Because newer swept-source OCT (SS-OCT) technology offers improved resolution and tissue penetration, researchers in Spain believe the technology can more effectively measure the ciliary muscle. Their study examined ciliary muscle dimensions in vivo by SS‐OCT in a healthy population of 495 eyes. They then assessed the measurements based on age, gender, refractive error, anterior chamber angle and IOP.

The mean ciliary muscle length was 4.57±0.73mm, while the area was 1.35±0.31mm2. The ciliary muscle thickness was 558±98μm at 1,000µm, 366 ±100μm at 2,000µm and 210±75μm at 3,000µm.

The findings revealed a negative correlation between both length and area with age and refractive error. The researchers observed no differences based on gender. Both ciliary muscle length and area were correlated with anterior chamber angle and slightly with IOP.

When the researchers took a look at the reproducibility of the measurements for 85 of the participants, they found it was excellent.

The researchers concluded that SS-OCT is a valid tool for in vivo ciliary muscle measurements. Their data indicated a larger ciliary body in myopia, a decrease with age, no correlation with gender and good correlation with angle.

Fernández-Vigo JI, Shi H, Kudseih B, et al. Ciliary muscle dimensions by swept-source optical coherence tomography and correlation study in a large population. Acta Ophthalmol. November 26, 2019. [Epub ahead of print].