Ophtho Flashcards

(54 cards)

1
Q

Why do horses have high amounts of ocular trauma?

A
  • prominent location of eyes
  • propesity for horses to throw their heads
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2
Q

most common ocular disease in horses

A

corneal ulcers

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3
Q

corneal ulcers are almost always caused by ______

A

trauma

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4
Q

How are corneal ulcers diagnosed?

A

fluorescein dye-binds to stroma

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5
Q

complicated corneal ulcers:

A
  • do not heal in 3-7 days
  • have a collagenase component
  • mechanical obstruction to healing
  • infected
  • danger of perforation-ulceration into anterior chamber
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6
Q

Clinical features of complicated corneal ulcers

A
  • obvious corneal defect
  • white/yellow cellular infiltrate
  • surrounding corneal edema
  • secondary uveitis
  • +/- chronic
  • +/- pain
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7
Q

What should you do any time you have a complicated corneal ulcer?

A

CULTURE-aerobic & fungal

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8
Q

Where should you obtain the sample for culture of a corneal ulcer?

A
  • margin of ulcer
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9
Q

When is corneal cytology indicated?

A

any cornea with cellular infiltrate

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10
Q

What is a topical anesthetic used in ophtho?

A

proparacaine

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11
Q

Presence of _____ in the scraping ensures adequate sample for cytology

A

epithelial cells

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12
Q

concerns if PMNs are the main cell type found in corneal cytology

A

bacterial or fungal infection

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13
Q

concerns if lymphocytes/plasma cells are main cell present in corneal cytology

A

immune-mediated process

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14
Q

What are your concerns if eosinophils dominate the corneal cytology?

A

parasitic or eosinophilic keratitis

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15
Q

Superficial ulcers with a redundant epithelial border, minimal corneal neovascularization, focal edema, no cellular infiltrate or signs of infection

A

indolent corneal ulcers

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16
Q

Pathogenesis of indolent corneal ulcers

A
  • routine corneal ulcer
  • basal epithelial cells migrate to cover wound but cannot attach to underlying stroma
  • minor trauma results in repeat ulceration
  • likely superficial stromal defect
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17
Q

Indolent ulcer treatment

A
  • debridement-remove any loose epithelium
    • standing keratectomy
    • diamond burr keratectomy-doesnt leave scar
  • oxytetracycline (Terramycin) BID-TID-decreases matrix metalloproteinases and promotes epithelialization
  • oral doxy?
  • topical serum-anticollagenase, growth factors
  • equine contact lens-efficacy unknown
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18
Q

Most common agent isolated from infected corneal ulcers

A

Pseudomonas

also Streptococcus

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19
Q

Clinical signs of “melting” corneal ulcers

A
  • white-yellow cellular infiltrate
  • corneal edema
  • increasing ocular inflammation
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20
Q

Serum contains _________, a very effective anticollagenase

A

alpha-2 antiglobulin

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21
Q

What are some topical anticollagenase medications?

A
  • serum
  • acetylcysteine
  • EDTA
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22
Q

What is a non-topical medication that has anticollagenase properties?

23
Q

Characteristics of Moxifloxacin

A
  • 4th generation fluorinated quinolone
  • less ocular toxicity
  • better penetration
  • better bacterial coverage – esp. Staph, Strep
24
Q

Surgical procedures that may be indicated for an infected corneal ulcer

A
  • keratectomy
  • conjunctival flap or amnion membrane
25
What is the purpose of corneal cross-linking?
stabilize melting corneas
26
How is corneal cross linking performed?
Instill riboflavin eye drops q2 min. for 25 minutes then treat cornea with UV light for 30 minutes
27
What is the most common fungal agent involved in corneal ulcers?
*Aspergillus*
28
Topical corticosteroids may predispose to what?
fungal keratitis
29
When are fungal infections more common in the northern US?
summer
30
When are fungal infections more comon in the southern US?
winter
31
Typical history with fungal keratitis
ulcer present for 7-14 days and now getting worse
32
Diagnostic options for fungal keratitis
* cytology * histology of corneal biopsy * culture * PCR for DNA
33
Treatment plan for mycotic corneal ulcers
* effective debridement or superficial keratectomy +/-conjunctival flap-reduce organism&inflammatory debris * topical antifungals * systemic antifungals * topical & systemic antibacterials-(since commonly co-infected with bacteria) * uveitis control-uveitis usually the cause of ocular loss and blindness
34
Voriconazole is effective against\_\_\_\_\_\_\_\_\_\_
filamentous fungi
35
What is the role of atropine administration in the treatment of fungal keratitis?
uveitis
36
most common cuase of blindness in horses
recurrent uveitis
37
Components of the uveal tract
* iris * ciliary body * choroid
38
anterior uveitis
inflammation of the iris and ciliary body
39
posterior uveitis
inflammation of the choroid and retina
40
pan-uveitis
inflammation of the entire uveal tract (most common)
41
Three important questions about suspect uveitis cases
1. does horse have signs of _active or quiescent_ (chronic) uveitis? 2. is the uveitis acute, chronic, or recurrent? 3. is the uveitis primary (endogenous) or secondary to an ocular are systemic abnormality?
42
Signs of active uveitis
* aqueous flare/hypopyon * miosis * hypotony * photophobia * pain/blepharospasm * vitreous debris * mild corneal edema * hyphema * decreased vision
43
Corneal edema is a sign of what type of uveitis?
chronic
44
What is the most common cause of cataract formation in horses?
chronic uveitis
45
Ophthalmic causes of uveitis
* corneal disease * neoplasia * trauma
46
what is the underlying cause of equine recurrent uveitis?
immun-mediated
47
Three recognized clinical types of equine recurrent uveitis
1. classic recurrent "anterior" uveitis 2. persistent "subclinical" uveitis 3. primary posterior uveitis
48
What form of recurrent uveitis is most common?
"classic" anterior uveitis
49
What breeds have increased incidence of subclinical uveitis?
* Appaloosa-up to 25% * Draft breeds
50
Primary posterior uveitis is most common in what breed?
warmbloods
51
Poor prognostic indicators for long-term vision with uveitis
* Appaloosa * elevated IOP * positive leptospiral titer (serum or AH); especially C\>4
52
What are two steroids that will penetrate the eye well?
Pred acetate dexamethasone HCl
53
What is a consideration of using atropine HCl in terms of possible negative side effects?
decreased gut motility-predispose to colic
54
Cyclosporine implants may be indicated in horses that meet what criteria?
* ERU greater than three months duration * uveitis controlled medically * have frequene recurrence * are still visual