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Ophtho (sophomore) > Cornea dzs (Plummer) > Flashcards

Cornea dzs (Plummer) Flashcards

1
Q

Corneal anatomy

A
  • Outermost epithelium
    • 6-10 cell layers thick
  • Stroma
    • 90% of corneal thickness
    • mostly collagen
  • Descemet’s membrane
    • BM of endothelium
    • Thickens with age
  • Innermost endothelium
    • Monolayer of cells
    • The pump
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2
Q

Corneal stroma

A
  • regular parrallel arrangement of collagen fibers
  • Keratocytes
  • GAGs
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3
Q

Corneal innervation

A
  • Anterior stroma
  • Decreased sensitivity can affect healing
    • brachycephalics
    • Sick foals
    • Diabetics
  • Protection
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4
Q

Functions of cornea

A
  • anterior structure for globe
    • front of fibrous tunic
  • protection of interior structures from injury/infection
  • Clear medium for vision
  • Refraction
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5
Q

Corneal clarity

A
  • Avascular
    • normal state
    • except manatees
  • Anhydrous
  • Regular arrangement of collagen fibers
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6
Q

Corneal opacification

A
  • Cellular infiltrate
  • FIbrosis
  • Pigment
  • Neovascularization
  • Edema
  • Mineralization/Lipid deposition
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7
Q

Cellular infiltrate

A
  • Yellow or white appearance to stroma
  • WBCs migrate in
  • Often indicative of infection
  • Complicated
    • ulcers
    • stromal abscesses
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8
Q

Hypopion

A
  • White creamy infiltrate in anterior chamber
  • Indication of intraocular inflammation
  • concurrent with anterior uveitis (I think)
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9
Q

Fibrosis

A
  • White-grey color to cornea
  • End result of healing response, scar
  • Irregular rearrangement of collagen lamellae following injury
  • Quiet appearance
  • No fluid
  • Minimal vessels
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10
Q

Pigment

A
  • Usually secondary to chronic irritation
  • Pigment migrates in from limbus
  • Usually located superficial cornea
  • Frequently develops in association with conjuctival grafts

*Chronic inflammation/chronic irritation = pigment

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11
Q

Vascularization

A
  • Blood vessels grow into cornea
  • May be deep or superficial
    • brush border: deep vessels
    • Long singular branches: superficial vessels
  • Frequently leak fluid into cornea
  • Any sort of inflammatory stimulus

*bluer colorizarion is edema instead of fibrosis

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12
Q

Edema

A
  • Fluid within corneal stroma
  • Occurs at different levels
  • May appear
    • patchy
    • focal
    • diffuse
  • can form bullae or vesicles
  • Blue appearance
  • Lesions
    • Ulcers
    • keratitis
    • endothelial decompensation
    • galucoma
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13
Q

Mineralization

A
  • Usually dystrophic, in association with a degenerative process
  • rarely metastatic
  • usually just underneath epithelium
  • Difficult to treat
  • lesions
    • corneal dystrophies
    • band keratopathy
    • chronic uveitis
    • topical steroids
  • Lipid dystrophies
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14
Q

Corneal ulcer

A
  • most common presenting ophthalmic condition
  • Defect in cornea with loss of tissue
    • scratch
    • defect
    • wound
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15
Q

Corneal ulcer classification

A
  1. Depth
  2. Etiology
  3. Response to therapy
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16
Q

Corneal ulcer

Depth

A
  • Superficial
  • Stromal
  • Descemetocele
  • Full-thickness - iris prolapse
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17
Q

Corneal ulcer

Etiology

A
  • Traumatic
  • Infectious
    • bacterial
    • fungal
  • Immune-mediated
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18
Q

Corneal ulcer

Response to tissue

A
  • Simple
  • Complicated
    • indolent
    • melting
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19
Q

Superficial ulcer

Response to injury

A
  • Eipthelial cell mitosis in basal layer only
    • thickness increases from 8-15 cell layers
  • After injury, mitosis stops, loss of attachments and cells migrate over wound
    • migration at 0.6 mm/day if no infection
  • Mitosis resumes after wound closure
  • Stem cells at limbus maintain fresh supply of mitotically active basal epithelial cells
    • 6 weeks for epithelial cells to reattach basement membrane to stroma
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20
Q

Stroma response to injury

A
  • re-synthesize and cross-linking of collagen
  • balance of resorptive remodeling and restorative repair by fibroblasts
    • resorptive remodeling
      • proteinases from bacteria, PMNs and corneal cells
  • PMNs appear around necrotic areas
  • Cells adjacent to wound edge transform
    • leads to accumulation of fibroblasts
  • Firbroblasts proliferate and produce collagen
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21
Q

Vascularization response to injury

A
  • Non-specific response to insult
    • infection
    • inflammation
    • degeneration
  • Can be
    • superficial
    • deep
    • focal
    • curcumlimbal
  • result from vascular cellular sprouting from perilimbal vessels
  • Ghost vessels
    • receded, deperfused vessels

*migrate about 1mm/day I think

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22
Q

TO REMEMBER about corneal wound healing

A
  • Corneal blood vessels move at about 1mm/day
  • WBC move in cornea at 8.6 mm/day
  • Epithelial cells move about 1mm/day
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23
Q

Corneal dzs

A
  • Congenital
    • Dermoids: normal tissue in abnormal locale
      • tx: supervicial keratectomy
  • Acquired
    • Ulcers
    • Trauma
    • Inflammation
    • Dystrophy
    • Degeneration
    • Neoplasia
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24
Q

Corneal ulcer principal strategies

A
  • Quick dx is difference between sight and blindness
  • Assume ulcers will get worse
  • Treat aggressively
  • Recheck often
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25
Corneal ulcer CS
* Blepharospasm * Epiphora * Serous to mucopurulent d/c * Miosis d/t reflex uveitis * Corneal edema * Corneal vascularization
26
Corneal ulcer DXs
* Culture infected lesions before meds/drugs * aerobic * fungal (esp. horses) * Schirmer's tear test (esp. SA) * unless eye is about to rupture * N: 15-25 depending on clinical scenario * should be higher if ulcerative * Fluorescein stain painful eyes * squinting * tearing * cloudiness * redness * droopy eyelashes * Cytology (esp. horses)
27
Corneal cytology
* Topical anesthesia * end of scalpel blade/cytology brush * Diff Quick or Gram stain * Guides Tx choice and prognosis
28
Ulcerative Keratitis
* Corneal epithelium: barrier against bacterial * Progression to deep stromal ulcer if * infection * epithelium unable to attach to stroma * delayed healing
29
Descemetoceles
* Epithelium and stroma lost * very thin, fragile, prone to rupture * if rupture **iris prolapse** usually follows AqH and plugs hole * bulges to do AqH pressure * surgical ulcer
30
Melting ulcers
* Complicated stromal ulcer * Ulcers with active proteases * gray-ish gelatinous appearance * potentiated by topical corticosteroids * distinguish from corneal edema * corneal edema doesn't usually distort ocular surface
31
Melting corneal ulcer Pathophys
* Normal tear fluid contains soluble proteins * MMPs, NE * In injury imalance of degradation and rebuilding factors can happen * Target of therapy * MMPs and NE
32
Infectious ulcers
* Bacteria * Pseudomonas * Stretococcus * Staphylococcus * Fungi * Aspergillus * Candida * Fusarium * Virus * Herpes
33
Identifying an infected ulcer
* presence of cellular infiltrate * melting * degree of uveitis * delayed healing * positive cytology or culture
34
Herpetic Dz
* Cats * URI * Epiphora * Cytolytic * conjuctivitis * Ulcerative keratitis * Symbleparon * adhesions of conjunctiva * Immunopathologic * stromal keratitis * eosinophilic keratitis * sequestra * TX * topical antivirals * topical antibiotics
35
Dendritic ulcers
* Pathopneumonic for herpes virus infection * infects epithelial cells that cover nerves
36
Goals of ulcer therapy
* Sterilize wound bed * control secondary anterior uveitis * ALWAYS PRESENT * Slow collagen breakdown * Provide structural support
37
Medical Treatment of Ulcers
* Treat etiology * Broad spectrum antibiotics * Reduce tear protease activity * EDTA, Acetylcysteine * Serum * contains alpha-2 macroglobulin with anticollagenase activity * Treat Uveitis * Topical mydriatic * topical atropine (also stabilizes blood aqueous barrier) * Systemic NSAIDs
38
Topical NSAIDS
* Can use if MAIN PROB is uveitis * May potentiate keratomalacia * Systemic NSAIDs and atropine are preferred
39
Antibiotics
* Toxic to epithelial cells * use least toxic one indicated
40
TX protocol for simple superficial ulcer
* Triple antibiotic TID-QID * 1% atropine SID * colic in horses * +/- Serum QID * e-collar * recheck 2-3 days * Response * should take up less fluorescein and be less painful in 24-48 hours * if not consider a complicating factor - add serum
41
TX protocol for stromal/complicated ulcers
* Antibiotics based on cytology/C&S * Antifungals if indicated * Serum, EDTA or acetylcysteine q 1-4 * Atropine TID * Systemic NSAIDS * +/- surgical stabilization
42
Healing of complicated ulcers
* observed healing from limbus in * clearing * blood vessels * Reduced stimulus for uveitis * pupil stays dilated easier * can reduce frequency of atropine admin * can decrease systemic non-steroidals
43
Melting ulcers TX
* aggressive * antibiotics initially q 1-2h * antifungals if indicated * atropine TID until dilated * Serum, EDTA or acetylcystein q 1h * Systemic NSAIDS * Analgesics * +/- surgical stabilization * keratectomy and conjunctival flap
44
Anti-melting therapy frequency of therapy Making eyedrops
* Gross melting * treat hourly * Prevention/to speed healing * use q2-6 * Serum or plasma * Best and cheapest * pull blood and spin down in serum separator (Tiger top) * refridgerate * good for 8 days * EDTA (0.17%) * lavendar top tube, fill to line with sterile water * Chelates Ca and Zn * so they are unavailable for MMPs to use as substrate * N-acetylcysteine (5%) * 5 mL 20% mucomyst + 1.5 mL artificial tears
45
Autologous Serum
* prefered anticoagenase * contains * alpha -2 macroglobulin * nutrients to stimulate healing * maintain in sterile bottle
46
Melting ulcer healing progression
* should show increase in stromal rigidity in the first 24 hours * if not structural stabilization by surgery
47
Epithelialization can move in in .....
days
48
Stromal filling can take
weeks
49
Surgery generally indicated for
* deep ulcers * desmetoceles * perforated Ulcers
50
PK/CF surgery
* Brings fibroblasts * vascularization * physical support
51
Types of conj flaps
* 360 degrees * hood * island * pedicle * bridge
52
Iris Prolapse
* Emergency * systemic antibiotics * general anesthesia and surgical repair of cornea * reposition or amputate * suture cornea * CF if needed * Topical antibiotic **solutions** * NOT OINTMENTS=vehicle is damaging to inside of eye * Topical atropine
53
Other surgical options
* Penetrating keratoplasty * corneal transplants * synthetic grafts * amniotic membrane grafts * keratoprostheses
54
Corneal lacerations
* Ability to repair depends on * length * damage to interior structures * involvement of limbus * Initiate systemic antibiotics * almost always require surgical tx * sx for all full thickness lesions * following tx like a serious corneal ulcer
55
Corneal foreign bodies
* Look at entire eye * Depth * Fibrin * fibrin in anterior chamber indicates full thickness breach * Remove and treat ulcer
56
Non-healing ulcers
* check eyelid position * lash abnormalities * Tear production * presence of foreign bodies * behind third eyelid * infection * no underlying problems * indolent/refractory
57
refractory ulcers
* AKA Indolent/'Boxer' ulcer * also aged animals * Superficial corneal erosion with epithelial 'lips' * epithelium rolled up and back at the edges * Chronic blepharospasm, epiphora, photophobia * Fluorescein diffuses uder epithelium
58
Indolent ulcers Pathophys
* Defect in hemidesmosomes of basal corneal epithelial cells * Abnormal basement membrane of basal corneal epithelium? * Hyaline membrane forms on ulcer * defect in anterior stroma?
59
Tx for indolen ulcers
* Remove abnormal epithel * topical anesthetic * debride with q-tip * may have to repeat several times * rub cornea with dry q-tips * superficial ulcers only * Medical tx * just like simple superficial ulcer * may add hyperosmotic agents * 5% NaCl ointment or soln * Bandage soft contact lense * supports stroma in healing * Grid Keratotomy * rule out infection * diamond bur * **don't perform on cats or horses**
60
Corneal sequestration in cats
* AKA * corneal black spot * corneal nigrum * breeds most commonly affected * brachycephalics: * troubles distributing tear films * corneal axial denervation compared to other breeds * Surgical excision recommended
61
Keratitis
* Non-specific inflammation of the cornea * vascularization, edema * pigment, infiltrate * Variety of etiologies * healing corneal ulcer * chronic irritation * KCS * Trichiasis * Exposure * Immune mediated
62
Pannus
* AKA Chronic superficial keratitis * Immune-mediated keratitits * Predisposed breeds * German shepherds * greyhounds * exacerbated by UV radiation * Temporal corneosclera initially * migrates medially * Corneal vascularization * Pigmentation follows vessels
63
Pannus tx
* no cure * medical management * topical steroids * topical cyclosporine * keratectomy * beta irradiation
64
Herpetic Stromal Keratitis
* Features * Non-ulcerative * Chronic * Fibrosis, edema, blood vessels * immune mediated/immunopathologic * med management * steroids * CsA * Antivirals
65
Eosinophilic Keratitis
* Characteristics * Proliferative keratitis * Non-healing ulcers * Fleshy plaques * **Cytology** * **Eosinophilia** * Mast cells * plasma cells * lymphs * Med management * steroids * CsA
66
Corneal Dystrophies Dogs
* bilaterial * inherited/breed related * no corneal inflammation, no pain * deposition of cholesterol and tryglycerides in stroma * serum cholesterol and tryglycerides not usually elevated * hypoT4
67
Endothelium Response to injury
* minimal to no mitosis * limited capacity for regeneration * When cells lost, remaining cells enlarge and migrate
68
Corneal Endothelial disease
* Hallmark: dense corneal edema * Focal or diffuse * Inflammation * trauma * immune-mediated * hepatitis: 'blue eye' * Degeneration
69
Corneal Endothelial dystrophies
* anomalous to Fuch's Dystrophy * predispositions * Boston Terrier * Chihuahua * Dachshund * Starts as temporal corneal edema * extends axially * become progressively more dense and opaque * Decreased nubers and metaplasia of endothelium \*animal predisposed to ulcers
70
Corneal dz vs glaucoma
Measure IOP
71
Endothelial dz TX
* topical hyperosmotics * (5% NaCl) * thin permanent conj grafts * thermal keratotomy * penetrating keratoplasty with corneal transplant
72
Train your client: Painful eyes are....
Same day emergencies

Ophtho (sophomore) (11 decks)

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