anatomy of eye, how we see & eye problems

Anatomy of Eye, How we see and eye problems

Nusrat ZerinFor BSEd course

Bangladesh Institute of Special Education

Anatomy of Eye

Outer eye: Eyelid, eyelashesInner eye: Eye ball, optic nerve

Three different layers of eye:

1. The external layer - Sclera (white & gives eye it’s shape)

2. The intermediate layer – Choroid (contains blood vessel)

3. The internal layer - Retina the sensory part of the eye

The eye has a number of components 1. Sclera2. choroid3. Retina4. Conjunctiva5. Cornea6. Iris7. Pupil8. Lens9. Macula10. optic nerve11. Vitreous body12. Aqueous body13. Optic nerve

Three chambers of fluid: 1. Anterior chamber (between cornea and

iris)2. Posterior chamber (between iris and lens) 3. Vitreous chamber (between the lens and

the retina).

The first two chambers are filled with aqueous humor the vitreous chamber is filled with a more sticky fluid, the vitreous humor.

Cornea: clear front window of the eye that transmits and main function is refraction & transfer light into the eye, .Conjunctiva: transparent layer covers cornea and sclera, contribute to tear production & protect eye from infectionIris: colored cell of the eye that helps regulate the amount of light that entersPupil: dark aperture/hole in the iris that determines how much light is let into the eye (adjust light entry)Ciliary body: joins Iris with Choroid & makes aqueous humourLens: transparent structure inside the eye that focuses light rays onto the retinaRetina: nerve layer that lines the back of the eye, senses light, and creates electrical impulses that travel through the optic nerve to the brainMacula: small central area in the retina that contains special light-sensitive cells and allows us to see fine details clearlyOptic nerve: connects the eye to the brain and carries the electrical impulses formed by the retina to the visual cortex of the brainVitreous: clear, jelly-like substance that fills the middle of the eye

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How we see-

Vision problems:1. Myopia: Myopia (nearsightedness) is a refractive error, which

means the eye does not bend or refract light properly.

2. Hyperopia: Hyperopia (farsightedness), is a refractive error, which means that the eye does not bend or refract light properly to a single focus to see images. It occurs when the eye is shorter than normal or has a cornea (clear front window of the eye) that is too flat.

3. Astigmatism: Astigmatism is an imperfection in the curvature of your cornea — the clear, round dome covering the eye's iris and pupil — or in the shape of the eye's lens.

Causes of vision loss

- Congenital

- Disease (Cataract, vit A deficiency, myopia, hyperopia, astigmatism, lazy eye, albinism, Glaucoma, Trachoma, dry eye, diabetic retinopathy, Retinitis pigmentosa)

- Accidents / trauma

Types of vision loss

• Total blind• Low vision