Abstract
Purpose :
To determine the dimensional changes in the anterior segment of the human eye and ciliary muscle during accommodation using ultra-long spectral OCT(UL-OCT) and 1310 nm spectral domain OCT.
Methods :
UL-OCT and 1310 nm OCT were used to image the anterior segment from the cornea to the back surface of the crystalline lens through the pupil and ciliary muscle. 27 eyes of 27 healthy prepresbyopic subjects were imaged in two repeated measurements during accommodation. The dimensional results including central corneal thickness (CCT), anterior chamber depth (ACD), anterior chamber width (ACW), pupil diameter (PD), lens thickness (LT), anterior segment length (ASL=ACD+LT), lens central position (LCP=ACD+1/2LT), horizontal radii of the lens anterior and posterior surface curvature (LAC, LPC) and ciliary muscle parameter were measured at minimal and maximal accommodative statuses.
Results :
Between two measurements at each status, none of the variables differed significantly (p＞0.05). CoRs for CCT, ACW, ACD, LT, LCP and ASL were excellent (0.50% to 2.93%), relative high for PD, LAC and LPC (7.65% to 14.97%). ICCs for CCT, ACD, LT, ASL and LCP were excellent (0.966 to 0.998), relative low for (0.191to 0.9470). No clear trend towards over or underestimation of anterior segment dimension repeatability between the first and second measurements in both maximum-accommodative and relaxed accommodative states was evident, as showed by Bland–Altman scatter diagram. Compared to the minimal accommodation status, PD, ACD, LAC and LPC decreased and LT increased significantly during the maximal accommodation status (P < 0.05). ASL increased and LCP decreased (P < 0.05), while CCT and ACW did not change (P > 0.05). In contrast to decreased posterior portion (P < 0.05), the thickness and area of anterior portion of the ciliary muscle increased with accommodation (P < 0.05). The anterior portion of the ciliary muscle was linearly correlated with the anterior segment parameters during accommodation (P < 0.05).
Conclusions :
UL-OCT appeared to be able to measure the dimensional changes of the anterior segment during accommodation with good repeatability. During accommodation, the back surface of the lens appeared to become steeper although the lens moved forward. The anterior portion of the ciliary muscle was correlated with the anterior segment parameters during accommodation.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.