Lecture 2 1/28/25

Question 1

What are the characteristics of ophthalmic solutions?

Answer 1

-safer when ocular integrity is questionable
-shorter contact time; does not last as long

Question 2

What are the characteristics of ophthalmic ointments?

Answer 2

-cause severe uveitis if they enter the globe; should not be used when ocular integrity is compromised
-longer contact time; longer lasting

Question 3

What are the characteristics of ophthalmic antimicrobial pharmacology?

Answer 3

-choose antibiotics based on C&S when possible
-base drug choice on cytology while waiting on C&S
-topical formulations can be prepared from IV preparations
-fortified concentrations can be made
-oral antibiotics may be indicated in perforations, eyelid disease, nasolacrimal disease, and vitreal infections

Question 4

What are the components of triple antibiotic?

Answer 4

-neomycin
-polymyxin B
-bacitracin

Question 5

Why is triple antibiotic routinely used for prophylaxis?

Answer 5

the combined drugs have a range that covers both gram + and gram - bacteria while rarely having resistance

Question 6

What are the characteristics of aminoglycosides?

Answer 6

-covers gram - bacteria
-tobramycin is best choice; not toxic to corneal epithelium

Question 7

What are the characteristics of chloramphenicol?

Answer 7

-covers gram +, some gram -, and mycoplasma
-does NOT cover pseudomonas
-penetrates deep into cornea even when cornea is intact
-not commonly used due to risk of causing aplastic anemia

Question 8

What are the characteristics of cephalosporins?

Answer 8

-covers gram + and gram -
-low efficacy against pseudomonas
-can be mixed from pre-op cefazolin into an eye drop

Question 9

What are the characteristics of fluoroquinolones?

Answer 9

-broad gram + and gram - spectrum, including mycoplasma and chlamydia
-reserved for severe infections; not for prophylaxis
-good penetration of intact epithelium

Question 10

When is oxytetracycline/terramycin used?

Answer 10

indolent ulcers in dogs

Question 11

What are the characteristics of serum as an anticollagenase agent?

Answer 11

-contains alpha macroglobulins that decrease matrix metalloproteinase activity; stops ulcer progression
-serum can be harvested from a healthy donor dog and frozen for a few months at a time
-important to not use cat serum for cats without running tests for infectious dz

Question 12

Why must artificial tear gels and ointments be used in dogs instead of drops?

Answer 12

-drops have too brief of an effect to be useful
-ointments last the longest, while gels are less oily

Question 13

What are the characteristics of atropine?

Answer 13

-onset of action is 1-2 hours in normal eyes
-duration of action is several days to several weeks in normal eyes
-uveitis prolongs onset of action and decreases duration of action
-should be avoided in glaucoma patients
-can cause decreased tear production

Question 14

What is the action of atropine?

Answer 14

-paralyzes ciliary muscle to decrease pain
-paralyzes iris sphincter muscle to dilate pupil

Question 15

What are the characteristics of tropicamide?

Answer 15

-routinely used for ophthalmic examinations
-onset of action of 10-20 minutes
-duration of action of 6-12 hours
-may not work in eyes with uveitis
-more safely used in glaucoma patients

Question 16

What are the characteristics of proparacaine?

Answer 16

-topical anesthetic
-begins working almost immediately and lasts for about 20 minutes
-cannot be prescribed for home use; epithelial toxic
-should not be applied prior to a schirmer’s tear test

Question 17

What is corneal ulceration?

Answer 17

lesion of the cornea that is a result of the loss of corneal epithelium +/- loss of stroma

Question 18

How can loss of stroma be determined when looking at a corneal ulcer?

Answer 18

the ulcer will have a “scooped out” appearance

Question 19

What are the four things that must be assessed about an ulcer?

Answer 19

-cause (most important part of evaluation)
-ulcer depth
-presence/absence of infection and matrix metalloproteinases
-rate of progression

Question 20

What are the clinical signs associated with corneal ulcers?

Answer 20

-blepharospasm/squinting
-epiphora/excessive tearing
-corneal edema
-corneal vascularization

Question 21

What causes pain from corneal ulcers?

Answer 21

-the cornea itself due to damaged nerve endings
-the ciliary body

Question 22

What are the characteristics of fluorescein stain?

Answer 22

-diagnostic modality of choice for corneal ulcers
-fluorescein is hydrophilic and is taken up by the stroma
-descemet’s membrane and the epithelium are lipophilic and do not take up stain
-ulcer will appear green; color is accentuated by a cobalt blue light filter

Question 23

What are the causes of corneal ulcers?

Answer 23

-trauma
-eyelash abnormalities
-eyelid abnormalities
-foreign bodies
-keratoconjunctivitis sicca/dry eye
-indolent ulceration

Question 24

What is most important regarding treatment of ulcers that result from trauma?

Answer 24

-want to prevent infection in newly formed ulcers; treat with triple antibiotic ointment
-use atropine drops in clinic to prevent pain

Question 25

How can an ulcer be determined to be chronic?

Answer 25

the presence of blood vessel formation within the cornea/surrounding the ulcer

Question 26

What are ectopic cilia?

Answer 26

cilia originating from the tarsal gland that emanate from palpebral conjunctiva

Question 27

What is the treatment for ectopic cilia?

Answer 27

excise cilia en bloc from conjunctiva using a derm punch; monitor patient at future appointments for growth of more cilia

Question 28

What is entropion?

Answer 28

in turning of the eyelid margin, which results in hairs rubbing the cornea

Question 29

What are the types of entropion?

Answer 29

-conformational -spastic -cicatricial

Question 30

What are the characteristics of conformational entropion?

Answer 30

-due to disproportionate size of orbit and globe position -common in shar peis, rottweilers, chows, and bulldogs -does not correct with topical anesthesia

Question 31

What is involutional entropion?

Answer 31

an acquired conformational entropion that occurs secondary to loss of orbital tissue

Question 32

What are the characteristics of spastic entropion?

Answer 32

-secondary to ocular pain (such as with ulcers) -pain causes animal to retract globe; allows eyelids to roll in -corrects with topical anesthesia

Question 33

What are the characteristics of cicatricial entropion?

Answer 33

-occurs when chronically spastic tissue scars and rolls in -scar formation from trauma or severe skin disease can also be causatory -does not correct with topical anesthesia

Question 34

What are the characteristics of puppy entropion?

Answer 34

-occurs in puppies of breeds that often suffer from entropion -permanent surgical correction is not done until dogs are older to prevent too much tissue from being removed -temporary vertical mattress tacking sutures are placed to roll out the eyelids -temp. sutures may help the eyelids develop a more normal position and reduce the need for permanent correction surgery

Question 35

What is the modified holz celsus procedure?

Answer 35

corrective procedure from entropion that involves removing a crescent-shaped area of skin; suturing the incision pulls the eyelids out and places them in a normal position