Ciliary muscle dimensions measured by swept-source optical coherence tomography in eyes with primary open-angle glaucoma and healthy eyes.

Abstract

To compare in vivo swept-source optical coherence tomography (SS-OCT) measurements of the ciliary muscle (CM) in patients with primary open-angle glaucoma (POAG) and healthy subjects, and examine correlations between CM dimensions and several covariates. This was a cross-sectional study of the right eyes of 181 subjects: 89 POAG patients and 92 healthy subjects. Using the Triton SS-OCT device (Topcon, Tokyo, Japan), CM length (CML), area (CMA) and thickness measured 1000µm (CMT1), 2000µm (CMT2) and 3000µm (CMT3) from the scleral spur were determined in the temporal and nasal quadrants. POAG patients were subjected to visual field (VF) and peripapillary retinal nerve fiber layer (RNFL) assessment. CM dimensions were then assessed for correlation with VF mean defect (MD), mean RNFL thickness and intraocular pressure (IOP). Mean CMLs were 4325 ± 340µm and 4195 ± 843µm for the healthy subjects and POAG patients, respectively (p = 0.17). Mean CM thicknesses were CMT1 = 546 ± 56µm, CMT2 = 326 ± 44µm and CMT3 = 174 ± 16µm in the healthy eyes versus CMT1 = 534 ± 108, CMT2 = 332 ± 99 and CMT3 = 183 ± 74 in the POAG eyes, with no significant differences detected (all p ≥ 0.25). In the temporal quadrant, mean CMA was 1.12 ± 0.29mm2 and 1.15 ± 0.24mm2 for the healthy and POAG subjects, respectively (p = 0.45). No correlations were observed between CM measurements and RNFL thickness (p ≥ 0.15), IOP or VF MD (p ≥ 0.14) in POAG subjects irrespective of glaucoma severity (p ≥ 0.19). While SS-OCT proved useful to measure CM dimensions in vivo, these dimensions did not differ between healthy individuals and POAG subjects. In the patients with POAG, no correlations were detected between CM dimensions and VF, RNFL or IOP.