Ocular anterior segment biometry and high-order wavefront aberrations during accommodation

Abstract

Purpose: We investigated the relationships between the ocular anterior segment biometry and the ocular high-order aberrations (HOAs) during accommodation by combined ultralong scan depth optical coherence tomography (UL-OCT) and wavefront sensor.

Methods: We enrolled 35 right eyes of young healthy subjects (21 women and 14 men; age, 25.6 ± 3.1 years; spherical equivalent refractive error, -0.41 ± 0.59 diopters [D]). A custom-built UL-OCT and a wavefront sensor were combined. They were able to image the ocular anterior segment and to measure the HOAs during accommodation. The differences in the biometric dimensions and in the HOAs between the nonaccommodative and accommodative states were compared, and the relationships between them were investigated.

Results: Compared to the nonaccommodative condition, anterior chamber depth, pupil diameter, and radii of the crystalline lens surface curvatures decreased significantly, while the lens thickness and root-mean-square of high-order aberration (HORMS) of fixed 3-mm pupil size increased under the accommodative stimulus (P < 0.01). A negative correlation was found between the change in the radius of the lens anterior surface curvature and the change in HORMS (r = -0.370, P = 0.014). For nonaccommodative and accommodative conditions, HORMS for a fixed pupil size was correlated negatively with pupil diameter (r = -0.532 and -0.801, respectively, P < 0.01).

Conclusions: The anterior segment biometry and the HOAs changed significantly during accommodation. The increase in HOAs mainly was due to the increased convexity of the anterior surface of the lens during accommodation. Contraction of the pupil may help to decrease HOAs.

Keywords: aberrations; accommodation; anterior segment; crystalline lens; optical coherence tomography; pupil.