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Kate Gifford, Paul Gifford, Peter L Hendicott, Katrina L Schmid; Binocular vision in orthokeratology contact lens wear for myopia. Invest. Ophthalmol. Vis. Sci. 2017;58(8):2389.
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© ARVO (1962-2015); The Authors (2016-present)
Binocular vision (BV) disorders are implicated in myopia progression and affect visual comfort. We performed a prospective repeated measures study to examine changes in BV function due to orthokeratology (OK) wear in pediatric and young adult myopes
Sixteen children (8-16 years) and 11 young adults (18-29 years) were recruited to compare baseline (BL) measures in single vision soft contact lenses (SCL) to 1, 6 and 12 months of OK wear. Outcome measures were distance phoria; near phoria, AC/A ratio, base-in (BIFR) and base-out fusional reserves (BOFR), accommodative lag (AL), positive relative accommodation (PRA) and negative relative accommodation (NRA) at 33cm; and axial length (IOL master)
Twelve children (C:13.2±2.1 years, R-2.19±0.96D L-1.78 ± 0.67D) and 8 young adults (A:23.4±3.5 years, R -2.55±1.32D L -2.61±1.28D) completed the study. Distance phoria, AC/A ratio and NRA did not change. Near phoria became more exophoric after 12 months (M12) (C:BL -0.95±2.41ΔD, M12 -2.08±2.91ΔD, p=0.010; A:BL +0.13±5.82ΔD, M12 -1.25±5.31ΔD, p=0.038). BOFR was stable in adults but one measure reduced in children (M12). BIFR increased in children at 1 and 6 months (M1&M6) and in adults at M6. AL reduced in children at M1, M6 and M12 and in adults at M6 and M12 (C:BL 1.69±0.62D, M12 1.19±0.61D, p=0.046; A:BL 1.81±0.48D, M12 0.94±0.35D, p=0.029). PRA increased in children (M12) and adults (M1&M12) (C:BL -1.73±0.67D, M12 -3.04±1.37D, p=0.045; A:BL -1.78±0.67D, M12 -3.56±1.27D, p=0.048). Higher baseline myopia was correlated with a lower BIFR change in adults, with the reverse seen in children. In OK wear, cross-linked accommodation-convergence correlations were identified more frequently in adults than children. BV in SCLs was not predicted by baseline myopia, and there was no change in axial length
OK wear in paediatric and young adult myopes shifts BV towards a cross-linked increased accommodative response-decreased convergence profile, in line with lower myopia progression risk. Accommodation changes were observed at M1; vergence changes occurred at M6&M12. Most changes were not predicted from baseline myopia or BV status, and less predictability was noted in children than adults. Stability of axial length in both groups did not allow for BV changes to be correlated to OK’s myopia control effect. These results have relevance to both the visual acceptance of OK and managing risk factors for myopia progression
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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