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First Author: D.López-Alcón SPAIN
Co Author(s): V. Fernández-Sánchez F. Lara E. Usón P. Bernal-Molina R. Montés-Micó N. López-Gil
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It has been studied the relationship between the amplitude of accommodation (AA) with optical eye parameters which may explain the variability of the AA in patients with the same or a similar age.
Laboratorio Interuniversitario de Investigación en Visión y Optometría. University of Murcia and University of Valencia, Spain.
A commercial aberrometer (irx3, Imagine Eyes, France) was used to obtain the wavefront of 120 eyes during the full range of accommodation. A custom-made Badal optometer was also used to obtain the subjective refraction (spherical equivalente) and the subjective AA. Then, we performed a statistical analysis mainly consisting in a multiple linear regression using SPSS (SPSS Inc, Chicago, Ill). The whole population was divided in three groups of ages: 21-25 years (65 eyes); 38-40 years (20 eyes); and 50-58 years (35 eyes). As potential optical parameters that predict the subjective AA it was used: pupil diameter in the relaxed eye and its reduction with accommodation; fourth- and six-order spherical aberration Zernike coefficient, C40 and C60, and their reduction with accommodation; and the subjective refraction.
The results in the younger group show a significant (p=0.01) but weak (R2 = 0.137) negative correlation between the fourth- and sixth-order spherical aberration coefficients and the AA. The middle age group showed a significant (p = 0.013) negative correlation (R2 = 0.298) between the subjects refraction and AA. Finally, the older group did not showed any statistical significant relationship between the AA and any of the variables studies.
Our results indicate that young subjects with low or negative spherical presents a large value of AA. This result can be explained optically taking into account the decreases of the spherical aberration a pupil diameter during accommodation. The lack of optical predictors of the AA in the more aged groups can be explained taking into account the small intersubject variability in the AA due to their accommodative limitations.