Optical Coherence Elastography Measures Mechanical Tension in the Lens and Capsule.

Abstract

Lens tension is essential for accommodative vision but remains difficult to measure with precision. Here, we present an optical coherence elastography (OCE) technique that quantifies both tension and elastic modulus in the lens capsule and underlying tissue. This method derives mechanical parameters from surface wave dispersion across a critical frequency range of 1-30 kHz. Using isolated lenses from six-month-old pigs, we measured intrinsic anterior capsular tensions of 0-20 kPa and posterior capsular tensions of 40-50 kPa, induced by intra-lenticular pressure at the cortical surface. The mean shear moduli of anterior and posterior capsules were 630 kPa and 400 kPa, respectively, nearly 100-fold greater than that of the cortical tissues, where tensions were below 1 kPa. Biaxial zonular stretching (∼4% strain) increased anterior capsular tension by 67 kPa, with a low uncertainty of only 2 kPa. This optical method holds significant promise for diagnosing and managing accommodative dysfunctions through lens mechanics assessment in clinical settings. STATEMENT OF SIGNIFICANCE: Optical coherence elastography (OCE) is a rapidly advancing imaging modality, but its applications have been limited to stiffness measurements. This work represents a significant innovation by extending OCE capabilities to include force and stress quantification, broadening its potential applications in biomedical and clinical contexts. The ability to measure in situ capsular tension in the eye lens is a major breakthrough, as capsular tension is essential for transferring zonular fiber forces to the lens tissue during accommodation-a process critical for vision. This study provides quantitative insights into the mechanical mechanisms of accommodation and holds strong promise as a clinical tool for assessing lens tissue mechanics, addressing a capability gap in current clinical practice.