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Chapter 49 Drugs for Eye & Ear Disorders
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Aqueous humor: a fluid in the anterior cavity of the eye
o has 2 divisions
 Anterior chamber – extends from the cornea to the anterior iris
 Posterior chamber – lies between the posterior iris and the lens
o Formed by the ciliary body: a muscular structure in the posterior chamber
o Helps retain the shape of the ye and circulates to bring nutrients to the area
and removes wastes
o From its origin in the ciliary body, aqueous humor flows from the
posterior chamber through the pupil into the anterior chamber
o Within the anterior chamber & around the periphery is a network of
spongy CT (trabecular network), that contains an opening called the
canal of Schlemm
o The aqueous humor drains into the canal of Schlemm & out the anterior
chamber into the venous system
Glaucoma: an eye disease caused by damage to the optic nerve that results in gradual
loss of vision & possibly advancing to blindness; accompanied by increased intraocular
pressure (IOP)
 Occurs when the IOP becomes so high that it causes damage to the optic nerve
 Median IOP is 15-16 mmHg, normal pressure varies greatly with age, daily activities,
and even time of day
 IOPs consistently above 21mmHg are considered abnormal & at risk
 IOPs above 30mmHg require treatment because they are associated with permanent
vision changes
 Usually occurs in primary conditions without an identifiable cause
o Found in persons older than 60 years
o Associated with genetic factors
o It can be congenital & occur in young children
 Can also be secondary to…
o Eye trauma, Infection, Diabetes
o Inflammation, Hemorrhage, Tumor, cataracts
 Some medications can contribute to the development or progression of glaucoma,
including the long-term use of topical corticosteroids
 antihypertensives, antihistamines, and antidepressants
 Major risks factors = high blood pressure, migraine headaches, high degrees of
nearsightedness or farsightedness, and normal aging
 Leading cause of preventable blindness
Types of Glaucoma
o Buildup of aqueous humor in the anterior cavity
o Caused by either excessive production of aqueous humor or by blockage
of its outflow
o IOP increases, leading to progressive damage to the optic nerve
o As degeneration of the optic nerve occurs, the patient will first notice a
loss of central visual acuity & finally total blindness
o Major differences = how quickly IOP develops and whether there is
narrowing of the anterior chamber angle between the iris & cornea
 Closed-angle glaucoma
Chapter 49 Drugs for Eye & Ear Disorders
o Also called narrow-angle glaucoma accounts for only 5% of all primary
glaucoma
o Usually unilateral and maybe caused by stress, impact injury, or
medications
o Caused by the normal thickening of the lens and may develop
progressively over several years
o Pressure inside the anterior chamber increases suddenly because the iris is
being pushed over the area where the aqueous humor normally drains
o Signs & Symptoms – dull to severe eye pain, headaches, bloodshot eyes,
foggy vision with halos around bright lights, and a bulging iris
o Options include iridectomoy, laser trabeculoplasty, trabeculectomy, and
drainage implants
 Open-angle glaucoma
o Cause not known; accounts for 90% of glaucoma cases
o Usually bilateral, with intraocular pressure developing over years
o Called “open-angle” because the iris does not cover the trabecular
meshwork, it remains open
Glaucoma Pharmacotherapy
 Expensive, potential for adverse drug effects, carefully monitor the patient
 Wait until the IOP rises to 28-30mmHg before initiating drug therapy
 If signs of optic nerve damage or visual field changes are evident, the patient is
treated regardless of the IOP
 Drugs for glaucoma work by 1 of 2 mechanisms
o Increasing the outflow of aqueous humor at the canal of Schlemm
o Decreasing the formation of aqueous humor at the ciliary body
 Many agents for glaucoma act by affecting the autonomic nervous system
Antiglaucoma Drugs – topical drugs are most frequently prescribed, oral medications are
available for severe disease
 Prostaglandins
o Long duration of action, produce fewer side effects, drug of choice
o Monotherapy or combined with beta-adrenergic blockers to produce an
additive reduction in IOP in patients with resistance glaucoma
o Decrease IOP by enhancing the outflow of aqueous humor
o Latanoprost (Xalatan) eye drop solution
o Adverse effects = heightened pigmentation, which turns a blue iris to a
more brown color, thicker & longer eyelashes, local irritation, stinging of
the eyes, and redness during the 1st month
 Autonomic Drugs – a significant number of autonomic agents have been used to
treat glaucoma and to aid in ophthalmic examinations of the eye
o Beta-Andrenergic Blockers
 Drug of choice for open-angle glaucoma
 Decrease the production of aqueous humor by the ciliary body
 Can lower IOP by 20 – 30%
 Produces fewer ocular adverse effects
 Adverse effects = bronchoconstruction, dysrhythmias, and
hypotension
Chapter 49 Drugs for Eye & Ear Disorders
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 Caution in patients with asthma or heart failure
o Alpha2-Andrenergic Agonists
 Act by decreasing the production of aqueous humor
 Only 2 are currently approved for open-angle glaucoma but neither
is frequently prescribed
 Apraclonidine (Iopidine) – reduction in IOP during or following
eye surgery
 Brimonidine (Alphagan) used as an adjunct in combination with
other Antiglaucoma agents
 Adverse Effects = allergic reactions, headache, drowsiness, dry
mucosal membranes, blurred vision, and irritated eyelids
o Cholinergic Agonists
 Activate cholinergic receptors in the eye & produce miosis,
constriction of the pupil, and contraction of the ciliary muscle
 These actions physically pull open the trabecular meshwork to
allow greater outflow of aqueous humor and a lowering of the IOP
 Pilocarpine (IsoptoCarpine)
 Adverse Effects = headache, induced myopia, and decreased vision
in low light
 Greater toxicity, normally only used in patients with open-angle
glaucoma
o Nonselective Sympathomimetics
 Activate the sympathetic nervous system to produce mydriasis
(pupil dilation), which increases the outflow of aqueous humor,
resulting in a lower IOP
 Not as effective as beta-adrenergic blockers or prostaglandins
 Dipivefrin is converted to epinephrine in the eye
 If epinephrine reaches the systemic circulation, it increases blood
pressure and heart rate
Carbonic Anhydrase Inhibitors (CAIs)
o Topically or systemically to reduce IOP in patients with open-angle
glaucoma
o Act by decreasing the production of aqueous humor
o Dorzolamide (Trusopt) topical, treats open-angle glaucoma
o Advesre Effects = photosensitivity
o Acetazolamide (Diamox) oral, very effective at lowering IOP
o Systemic effects = lethargy, nausea, vomiting, depression, paresthesias,
and drowsiness
o Serum electrolytes should be monitored during treatment
Osmotic Diuretics
o Used preoperatively and postoperatively with ocular surgery or as
emergency treatment for acute closed-angle glaucoma attacks
o Isosorbide (Ismotic) quickly reduces plasma volume; effective in reducing
the formation of aqueous humor
Chapter 49 Drugs for Eye & Ear Disorders
o Adverse effects = headache, tremors, dizziness, dry mouth, fluid &
electrolyte imbalances & thrombophlebitis or venous clot formation near
the site of IV administration
Pharmacotherapy for Eye Exams & Minor Eye Conditions
 Mydriatic drugs: dilate the pupil to allow better assessment of retinal structures
o Cause intense photophobia nad pain in response to bright light
o Can worsen glaucoma by impairing aqueous humor outflow and thereby
increasing IOP
 Cycloplegic drugs: mot only dilate the pupil but also paralyze the ciliary muscle and
prevent the lens from moving during assessment
o Cause severe blurred vision and loss of near vision
 Vasoconstrictors are commonly used to treat minor eye irritation
o Phenylephrine (Neo-Synephrine)
o Naphazoline (Clear Eyes)
o Tetrahydrozoline (Visine)
o Adverse Effects = blurred vision, tearing, headache, and rebound
vasodilation with redness
 Conjunctivitis: an inflammation or infection of the lining of the eye
o Topical corticosteroids and NSAIDs are used to treat conjunctivitis and
other inflammatory conditions
Ear Conditions
 The ear has 2 major sensory functions
o Hearing
o Maintenance of the equilibrium & balance
 3 structural areas carry out these functions
o Outer ear
o Middle ear
o Inner ear
Pharmacotherapy with Otic Preparations
 Otis: inflammation of the ear
 External otitis: (swimmer’s ear) inflammation of the outer ear that is most often
associated with water exposure
 Otitis media: inflammation of the middle ear, most often associated with upper
respiratory infections, allergies, or auditory tube irritation
o Treated with a course of systemic antibiotics
o Amoxicillin, at a dose of 80-90mg/kg/day is prescribed for most children
o Drugs for pain, edema, and itching may also be necessary
 Mastoiditis: inflammation of the mastoid sinus
o can be a serious problem because if left untreated, it can result in hearing
loss
o frequently the result of chronic or reoccurring bacterial otitis media
o infection moves into the bone & surrounding structures of the middle ear
o treatment involves aggressive antibiotic therapy
o IV gentamicin or ticarcillin may be used initially
 Chloramphenicol (Pentamycetin) topical otic antibiotics
 Cerumen (ear wax) softener are also used for proper ear health