Eyes and Ears Flashcards
what are the two chambers that the eyes are divided into?
aqueous and vitreous chambers
aqueous chamber contains watery aqueous humor
vitreous chamber contains gelatinous vitreous body
globe
multi-layered sphere that makes up the majority of the eye
sclera
outer layer of the globe
cornea
transparent anterior portion of the sclera
choroid
middle layer of the globe
contains iris, pupil, lens, and ciliary body
iris
pigmented, helps regulate the amount of light entering the pupil
pupil
circular opening in the center of the iris
lens
clear, flexible, curved capsule behind the iris/pupil
responsible for focusing
ciliary body
extension of the choroid that assists in accommodation of the lens
uvea
iris, ciliary body, and choroid
retina
inner layer of the globe
receives images
contains rods and cones that convert visual images into nerve impulses that travel to the brain through the optic nerve
functions of ophthalmic drugs
treat infections, reduce inflammation, decrease pain, dilate/constrict pupil, decrease intraocular pressure, increase eye lubrication
how do ophthalmic drugs work?
topicals penetrate the cornea by diffusion and tend to be absorbed into the anterior chamber
water soluble drugs: penetrate cornea and reach their target tissue through the blood
lipid soluble drugs: penetrate the corneal epithelium and reach target tissue by diffusion
diagnostic drugs
used to locate lesions/foreign objects in the eye
topical anesthetics
numbs eyes
effective in 5-10 minutes
lasts up to 2 hours
store in fridge away from light
ex: Proparacaine, Hydrochloride, Tetracaine hydrochloride
Fluorescein sodium
diagnostic drug
aka Fluorescein stain
detects corneal abrasions, ulcers, foreign bodies
stain will appear in nasal secretions too
Schirmer tear test strips
diagnostic drug
used to diagnose keratoconjunctivitis sicca (KCS)
blue dye released when they become wet and held in eye for 1 minute
only used in dogs
< 10mm/min = KCS
mydriatic drugs function
pupil opening/dilating
used along or in combination with cycloplegics (which paralyze ciliary muscles that control lens shape) and decrease pain
used to reduce inflammation, as pre-op for ocular surgery, to sever or prevent adhesions between iris and lens
Atropine
anticholinergic mydriatic drug
produces mydriasis and cycloplegia
treats acute inflammation of anterior uvea
peak effect: 30-40 minutes for mydriasis, 1-3 hours for cycloplegia
contraindictions: glaucoma, KCS
Homatropine, Isopto Homatropine, Homatropine Ophthalmic
anticholinergic mydriatic drugs
produces mydriasis and cycloplegia
used for eye exams
treats uveitis
faster onset and shorter duration than Atropine
Phenylephrine
direct-acting alpha-1 sympathomimetic mydriatic drug
produces mydriasis only
used to dilate pupils prior to cataract removal
evaluates Horner’s Syndrome
causes local vasoconstriction
Tropicamide
acetylcholine receptor blocker mydriatic drug
used for fundic exam
rapid onset and short duration
slight cycloplegia effect
contraindications: glaucoma, KCS
miotic drug functions
pupil closing/constricting drugs
cholinergics
used to treat open-angle glaucoma by lifting the iris away from the filtration angle area to allow aqueous humor to flow out
Pilocarpine
topical cholinergic miotic drug
onset: 10-30 minutes
duration: 4-8 hours
primary glaucoma
acquired structural defect
secondary glaucoma
ocular disease or trauma
congenital glaucoma
genetic defect
Prostaglandins
topical pressure reducing drugs
increase outflow of aqueous humor
Latantoprost: causes miosis, store in fridge
other ex: Bimatoprost, Travoprost
Carbonic anhydrase inhibitor (CAI) functions
inhibit enzyme systems involved in the production of aqueous humor which decreases aqueous humor formation
oral or parenteral
takes 4-5 days to reach maximum effects
topical CAIs: Brinzolamide, Dorzolamide
systemic CAIs: Acetazolamide, Dichlorphenamid, Methazolamide
Beta-adnergic blockers
pressure reducing drugs
decrease aqueous humor production
sympatholytic drugs
caution with cardio patients
treats primary glaucoma
-lol
Alpha-adnergic agonists
pressure reducing drugs
reduce aqueous humor secretion
sympathomimetic drugs
typically combined with other drugs
ex: Apraclonidine, Brimonidine
Osmotic diuretics
pressure reducing drugs
promotes release of water from tissues
used before surgery or as an ER treatment for glaucoma
given IV
ex: Mannitol
Dry eye correcting drug functions
treats KCS
pressure reducing drug functions
treats glaucoma
keratoconjunctivitis sicca (KCS)
decreased tear production resulting in persistent mucopurulent conjunctivitis and corneal scarring and ulceration
thought to be immune related
use of Sulfonamides may cause
Immunomodulating drug functions
dry eye correcting drugs
decrease immune response to a desired level
Cyclosporine (Optimmune)
immunomodulating dry eye correcting drug
interferes with interleukin production by T lymphocytes, stops local inflammation, improves tear production
local, no systemic absorption
Tacrolimus
immunomodulating dry eye correcting drug
used in cyclosporine-resistant cases of KCS
compounded to an ophthalmic aqueous suspension
used extra-label in vet
Lacrimogenic drug functions
increase tear production by stimulating the parasympathetic nervous system
Pilocarpine
lacrimogenic dry eye correcting drug
formerly used topical and oral
Artificial tears
lacrimogenic dry eye correcting drug
isotonic solution, pH buffered, lubricant for dry eyes, OTC
antibiotic-glucocorticoid preparations
lacriomogenic dry eye correcting drug
treats bacterial infections, decreases inflammation due to KCS
only use if there aren’t any corneal ulcers
topical antibacterial agents
used to treat bacterial infections, decrease inflammation of the eye, and relieve allergic conditions
ex: triple antibiotic ointments (Neomycin, Bacitracin, Polymyxin B)
topical agents with steroids
typical antibiotic + glucocorticoid
only use if there aren’t any corneal ulcers
common steroids used: Prednisolone, Hydrocortisone, Dexamethasone
common ear issues
infection/infestation (bacteria, yeast, mites), trauma (ear hematoma), allergies (inflammation, itching)
what is the key to controlling otitis?
determine the primary cause
perform a physical exam with otoscope and check tympanic membrane
perform diagnostic testing: ear cytology (yeast vs bacteria) and ear culture (antibiotic resistant?)
otic drug classes
class 1: topical antifungals
class 2a: topical antibiotics
class 2b: topical antibiotics (long-acting)
class 3: antiparasitics
class 1 otic drugs
topical antifungals
used to treat yeast infections
-azole drugs
ex: Nystatin
super common ones: Clotrimazole, Thiabendazole
class 2a otic drugs
topical antibiotics
can be combined with steroids
some are the same as antifungals and can treat both
some are ototoxic (= harmful to inner ear)
ex: Gentamicin (ototoxic), Neomycin (ototoxic), Thiostrepeon (ototoxic), Enrofloxacin, Orbifloxacin
class 2b otic drugs
topical antibiotics (long-acting)
meds applied once or twice and last long term
clients instructed not to clean/medicate at home after leave in med is applied
ex: Florfenicol (can treat yeast as well)
glucocorticoids sometimes used with antibacterials/antifungals to reduce inflammation (ex: Fluocinolone, Mometasome, -sone/-lone)
