Abstract
Purpose :
Like most infants, those with esotropia (ET) are hyperopic. Unlike most infants, they fail to emmetropize during the first year of life. We examined two hypotheses for the failure of emmetropization in infantile ET: 1) relative peripheral myopia inhibits early eye growth, resulting in persistent hyperopia, 2) accommodation fails to provide a dose-dependent signal for eye growth.
Methods :
Refractive error was measured in 70 infants with ET at 6, 9, 18, and 30 months using a Power Refractor with the camera at 1m. Measurements were made with the infant fixing a toy at 1m at 0, 10, 20, and 30deg (to assess peripheral refraction in the nasal visual field), and at 0.57m and 0.33m at 0deg (to assess accommodation).
Results :
Mean cycloplegic refractive error remained constant throughout the study period (+2.76±0.66D at 6 months, +2.66±0.57D at 9 months, +2.63±0.34D at 18 months, and +2.73±0.46D at 30 months). Relative peripheral myopia (30 deg-0deg) was present at all ages (-0.24±0.17D at 6 months, -0.24±0.18D at 9 months, -0.36±0.13D at 18 months, -0.46±0.12D at 30 months). At 6 months, the accuracy of accommodation was similar to that of normal infants (0.33±0.30D lag at 0.57m; 0.48±0.36D lag at 0.33m; for comparison, see normative data in Mutti et al Optom Vis Sci 2009) but accommodative leads of approximately -0.2D were present at 9, 18, and 30 months for both 0.57m and 0.33m.
Conclusions :
The persistence of hyperopia and failure to emmetropize are associated with a mild relative peripheral myopia that is perhaps exacerbated by an accommodative lead. Vision-dependent growth signals may either be inhibitory or insufficient to promote emmetropization in these infants. Alternatively, esotropia may be associated with a genetically determined slow rate of axial elongation and inherently stable refractive error.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.