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Alexandra Benavente-Perez, Ann Nour, David Troilo; Peripheral Refraction as a Predictor for Induced Changes in Vitreous Chamber Growth Rates in Marmosets. Invest. Ophthalmol. Vis. Sci. 2012;53(14):4662.
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In the marmoset, compensatory changes in eye growth are known to occur after imposing retinal defocus with single vision lenses as soon as 4-6 weeks into treatment. Changes in peripheral refraction and eye shape with nasal-temporal asymmetries have been observed after treatment; however, the role that pre-treatment peripheral refraction might play as a predictor for the compensatory growth changes remains unclear. The aim of this study was to determine if a specific pattern of pre-treatment nasal-temporal asymmetry in refraction is related to, and can predict, compensatory responses to imposed retinal defocus.
The peripheral refractive state was measured before treating marmosets with single vision positive (n=17) or negative (n=19) contact lenses, and at corresponding ages in untreated marmosets (n=14). Refractive measures were taken along the sagittal, tangential and spherical equivalent (SphEQ) image shells at 0, 20 and 40 deg eccentricities on the nasal and temporal retina using an infrared video photorefractor (Power Refractor, MultiChannel System). Nasal-temporal asymmetry was calculated by subtracting the relative temporal from the relative nasal refraction and a multiregression analysis model was used to evaluate the relationship between refractive nasal-temporal asymmetries at baseline, and the vitreous chamber growth rates after 4-6 weeks of treatment (equivalent time in untreated marmosets).
Nasal-temporal asymmetries in peripheral refraction predicted the compensatory vitreous chamber growth rates in marmosets treated with single vision negative contact lenses such that relative hyperopia on the temporal retina in all image shells at baseline correlated with greater growth rates (R2= 0.85, p=0.013). No correlations were observed, however, in single vision positive (R2= 0.63, p=0.20) or untreated marmosets (R2= 0.61, p=0.38).
These results suggest a potential interaction between the visual regulation of emmetropization and the image quality of the temporal retina, such that imposing full field hyperopia on a retina that already exhibits more hyperopia temporally might make it more susceptible to increasing axial eye growth and myopia development.
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