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G.F. Schmid; Eye Shape Variability in Children 7-15 Years of Age . Invest. Ophthalmol. Vis. Sci. 2003;44(13):4771.
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Purpose: Although most studies of the effect of optical defocus upon eye growth have concentrated on visual axis effects, considerable evidence suggests that off-axis defocus also plays an important role. There is a large variability in the peripheral defocus in both adults and children, which indicates that the peripheral retina is exposed to a wide range of refractive errors. The current lack of appropriate measurement techniques has hampered the determination of whether variability in peripheral defocus between individuals can be correlated with variability in eye shape. We have developed an Optical Low Coherence Reflectometer (OLCR) for the determination of eye shape by the precise measurement of both axial and peripheral eye length (EL). Methods: Eye shape was assessed in right eyes of 63 children 7-15 years of age by measuring EL and spherical equivalent refraction (SER) axially and at 15° temporally, nasally, inferiorly and superiorly with OLCR and Binocular Auto-Refractometry, respectively, during cycloplegia. At each peripheral location, relative peripheral EL and SER (i.e. the difference between peripheral and axial readings) were compared between myopic, emmetropic and hyperopic eyes, and the correlation between relative peripheral EL and SER was analyzed. Results: Although the standard deviations were large, significant differences in relative peripheral EL and SER between refractive groups as well as a significant correlation between relative peripheral EL and SER were observed at several of the assessed locations. Conclusions: The results strongly suggest that peripheral defocus is correlated with eye shape and that previously observed variability in peripheral defocus chiefly reflects variability in eye shape. If peripheral defocus represents a determining parameter in the control of eye growth, the precise measurement of eye shape could be used not only to improve estimates of myopic progression, but also to identify children who are at high risk of developing myopia. A better understanding of this concept may also lead to specialized clinical/optical treatments that are more effective than current treatments in individuals who are at risk of myopia development or progression.
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