1. Drugs and Body Systems – Drugs Affecting the Special Senses: Eyes
Unit 15
Drugs and Body Systems – Drugs Affecting the Special Senses: Eyes

2. 1. Visual Senses (Eye) Eyes-housed in a bony socket of the face.
—Major Structures and Functions
Eyes-housed in a bony socket of the face.
Eyelids-cover the outer surface.
Conjunctiva-mucous membrane lining the inner surface of the eyelids and the anterior portion of the eyeball.
Lashes-whisk away dirt and dust, shade eye from light.
Lacrimal glands (inside corner of eyes)-produce tears.
Nasolacrimal duct-drains the fluid away from the surface of the eye down through the nose.

3. Eye structure—three layers
Sclera and cornea-outer layer—white of the eye. Cornea is the front portion of the sclera. Protects the delicate structures (retina). Cornea-clear surface of the anterior eye, covers the iris and lens.
Choroid, ciliary body, and iris-middle layer-highly vascular, nourish the eye.
Iris-pigmented circular muscle which adapts the eye to light and gives color to the eye. Contracts over the opening to the lens and posterior chamber, reducing the amount of light. Dilates to allow more light.
Pupil-opening in the center of the iris regulating the light to the lens and the retina.
Lens-clear disk-shaped structure behind the iris; elasticity allows it to change shape, focus image short and long distance.
Retina-inner layer-sensitive to light and contains the nerve endings which sense light and dark (rods) and colors (cones).
Rods and cones-come together and exit the eye at the back and form the optic nerve which connects to the brain.
Optic nerves-carry the "sight" messages back to the part of the brain which interprets it.

4. 2. Mechanisms of Sight
Light entering the eye passes through the cornea then the pupillary opening of the iris, on through the lens and the vitreous body to the retina.
Refraction is accomplished through the aqueous humor, lens, and vitreous body. Light is focused on the retina through changes in the curvature of the lens, because of the elasticity and contractility of the ciliary muscles.
Rods and cones are stimulated by the light (sensory receptors). Cones are concerned with color vision; rods are concerned with vision in dim light.
Sensory impulses are conveyed to the brain through the optic nerve where, in the visual area of the cerebral cortex of the occipital lobe, visual sensations are registered.
Shape —maintained by two major fluid-filled compartments.
Anterior or ocular chamber-in front of the lens. It is divided by the iris into the anterior and posterior chamber and is filled with watery aqueous humor.
Posterior chamber-behind the lens—filled with jelly-like vitreous humor.

5. 3. Effects of Aging on the Structures of Vision
Presbyopia-farsightedness that normally occurs with aging, usually after age 40. Near-focus capability is reduced due to loss of lens elasticity.

6. 4. Eye Disorders -General symptoms Blurred vision Loss of sight Pain
Bloodshot eyes
Abnormally dilated pupils
Nausea and vomiting
Terms and diseases
Diplopia-double vision-can also mean a CNS disorder.
Conjunctivitis-infections of the conjunctiva-membrane of the eye; may also be referenced as "pink eye."
Glaucoma-fluid that is made in the anterior cavity of the eye does not drain fast enough, so it builds up, causing the pressure in the eye to become too high. May cause blindness. Intraocular pressure (pressure within the eye) builds. Surgical, medical and laser therapies may be used. Types:
Chronic open-angle (high-pressure or normal pressure).
Pupillary block (acute, sub-acute, chronic angle-closure or combined).
Developmental (congenital, juvenile, others).
Associated with other ocular diseases.
Associated with elevated episcleral venous pressure.
Associated with inflammation and trauma.
Post intraocular surgery.

7. Dry eyes-individuals, as they grow older, may have insufficient tear production.
Floaters-cells in the form of specks that float across the visual field.
Photophobia—an extreme sensitivity to light.
Blepharitis-inflammation of the edges of the eyelids, involving the hair follicles and glands of the lids.
Sty-inflammation of a sebaceous gland of the eyelid.
Related medications and treatments:
Antibiotics-decrease bacteria growth in the eye, reduce inflammation. May be used for specific infection or as a preventative after cataract surgery. Can cause irritation or allergic response.
Neosporin Ophthalmic (combination of three antibiotics)
Steroids-reduce inflammation, reduce body's immune response.
Neo-Cortef
Sulfonamides/combinations-bacteriostatic, interfere with functioning of enzyme systems necessary for bacteria to grow and reproduce.
Sodium sulfacetamide (Sodium Sulamyd)

8. Glaucoma agents-
Miotics constrict the pupil to open drainage channels and promote decreased fluid in anterior chamber and decrease pressure. May cause eye pain, itching, blurring, dryness of the eye area, bitter taste, head ache.
Pilocarpine (IsoptoCarpine, Piloptic, Pilostat)
Mydriatics dilate the pupil. May cause blurred vision, headache, and light-sensitivity.
Atropine.
Homatropine (Isopto Homatropine)
Scopolamine (Isopto-Hyoscine)
Carbonic anhydrase inhibitors slow the production of aqueous humor. May raise blood sugar for those with diabetes. May increase risk of acidosis or trouble breathing for those with emphysema.
Acetazolamide (Diamox)
Bcta-adrenergic receptor blocking agent reduces intraocular pressure.
Timolol (Timoptic)
Nursing care and side effects:
Provide adequate lighting, especially at night.
Pain in the eye may be a sign of increasing pressure. Report this to the licensed nurse supervisor immediately.
Lubricating agents-provide moisture to the eye, similar to tears. Used temporarily after cataract surgery, with contact lenses and with artificial eyes.
Polymeric dextran, hydroxypropyl methylcellulose (Tears Naturale II)

9. 5. Terminology
-used to identify how to administer eye medication (based on Latin)
O.D.-right eye (oculus dexter)
O.S.-left eye (oculus sinister)
O.U.-both eyes (oculus unites)
Nursing care for eye medications:
May be applied as ointment or drops
Proper application is critical for effectiveness.
Watch for increased symptoms, irritation, other signs of possible drag allergy.
Special considerations:
Mucous membranes of the eye are the most sensitive in the body.
Absorption of drugs is rapid.
Ophthalmic ointments must be in contact with the eye for a longer time than drops. It can cause blurred vision for awhile after application.
Some eye drops cause stinging and discomfort to the eye. Warn the resident if this may occur.
Medications that dilate the pupil cause sensitivity to light. Tinted or sunglasses may be needed until effect wears off.