A test of the relationship between deformation of the lens and refractive error in the accommodated eye of myopia

Abstract

Purpose : It has been suggested that developmental change in the shape of the crystalline lens and its power loss are involved in myopia development. In order to test if the lens shape and its accommodative change could also be involved in myopia progression, this study was designed to investigate relationship of the lens shape and its accommodative deformation with refractive error in myopic eye.

Methods : A custom developed Hartmann-Shack wavefront sensor, integrated with a custom developed spectral domain optical coherent tomography (SD-OCT) system, was used to measure accommodative responses (AR) for 31 young adults (aged 21 to 39 yrs old, Rx from -0.75 D to -8.625D with a mean of -4.61±2.28D). The wavefront sensor measured Zernike aberrations up to 7^th order for the right eye when accommodative stimulation (AS) was presented for the same eye at 0.0, 2.0, 4.0 and 6.0D with a Badal system. The 840nm SD-OCT system, co-axially aligned with the wavefront sensor, was used to image the cornea and the lens. We looked at accommodative changes in anterior chamber depth (ACD), lens thickness (LT), anterior lens curvature (ALC), and posterior lens curvature (PLC) and tested the correlation of their changes with the refractive error.

Results : At 0D, there was no significant correlation between refractive error and ACD (R² = 0.019, p=0.44), LT (R² =0.030, p=0.34), ALC (R² = 0.019, p=0.45), or PLC (R² =0.015, p=0.51). When accommodating 6D, the mean accommodative changes were 5.50±0.39D in refractive power and -0.03±0.03micron in spherical aberration. With 6D accommodation, the mean ACD was shortened by 0.28±0.07mm while the LT thickened by 0.33±0.08mm. The mean ALC changed from 12.45±1.82mm at 0D to 8.60±1.49mm at 6D accommodation, while the mean PLC was more curved from 6.98±0.92 mm in radius at 0D to 5.87±0.74mm at 6D accommodation. There was no significant correlation between the refractive error and the accommodative changes in ACD (R² = 0.064, p=0.16), LT (R² =0.0036, p=0.75), ALC (R² = 0.013, p=0.54), or PLC (R² =0.014, p=0.53).

Conclusions : Neither the shape of the crystalline lens nor its accommodative change is associated with refractive error in myopic eye. It is therefore unlikely that morphological property of the lens is involved in the process of myopia progression.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.