Water diffusion in the rabbit lens in vivo

Area of Science:

• Ophthalmology
• Biophysics
• Medical Imaging

Background:

• Cataracts are a leading cause of vision loss, often associated with altered water content in the crystalline lens.
• Understanding water dynamics within the lens is crucial for early detection and management of cataract formation.

Purpose of the Study:

• To investigate in vivo water self-diffusion in the crystalline lens of rabbits with experimentally induced sugar cataracts.
• To assess the utility of diffusion imaging in detecting early changes in lens water mobility.

Main Methods:

• Magnetic resonance imaging (MRI) was employed to examine water self-diffusion in the lens cortices of alloxan-diabetic and galactosemic rabbits.
• Diffusion-weighted MRI utilized a pulsed-gradient spin-echo sequence with specific parameters (TR/TE, field of view, matrix size) on a 4.7-tesla animal system.
• Gradient strengths were applied in primary and secondary coordinates to quantify diffusion coefficients.

Main Results:

• Increased water relaxation and altered lens dimensions (equatorial cortex depth/lens long axis) were observed in diabetic and galactosemic rabbits compared to normal rabbits.
• Water diffusion coefficients changed significantly in diabetic rabbit lenses, indicating increased intracellular fluidity along cortical fibers.
• Elevated water diffusivity was noted in the aqueous humor of galactosemic rabbits, suggesting increased free water or thermal convection.

Conclusions:

• Water self-diffusion in the lens is influenced by lens fiber orientation and intracellular protein order.
• Diffusion imaging is a valuable tool for detecting early osmotic alterations in lens fibers, preceding visible cataract development.
• These findings highlight the potential of MRI-based diffusion analysis for early diagnosis of lens abnormalities.