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Ryo Kubota, Nabin R Joshi, arkady selenow, amitava gupta, steven ali, inna samandarova, maksud oliva, Kenneth J Ciuffreda; Effect of temporary full-field defocus on ocular biometric components and their subsequent normalization: a pilot study. Invest. Ophthalmol. Vis. Sci. 2020;61(7):2700.
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In this pilot study, we observed the effects of temporary full-field defocus on axial length and other components of the eye, and their normalization for up to half an hour following the removal of defocus.
15 visually-normal subjects (9 females and 6 males) of mean age 25.70 years (range 21-32) with spherical refractive error within ± 2.0 D and cylinder less than 0.75 D were enrolled in the study, confirmed with cycloplegia (Cyclopentolate 1%). 11 out of 15 subjects were of Asian ethnicity. The subjects underwent 3 separate defocus sessions under controlled conditions viewing distance tasks. For the first session, a defocus of +2.0 D was applied to the non-dominant eye with a distance refractive correction in the dominant eye with standard spectacle lenses for 2 hours (hrs). The same subjects underwent defocus sessions under controlled conditions with +3.50 D of defocus for 4 hrs, and +5.0D of defocus for 6 hrs, each after washout periods. Data collection for these two sessions is ongoing, including analysis of choroidal thickness measurements obtained from Heidelberg SD-OCT with EDI, which will be presented. The abstract deals with the first defocus session with only the non-dominant eye defocused by +2.0D. Axial length was measured with a Lenstar APS 900 from Haag-Streit Holding before the defocus sessions, immediately after, and twice after in a 15-minute interval.
The mean percent increase of axial length relative to the baseline following defocus for the test eyes was +0.004% with a SD of 0.05, and it was +0.03% (SD ± 0.05) for the control eyes with rank-sum test significant at p<0.05. The coefficient of determination (r2) for the percent increase from baseline was 0.35 when the test eyes were plotted against control eyes immediately following defocus, which increased to 0.78 with p<0.01 after half an hour following defocus.
Percent increase in axial length from the baseline was smaller for the test eyes relative to the control eyes after 2 hours of full-field defocus. The correlation of change was normalized after half an hour following the removal of defocus. Growth signals generated by myopic defocus may reduce the axial length by attenuating its increase driven by diurnal rhythms, and could be of significant utility in myopia control strategies.
This is a 2020 ARVO Annual Meeting abstract.
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