Structure of Eye Lens and Role of Ciliary Muscle

The eye lens is a biconvex lens made of a transparent fibrous jelly-like substance. The ciliary muscles’ primary job was to alter the curvature of the lens in the eye to aid in focusing. The ciliary muscles also assist in regulating the flow of aqueous fluid in the eye.

These muscles stabilise the lens. The pictures of objects at various distances from the eye are brought into focus on the retina by varying the focal length of the eye lens. The focal length of the eye lens, which is comprised of fibrous jelly-like material, may be adjusted to a certain extent by the ciliary muscles.

External Components

• Sclera
• Conjunctiva
• Cornea
• Iris
• Pupil

Internal Components

• Lens
• Retina
• Optic nerve
• Aqueous Humour
• Vitreous Humour

Lens

In the eye, the lens is placed. The lens alters the focus distance of the eye by altering its shape. In other words, it concentrates the light rays that travel through it (and onto the retina) to produce sharp pictures of things at varying distances. Additionally, it collaborates with the cornea to refract or bend, light.

Lens Shape

The lens is elliptic in form and biconvex. An ellipsoid is similar to a sphere, but it is stretched out, like an olive, and it is biconvex on both sides, similar to the shape of an olive. In adults, the lens is approximately 10 mm wide and 4 mm from front to back, however, its shape and size alter when the lens changes its focus.

Structure of Eye lens

The lens is made up of three components: the lens capsule, the lens epithelium, and lens fibres. The lens capsule is the lens’s smooth, clear outermost layer, whereas the lens fibres are the lens’s long, thin, transparent cells that make up the lens’s bulk. The lens epithelium is located between these two layers and is responsible for the lens’s stability. Additionally, it generates lens fibres necessary for the lens’s lifetime development.

Ciliary Body

The ciliary body is a circular structure that connects the iris, the coloured portion of the eye, to the ciliary body. The ciliary body generates the fluid known as aqueous humour in the eye. Additionally, it houses the ciliary muscle, which reshapes the lens when your eyes focus on a close object. This is referred to as accommodation.

Ciliary Muscle 

The ciliary muscle takes up the majority of the ciliary body, which is located between the choroid and iris anterior borders. It is made of smooth muscle fibres arranged longitudinally, radially, and circularly. Together with the sphincter pupillae, the ciliary muscle actions are primarily controlled by the oculomotor nerve’s parasympathetic nerve fibres (CN III).

Provision of Nerves

The ciliary muscle gets parasympathetic fibres through the ciliary ganglion’s short ciliary nerves. Postganglionic parasympathetic fibres are associated with cranial nerve V1 (Nasociliary nerve of the trigeminal), whereas presynaptic parasympathetic fibres to the ciliary ganglia are associated with the oculomotor nerve. The ciliary ganglion supplies the postganglionic parasympathetic innervation.

Function

The primary purpose of the ciliary muscles is to alter the shape of the lens in the eye, which aids in the process of focusing. In addition to their other functions, the ciliary muscles are responsible for helping to control the flow of aqueous fluid in the eye.

Conclusion

The lens is made up of three components: the lens capsule, the lens epithelium, and lens fibres. The lens capsule is the lens’s smooth, clear outermost layer, whereas the lens fibres are the lens’s long, thin, transparent cells that make up the lens’s bulk. By raising or lowering the curvature of the eye lens, ciliary muscles assist the eye lens in focusing the picture of an object on the retina.