Corneal and Conjunctiva Disease Flashcards
1
Q
What makes the cornea transparent?
A
- Small diameter and lamellar arrangement of collagen fibres
- No blood vessels
- No pigment
- Dehydration (maintained by endothelium)
- Smooth optical surface
- Precorneal tear film quality
2
Q
Major Corneal Pathological Reactions:
1. Red
2. Blue/grey
3. Yellow/white
4. Grey (scarring)
5. Black
6. Yellow/green
7. White
A
- Corneal vascularisation
- Corneal oedema
- Stromal malacia - melting
- Corneal fibrosis
- Corneal melanosis
- Stromal infiltration w WBC
- Stromal mineral/ lipid deposition
3
Q
Corneal Oedema
A
Excess fluid accum in stroma
Blue, fluffy indistinct borders
4
Q
Corneal Oedema - Diffuse, marked, no fluoresceine uptake
A
No Pain/inflam, normal IOP, no aq flare -rule out
- Endothelial degen
- Endothelial dystrophy
Pain, inflamed, abnormal IOP, aq flare - rule out
- Glaucoma
- Anterior uveitis
- Anterior lens luxation
5
Q
Corneal oedema - focal, mild, +ve fluoresceine uptake
A
Rule out ulcers
6
Q
Corneomalacia - What is it caused by?
A
Stromal Melting
Collagen fibres destroyed by proteinases from
1. Microorganisms - Pseudomonas (G-ve), Strep, staph pseudointermedius
2. WBCs = neutrophils
3. Corneal epithelial cells and keratocytes
7
Q
Corneal Melanosis
A
Due to chronic irritation
1. Insufficient corneal protection
- Lagophthalmos
- KCS
- Ectropion
- Macropalpebral fissure
- CNV/VII dysfunction
- Tear film deficiency
2. Excessive corneal irritation
- Entropion
- Distichiasis
- Ectopic cilia
- Trichiasis
- FB
- Blepharitis
- Eye lid mass
- Pannus
- Herpes
8
Q
Ulcerative Keratitis
A
- superficial corneal ulcer
- spontaneous chronic corneal epithelial defect (SCCED)
- stromal ulcer (superficial and deep) -descemetocele
- melting ulcer
- ruptured ulcer
- corneal foreign body
- corneal sequestrum (cats only)
9
Q
Non-Ulcerative Keratitis
A
- chronic immune-mediated superficial keratoconjunctivitis (pannus)
- keratoconjunctivitis sicca (KCS)
- pigmentary keratitis/keratopathy -eosinophilic keratitis
- corneal lipid/mineral dystrophy
- corneal endothelial dystrophy
- corneal degeneration -dermoid
10
Q
Common Causes of Corneal Ulcerative Dx
A
- Eyelid abnormalities = eyelid agenesis (coloboma), entropion, blepharitis, neoplasia, lagophthalmos
- Eyelash/ hair abnormalities = ectopic cilia, distichiasis, trichiasis, nasal fold trichiasis
- Tear film abnormalities - KCS, facial nerve paralysis, exposure keratitis
- Infection - cats = herpes
- Irritants = cosmetics, smoke, UV, strong alkali/ acid
- Trauma - RTA, blunt, cat scratch, FB, thermal
- Dystrophy/degen - stromal corneal lipid/ mineral accum, corneal oedema w glaucoma, corneal endothelial dystrophy
11
Q
Complicated vs Simple Ulcers
A
Complicated:
- >7d
- Involves stroma
- Both
Simple:
- Heals in 7d
- Not involving stroma
12
Q
Ulcer Treatment - Medical
A
- Topical Ab - chloramphenicol
- Topical antivirals
- Artificial tears
- Collagenase inhibitors
- Atropine - reflex uveitis (not KCS)
- Analgesics
- Contact lenses
13
Q
Ulcer Treatment - Surgical
A
- Epithelial debridement
- Superficial keratotomy- SCCED
- Conjunctival graft, island graft, 360- degree conjunctival flap
- Corneoscleral transposition
- Cyanoacrylate adhesives - ophthalmic glue
- Third eyelid flap?
14
Q
Superficial Chronic Corneal Epithelial Defect (SCCED) - Synonyms
A
- Non-healing ulcer
- Indolent ulcer
- Boxer ulcer
- Refractory ulcer
- SCCED spontaneous chronic corneal epithelial defect
15
Q
Superficial Chronic Corneal Epithelial Defect (SCCED) - Seen in:
A
- Boxers
- Corgis
- Middle aged and older animals
16
Q
Superficial Chronic Corneal Epithelial Defect (SCCED) - Characteristics:
A
- Dev w no trauma
- Shallow, slow to heal
- Blurred edges - fluoresceine uptake underneath the epithelium
- Nonadherent epithelium
- Spontaneous occurrence
- Usually unilateral but occasionally bilateral
- Abnormal adhesion between epithelial cells and stroma
17
Q
Superficial Chronic Corneal Epithelial Defect (SCCED) - Medical Tx
A
Topical Abs - chloramphenicol, chlortetracyclcine
Tear replacement - remed, vizovet
Atropine
Pain control - systemic/topical NSAID
Prevent self trauma - cone
18
Q
Superficial Chronic Corneal Epithelial Defect (SCCED) - Surgical Tx
A
- Debride - remove loose epithelium
- Grid/ punctate keratectomy
- Diamond burr debridement
- Tarsorrhaphy and bandage contact lens
19
Q
Stromal Corneal Ulceration - Management
A
- Broad spectrum topical antibiotic therapy (Fluoroquinolones)
- Don’t use ointments (risk of anterior uveitis)
- Antiproteolytic agents: autologous serum,
- N-Acetylcysteine (Stromease), EDTA, Tetracyclines
- Cytoplegic-topical 1% Atropine (not in KCS)
- Systemic NSAID +/-more potent analgesia
- DO NOT USE TOPICAL CORTICOSTEROIDS
- Surgery
20
Q
Melting Ulcer - What
A
Emergency
Cytology and culture
Neutrophils
Pseudomonas
Strep
Staph pseudointermedius
21
Q
Melting Ulcer - Tx
A
- Loading dose: 1 drop every 5 minutes for 6-12 doses, followed by 1 drop every 1-2h for 24-48h
- Ciprofloxacin-Ciloxan- usually a 1st choice
- Ofloxacin-Exocin –reserve for cases where other antibiotics are ineffective
- Chloramphoenicol
- Autologous serum: anti-collagenase agent (acts against serine
proteases and MMPs) - EDTA and N-acetyl cysteine are only effective against MMPs
- Systemic antibiotics should be used if there is a risk of a globe
rupture - Cytoplegic-topical 1% Atropine (not in KCS)
- Provide analgesia: NSAID, stronger if required.
22
Q
Chronic Superficial Keratitis - Pannus - What?
A
- Immune-mediated progressive superficial keratitis with a genetic basis
- Bilateral, potentially blinding
- Temporal limbus-red vascularised conjunctival lesion, but can start anywhere
- Progressing to temporal cornea as a fleshy vascularised lesion
- Corneal vascularization, granulation & pigmentation appears then at the nasal limbus
- Cholesterol deposits within stroma
- Thickened third eyelid
- Females affected more frequently than males
23
Q
Chronic Superficial Keratitis - Pannus - Tx
A
- No cure, requires life-long therapy
- Initially topical corticosteroid (1% prednisolone,
0.1% dexamethasone) 3-4x daily - Topical cyclosporine (0.2-2%) with or without
corticosteroids 2x daily - For refractory cases:
- Subconjunctival injection of corticosteroids
- β-radiation
- Superficial keratectomy
24
Q
Corneal Lacerations - Non-Penetrating
A
- Common ocular emergency
- Cat claw, thorn, nail etc.
- Partial thickness puncture or laceration
- Can lead to a corneal flap
- Medical treatment –if stromal exposure is small – frequent re-examinations necessary
- Debridement, antibiotics, analgesic
- Direct suturing or conjunctival graft
25
Corneal Lacerations - Full Thickness
* Without iris prolapse
* With iris prolapse
* Without lens injury
* With lens injury
Sudden decompression of the anterior chamber leads to extravasation of the protein, including fibrinogen, from iris and ciliary body. Fibrinogen converts to fibrin and acts as a plug that covers corneal defect.
Prolapsed iris may or may not be visible under the coagulated fibrin.
26
FHV-1 Keratitis Cats:
Never keratotomy -> corneal sequestration
* Tropism for the conjunctiva but commonly cause corneal disease
* Different clinical presentations
* Virus remains latent in ganglia - trigeminal
* Recrudescence -> cytolytic or immunologic dx
* Subclinical shedding in latent disease possible
* PCR = gold standard - cytobrush
27
FHV-1 Keratitis Cats - Clinical Signs
* Unilateral
* Epiphora- crying in one eye
* Blepharospasm
* Dendritic lesions-short lasting
* Geographic ulceration
* May look like SCCED but the pathophysiology is
different
* Qualitative tear film disease (the eye looks very
watery but the cornea is dry!)
* Stromal keratitis is caused by immune mediated
inflammation
28
FHV-1 Keratitis Cats - Tx
* Topical antibiotic (Chloramphenicol, Fusidic acid)
* Famciclovir 90mg/kg q12h
* Topical ganciclovir (Virgan) q 6-8h for 21days
* Autologous serum
* Tear replacement therapy
* Environmental modifications- stress reduction,
overcrowding control
29
Feline Eosinophilic Keratitis - What?
* Proliferative keratoconjunctivitis
* Immune-mediated
* White and pink deposits (resembling cottage cheese) slowly progressive
* Affects conjunctiva, epithelium and superficial stroma
* Starts at the limbus (immunologically most active
part of the eye)
* Young to middle aged cats
* May be part of eosinophilic granuloma complex
* Possibly associated with FHV-1 infection (76% of cats with FEK demonstrated FHV-1 DNA in corneal samples)
* Cytology-use the brush! Look for eosinophils.
30
Feline Eosinophilic Keratitis - Tx:
Ophthalmic/ systemic corticosteroids
NOT CURABLE, recurrence up to 65%
Famciclovir 90mg/kg q12h –if ulcerative disease present as well
Topical 0.1% dexamethasone phosphate
Topical cyclosporine??? Autologous serum?
Tear replacement therapy
Resolution: weeks to months
31
Corneal Sequestrum:
TREAT LIKE FHV-1 UNLESS OTHER CAUSE IS IDENTIFIED
* Unique cat disease, any breed, any age
* Early clinical signs: epiphora, brown stromal discoloration
* Late clinical signs: firm dark brown lesion (stromal necrosis) superficial vascularization
* Brachycephalic breeds predisposed (reduced corneal sensitivity, qualitative tear film deficiencies, low blink rate)
* Secondary to chronic irritation (entropion, chronic ulceration, tear film deficiencies)
* Sphynx breed may be predisposed
* Treatment complex, medical, surgical
32
Conjunctiva
* Nonkeratinized stratified squamous epithelium
* Goblet cells ( mucoid layer of precorneal tear film)
* Substantia propria
* Lymphoid nodules
* Conjunctival associated lymphoid tissue (CALT)
* Conjunctival vessels
33
Normal Conjunctival Flora
Dogs G+ve = Staph, Bacillus, Corynebacterium
Cats G+ve = Staph felis
Cats G-ve = Moraxella osloensis
34
Conjunctivitis
*Conjunctival hyperaemia = deep, vision threatening
*Rule out uveitis, glaucoma, orbital disease, KCS, keratitis
*Chronic conjunctivitis or severe acute conjunctivitis = goblet cell deficiency
*Decreased mucin = qualitative precorneal tear film deficiency (epithelial dry spots/ desiccation/ irritation in very watery eye !)
*Feline conjunctivitis = infectious (FHV-1, FCV, Chlamydophila felis, Mycoplasma felis)
*Canine conjunctivitis = non-infectious : entropion, ectropion, KCS, allergy (unless swim in dirty water)
35
Conjunctivitis - Clinical Signs:
Conjunctival hyperaemia, oedema, follicles formation
Chemosis (conjunctival oedema)
Conjunctival haemorrhage
Purulent/serous ocular discharge
36
Approach to Conjunctivitis
Schirmer Tear Test
<10mm/min = KCS
>20mm/min -> Fluoresceine stain
- Nasolacrimal passage present, eyelid, corneal and globe disorders ruled out = EVAL CONJUNCTIVA
- No nasolacrimal passage - flush, tx w Abs +/ corticosteroids - re-exam 2-5d
37
Conjunctivitis - Surfaces
Diffuse hyperaemia: bacterial, viral infections Focal hyperaemia: foreign body, trauma Pigmentation: any chronic inflammation, KCS
Follicles: chronic inflammation, allergic, parasitic, immune-mediated
38
Conjunctivitis - Exudates
Serous to mucus: allergic, limited to no bacterial infection
Mucus: early KCS, early bacterial infection Mucopurulent: bacterial infection Purulent: bacterial infection
39
Bacterial Conjunctivitis Tx - General
1. Correct primary cause
2. Remove exudate, crusts
3. Topical broad-spec AB
4. Prevent self trauma - cone
5. Systemic AB if belpharitis, dermatitis, otitis
40
Keratoconjunctivitis Sicca - KCS
Quantitative vs Qualitative
Inflam of the cornea and conjunctiva
Secondary to a deficiency of the precorneal tear film (PTF)
Quantitative KCS = decrease in aq part of the tear film on Schirmer tear test (STT); more common
Qualitative KCS = decrease in the lipid or mucin parts of tear film, diagnosed by documenting decreased tear film breakup time (TBUT).
41
Quantitative KCS Clinical Signs
* Thick, adherent mucopurulent discharge * Conjunctivitis
* Blepharospasm
* Dry, lustreless corneal appearance
* Ulcerative keratitis, ranging from superficial ulcers to perforations
* Corneal pigmentation, neovascularization
42
Quantitative KCS - Dx
* History
* Ophthalmic Examination
* STT1 (no local anaesthetic, reflex tear production). Normal production in dogs is
> 15 mm/min.
* TBUT (tear break up time, to assess deficiency in mucin component): 1. Fluorescein 1 drop (hold the eyelids open)
2. Use cobalt-blue illumination
3. Note how many seconds it takes for dark spots to appear
4. as the PTF “breaks up”
5. A normal TBUT is ≥ 20 seconds
43
KCS Tx - Cyclosporine A:
* Immunomodulator, anti- inflammatory
* Inhibits production of interleukin-2 (proliferation of T-helper and cytotoxic T cells) in the lacrimal gland
* Directly stimulates lacrimation
* Decreases pigmentation
* Normalizes goblet cell mucin
secretion
81.8% of dogs showing improvement
* STT < 2 mm/min - response in 50%
* STT ≥ 2 mm/min – response in 80%
44
KCS Tx - Tacrolimus:
* Mechanism of action compared with CsA but more potent,
* Patients that are unresponsive to CsA may respond to tacrolimus
* Second line treatment if not responding to CsA
* Off-label use
45
KCS Tx - Tear Replacement Therapy
Provides lubrication
Lifelong therapy
Solutions, gels, and ointments
46
KCS Tx - Pilocarpine
* Neurogenic KCS (ipsilateral dry nose+ low STT)
* Parasympathomimetic
* Stimulates tear production
