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Paul Gifford, Kate Gifford, Peter L Hendicott, Katrina L Schmid; Relative peripheral refraction and binocular vision changes in myopic orthokeratology. Invest. Ophthalmol. Vis. Sci. 2017;58(8):2390.
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© ARVO (1962-2015); The Authors (2016-present)
Orthokeratology (OK) has been shown to alter relative peripheral refraction (RPR) and binocular vision function (BV). We performed a prospective repeated measures study to correlate changes in RPR and BV due to myopic OK wear in children and young adults
Sixteen children (8-16 years) and 11 adults (18-29 years) were recruited to compare baseline measures in single vision soft contact lenses (SCL) to 1, 6 and 12 months (M12) of OK wear. Clinical BV 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. By autorefractor, accommodative accuracy was measured at 1D, 2D, 3D and 4D demand (AA1-4), and RPR at 100, 200 and 300 nasally and temporally (10N,20N,30N,10T,20T,30T). Axial length (IOL master) was also measured
Twelve children (C:13.2±2.1 years, R-2.19±0.96D L-1.78 ± 0.67D) and 8 adults (A:23.4±3.5 years, R -2.55±1.32D L -2.61±1.28D) completed the study. RPR shifted in the myopic direction at 30T, 20N and 30N in all subjects after 1 month of OK wear, with temporal stability thereafter. In SCLs, larger AA3 was correlated with a more hyperopic RPR (A:N30-AA3 r=0.86,p=0.001;N20-AA3 r=0.78,p=0.008; C:T30-AA3 r=0.55,p=0.042) and AC/A ratio showed an elevated convergence (C:N30-ACAminus r=0.56,p=0.038), reduced divergence response (A:T30-ACAplus r=-0.64,p=0.047). At M12, both groups showed increased BIFR and RPR change at N20 (A:r=-0.56,p=0.047; C:r=-0.60,p=0.042). Children showed reduced AL (N30-AL r=0.54,p=0.049;N20-AL r=0.64,p=0.015) and improved PRA (N30-PRA r=0.548,p0.042, T30-PRA r=0.58,p=0.028) with RPR change. No further relationships after OK wear held in adults, and axial length was stable in both groups
OK altered RPR in line with previous studies. T30 and N30 bear strongest relationships to baseline BV function in SCL wearing children and adults, and to changes in BV function after 12 months of pediatric OK wear. In adults these relationships are minimal after OK. Since RPR change is related to baseline myopia, these results indicate that in children, higher baseline myopia and hence larger changes in RPR are related to larger improvements in BV function. This is the first study evaluating the relationship between RPR and BV and has relevance for clinical management and OK fitting of young myopic patients
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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