Ophtalmotoxicity

1. Preparedby : MoslahSerine 2nd LF (S.B) Ophtalmotoxicity

2. 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.

3. II-Presentationof 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.

4. III-Anatomyof an eye:

5. III-Anatomyof 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

6. III-Anatomyof 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. Retinais a light-sensitive layer of tissue, lining the inner surface of the eye 2-Interior Portion

7. IV-Principalsphysiologicfunctions: • 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.

8. Eye Movement:The eyes must move in order to focus light upon the retina to perceive the object of interest. • Light Detection • EYE function • 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.

9. V-Main toxicaltering 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…

10. 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.

12. 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.

13. Cataract • It is most commonly due to biological aging but there are a wide variety of other causes: • Radiation • Medications

14. Medications • Some drugs, such as corticosteroids, and the antipsychotic drug quetiapine can induce cataract development.

15. 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.

16. Use of corticosteroids has several severe side-effects as for example:  • Hyperglycemia • Insulin resistance • Diabetes mellitus  •  Retinopathy • Cataract

17. Anxiety • Depression  • Colitis • Hypertension

18. 3-Methanol (wood alcohol) • Methanol, also known as methyl alcohol, wood alcohol, wood naphtha or wood spirits, is a chemical with the formula CH3OH 

19. 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).

20. 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.

21. Fuel for vehicles • Methanol is also used, as the primary fuel ingredient since the late 1940s, in the powerplantsforradio control, control line and free flight airplanes

22. 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.

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

24. 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.

25. 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.

26. 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!