Ophtalmotoxicity

Prepared by :Moslah Serine

2nd LF (S.B)

I-Introduction: vision is one of

the most useful senses

allow a person to experience the color and form of the environment

allows the recognition of approaching dangers.

The human body is equipped with two eyes to provide binocular vision.

The eye functions in many

ways to produce images that enhance, assist and alert.

II-Presentation of the eye The eyes are undoubtedly

the most sensitive and delicate organs we possess, and perhaps the most amazing. 

They present us with the window through which we view the world, and are responsible for four fifths of all the information our brain receives – which is probably why we rely on our eyesight more than any other sense.

III-Anatomy of an eye:

III-Anatomy of an eye: The cornea and

sclera are the two parts of the outermost layer of the eye The sclera appears white and contains blood vessels, while the cornea is transparent to allow light into the eye.

1-Visible Portion of the eye

III-Anatomy of an eye:

The lens of the eye helps to focus light entering the eye. It is held in place by a suspensory ligament and the ciliary body.

Retina is a light-sensitive layer of tissue, lining the inner surface of the eye

2-Interior Portion

IV-Principals physiologic functions:

The eye functions similar to that of a camera.

Just as light passes through a lens, which is then focused at the back of the camera, the eye focuses light through a lens onto the back of the eye, where it is converted to nerve impulses that the brain perceives as sight and interprets it so that we are aware of what we are seeing.

EYE function

Eye Movement:The eyes must move in order to focus light upon the retina

to perceive the object of interest.

Light Detection

Light Refraction Light enters the eye and is refracted by the cornea and lens

Light Attenuation to maintain focus and to protect the structures of the eye from harmful ultraviolet rays.

Color and Brightness Special photoreceptors within the retina,

called cones, detect different wavelengths of light.

V-Main toxic altering the eye

Eye Toxicity results from: Direct contact or internal distribution to the eye. Many household items can cause conjunctivitis. Chemicals in the circulatory system can distribute

to the eye. Medications. Radiation.

Resault: corneal opacity, cataracts, retinal and

optic nerve damage…

1- Radiation Most UV light from the sun is

filtered out by the atmosphere but airline pilots often have high rates of cataract because of the increased levels of UV radiation in the upper atmosphere

Ultraviolet light, specifically UV-B, has been shown to cause cataract and there is some evidence that sunglasses worn at an early age can slow its development in later life.

Cataract A cataract is a

clouding of the lens inside the eye which leads to a decrease in vision. It is the most common cause of blindness and is conventionally treated with surgery.

Cataract It is most

commonly due to biological aging but there are a wide variety of other causes:

Radiation Medications

Medications  Some drugs, such

as corticosteroids, and the antipsychotic drug quetiapine can induce cataract development.

2-Corticosteroids

Corticosteroids are a class of chemicals that includes steroid hormones naturally produced in the adrenal cortex of vertebrates and analogues of these hormones that are synthesized in laboratories.

Synthetic pharmaceutical drugs with corticosteroid-like effects are used in a variety of conditions, ranging from brain tumors to skin diseases.

Use of corticosteroids has several severe side-effects as for example: 

Hyperglycemia Insulin resistance Diabetes mellitus   Retinopathy Cataract

Anxiety Depression  Colitis

Hypertension

3-Methanol (wood alcohol)

Methanol, also known as methyl alcohol, wood alcohol, wood naphtha or wood spirits, is a chemical with the formula CH3OH 

Methanol is the simplest alcohol, and is a light, volatile, colorless, 

flammable liquid with a distinctive odor very similar to, but slightly sweeter than ethanol (drinking alcohol).

Feedstock The largest use of

methanol by far is in making other chemicals. About 40% of methanol is converted to formaldehyde

and from there into products as diverse as plastics, plywood and paints,explosives.

Fuel for vehicles Methanol is also

used, as the primary fuel ingredient since the late 1940s, in the powerplants forradio control, control line and free flight airplanes

Methanol has a high toxicity in humans. If as little as 10 mL of pure methanol is ingested, for example, it can break down into formic acid, which can cause permanent blindness by destruction of the optic nerve.

Toxic effects take hours to start, and effective antidotes can often prevent permanent damage. 

 What is Optic Nerve Damage?

Any damage or death to the tissue that composes the optic nerve can result in permanent loss of vision. Damage can occur to the optic nerve either functionally or structurally. When optic nerve damage occurs, the result can be temporary or permanent vision loss. Damage can occur because of diseases, injuries, and side effects of drugs.

Conclusion Eyes are very important to us, so

we have to be careful to look after them. They show us our world and they show others how we are feeling. When we talk to other people, we notice what their eyes are saying as well as what they are saying with their mouths.

Because eyes are so precious, we need to really take care of them.

How to do so??!!Never stare into direct

sunlight or at any object reflecting the sun's rays

Invest in a pair of good-quality sunglasses

Even if you're wearing sunglasses, never look directly at the sun.

Clean those eyes. If anything that isn't completely sterile/clean gets in your eyes, flush them with water immediately.

Eat lots of fruits and veggies. Like carrots.

Take lots of vitamin A!