Ophthalmic and Otic Ophthalmic and Otic MedicationsMedications

Chapter 18Chapter 18

Basic Anatomy & PhysiologyBasic Anatomy & Physiology The ocular system is responsible for visionThe ocular system is responsible for vision The ocular system is comprised of the eyes The ocular system is comprised of the eyes

and adnexaand adnexa Globe consists of three layers:Globe consists of three layers:

• Sclera (white of the eye), choroid (middle, vascular Sclera (white of the eye), choroid (middle, vascular coat of the eye), and retina (“the film in the camera”)coat of the eye), and retina (“the film in the camera”)

Adnexa consists of the surrounding structures:Adnexa consists of the surrounding structures:• Orbit, eye muscles, eyelids, eyelashes, conjunctiva, Orbit, eye muscles, eyelids, eyelashes, conjunctiva,

and lacrimal apparatusand lacrimal apparatus

Basic Anatomy & PhysiologyBasic Anatomy & Physiology

Ophthalmic DrugsOphthalmic Drugs Things to consider when using topical Things to consider when using topical

ophthalmic drugsophthalmic drugs Drug penetrationDrug penetration - They must be absorbed into - They must be absorbed into

the anterior chamberthe anterior chamber Frequency of drug applicationFrequency of drug application - They may be - They may be

administered at different frequencies depending administered at different frequencies depending on whether they are in ointment or solution formon whether they are in ointment or solution form

Ease of applicationEase of application - They must be relatively - They must be relatively easy to administer so that client compliance easy to administer so that client compliance occursoccurs

Diagnostic Ophthalmic DrugsDiagnostic Ophthalmic Drugs Topical anesthetics such as Topical anesthetics such as proparacineproparacine and and

tetracainetetracaine are used to help perform are used to help perform comprehensive eye exams or to remove comprehensive eye exams or to remove foreign material from the eye.foreign material from the eye.

Corneal anesthesia is accomplished in about Corneal anesthesia is accomplished in about one minute and lasts for about ten minutes.one minute and lasts for about ten minutes.

Store open bottles in refrigerator.Store open bottles in refrigerator. Discard discolored solutions.Discard discolored solutions. Do not apply before performing STT!!!!Do not apply before performing STT!!!!

Tonometry (TonoPen®)Tonometry (TonoPen®)

Diagnostic Ophthalmic DrugsDiagnostic Ophthalmic Drugs Fluorescein sodium stain Fluorescein sodium stain is applied to the is applied to the

cornea (using sterile saline) to assess any cornea (using sterile saline) to assess any corneal defects (the stain is orange until it corneal defects (the stain is orange until it adheres to a corneal defect, where it appears adheres to a corneal defect, where it appears green)green)• Stain is fat soluble and therefore unable to Stain is fat soluble and therefore unable to

penetrate or adhere to intact cornea (can only penetrate or adhere to intact cornea (can only penetrate damaged tissues)penetrate damaged tissues)

• Stain should be washed from the eye before and Stain should be washed from the eye before and after examination is complete.after examination is complete.

• Use a Wood’s Lamp to examine eye for abrasions.Use a Wood’s Lamp to examine eye for abrasions.

Fluorscein StainFluorscein Stain

MioticsMiotics Cholinergic drugs Cholinergic drugs

that constrict the that constrict the pupilpupil

Used to treat open-Used to treat open-angle glaucoma angle glaucoma because they because they decrease intraocular decrease intraocular pressure.pressure.

An example is An example is pilocarpine pilocarpine (Piloptic®)(Piloptic®)

Miotics Constrict the PupilMiotics Constrict the Pupil

Mitotics vs. MydriaticsMitotics vs. Mydriatics

Mitotics Mitotics are cholinergic or sympatholytic are cholinergic or sympatholytic drugs.drugs.

Mydriatics Mydriatics are sympathomimetic or are sympathomimetic or anticholinergic drugs.anticholinergic drugs.

Mydriatics and CycloplegicsMydriatics and Cycloplegics MydriaticsMydriatics dilate the pupil dilate the pupil

and are used to aid in eye and are used to aid in eye exams, to relieve exams, to relieve inflammation associated with inflammation associated with uveitis (inflammation of the uveitis (inflammation of the iris, ciliary body, and choroid) iris, ciliary body, and choroid) and keratitis (inflammation of and keratitis (inflammation of the cornea), to break up or the cornea), to break up or prevent adhesions between prevent adhesions between the iris and the lens, and to the iris and the lens, and to prepare an animal for ocular prepare an animal for ocular surgerysurgery

CycloplegicsCycloplegics paralyze the paralyze the ciliary muscles and minimize ciliary muscles and minimize painpain

AtropineAtropine Anticholinergic drug used for Anticholinergic drug used for

treatment of acute treatment of acute inflammation of anterior uvea inflammation of anterior uvea and aid in exam of retinaand aid in exam of retina

Mydriasis and cycloplegiaMydriasis and cycloplegia Side effects = salivationSide effects = salivation Contraindications: glaucoma Contraindications: glaucoma

(increases intraocular (increases intraocular pressure); KCS (decreases pressure); KCS (decreases tear production)tear production)

Solution or ointmentSolution or ointment

HomatropineHomatropine Same uses, side Same uses, side

effects, and effects, and contraindications as contraindications as atropine.atropine.

Faster onset and Faster onset and shorter duration of shorter duration of action than atropineaction than atropine

Isopto Homatropine®Isopto Homatropine®

PhenylephrinePhenylephrine Sympathomimetic drug used Sympathomimetic drug used

to evaluate eye diseases to evaluate eye diseases such as uveitis and Horner’s such as uveitis and Horner’s syndromesyndrome

May be used prior to May be used prior to conjunctival surgery to conjunctival surgery to decrease hemorrhagedecrease hemorrhage

Mydriasis/no cycoplegiaMydriasis/no cycoplegia Produces vasoconstriction, Produces vasoconstriction,

ocular discomfort, tearing, ocular discomfort, tearing, and rebound miosisand rebound miosis

Mydfrin®Mydfrin®

Horner’s SyndromeHorner’s Syndrome Enophthalmos Enophthalmos

(backward displacement (backward displacement of eyeball into the orbit)of eyeball into the orbit)

Ptosis of the upper Ptosis of the upper eyelideyelid

Slight elevation of the Slight elevation of the lower lidlower lid

Constriction of pupilConstriction of pupil Narrowing of palpebral Narrowing of palpebral

fissurefissure

TropicamideTropicamide Used for fundic Used for fundic

examinationexamination Rapid acting mydriatic with Rapid acting mydriatic with

slight cycloplegic effect.slight cycloplegic effect. More rapid onset and More rapid onset and

shorter duration of action shorter duration of action than atropine.than atropine.

Side effects: local Side effects: local discomfort and salivationdiscomfort and salivation

Contraindicated in animals Contraindicated in animals with glaucoma or KCSwith glaucoma or KCS

EpinephrineEpinephrine Sympathomimetic Sympathomimetic

drug that reduces drug that reduces intraocular pressure intraocular pressure and produces and produces mydriasis.mydriasis.

Used to prevent Used to prevent glaucoma in the glaucoma in the unaffected eyeunaffected eye

May cause ocular May cause ocular discomfort.discomfort.

GlaucomaGlaucoma GlaucomaGlaucoma is a group of diseases that is a group of diseases that

increase intraocular pressure (drugs used increase intraocular pressure (drugs used to treat glaucoma decrease intraocular to treat glaucoma decrease intraocular pressure)pressure)

Primary glaucomaPrimary glaucoma: caused by an acquired : caused by an acquired structural defect within the eyestructural defect within the eye

Secondary glaucomaSecondary glaucoma: a consequence of : a consequence of another ocular disease or traumaanother ocular disease or trauma

Congenital glaucomaCongenital glaucoma: resulting from a : resulting from a genetic defectgenetic defect

If left untreated, glaucoma can result in If left untreated, glaucoma can result in blindness.blindness.

GlaucomaGlaucoma

Narrow vs Open-Angle Narrow vs Open-Angle GlaucomaGlaucoma

Aqueous humor is constantly produced Aqueous humor is constantly produced by ciliary process behind irisby ciliary process behind iris

Production is controlled by carbonic Production is controlled by carbonic anhydraseanhydrase

Once aqueous humor enters eye, it Once aqueous humor enters eye, it passes from posterior chamber, through passes from posterior chamber, through pupil, into anterior chamber, and is then pupil, into anterior chamber, and is then drained through drained through trabecular meshwork.trabecular meshwork.

When intraocular pressure increases, When intraocular pressure increases, outflow mechanism for aqueous humor outflow mechanism for aqueous humor is blockedis blocked

Narrow vs. Open-Angle Narrow vs. Open-Angle Glaucoma (cont’d)Glaucoma (cont’d)

If iris occludes trabecular meshwork, If iris occludes trabecular meshwork, normal outflow of humor is prevented, and normal outflow of humor is prevented, and animal is said to have animal is said to have narrow-angle narrow-angle glaucoma.glaucoma.

If there is no change in chamber angle of If there is no change in chamber angle of eye, but aqueous humor outflow is impeded eye, but aqueous humor outflow is impeded because of degenerative changes, animal because of degenerative changes, animal is said to have is said to have open-angle glaucoma.open-angle glaucoma.

Drugs Used to Treat GlaucomaDrugs Used to Treat Glaucoma MioticsMiotics: covered previously: covered previously Carbonic anhydrase inhibitorsCarbonic anhydrase inhibitors interfere with the interfere with the

production of carbonic acid, leading to a decrease production of carbonic acid, leading to a decrease of aqueous humor productionof aqueous humor production

• Examples include acetazolamide, dichlorphenamide, and Examples include acetazolamide, dichlorphenamide, and methazolamidemethazolamide

Beta-adrenergic blockersBeta-adrenergic blockers decrease production of decrease production of aqueous humor. Systemic side effects aqueous humor. Systemic side effects (bradycardia, hypotension, bronchospasms). Used (bradycardia, hypotension, bronchospasms). Used with primary glaucoma to prevent development of with primary glaucoma to prevent development of disease in both eyes. May cause blurred vision. disease in both eyes. May cause blurred vision.

• Examples include timolol maleate and betaxolol hydrochlorideExamples include timolol maleate and betaxolol hydrochloride

Drugs Used to Treat GlaucomaDrugs Used to Treat Glaucoma

Osmotic diureticsOsmotic diuretics: used prior to surgery or : used prior to surgery or as an emergency treatment of glaucoma.as an emergency treatment of glaucoma. Given IV to decrease vitreous humor volume Given IV to decrease vitreous humor volume

and rapidly decrease intraocular pressureand rapidly decrease intraocular pressure Side effects: electrolyte imbalances, Side effects: electrolyte imbalances,

cardiovascular problems, vomitingcardiovascular problems, vomiting• Examples include mannitol and glycerinExamples include mannitol and glycerin

Drugs used to treat KCSDrugs used to treat KCS KCSKCS is a disease in which tear production is is a disease in which tear production is

decreased, resulting in mucopurulent decreased, resulting in mucopurulent conjunctivitis and corneal scarring/ulcerationconjunctivitis and corneal scarring/ulceration

Examples of drugs used to treat KCS:Examples of drugs used to treat KCS:• Artificial tearsArtificial tears• Antibiotic-steroid preparationsAntibiotic-steroid preparations• Lacrimogenics (increase tear production) such as Lacrimogenics (increase tear production) such as

pilocarpinepilocarpine• Immunomodulators (interfere with interleukin Immunomodulators (interfere with interleukin

production by T-lymphocytes) such as production by T-lymphocytes) such as cyclosporinecyclosporine

Keratoconjunctivitis Sicca (KCS)Keratoconjunctivitis Sicca (KCS)

Schirmer Tear TestSchirmer Tear Test

Other Ophthalmic DrugsOther Ophthalmic Drugs Other ophthalmic drugs used to treat ocular Other ophthalmic drugs used to treat ocular

diseases include:diseases include: AntibioticsAntibiotics AntifungalsAntifungals AntiviralsAntivirals CorticosteroidsCorticosteroids NSAIDsNSAIDs Tear supplementsTear supplements

See Table 18-1 in your textbook for a list of See Table 18-1 in your textbook for a list of anti-infectives, anti-inflammatories, and tear anti-infectives, anti-inflammatories, and tear supplements used in veterinary medicinesupplements used in veterinary medicine

Basic Anatomy & PhysiologyBasic Anatomy & Physiology The ear is the sensory organ that allows hearing The ear is the sensory organ that allows hearing

and maintains balanceand maintains balance The ear is comprised of three parts:The ear is comprised of three parts:

Outer: pinna and external auditory canalOuter: pinna and external auditory canal Middle: tympanic membrane, auditory ossicles, Middle: tympanic membrane, auditory ossicles,

eustachian tube, oval window, and round windoweustachian tube, oval window, and round window Inner: vestibule, cochlea, and semicircular canalsInner: vestibule, cochlea, and semicircular canals

Otitis interna is an inner ear infectionOtitis interna is an inner ear infection Side effects include head tilt toward the infected side, Side effects include head tilt toward the infected side,

ataxia, nausea, and vomitingataxia, nausea, and vomiting

Basic Anatomy & PhysiologyBasic Anatomy & Physiology

Ear Infection vs Ear MitesEar Infection vs Ear Mites

Microscopic DifferenceMicroscopic Difference

Otic MedicationsOtic Medications Many drug combinations are used in veterinary medicine to Many drug combinations are used in veterinary medicine to

treat ear disease, including:treat ear disease, including: AntibioticsAntibiotics Antiparasitics Antiparasitics AntifungalsAntifungals Corticosteroids (in combination with anti-infectives)Corticosteroids (in combination with anti-infectives) Otic drying agentsOtic drying agents Otic cleansing agentsOtic cleansing agents Otic dewaxing agents (Otic dewaxing agents (cerumencerumen = earwax) = earwax)

Refer to Table 18-2 in your textbook for a complete list of Refer to Table 18-2 in your textbook for a complete list of otic drugsotic drugs

Epi-Otic & CerulyticEpi-Otic & Cerulytic

Propylene glycol & salicylic acid Ceruminolytic (propylene glycol, benzyl alcohol)

MilbeMite & AcarexxMilbeMite & Acarexx

Mometamax & SynoticMometamax & Synotic

The EndThe End