Department of Biomedical Engineering
Air University, Islamabad, Pakistan
Program: BE Biomedical Engineering
Subject: BM-112L Human Anatomy
Experiment 12:
Demonstration of the Eye structure using an Eye model.
Objectives:
(i) To be familiarized with the structure involved with sense of vision.
Lab Performance Indicator Total Marks Obtained
Performanc
e
Recognition of the Anatomical Structures 5
(CLO1)
Individual and Teamwork (CLO3) 5
Participation, Attitude and Behavior (CLO4) 5
Engagement in lifelong learning (CLO5) 5
Lab Report Documentation of Lab Report (CLO3) 5
Total Marks 25
Total Marks Obtained
Remarks (if any): ………………………………….
Name & Signature of faculty: …………………………………
Experiment 12:
Demonstration of the Eye structure using an Eye model.
Introduction:
The eyeball is a bilateral and spherical organ, which houses the structures responsible for vision.
It lies in a bony cavity within the facial skeleton – known as the bony orbit.
Anatomically, the eyeball can be divided into three parts – the fibrous, vascular and inner layers.
Layers of the Eyeball:
The eyeball is formed by three layers – fibrous, vascular and inner. Each of these layers has a
specialized structure and function.
Fibrous:
The fibrous layer of the eye is the outermost layer. It consists of the sclera and cornea, which are
continuous with each other. Their main functions are to provide shape to the eye and support the
deeper structures. The sclera comprises the majority of the fibrous layer (approximately 85%). It
provides attachment to the extraocular muscles – these muscles are responsible for the movement of
the eye. It is visible as the white part of the eye. The cornea is transparent and positioned centrally at
the front of the eye. Light entering the eye is refracted by the cornea.
Vascular:
The vascular layer of the eye lies underneath the fibrous layer. It consists of the choroid, ciliary body
and iris:
Choroid – layer of connective tissue and blood vessels. It provides nourishment to the outer layers of
the retina.
Ciliary body – comprised of two parts – the ciliary muscle and ciliary processes. The ciliary muscle
consists of a collection of smooth muscles fibres. These are attached to the lens of the eye by the
ciliary processes. The ciliary body controls the shape of the lens, and contributes to the formation of
aqueous humor
Iris – circular structure, with an aperture in the centre (the pupil). The diameter of the pupil is altered
by smooth muscle fibres within the iris, which are innervated by the autonomic nervous system. It is
situated between the lens and the cornea.
Inner:
The inner layer of the eye is formed by the retina; its light detecting component. The retina is
composed of two layers:
Pigmented (outer) layer – formed by a single layer of cells. It is attached to the choroid and supports
the choroid in absorbing light (preventing scattering of light within the eyeball). It continues around
the whole inner surface of the eye.
Neural (inner) layer – consists of photoreceptors, the light detecting cells of the retina. It is located
posteriorly and laterally in the eye.
Anteriorly, the pigmented layer continues but the neural layer does not – this is part is known as the
non-visual retina. Posteriorly and laterally, both layers of the retina are present. This is the optic part
of the retina.
Structures of the Eyeball:
Vitreous Body
The vitreous body is a transparent gel which fills the posterior segment of the eyeball (the area
posterior to the lens). It is marked by a narrow canal which runs from the optic disc to the lens – the
hyaloid canal. This is a fetal remnant.
The vitreous body has three main functions:
∙ Contributes to the magnifying power of the eye
∙ Supports the lens
∙ Holds the layers of the retina in place
Lens:
The lens of the eye is located anteriorly, between the vitreous humor and the pupil. The shape of the
lens is altered by the ciliary body, altering its refractive power. In old age, the lens can become
opaque – a condition known as a cataract.
Anterior and Posterior Chambers:
There are two fluid filled areas in the eye – known as the anterior and posterior chambers. The
anterior chamber is located between the cornea and the iris, and the posterior chamber between the
iris and ciliary processes.
The chambers are filled with aqueous humor – a clear plasma-like fluid that nourishes and protects
the eye. The aqueous humor is produced constantly, and drains via the trabecular meshwork, an area
of tissue at the base of the cornea, near the anterior chamber.
If the drainage of aqueous humor is obstructed, a condition known as glaucoma can result.
Detailed Eye Structure:
Questions:
1. Discuss focusing problem in human eye and describe how treat these focusing problems.
2. Discuss Optical illusions.
3. Discuss technology to fill color in blind person’s life. Draw a detailed block diagram to
illustrate the technology to aid blind person.
