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Deborah S Laughton, Amy L Sheppard, Leon N Davies; Refractive and morphometric changes during incipient presbyopia: the Aston Longitudinal Assessment of Presbyopia (ALAP) study 18 month review. Invest. Ophthalmol. Vis. Sci. 2014;55(13):3744. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To investigate the refractive and morphometric changes that occur during incipient presbyopia (IP), and in particular, to elucidate the origin of the myopic refractive shift reported to occur in a proportion of individuals during this phase of presbyopia.
Starting from April 2012, 58 emmetropic and myopic subjects (aged 33-45 years) were reviewed every 6 months over 2.5 years. Objective refraction was measured by the WAM-5500 autorefractor (Grand Seiko, Japan). Corneal thickness (CT), anterior chamber depth (ACD), crystalline lens thickness (LT), anterior segment length (ASL), vitreous chamber depth (VCD) and axial length (AXL) were derived from Lenstar LS900 biometer (Haag-Streit, Switzerland) measurements.
Ninety-three percent of the recruited cohort completed the 18 month review (22 myopes, 32 emmetropes). A significant increase in mean LT (+0.198 ± 0.202; p<0.001) and ASL (+0.085 ± 0.141; p=0.001) and a decrease in mean ACD (-0.132 ± 0.199; p<0.001) and VCD (-0.081 ± 0.145; p=0.002) was observed after 18 months. Both mean CT (-0.036 ± 0.135; p=0.187) and mean AXL (+0.002 ± 0.034; p=0.144) were invariant, however changes in AXL were dependent on baseline refractive error group classification (p=0.018). The prevalence of a clinically significant myopic shift in refraction > 0.25 DS was 22% and 6% amongst the myopic and emmetropic groups, respectively. AXL elongation was the most closely linked biometric factor to the myopic shift in refraction (p=0.043). A trend emerged for a less posterior movement of the posterior crystalline lens surface in participants who became more myopic (p=0.259).
Our preliminary data supports the notion that a small proportion of patients become more myopic during IP, which is associated with concurrent AXL elongation.
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