Chapter 19

1. Visual and Auditory Systems Chapter 19

2. Objectives List both trade and generic drug names covered in this chapter. Describe the functions of the eyes and ears. List the major components of the eyes and ears. Explain the drug action of the medications listed.

3. Objectives (cont’d) Describe what causes glaucoma. Describe the different types of conjunctivitis and their treatments. List the various infections that affect the eyes and ears. Explain how medications work to relieve glaucoma.

4. Introduction Five main senses of body system are sight, hearing, touch, smell, taste. Two senses that can change life dramatically are seeing and hearing. Equilibrium is another sense that plays a role in the ability to balance.

5. The Eyes (Opthalmic System) Eyes link outside world to the mind. Images translate into impulses that create lasting memories in the mind. Three different levels of eye specialists: Opticians make lenses. Optometrists perform eye exams. Ophthalmologists are medical doctors.

6. Anatomy of the Eye Eyebrows shade eyes from light. Eyelashes (more than 2000) catch debris, keep eyes moist, shade the eyes. Orbit is bony socket that holds the eye. Eye position able to rotate 100 degrees laterally.

7. Anatomy of the Eye (cont’d) Eyelids: Eyelids have four layers (outer skin, muscles, connective tissue, conjunctiva. Layers allow the eyes to open and close. Blinking protects eyes from foreign objects. Lacrimal fluid cleanses the eye.

8. Anatomy of the Eye (cont’d) Conjunctiva is thin transparent layer, mucous membrane, covers anterior eyelids and sclera. Lacrimal gland, in orbit, secretes tear into eye; has ducts to nasal cavity. Lysozyme is enzyme in tears with antimicrobial properties.

9. Anatomy of the Eye (cont’d)

10. Anatomy of the Eye (cont’d) Cornea: transparent cover allows light into the eye Connective tissue covered with thin epithelial layer No blood vessels—nourished by aqueous humor (tissue fluid) and oxygen Nerve fibers sensitive to pain

11. Anatomy of the Eye (cont’d) Sclera: Attached to cornea; wraps around back of eyeball White portion of eye: many fibers and muscles with opening for optic nerve Optic nerve sends images to brain for interpretation

12. Anatomy of the Eye (cont’d) Choroid coat: layer inside sclera Fovea: innermost layer where sharpest vision occurs Sclera joins with iris and ciliary body in front of eye Iris: colored part of eye to filter light

13. Anatomy of the Eye (cont’d) Posterior cavity: largest space in eye; surrounded by lens, ciliary body, retina Ciliary body: forms ring around front of eye; holds lens in place Vitreous body: holds shape and form of eye Vitreous humor: nourishes and cleanses eye

14. Anatomy of the Eye (cont’d) Retina: Thin layer; contains layers of neurons, nerves, pigmented epithelium, membranous tissues Receptor cells responsible for vision Six muscles responsible for eye movements

15. Eye Muscles and Direction of Movement

16. Anatomy of the Eye (cont’d) Pupil: Dilates (mydriasis) when focusing on distant figure or darkness Constricts (miosis) in extreme light Aqueous humor provides the nutrients and oxygen to maintain lens and cornea.

17. Anatomy of the Eye (cont’d) Aqueous humor: Accumulates; must be released to maintain pressure Canal of Schlemm: ducts used to release aqueous humor Retina contains nerve endings to transmit electrical impulses to brain.

18. Vision Retina contains rods and cones responsible for vision. Rods: sight in dim light; produce black and white images. Cones detect color. Rods and cones synapse with nerve endings; signals sent through optic nerve to brain. Occipital lobe—visual interpretation.

19. Conditions That Affect the Eye New developments/treatments: Laser surgery-correct vision Lens implantation—for blindness Conditions: glaucoma, conjunctivitis, congestion of eye, viral and bacterial infections

20. Allergies With allergies,eyes become itchy, red and watery. Treatment includes: avoiding irritants, getting allergy shots, mast cell stabilizers, antihistamines, and decongestants.

21. Drug Treatment for Allergies • Mast cell stabilizers: prevent allergy cells from opening and releasing chemicals that cause inflammation. • Solutions, suspensions, systemic agents • Antihistamines and decongestants • alleviate symptoms of and inflammation. • Corticosteroids: relieve inflammation.

22. Conjunctivitis Conjunctivitis known as “pink eye.” Is common in daycare centers; contagious. Is acute inflammation of the conjunctiva. Causes include: viral, bacterial, fungal, allergies. Symptoms include: inflammation, itching, burning, white mucus. Wash hands and avoid touching the eyes.

23. Drug Treatment for Conjunctivitis No treatment for viral infection; antibiotics for bacterial infection Antiinfectives: vidarabine, natamycin, gentamicin, ciprofloxacin Ophthalmic sulfonamides Aminoglycosides Macrolides

24. Cataracts • Cataracts are characterized by a film over the eyes. • Vision becomes blurred; can lead to blindness. • Cause: formation of protein buildup onto the lens. • Eyeglasses/contacts can clear up vision problems. • Surgery

25. Cataracts (cont’d) • Mydriatic-cycloplegic drugs used to dilate eyes • Atropine, cyclopentolate, homatropine tropicamide

26. Glaucoma Pressure within the eyes is higher than normal (increased ocular pressure [IOP]). Two causes: overproduction of aqueous humor; blocked ducts that drain excess aqueous humor. Left untreated, causes blindness. Types of glaucoma include primary, acute congestive, and chronic simple.

27. Drug Treatment for Glaucoma β-adrenergic blockers: lower intraocular pressure Carbonic anhydrase inhibitors Miotics: reduce intraocular pressure Sympathomimetics: decrease aqueous humor Prostaglandin agonists: increase outflow of aqueous humor

28. Blindness • Blindness is partial or total lack of vision. • Blindness has many causes. • Macular degeneration - only peripheral vision • Retinitis pigmentosa: field of vision is limited to a small circular opening in the middle. • Most common treatment: eyeglasses.

29. Blindness (cont’d) Corneal transplant—may correct blindness. Stem cell transplant—may reverse blindness.

30. Miscellaneous Ophthalmic Agents Artificial tears bought OTC. Used to relieve dry eyes, irritation. Ingredients include: sodium chloride, buffers to adjust pH, additives to prolong effects. Dosage form is solution. Comes in various strengths, combinations.

31. Miscellaneous Ophthalmic Agents (cont’d) All contain sodium chloride and all used for same reasons. Artificial tear inserts available by prescriptions for dry eye syndrome, severe keratoconjunctivitis.

32. Artificial Tears Products Trade NameManufacturerIngredients Tear Drop Parmed Polyvinyl alcohol, NaCl, EDTA, benzalkoniumCl Artificial Tears Various mfg Polyvinyl alcohol, povidone, NaCl, chlorbutanol CellufreshAllerganCarboxymethylcellulose, NaCl, KCl, Na lactate Refresh Allergan Polyvinyl alcohol, povidone, NaCl Just Tears BlairexBenzalkoniumCl, EDTA, polyvinyl alcohol, NaCl Murine Ross Polyvinyl alcohol, povidone, benzalkoniumCl, dextrose, EDTA, NaCl, sodium bicarbonate, sodium phosphate RestasisAllergan Cyclosporine, glycerin, polysorbate,, carbomer, purified water, sodium hydroxide

33. The Ears (Auditory System) Human ear responsible for hearing, balance, equilibrium, communication skills. Ear is composed of three sections: external, middle, inner. External ear—auricle; composed of cartilage and skin; entrance for sound waves.

34. Anatomy of the Ear

35. External Ear Auditory canal: about 1 inch long; leads to tympanic membrane (eardrum). There are two major functions of tympanic membrane: protection of middle ear from foreign objects; transmission of sounds to middle ear. Sounds transmitted by vibrations. Cerumen is wax substance produced by glands.

36. Middle Ear Vibration carried to middle ear. Cavity (space) contains bony structures (ossicles): malleus, incus, stapes. Ossicles connected to each other. Eustacian tube: Eustacian tube eads to nasopharynx. It equalizes pressure between outside and inside atmosphere.

37. Inner Ear Stapes continues transfer of sound to inner ear. Fluid-filled cavity—labyrinth; comprise many components that process and transmit audible sounds via nerve impulses to brain. There are two areas: perilymph, membrane division.

38. Inner Ear (cont’d) Three main areas of the inner ear include: Cochlea Vestibule Semicircular canal

39. Conditions Affecting the Ear Various conditions affect quality of hearing: infections, ear wax accumulation, damage to eardrum, genetic defects. Most infections are viral but may lead to bacterial infection as well.

40. Deafness Causes include: aging, heredity, infections, loud noises, medications, trauma. Loud noises break hair-like structures in middle ear; do not regenerate No medication available—hearing aids, implants.

41. Otitis Media Otitis media is infection of the middle ear associated with inflammation of eustachian tube. Sore throat—can lead to middle ear infection—often seen in children. For reoccurring infections, insertion of small tubes by physicians to drain middle ear.

42. Drug Treatment for Otitis Media • Antiinfectives: treat infection • Antibiotics if infection is severe: amoxicillin or sulfamethoxazole/trimethoprim • Antihistamines, decongestants, and analgesics: treat symptoms

43. Cerumen Buildup Excessive wax builds up or dries—impedes hearing quality. Doctor removes wax buildup. Irrigation kit includes saline solution and ear syringe. Other treatments include: mineral oil, glycerin, or hydrogen peroxide in the ear to soften the wax.

44. Ototoxicity Ototoxicity caused by some drugs. Tinnitus—buzzing or ringing in ears—if untreated leads to permanent ear damage. Balance may also be affected. Prognosis: some cases reverse themselves; others cause permanent hearing loss.

45. Miscellaneous Otic Preparations Bacterial infections treated with bactericidal or bacteriostatic preparations. All ear agents—combinations—antibiotics, steroids, ear wax removers.