- Developed and validated DIC methodology with swept source OCT to quantify in vivo ciliary muscle deformation and strain during accommodation.
- Under -5.0 D stimulus effective strain showed graded attenuation CN>HM>Elderly; anterior CM thickening significantly greater in control group.
- Mean effective strain correlated strongly with macroscopic muscle thickening (r=0.70) and accommodation amplitude (r=0.69), indicating a functional biomarker.
Eye Vis (Lond). 2026 Jul 6;13(1):28. doi: 10.1186/s40662-026-00498-w.
ABSTRACT
BACKGROUND: This study aimed to develop and validate a digital image correlation (DIC) methodology based on swept-source optical coherence tomography (SS-OCT) for quantifying in vivo ciliary muscle (CM) deformation and strain during accommodation.
METHODS: This study was comprised of three phases. First, the measurement performance was examined across two SS-OCT systems (CASIA2 and VG200D) and four scanning modes (R1, R8, R16, and R64) by comparing the DIC-derived displacements with the simulated ground-truth fields. Second, reliability was validated using a “cross-image” strategy, in which artificial deformations were applied to biological images to assess tracking accuracy under realistic speckle noise. Third, 23 subjects were recruited and divided into three groups: control group (CN, n = 7), high myopia group (HM, n = 7), and elderly group (n = 9). Macroscopic morphological parameters (anterior CM length change and maximum CM thickness change) and biomechanical parameters (e.g., equivalent strain) were extracted synchronously.
RESULTS: The R8 scanning mode in the CASIA2 device exhibited the most stable acquisition configuration. The robustness of the ncorr‑DIC algorithm was verified through the second-step experiment. Under the accommodative stimulus of – 5.0 D, the effective strain exhibited a highly significant graded attenuation among groups: CN (0.28 ± 0.06) > HM (0.20 ± 0.03) > Elderly (0.16 ± 0.05) (P = 0.002). Morphological changes were consistent with this finding, and CM thickening was significantly greater in the CN group than in the other two groups (P = 0.003). Combined analysis revealed that the mean effective strain was not only significantly positively correlated with macroscopic muscle thickening (r = 0.70, P < 0.001) but was also highly correlated with accommodation amplitude (r = 0.69, P < 0.001).
CONCLUSION: DIC-based OCT analysis is feasible for assessing the biomechanical response of CM. By quantifying mechanical attenuation associated with HM and age-related decline, this method provides a new functional biomarker for investigating the mechanisms of accommodation dysfunction and guiding clinical interventions.
PMID:42402615 | DOI:10.1186/s40662-026-00498-w
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