Lens fibers are specialized, transparent cells that constitute the bulk of the crystalline lens in the eye. They are responsible for the lens's refractive properties, allowing it to focus light onto the retina.
Characteristics of Lens Fibers:
- Shape: They are long, thin, and hexagonal in cross-section.
- Size: Typically, they have diameters between 4-7 micrometers and can be up to 12 mm long.
- Composition: Lens fibers are packed with crystallin proteins, contributing to their transparency and refractive index.
- Arrangement: These fibers are precisely arranged in concentric layers, similar to the layers of an onion. New lens fibers are continuously added throughout life, layering over older fibers.
- Transparency: They lack nuclei and other light-scattering organelles to maximize transparency.
Function of Lens Fibers:
- Light Transmission: Their primary function is to transmit light efficiently with minimal scattering to the retina.
- Refraction: Their high refractive index, due to the crystallin proteins, allows the lens to bend light rays for focusing.
- Accommodation: The lens changes shape (accommodation) to focus on objects at varying distances. This process depends on the arrangement and properties of lens fibers.
- Maintaining Lens Structure: Lens fibers contribute to the structural integrity and elasticity of the lens.
Formation and Growth:
Lens fibers are formed from epithelial cells located at the lens equator. These cells elongate, lose their nuclei and organelles, and become mature lens fibers. This process continues throughout life, with new fibers being added to the outer layers of the lens. The oldest fibers are located in the lens nucleus.
