Biometry of Anterior Segment of Human Eye on Both Horizontal and Vertical Meridians during Accommodation Imaged with Extended Scan Depth Optical Coherence Tomography

Abstract

PurposeTo determine the biometry of anterior segment dimensions of the human eye on both horizontal and vertical meridians with extended scan depth optical coherence tomography (OCT) during accommodation.MethodsTwenty pre-presbyopic volunteers, aged between 24 and 30, were recruited. The ocular anterior segment of each subject was imaged using an extended scan depth OCT under non- and 3.0 diopters (D) of accommodative demands on both horizontal and vertical meridians. All the images were analyzed to yield the following parameters: pupil diameter (PD), anterior chamber depth (ACD), anterior and posterior surface curvatures of the crystalline lens (ASC and PSC) and the lens thickness (LT). Two consecutive measurements were performed to assess the repeatability and reproducibility of this OCT. They were evaluated by calculating the within-subject standard deviation (SD), a paired t-test, intra-class correlation coefficients (ICC) and the coefficient of repeatability/reproducibility (CoR).ResultsThere were no significant differences between two consecutive measurements on either horizontal or vertical meridians under both two different accommodative statuses (P>0.05). The ICC for all parameters ranged from 0.775 to 0.998, except for the PSC (0.550) on the horizontal meridian under the non-accommodative status. In addition, the CoR for most of the parameters were excellent (0.004% to 4.89%). In all the parameters, only PD and PSC were found different between the horizontal and vertical meridians under both accommodative statuses (P<0.05). PD, ACD, ASC and PSC under accommodative status were significantly smaller than those under the non-accommodative status, except that the PSC at the vertical meridian did not change. In addition, LT was significantly increased when accommodation.ConclusionThe extended scan depth OCT successfully measured the dimensions of the anterior eye during accommodation with good repeatability and reproducibility on both horizontal and vertical meridians. The asymmetry of lens posterior surface and oval-shaped pupil were found during accommodation.

OCT-based crystalline lens topography in accommodating eyes

“…Most previous studies quantifying lens geometry in vivo using different imaging modalities were limited to only one or two central cross-sections (2-D information) and generally report only central thickness and radii of curvature [19][20][21]. However, the cornea and the crystalline lens surfaces are non-rotationally symmetric, therefore 3-D measurements are required.…”

“…Information on the crystalline lens provided by commercial instruments is generally limited to axial properties (e.g., crystalline lens thickness). There are also numerous reports in the literature reporting lens radii of curvature, measured generally with adapted commercial or custom-developed instruments: Purkinje imaging [12,13], Scheimpflug camera [14][15][16], Magnetic Resonance Imaging (MRI) [17] and, recently, Optical Coherence Tomography (OCT) [18][19][20][21].…”

Anterior Segment Biometry of the Accommodating Intraocular Lens and its Relationship With the Amplitude of Accommodation

“…used to image the accommodation-induced biometric changes in the entire anterior segment of normal subjects with a natural crystalline lens. 21 In the current study, similar methodology was applied to evaluate the movement of IOLs under the natural accommodative effort. The repeatability of the measurements for dimensional parameters showed the high precision of long scan depth SD-OCT, which is necessary to quantify lens movement during accommodation, and may help to understand the accommodative mechanism of AIOLs.…”

“…Optical coherence tomography (OCT) has the ability to monitor the changes in the ocular anterior segment during accommodation, especially with the advanced technology that extends the scan depth in spectraldomain optical coherence tomography (SD-OCT) for imaging the entire anterior segment. 20,21 Crystalens AIOL (Bausch & Lomb, Rochester, NY) has been shown not to provide the lens movement needed to create changes in true refractive power in the study using OCT. 15 However, it is not clear if the latest Tetraflex AIOL model from the other market provides true accommodation.…”

Influence of exercise on the structure of the anterior chamber of the eye

“…In addition, using optical coherence tomography (OCT) measurements (Leng et al. ; Zhong et al. ; Zhu et al.…”