Transcript Conjunctiva

Equine
Conjunctivitis
October 17, 2007
Eric C. Ledbetter, DVM
Diplomate American College of Veterinary Ophthalmologists
Cornell University
College of Veterinary Medicine
Ithaca, New York, USA
Outline
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Anatomy/Physiology
Clinical signs
Clinical and diagnostic
examination
Outline
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Etiologies
Diagnosis/treatment of
selected etiologies
Conjunctival Anatomy/Physiology
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Composed of nonkeratinized,
stratified squamous epithelium and
underlying substantia propria
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Capable of rapid and dramatic
response to insults
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Richly supplied by blood vessels
Loose arrangement of
conjunctival stroma
Resident lymphoid tissue
Specialized antigen-presenting cells
(M-cells)
Conjunctival Anatomy/Physiology
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Often secondarily involved in other
intraocular, extraocular, and
systemic diseases
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Anatomical proximity and shared
blood supply with other ocular
structures
Extensive vascular/lymphoid
tissue
Relatively accessible and
observable
Conjunctivitis Clinical Signs
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Conjunctivitis associated with
some combination of the
following clinical signs:
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Ocular discharge: epiphora,
mucoid, or mucopurulent
Chemosis: edema resulting
from increased permeability of
conjunctival vessels with fluid
extravasation
Hyperemia: red discoloration
from conjunctival vessel
vasodilatation
Ocular discomfort:
blepharospasm, rubbing
Conjunctivitis Clinical Signs
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Conjunctivitis associated with
some combination of the
following clinical signs:
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Tissue proliferation:
lymphatic, epithelial
hyperplasia, or keratinization
Ulceration: any severe
conjunctivitis or those
associated with particular
etiologies (viral, chemical,
trauma)
Pigmentation or
depigmentation
Conjunctivitis Examination
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Physical examination
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To rule-out primary or
concurrent systemic
diseases
Conjunctivitis Examination
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Complete ophthalmic
examination:
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Focal light source and
magnification
Adnexa, extraocular, and
intraocular structures
Including Schirmer tear
tests, fluorescein stain,
tonometry
Examine behind nictitans
membrane
Conjunctivitis Examination
Conjunctivitis diagnostics:
 Conjunctival cytology
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Microbiologic diagnostics
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Scrapings, swabs, aspirates
often helpful in diagnosis
Cultures, PCR, IFA, etc… as
indicated for select cases where
infectious etiology suspected
Biopsy/histopathology
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For conjunctivitis that is
severe, chronic, unresponsive
to treatment, or associated with
mass formation
Conjunctivitis Etiologies
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Inflammation of the
conjunctiva is a common
condition and may be a:
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Primary or secondary
disease process
Result of ocular or
systemic disease
Conjunctivitis Etiologies
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The conjunctiva has
limited mechanisms by
which it can respond to
insults, thus the etiology
of conjunctivitis can
usually not be
determined from clinical
signs alone
Conjunctivitis Etiologies
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Secondary conjunctivitis
more common than primary
in the horse
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Secondary conjunctivitis
typically occurs as a result of
adjacent ocular inflammation
or systemic disease:
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Intraocular disease: uveitis,
glaucoma
Extraocular disease: corneal
ulcers or abscesses, blepharitis
Systemic disease: infectious,
neoplastic, immune-mediated
Conjunctivitis Etiologies
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The diagnosis and treatment
of secondary conjunctivitis
should be directed toward
the underlying ocular or
systemic condition
Secondary Conjunctivitis
Conjunctivits secondary to
a corneal ulcer
Conjunctivits secondary to
anterior uveitis
Primary Conjunctivitis Etiologies
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Idiopathic, immune-mediated:
eosinophilic, lymphocytic
Allergic
Infectious
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Bacterial: Streptococcus equi,
Moraxella equi, Chlamydia, etc…
Fungal: Aspergillus, Rhinosporidium,
Histoplasmosis, Blastomycosis,
Cryptococcus, etc…
Viral: Equine herpesvirus 2 and 5
Parasitic: Onchocerciasis,
Habronemiasis, Thelazia lacrimalis,
Trypanosomiasis
Toxic/Chemical:
Stachybotryotoxicosis, alkali/acid burn
Primary Conjunctivitis Etiologies
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Trauma: blunt or penetrating
Frictional irritants: entropion,
ectopic cilia, distichia, foreign
bodies
Keratoconjunctivitis sicca
Exposure: facial nerve dysfunction,
lagophthalmos
Actinic
Neoplastic
Eosinophilic Conjunctivitis
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Idiopathic infiltration of
conjunctiva with eosinophils
May be present with or without
corneal lesions
Diagnosis: eosinophils on cytology
or histopathology without parasites
present
Eosinophilic Conjunctivitis
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Treatment:
Topical corticosteroids or
cyclosporine: tapered to least
frequent effective dose
Topical mast cell stabilizers
(cromolyn, olopatadine,
lodoxamide) may also be effective
in some cases
Eosinophilic Conjunctivitis
Conjunctival biopsy from a horse with eosinophilic
keratoconjunctivitis displaying numerous eosinophils
Lymphocytic Conjuctivitis
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Lobulated or smooth, pink
conjunctival masses
 Composed of
lymphocytes and
macrophages
 Most common locations:
dorsal bulbar conjunctiva
and third eyelid
Lymphocytic Conjuctivitis
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Diagnosis: lymphocytic
aggregates on
cytology/histopathology
Treatment: topical or
intralesional corticosteroids,
topical cyclosporine, or
surgical excision
Lymphocytic Conjuctivitis
Conjunctival biopsy from a horse with lymphocytic conjunctivitis
displaying numerous lymphocytes and occasional plasma cells
Bacterial and Fungal Conjunctivitis
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Bacterial and fungal
conjunctivitis usually
secondary infections
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Diagnosis based upon
cytology and culture
findings
Fungal conjunctivitis secondary
to keratomycosis
Bacterial and Fungal Conjunctivitis
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Treatment: identify and
treat underlying cause
along with the
opportunistic infection
Fungal conjunctivitis secondary
to keratomycosis
Viral Conjunctivitis
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Equine herpesvirus 2
and 5 may cause primary
conjunctivitis in the
horse
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Diagnosis: virus isolation,
PCR, IFA
Treatment: topical
idoxuridine, trifluridine,
or interferon
Viral Conjunctivitis
Equine viral arteritis, equine
adenovirus, equine
infectious anemia, equine
influenza, and African
horse sickness often cause
mild conjunctivitis
associated with systemic
disease
Parasitic Conjunctivitis
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Parasitic conjunctivitis most
commonly occurs with
Onchocerca cervicalis:
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Insect vectors: Culicoides spp.
Larvae migration incites
inflammation
Lesions: temporolimbal
conjunctival thickening,
nodules, and depigmentation
+/- keratitis
Parasitic Conjunctivitis
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Diagnosis:
conjunctival
biopsy
or
cytology
(microfilaria,
lymphocytes) eosinophils,
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Treatment: systemic
ivermectin and topical
corticosteroids
Parasitic Conjunctivitis
Onchocerca limbal conjunctival nodules
in a horse
Cytology of conjunctival
nodules with eosinophils
and Onchocerca microfilara
Parasitic Conjunctivitis
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Habronemiasis may also cause
conjunctivitis
 Habronema and Draschia spp.
(equine gastric worms)
 Larvae deposited on
conjunctiva by flies, migration
incites intense granulomatous
or eosinophilc inflammation
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Lesions: proliferative nodules,
granulation tissue appearance,
may be ulcerative, may have
yellow-white exudates (“sulfur
granules”)
 Occur on conjunctiva,
nictitans, and periocular skin;
most commonly adjacent to
medial canthus (where flies
feed)
Parasitic Conjunctivitis
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Diagnosis: seasonal, clinical
appearance, cytology/histopath
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Treatment: systemic ivermectin,
topical/intralesional/systemic
corticosteroids, surgical debulking
for large masses
Parasitic Conjunctivitis
Habronemiasis “sulfur granules”
at medial canthus in a horse
Habronema conjunctival nodule
and blepharitis in a horse
Parasitic Conjunctivitis
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Thelazia lacrimalis
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Nematode inhabiting conjunctival
fornices and nasolacrimal duct
Diagnosis: identification of
parasites during clinical
examination
Parasitic Conjunctivitis
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Treatment:
Manual removal of parasites with
lavage, swabs, or forceps
 Systemic ivermectin or topical
levamisole
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Traumatic Conjunctivitis
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May occur from blunt or
penetrating injuries
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Often dramatic chemosis initially
 May be associated with
subconjunctival hemorrhages
or emphysema
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Diagnostics: exclude other ocular
injuries and foreign bodies
 May be difficult on initial
presentation
Traumatic Conjunctivitis
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Treatment
 Most lacerations/punctures do
not require sutures as the
conjunctiva heals
spontaneously and rapidly
 Cold compresses acutely may
decrease clinical signs
 Topical antibiotics until
resolved
 Systemic antibiotics if
penetrating or full-thickness
wounds
 Consider systemic nonsteroidal
anti-inflammatories
Traumatic Conjunctivitis
Traumatic conjunctivitis with
subconjunctival hemorrahge
Traumatic conjunctivitis with
conjunctival emphysema
Actinic Conjunctivitis
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Occurs following chronic
UV-light exoposure
Diagnosis: ulcerative
conjunctivitis adjacent to
lid margins, develops in
areas of conjunctiva that
are not pigmented
Actinic Conjunctivitis
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Precursor to squamous cell
carcinoma
Treatment: shade (fly
mask, stabling), monitor
for neoplasia
development
Conjunctival Neoplasia
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Conjunctival neoplasia may
masquerade as conjunctivitis
initially
Most common types:
squamous cell carcinoma,
lymphoma, hemangioma,
hemangiosarcoma, papilloma,
and melanoma
Diagnosis based upon
excisional/incisional biopsy,
scrapings, or aspirates
Conjunctival Neoplasia
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Treatment:
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Surgical excision (always
treatment of choice when
complete excision possible)
Ancillary therapies often
indicated based upon tumor
type, location, extent:
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Diode laser ablation,
cryotherapy, radiation,
chemotherapy
Conjunctival Neoplasia
Conjunctival squamous cell carcinoma
Conjunctival lymphoma
Questions????