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Dog & Cat Medicine and Surgery > Sclera, Conjunctiva, Cornea > Flashcards

Sclera, Conjunctiva, Cornea Flashcards

1
Q

Sclearitis

A

Usually immune mediate and in conjunction with uveitis. Can be treated with corticosteroids (topical idea, systemic), azathioprine (more powerful. You are aiming for control not cure.

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2
Q

Conjunctivitis

A

Very fine branching, usually doesn’t bulge out unless there is infection (edema = chemosis). With disruption you will usually have increased ocular discharge, starting to be serous with excess tear production and then if there is a secondary bacterial infection then muco-purulent.

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3
Q

Etiologies for conjunctivitis

A

KCS (major cause)
Corneal ulceration/abrasion
Intraocular disease
Bacterial/Viral/Allergy

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4
Q

Diagnosis & therapy for conjun

A

Cutlrure , biopsy, cytology

Therapy: broad spectrum antibiotics/with possible steroids

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5
Q

Follicular conjunctivitis

A

Usually for young dogs. Lymphoid hyperplasia/conjunctival hyperaemia
Debride follicles with cotton swab
Antiobiotic steroid therapy (Topical TID)

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6
Q

Conjunctival haemorrhage

A
  • Haemorrhage located between conjunctiva and sclera
  • Trauma, coagulopathy, systemic hypertension
  • Treat underlying problem – Time is on your side!
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7
Q

Conjunctival neoplasia

A

Can be benign or malignant

Hemangiomas & hemangiosarcomas

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8
Q

What is the function of the cornea

A
  1. Light refraction (corneal curvature bends light rays as they enter; major refractive surface of the eye)
  2. Light transmission (Transparency: dehydrated layer, parallel arrangement of collagen, lack of cells/blood vessels/pigments)
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9
Q

What is the nutrition for the tear film/aqueous

A

Tear film: oxygen, glucose

Aqueous fluid: Oxygen, glucose, protein, lipids, enzymes, electrolytes

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10
Q

White in the cornea - causes

A

White = probably lipid (genetic, too much in the diet) or calcium

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11
Q

Grey cornea

A

Grey = more of a scar.

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12
Q

Black cornea

A

Sometimes pigmentations can be a black scab on the cornea (sequestrum)
Brown in the middle = iris poking through. Will come up to plug the dam

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13
Q

Corneal Healing/Stroma

A

• Keratocytes proliferate, become fibroblasts
– 24 hours
• Collagen fibers form into bundles
• Scar: if collagen bundles disorganized

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14
Q

Corneal Healing: Endothelium

A
  • Spreading and enlargement of cells

* Replacement of basement membrane • Corneal edema if defect too large

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15
Q

Ulcerative Keratitis

A

Means corneal ulcerations. There is no epithelium, possibly some stromal loss (variable)
Most are due to trauma with secondary bacterial infection, very few bacteria can cause it on their own. KCS can set it off on its own.

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16
Q

Ulcerative Keratitis - diagnosis

A

• Ocular exam: Identify mechanical causes
• STT: >15 mm/min
• Fluorescein stain:
– Positive: stromal
– Negative: Descemetocele
• Cytology: bacteria, fungal, inclusion bodies • Culture: bacterial and fungal sensitivity

17
Q

Types of corneal ulcers

A

Simple - superficial non-infected
Complex/Deep Ulcer - could go to deceme’s membrane, could rupture
Refractory ulcer- superficial/non-infected but doesn’t want to eal.

18
Q

Simple corneal ulcers

A 
• Acute superficial ulcer
• No:
– Infiltrate
– Vascularization – Pigmentation
• Painful
– Miotic pupil
19
Q

Complicated corneal ulcers

A
  • Acute or chronic
  • Varies in depth – Descemetocele
  • Corneal infiltrate
  • Edema
  • Vascularization – If chronic
  • +/- Melting
20
Q

Refractory Ulcers

A 
• Chronic ulcer
– Not responding to therapy
• Loose epithelial edge
• No infiltrate
• Diffuse staining – Halo

21
Q

Treatment for corneal ulcers

A

• General considerations:
– Identify type of ulcer
– Frequency of medication: better too often
– Drops versus ointment
– If no positive response in 24-48hrs
• Re-evaluate therapeutic protocol
– Topical Steroids and NSAIDs: contraindicated! (Unless there is something more vision threatening)


22
Q

Treatment for simple corneal ulcers

A 
• Correct mechanical causes
• Broad-spectrum antibiotics QID
• +/- Atropine
         – Verify STT: lubricate if necessary
• Elizabethan collar • Recheck: 3-5 days
23
Q

Treatment for complicated corneal ulcers

A

• Debride / flush
– Dilute iodine to disinfect
• Topical bactericidal antibiotics q1-2 hours • Serum: melting
• Atropine: BID then to effect
• Systemic NSAIDs
• Recheck: within 24 hours if severe
• Surgery: keratectomy, conjunctival graft

24
Q

Treatment for refractory corneal ulcers

A

Grid keratotomy
– Topical anesthetic, sedation, GA
• Prophylactic bacteriostatic antibiotic QID
• Atropine: BID 3 days
• Contact lens - remove within 3 days – Alternative: third eyelid flap
• Recheck: 7 days
• May take up to 30-40 days to heal

25
Q

Pigmentary Keratitis

A 
Often in a pug, pigment on the corneal (Melanocyte in epithelium), will start on the medial canthus due to chronic irritation, KCS
• STT, Fluorescein stain
• Remove irritation
• Lubrification
• Steroids, cyclosporine
26
Q

Chronic Superficial Keratitis

A
  • Neovascularization and pigment • Immune-mediated
  • German Shepherd, greyhounds
  • Cytology: plasma cell
  • Steroid, cyclosporine • No cure
27
Q

Dystrophy vs. Degeneration in cornea

A 
Corneal dystrophy
• Inherited
• Bilateral / symmetrical
• Primary disorder
• Central cornea
• No vascularization
• No blindness
Corneal degeneration
• Acquired
• Unilateral/asymmetric 
• Underlying disease
• Anywhere
• Vascularization
• May lead to ulcer
28
Q

Endothelial inflammation

A 
• Secondary to uveitis
– Vaccine reaction
• Fluorescein negative
• Steroids:
– Topical and systemic
29
Q

Endothelial Dystrophy

A 
• Abnormal endothelial cells
– Leading to corneal edema
• Epithelial bullae formation
– Results in chronic ulcers • Penetrating keratoplasty • Thermokeratoplasty

30
Q

Corneal Masses

A

• Nodular granulomatous episcleritis (NGE)
– Raised mass
– Diagnosis: biopsy
– Steroids, tetracycline/niacinamide/azathioprine

31
Q

Dermoid

A

Hairy eyeballs
If taken off properly they shouldn’t grow back. Skin cells have lost heir way & implanted themselves. Operating microscope & delicate scapel blade to cut them out and leave the corneal to heal by second intention (ulcer)

32
Q

Corneal neoplasia etc.

A

• Hemangioma/sarcoma
– Vascular lesion onto cornea from limbus • Keratectomy
– Followed by cryotherapy or radiation

Dog & Cat Medicine and Surgery (24 decks)

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