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Rohan PJ Hughes, Stephen J Vincent, Scott A Read, Michael J Collins; Short-term changes in ocular biometry during accommodation in children. Invest. Ophthalmol. Vis. Sci. 2019;60(9):4360.
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© ARVO (1962-2015); The Authors (2016-present)
Myopia is typically characterised by increased axial length and develops during childhood. Excessive or intense near work may be associated with myopia development and progression, and ocular changes during accommodation have been proposed as a possible mechanism. Small increases in axial length during accommodation have been demonstrated in adults, however these changes have not been examined in children, nor at high accommodation demands.
Ocular biometry of the left eye was measured in 91 children (mean age: 8.3 ± 1.8 years) with a range of refractive errors (mean spherical equivalent: +0.51 ± 0.64 D), using a non-contact optical biometer (Zeiss IOLMaster 700) at four accommodation demands (0, 3, 6 and 9 D). Evidence of reliable biometry measures and anterior segment accommodative responses were observed at each demand for 49 participants who were included in the analysis. The average central corneal thickness (CCT), anterior chamber depth (ACD), lens thickness (LT), anterior segment length (ASL), vitreous chamber depth (VCD) and axial length (AL) were calculated at each accommodation demand. AL and VCD were also “corrected” to account for increased LT during accommodation (cAL and cVCD).
AL and cAL increased monotonically with increasing accommodation demand (p < 0.0001). The increase in cAL from 0 D was 5.4 ± 11.4 µm, 9.1 ± 10.0 µm and 17.4 ± 13.1 µm (mean ± standard deviation) at 3, 6 and 9 D, respectively (Figure 1). All other parameters, apart from CCT, changed significantly with accommodation. LT and ASL increased and ACD, VCD and cVCD decreased significantly with increasing accommodation demand (all p < 0.0001).
This study demonstrates that AL increases significantly with increasing levels of accommodation in children, the magnitude of which appears comparable to that reported in adults up to a 6 D demand. This study is also the first to examine changes in AL at an accommodation demand of 9 D and demonstrates increasing axial elongation with high levels of accommodation that children may experience during some near tasks. Further studies examining changes in ocular biometry with prolonged accommodation in children are required to examine a possible link with longer term myopia development.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
Figure 1: Mean change in measured and “corrected” axial length (AL) from 0 D at each accommodation demand. Error bars represent the standard error of the mean.
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