Effect of even and odd-order aberrations on the accommodation response

AIM： To investigate the potential effect that odd and even-order monochromatic aberrations may have on the accommodation response of the human eye. METHODS： Eight healthy subjects with astigmatism below 1 D, best corrected visual acuity 20/20 or better and normal findings in an ophthalmic examination were enrolled. An adaptive optics system was used in order to measure the accommodation response of the subjects＇ eyes under different conditions： with the natural aber- rations being present, and with the odd and even-order aberrations being corrected. Three measurements of accommodation response were monocularly acquired at accommodation demands ranging from 0 to 4 D （0.5 D step）. RESULTS： The accommodative lag was greater for the accommodate demands of 1.5, 3, 3.5 and 4 D for the condition in which the even-order aberrations were corrected, in comparison to that obtained for the natural aberrations and corrected odd-order aberrations for the same accommodation demands. No statistically significant differences were found between the accommodation responses under the three conditions. CONCLUSION： The odd and even-order aberrations are not helping the visual system to accommodate, because their partial correction do not affect the accommodation performance.

Changes in crystalline lens parameters during accommodation evaluated using swept source anterior segment optical coherence tomography

Backgrounds:To assess changes in anterior segment biometry during accommodation using a swept source anterior segment optical coherence tomography(SS-OCT).Methods:One hundred-forty participants were consecutively recruited in the current study.Each participant underwent SS-OCT scanning at 0 and−3 diopter(D)accommodative stress after refractive compensation,and ocular parameters including anterior chamber depth(ACD),anterior and posterior lens curvature,lens thickness(LT)and lens diameter were recorded.Anterior segment length(ASL)was defined as ACD plus LT.Lens central point(LCP)was defined as ACD plus half of the LT.The accommodative response was calculated as changes in total optical power during accommodation.Results:Compared to non-accommodative status,ACD(2.952±0.402 vs.2.904±0.382 mm,P<0.001),anterior(10.771±1.801 vs.10.086±1.571 mm,P<0.001)and posterior lens curvature(5.894±0.435 vs.5.767±0.420 mm,P<0.001),lens diameter(9.829±0.338 vs.9.695±0.358 mm,P<0.001)and LCP(4.925±0.274 vs.4.900±0.259 mm,P=0.010)tended to decreased and LT thickened(9.829±0.338 vs.9.695±0.358 mm,P<0.001),while ASL(6.903±0.279 vs.6.898±0.268 mm,P=0.568)did not change significantly during accommodation.Younger age(β=0.029,95%CI:0.020 to 0.038,P<0.001)and larger anterior lens curvature(β=−0.071,95%CI:−0.138 to−0.003,P=0.040)were associated with accommodation induced greater steeping amplitude of anterior lens curvature.The optical eye power at 0 and−3 D accommodative stress was 62.486±2.284 and 63.274±2.290 D,respectively(P<0.001).Age was an independent factor of accommodative response(β=−0.027,95%CI:−0.038 to−0.016,P<0.001).Conclusions:During−3 D accommodative stress,the anterior and posterior lens curvature steepened,followed by thickened LT,fronted LCP and shallowed ACD.The accommodative response of−3 D stimulus is age-dependent.