Ophthalmic Medication

This lecture will review opthalmic or eye medications. So let's review a little anatomy. We have the conjunctiva which is thin tissue that covers the sclera. The sclera is a hard protective layering on the outer eye or the white of the eye. The iris is the color part of the eye that adjusts light. the pupil is the black opening and the iris that lets light in. The aqueous humor is watery fluid between the cornea and the lens and the cornea is the outermost layer of layer of the eye which transmits light. So here's some more anatomy of the eye,. We have the lens which is behind the pupil. It focuses light. Vitreous humerus is thick fluid behind the lens and the posterior chamber. The retina is tissue at the back of the eye that acts like film to make an image. The rods and cones- the rods give us black and white vision and work with low-light and the cones work with color vision. Then we have the optic nerve which connects the eye to the brain and carries the impulse. You know doctors use a tonometer to measure the pressure in the eye. As healthcare professionals we need to encourage our older patients to see an ophthalmologist annually, because if pressure builds in the eye, it's usually because the aqueous or is not flowing out of the eye correctly. And, with increased intraocular pressure that can damage the optic nerve and lead to blindness. Glaucoma is the leading cause of blindness due to an increase in pressure in the eye which damages the optic nerve and its ability to transmit visual information from the eye to the brain. It's most common in patients with hypertension, diabetes, and advanced age. Primary open-angle glaucoma is the most common type of glaucoma. With open-angle, the scheme canal, which is the drainage tube for the aqueous humor, gets blocked and pressure builds up. There usually aren't any symptoms, but if not treated it can cause loss of vision. Glaucoma treatment usually starts with prescription topical eyedrops. Angle-closure is another type of glaucoma. This is where the iris is too small and it covers up the drainage canal. Pressure can rise rapidly and the patient can experience headaches, eye pain, nausea, and halos. Surgery is required for treatment. There are several types of glaucoma there's normal tension glaucoma, Congenital glaucoma, secondary glaucoma, and pigment area glaucoma. Secondary glaucoma is caused by medications, and it's usually temporary and subsides with discontinuation of the medication. Miotics are one of the major medications we use for glaucoma and they increase the outflow of aqueous humor. Isopto Carpine or the brand name pilocarpine is one of our prime miotics. These medications constrict the pupil (miotic little-o) constrict the pupil and because of the changes of visual acuity patient safety has to be considered. Okay next we have prostaglandins. Does this sound familiar? You know we talked about how the body makes prostaglandins in response to painful stimulus and it activates the inflammatory response. Well, there are many types of types of prostaglandins. The prostaglandins used for glaucoma, they dilate the meshwork of the anterior chamber and the schlemm canal and it decreases the pressure. An important side effect to note is that these medications can change the eye color! Note that they all end in PR P_R_O_S_T." Several other types of medication that can decrease the intraocular pressure by reducing the flow of aqueous humor. Think of ABCD. We have alpha blockers. These are your 'nidine's and the decrease pressure facilitate drainage, and they can have a mild effect on the heart. Beta blockers decrease production of the aqueous humor and are generally safe. Bu, they can't be absorbed systemically and cause hypotension. These are our " lol's" and we'll sure talk about these over the cardiovascular system medications. These are an anti-hypertensives. So we need to make sure though when we give these eye drops, that we apply gentle pressure in the inner eye to acclude that tear duct and prevent systemic circulation of these eyedrops. Carbonic anhydrase inhibitors also decrease production of intraocular fluid. The osmotic diuretics are frequently used in surgery and rapidly bring down the amount of aqueous humor. For eye and ear irritations, we can use drops appointments and injections. We can use pontocaines "caines" for local anesthetic for pain. And then we have the antibiotics like gentamicin, or tobramycin, erythromycin, that end in "myocin." There's also a topical NSAID for pain ketorolac and then again we have the glucocorticoids that end in O-N-E. Dexamethasone is an example of that. Pinkeye is also called conjunctivitis, and it can be viral or bacterial and can cause redness and swelling of the conjunctiva, the mucous membrane that lines the eyelid, and the eye surface. Gentamicin antibiotic ointment is a common treatment. Make sure though that you wash your hands vigorously with these patients because pinkeye is very contagious. A sty is a bacterial infection of the eyelid this can be treated with topical or oral antibiotics such as doxycycline. Here are some other eye medications. These medications we use for eye exams. The mydriatics are used to dilate the eye. For eye examinations staining agents are used to diagnose corneal defects or to find foreign objects. remember that mydriatics have a d for dilate the pupil and are motifs- little o they constrict the pupil. Artificial tears are lubricant eyedrops and they're used to treat dryness. They do not increase the body's ability to make their own tears. Restasis is an immunomodulator and these medications work by increasing tear production. Immunomodulators work by altering the immune system, they augment or reduce the ability of the immune system to produce antibodies or sensitized cells that recognize and react with an antigen that initiates their production. Other immunomodulators that we've talked about through our study of pharmacology include the corticosteroids and cytotoxic agents, which are used for chemotherapy. It's important that with these medications, they can cause ocular burning, itching, and stinging and they may take up to six months to see their maximum effect. That concludes our section on ophthalmic medications.

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