Ciliary muscle dimensions by swept‐source optical coherence tomography and correlation study in a large population

Abstract

Purpose: To examine ciliary muscle (CM) dimensions in vivo by swept-source optical coherence tomography (SS-OCT) in a large healthy population. To assess the reproducibility of CM measurements and correlations with different parameters. Methods: In this cross-sectional study, the following CM measurements were made in 495 eyes of 495 subjects in the temporal and nasal quadrants: length (CML), area (CMA) and thickness at distances of 1000 lm (CMT1), 2000 lm (CMT2) and 3000 lm (CMT3) from the scleral spur using the SS-OCT DRI-Triton â (Topcon, Tokyo, Japan). These dimensions were then assessed for correlations with the factors age, gender, refractive error, anterior chamber angle (ACA) and intraocular pressure (IOP). The reproducibility of CM measurements was determined in 85 of the participants. Results: Mean age was 41.4 AE 17.5 years (range 5-83). The following means were recorded as follows: CML = 4.57 AE 0.73 mm (range 2.16-6.97), CMA = 1.35 AE 0.31 mm 2 (2.04-5.45), CMT1 = 558 AE 98 lm (299-891), CMT2 = 366 AE 100 lm (89-629) and CMT3 = 210 AE 75 lm (36-655). Negative correlation was detected between CML/CMA and age (R = À0.516/ R = À0.404; p < 0.001) and refractive error (R = À0.519/R = À0.538; p < 0.001). No gender differences were observed (p ≥ 0.150). Both CML and CMA were correlated with ACA (R = 0.498 and 0.546; p < 0.001) and slightly with IOP (R = À0.175; p < 0.001). The reproducibility of the CM measurements was excellent (intraclass correlation coefficient ≥0.878). Conclusions: Swept-source optical coherence tomography is a valid tool for in vivo CM measurements. Our data indicate a larger CM in myopes and its diminishing size with age.

The Relationship Between Age and the Morphology of the Crystalline Lens, Ciliary Muscle, Trabecular Meshwork, and Schlemm’s Canal: An in vivo Swept-Source Optical Coherence Tomography Study

“…Other investigators, however, have not reported a difference between nasal and temporal TM values (Fernandez-Vigo et al, 2017;Chen et al, 2018). In most studies, a significantly larger CMA and thicker CM in the temporal quadrant was detected (Sheppard and Davies, 2010;Fernández-Vigo et al, 2020). In current study, the CMA (P < 0.001) was also significantly larger in the temporal quadrant.…”

“…Similarly, Chen et al ( 2018) noted a clear decline in the SC diameter and CSA as age increased, with a linear correlation analysis indicating a significant age-dependent tendency (P < 0.001) using the CASIA SS-1000 OCT. Zhao et al (Zhao et al, 2018) divided participants into four groups (16-20 years, 21-40 years, 41-60 years, and 61-80 years) and found that the nasal CSA was significantly smaller in the 61-80-years group. Studies have also reported that the crystalline lens thickness increases, the anterior lens curvature steepens, and the IA-SS and CMA decrease with age (Richdale et al, 2013(Richdale et al, , 2016Fernández-Vigo et al, 2020;Xie et al, 2020). Previous studies have reported that the SC size increases in response to accommodation efforts and shrinks with cycloplegia in children (Daniel et al, 2018;Xiang et al, 2020).…”

“…Thereafter, participants were asked to stare at left or right built-in fixation lights to ensure that the iridocorneal angle was centered in the instrument's field of view. The morphology of CM and TM/SC varies in different quadrants of the eye (Kagemann et al, 2010;Sheppard and Davies, 2010;Fernandez-Vigo et al, 2017;Li et al, 2017;Chen et al, 2018;Zhao et al, 2018;Fernández-Vigo et al, 2020). In this study, the scans were performed independently for the temporal and nasal quadrants (at the 3 and 9 o'clock positions) using the angle HD type.…”

“…The decreasing SC size in the elders (Chen et al, 2018;Zhao et al, 2018) might result from several factors, such as an age-related reduction in the number of SC cell count (Ainsworth and Lee, 1990), and a decreases in aqueous humor production with age (Becker, 1958). Though previous studies have proposed the effect of age on the morphology of crystalline lens, ciliary muscle (CM) or TM/SC solely (Richdale et al, 2013(Richdale et al, , 2016Chen et al, 2018;Zhao et al, 2018;Fernández-Vigo et al, 2020;Xie et al, 2020), the effect of age on these structures as an entity has not been fully studied. Evaluation of age-related changes in the crystalline lens, CM and TM/SC of human eyes might be helpful in understanding why the incidence of POAG increases with age.…”

Diagnostic imaging of the ciliary body: Technologies, outcomes, and future perspectives

“…Thickness is usually measured at a distance of 1, 2, and 3 mm (CBT1, 2 or 3 and CMT1, 2 or 3, respectively) from the scleral spur. 33–40 It should be noted that the different authors refer to CB or CM measurements without distinction. Through UBM, the CB can be actually measured as it theoretically includes the CP.…”