Mechanical changes in cataract lenses assessed with optical coherence elastography
HongqiuZhang, Chen Wu, Manmohan Singh, SalavatR. Aglyamov, Kirill V. Larin
Abstract
Cataract is the most prevalent cause of visual impairment worldwide. The World Health Organization reports that about 1/3 of all visually impaired people have cataracts. Therefore, understanding the mechanisms of cataract development and progression is critical for clinical diagnosis and treatment of this disease. Cataracts can be formed due to trauma, radiation, drug abuse, or low temperatures. Thus, early detection of cataract can be immensely helpful for preserving visual acuity by ensuring that the appropriate therapeutic procedures are performed at earlier stages of disease onset and progression. In this work, we utilized a phase-sensitive optical coherence elastography (OCE) system to quantify changes in biomechanical properties of porcine lenses in vitrowith induced cold and oxidative cataracts. The OCE system is based on the spectral domain OCT system. The OCT system utilized a superluminescent diode(SLD) with a central wavelength of 840 nm and bandwidth of 49 nm. The displacement stability of the system was 12 nm in air. The air-pulse delivery system used an electronically controlled pneumatic solenoid and control unit to produce a short duration (< 1 ms) air-pulse that was synchronized with the OCT system. The short duration air-pulse (≤1 ms) induced small amplitude displacements (≤10 μm) on the surface of lenses that propagated as an elastic wave. Successive M-mode images (n = 251) were acquired over a ~7.8 mm line, where the center of the scan and air-pulse excitation were at the apex of the lens. The group velocity of the elastic wave was determined by the slope of a linear fit of the wave propagation distances and the corresponding propagation times. The results show significant increase in Young’s modulus of the lens due to formation of the cold cataract (from ~ 35kPa to ~60 kPa) and oxidative cataract (from ~ 8 kPa to ~123 kPa). Young’s moduli of the lenses decreased after incubation in antioxidant α-Lipoic Acid (~123 kPa vs ~45 kPa). These results show that OCE can assess lenticular biomechanical properties and may be useful for detecting and, potentially, characterizing cataracts.
Speaker
Hongqiu Zhang
University of Houston
United States of America
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