Whole Eye Axial Biometry During Accommodation Using Ultra-long Scan Depth Optical Coherence Tomography

Abstract

PURPOSE To investigate changes of whole eye axial biometry during accommodation using ultra-long scan depth optical coherence tomography (UL-OCT). DESIGN Prospective, observational case series. METHODS Twenty-one adult subjects were enrolled. Using UL-OCT, the left eye of each subject was imaged with relaxed (0 D) and accommodative stimuli (+6 D). Full eye biometry included central corneal thickness (CCT), anterior chamber depth (ACD), lens thickness, vitreous length and axial length (AL). RESULTS During accommodation (+6 D), the axial biometry of the whole eye changed significantly. Compared to the rest state, ACD at the accommodative state decreased significantly from 3.128 ± 0.305 mm to 2.961 ± 0.298 mm (paired t-test, P < 0.001). The lens thickness increased significantly from 3.723 ± 0.237 mm to 3.963 ± 0.234 mm (P < 0.001). The vitreous length decreased significantly from 17.129 ± 0.864 mm to 17.057± 0.848 mm (P < 0.001). AL was 24.519 ± 0.917 mm at the rest state and increased to 24.545±0.915 mm with +6 D accommodation stimulus. The elongated AL of 26.1 ± 13.4 μm between the rest and accommodative states was significant (P < 0.001). CONCLUSIONS During accommodation, whole eye axial biometry changed, including a decrease in ACD and vitreous length, and an increase in lens thickness and AL. UL-OCT provides an alternative method that is suitable for full eye biometry during accommodation.

Regional Changes in Choroidal Thickness Associated With Accommodation

“…These findings show general agreement with previously published studies, 21,23,24 which reported increases in AL with accommodation, but no significant differences between the refractive groups. The increase we found in AL was also of a much smaller magnitude than studies that did not take into account the accommodation induced error related to optical path length and refractive index that is present in commercial partial coherence interferometry instruments.…”

“…Due to the proposed link between near work and myopia, [12][13][14][15][16][17] numerous studies have examined the way in which various ocular parameters change during accommodation. [18][19][20][21][22][23][24] Along with the well documented changes in anterior eye biometrics, 18 a number of recent studies have reported significant increases in AL to accompany accommodation. [19][20][21][22][23][24] Using optical low coherence reflectometry (OLCR), we have previously reported some evidence of a small but significant thinning of the subfoveal choroid during accommodation, which was weakly negatively associated with the observed axial elongation.…”

“…[18][19][20][21][22][23][24] Along with the well documented changes in anterior eye biometrics, 18 a number of recent studies have reported significant increases in AL to accompany accommodation. [19][20][21][22][23][24] Using optical low coherence reflectometry (OLCR), we have previously reported some evidence of a small but significant thinning of the subfoveal choroid during accommodation, which was weakly negatively associated with the observed axial elongation. 23 However, the use of OLCR to assess ChT in our previous study was a limitation, since the determination of ChT requires subjective judgment, and was only possible in 63% of subjects with this technique.…”

Versatile optical coherence tomography for imaging the human eye

“…Using the static design of the reference arm may be also suitable for further development of the system for clinic studies, in which clinicians and researchers with limited training may operate the system. Imaging the retina with high SNR using the third mirror in the eyes with short axial lengths may also facilitate automated axial biometry as we demonstrated previously [33]. To view the normally oriented retina in the eyes with short axial lengths, we realized that we could alternatively use the combined images of the third and fourth mirrors to enhance the SNR for imaging the retina.…”

Computer-animated model of accommodation and presbyopia

“…Axial elongation during accommodation has been confirmed using ultra-long scan depth optical coherence tomography. 22 Thus, accommodation causes changes in all elements of the uveal tract from the iris and pupil to the subfoveal choroid.…”