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Niall C. Strang, Bastian Cagnolati, Lyle S. Gray; Four Year Longitudinal Investigation Of Ocular Shape Changes During Refractive Development. Invest. Ophthalmol. Vis. Sci. 2012;53(14):139.
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© ARVO (1962-2015); The Authors (2016-present)
To characterise longitudinally, changes in central and peripheral ocular dimensions and refractive power as a function of refractive error, and elucidate the relationship between relative peripheral refraction and refractive development.
140 subjects between 5 and 20 years of age participated with informed consent in a 4 year longitudinal study of refractive development; 105 subjects completed the year 4 study period. At baseline there were 44 hyperopes (HYP), 61 emmetropes (EMM) and 35 myopes (MYO); mean spherical refractive error (MSE) ranged from -5.88 D to +3.45 D. Central and peripheral (25° temporally) non-cycloplegic refraction measurements were obtained at baseline and after 2 and 4 years using an open-field infrared autorefractor (Shin-Nippon NVision-K 5001). Central axial length (AL) and peripheral (19° superior, inferior, temporal and nasal) ocular dimensions were determined using partial coherence interferometry (Zeiss IOLMaster).
All results compare baseline measures with those obtained at year 4. Significant (all p<0.05) changes in MSE and AL were found in the HYP (-0.28±0.41 D; 0.25±0.32 mm), EMM (-0.23±0.58 D; 0.29±0.28 mm) and MYO (-0.90±0.74 D; 0.37±0.31 mm) groups. A significant change in relative peripheral refraction (RPR) was found in the MYO (-0.25±0.49 D, p0.05) or EMM (-0.01±0.52 D, p>0.05). The change in axial length was significantly correlated with the change in RPR in the HYP (R²=0.421) and EMM (R²=0.410) but not in the MYO (R²=0.004). Mean relative peripheral ocular length (RPL) was significantly different in the EMM (-0.05±0.11 mm, p0.05) or MYO (-0.01±0.11 mm, p>0.05). A significant negative linear correlation between change in axial length and change in RPL was observed in all 3 groups (R²=0.359-0.444). There were no significant differences (p>0.05) in refractive development or axial growth between subjects with a hyperopic or myopic RPR profile in all 3 groups.
Axial growth leads to greater myopic refractive change in subjects with existing myopia, due to previously identified failures in lenticular compensation. In subjects who are hyperopic or emmetropic coordinated ocular growth leads to changes in RPL which produce hyperopic RPR. These results suggests that the relative peripheral refraction is a correlated rather than a causative factor in myopic development.
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