偿玻璃体伸长的能力与近视眼生长的更高要求无关。 10岁后有限的代偿表明，阻止近视进展所需的近视控制延长目标可能是正视眼或更小。