4. Conjunctival Anatomy/PhysiologyConjunctival Anatomy/Physiology
Composed of nonkeratinized,Composed of nonkeratinized,
stratified squamous epithelium andstratified squamous epithelium and
underlying substantia propriaunderlying substantia propria
Capable of rapid and dramaticCapable of rapid and dramatic
response to insultsresponse to insults
Richly supplied by blood vesselsRichly supplied by blood vessels
Loose arrangement of conjunctivalLoose arrangement of conjunctival
stromastroma
Resident lymphoid tissueResident lymphoid tissue
Specialized antigen-presenting cellsSpecialized antigen-presenting cells
(M-cells)(M-cells)
5. Conjunctival Anatomy/PhysiologyConjunctival Anatomy/Physiology
Often secondarily involved in otherOften secondarily involved in other
intraocular, extraocular, andintraocular, extraocular, and
systemic diseasessystemic diseases
Anatomical proximity and sharedAnatomical proximity and shared
blood supply with other ocularblood supply with other ocular
structuresstructures
Extensive vascular/lymphoidExtensive vascular/lymphoid
tissuetissue
Relatively accessible andRelatively accessible and
observableobservable
6. Conjunctivitis Clinical SignsConjunctivitis Clinical Signs
Conjunctivitis associated withConjunctivitis associated with
some combination of thesome combination of the
following clinical signs:following clinical signs:
Ocular discharge:Ocular discharge: epiphora,epiphora,
mucoid, or mucopurulentmucoid, or mucopurulent
Chemosis:Chemosis: edema resultingedema resulting
from increased permeability offrom increased permeability of
conjunctival vessels with fluidconjunctival vessels with fluid
extravasationextravasation
Hyperemia:Hyperemia: red discolorationred discoloration
from conjunctival vesselfrom conjunctival vessel
vasodilatationvasodilatation
Ocular discomfort:Ocular discomfort:
blepharospasm, rubbingblepharospasm, rubbing
7. Conjunctivitis Clinical SignsConjunctivitis Clinical Signs
Conjunctivitis associated withConjunctivitis associated with
some combination of thesome combination of the
following clinical signs:following clinical signs:
Tissue proliferation:Tissue proliferation:
lymphatic, epitheliallymphatic, epithelial
hyperplasia, or keratinizationhyperplasia, or keratinization
Ulceration:Ulceration: any severeany severe
conjunctivitis or thoseconjunctivitis or those
associated with particularassociated with particular
etiologies (viral, chemical,etiologies (viral, chemical,
trauma)trauma)
PigmentationPigmentation oror
depigmentationdepigmentation
10. Conjunctivitis ExaminationConjunctivitis Examination
Conjunctivitis diagnostics:Conjunctivitis diagnostics:
Conjunctival cytologyConjunctival cytology
Scrapings, swabs, aspiratesScrapings, swabs, aspirates
often helpful in diagnosisoften helpful in diagnosis
Microbiologic diagnosticsMicrobiologic diagnostics
Cultures, PCR, IFA, etc… asCultures, PCR, IFA, etc… as
indicated for select cases whereindicated for select cases where
infectious etiology suspectedinfectious etiology suspected
Biopsy/histopathologyBiopsy/histopathology
For conjunctivitis that isFor conjunctivitis that is
severe, chronic, unresponsivesevere, chronic, unresponsive
to treatment, or associated withto treatment, or associated with
mass formationmass formation
11. Conjunctivitis EtiologiesConjunctivitis Etiologies
Inflammation of theInflammation of the
conjunctiva is a commonconjunctiva is a common
condition and may be a:condition and may be a:
Primary or secondaryPrimary or secondary
disease processdisease process
Result of ocular orResult of ocular or
systemic diseasesystemic disease
12. Conjunctivitis EtiologiesConjunctivitis Etiologies
The conjunctiva hasThe conjunctiva has
limited mechanisms bylimited mechanisms by
which it can respond towhich it can respond to
insults, thus the etiologyinsults, thus the etiology
of conjunctivitis canof conjunctivitis can
usually not beusually not be
determined from clinicaldetermined from clinical
signs alonesigns alone
13. Conjunctivitis EtiologiesConjunctivitis Etiologies
Secondary conjunctivitisSecondary conjunctivitis
more common than primarymore common than primary
in the horsein the horse
Secondary conjunctivitisSecondary conjunctivitis
typically occurs as a result oftypically occurs as a result of
adjacent ocular inflammationadjacent ocular inflammation
or systemic disease:or systemic disease:
Intraocular disease: uveitis,Intraocular disease: uveitis,
glaucomaglaucoma
Extraocular disease: cornealExtraocular disease: corneal
ulcers or abscesses, blepharitisulcers or abscesses, blepharitis
Systemic disease: infectious,Systemic disease: infectious,
neoplastic, immune-mediatedneoplastic, immune-mediated
14. Conjunctivitis EtiologiesConjunctivitis Etiologies
The diagnosis and treatmentThe diagnosis and treatment
of secondary conjunctivitisof secondary conjunctivitis
should be directed towardshould be directed toward
the underlying ocular orthe underlying ocular or
systemic conditionsystemic condition
18. Eosinophilic ConjunctivitisEosinophilic Conjunctivitis
Idiopathic infiltration ofIdiopathic infiltration of
conjunctiva with eosinophilsconjunctiva with eosinophils
May be present with or withoutMay be present with or without
corneal lesionscorneal lesions
Diagnosis: eosinophils on cytologyDiagnosis: eosinophils on cytology
or histopathology without parasitesor histopathology without parasites
presentpresent
19. Eosinophilic ConjunctivitisEosinophilic Conjunctivitis
Treatment:Treatment:
Topical corticosteroids orTopical corticosteroids or
cyclosporine: tapered to leastcyclosporine: tapered to least
frequent effective dosefrequent effective dose
Topical mast cell stabilizersTopical mast cell stabilizers
(cromolyn, olopatadine,(cromolyn, olopatadine,
lodoxamide) may also be effectivelodoxamide) may also be effective
in some casesin some cases
21. Lymphocytic ConjuctivitisLymphocytic Conjuctivitis
Lobulated or smooth, pinkLobulated or smooth, pink
conjunctival massesconjunctival masses
Composed of lymphocytesComposed of lymphocytes
and macrophagesand macrophages
Most common locations:Most common locations:
dorsal bulbar conjunctivadorsal bulbar conjunctiva
and third eyelidand third eyelid
22. Lymphocytic ConjuctivitisLymphocytic Conjuctivitis
Diagnosis: lymphocyticDiagnosis: lymphocytic
aggregates onaggregates on
cytology/histopathologycytology/histopathology
Treatment: topical orTreatment: topical or
intralesional corticosteroids,intralesional corticosteroids,
topical cyclosporine, ortopical cyclosporine, or
surgical excisionsurgical excision
23. Lymphocytic ConjuctivitisLymphocytic Conjuctivitis
Conjunctival biopsy from a horse with lymphocytic conjunctivitisConjunctival biopsy from a horse with lymphocytic conjunctivitis
displaying numerous lymphocytes and occasional plasma cellsdisplaying numerous lymphocytes and occasional plasma cells
24. Bacterial and Fungal ConjunctivitisBacterial and Fungal Conjunctivitis
Bacterial and fungalBacterial and fungal
conjunctivitis usuallyconjunctivitis usually
secondary infectionssecondary infections
Diagnosis based uponDiagnosis based upon
cytology and culturecytology and culture
findingsfindings
Fungal conjunctivitis secondaryFungal conjunctivitis secondary
to keratomycosisto keratomycosis
25. Bacterial and Fungal ConjunctivitisBacterial and Fungal Conjunctivitis
Treatment: identify andTreatment: identify and
treat underlying causetreat underlying cause
along with thealong with the
opportunistic infectionopportunistic infection
Fungal conjunctivitis secondaryFungal conjunctivitis secondary
to keratomycosisto keratomycosis
26. Viral ConjunctivitisViral Conjunctivitis
Equine herpesvirus 2 andEquine herpesvirus 2 and
5 may cause primary5 may cause primary
conjunctivitis in theconjunctivitis in the
horsehorse
Diagnosis: virus isolation,Diagnosis: virus isolation,
PCR, IFAPCR, IFA
Treatment: topicalTreatment: topical
idoxuridine, trifluridine,idoxuridine, trifluridine,
or interferonor interferon
27. Viral ConjunctivitisViral Conjunctivitis
Equine viral arteritis, equineEquine viral arteritis, equine
adenovirus, equineadenovirus, equine
infectious anemia, equineinfectious anemia, equine
influenza, and Africaninfluenza, and African
horse sickness often causehorse sickness often cause
mild conjunctivitismild conjunctivitis
associated with systemicassociated with systemic
diseasedisease
29. Parasitic ConjunctivitisParasitic Conjunctivitis
Diagnosis: conjunctivalDiagnosis: conjunctival
biopsy or cytologybiopsy or cytology
(microfilaria, eosinophils,(microfilaria, eosinophils,
lymphocytes)lymphocytes)
Treatment: systemicTreatment: systemic
ivermectin and topicalivermectin and topical
corticosteroidscorticosteroids
30. Parasitic ConjunctivitisParasitic Conjunctivitis
OnchocercaOnchocerca limbal conjunctival noduleslimbal conjunctival nodules
in a horsein a horse
Cytology of conjunctivalCytology of conjunctival
nodules with eosinophilsnodules with eosinophils
andand OnchocercaOnchocerca microfilaramicrofilara
31. Parasitic ConjunctivitisParasitic Conjunctivitis
Habronemiasis may also causeHabronemiasis may also cause
conjunctivitisconjunctivitis
HabronemaHabronema andand DraschiaDraschia spp.spp.
(equine gastric worms)(equine gastric worms)
Larvae deposited onLarvae deposited on
conjunctiva by flies, migrationconjunctiva by flies, migration
incites intense granulomatousincites intense granulomatous
or eosinophilc inflammationor eosinophilc inflammation
Lesions: proliferative nodules,Lesions: proliferative nodules,
granulation tissue appearance,granulation tissue appearance,
may be ulcerative, may havemay be ulcerative, may have
yellow-white exudates (“sulfuryellow-white exudates (“sulfur
granules”)granules”)
Occur on conjunctiva,Occur on conjunctiva,
nictitans, and periocular skin;nictitans, and periocular skin;
most commonly adjacent tomost commonly adjacent to
medial canthus (where fliesmedial canthus (where flies
feed)feed)
32. Parasitic ConjunctivitisParasitic Conjunctivitis
Diagnosis: seasonal, clinicalDiagnosis: seasonal, clinical
appearance, cytology/histopathappearance, cytology/histopath
Treatment: systemic ivermectin,Treatment: systemic ivermectin,
topical/intralesional/systemictopical/intralesional/systemic
corticosteroids, surgical debulkingcorticosteroids, surgical debulking
for large massesfor large masses
33. Parasitic ConjunctivitisParasitic Conjunctivitis
Habronemiasis “sulfur granules”Habronemiasis “sulfur granules”
at medial canthus in a horseat medial canthus in a horse
HabronemaHabronema conjunctival noduleconjunctival nodule
and blepharitis in a horseand blepharitis in a horse
34. Parasitic ConjunctivitisParasitic Conjunctivitis
Thelazia lacrimalisThelazia lacrimalis
Nematode inhabiting conjunctivalNematode inhabiting conjunctival
fornices and nasolacrimal ductfornices and nasolacrimal duct
Diagnosis: identification ofDiagnosis: identification of
parasites during clinicalparasites during clinical
examinationexamination
35. Parasitic ConjunctivitisParasitic Conjunctivitis
Treatment:Treatment:
Manual removal of parasites withManual removal of parasites with
lavage, swabs, or forcepslavage, swabs, or forceps
Systemic ivermectin or topicalSystemic ivermectin or topical
levamisolelevamisole
36. Traumatic ConjunctivitisTraumatic Conjunctivitis
May occur from blunt orMay occur from blunt or
penetrating injuriespenetrating injuries
Often dramatic chemosis initiallyOften dramatic chemosis initially
May be associated withMay be associated with
subconjunctival hemorrhagessubconjunctival hemorrhages
or emphysemaor emphysema
Diagnostics: exclude other ocularDiagnostics: exclude other ocular
injuries and foreign bodiesinjuries and foreign bodies
May be difficult on initialMay be difficult on initial
presentationpresentation
37. Traumatic ConjunctivitisTraumatic Conjunctivitis
TreatmentTreatment
Most lacerations/punctures doMost lacerations/punctures do
not require sutures as thenot require sutures as the
conjunctiva healsconjunctiva heals
spontaneously and rapidlyspontaneously and rapidly
Cold compresses acutely mayCold compresses acutely may
decrease clinical signsdecrease clinical signs
Topical antibiotics untilTopical antibiotics until
resolvedresolved
Systemic antibiotics ifSystemic antibiotics if
penetrating or full-thicknesspenetrating or full-thickness
woundswounds
Consider systemic nonsteroidalConsider systemic nonsteroidal
anti-inflammatoriesanti-inflammatories
38. Traumatic ConjunctivitisTraumatic Conjunctivitis
Traumatic conjunctivitis withTraumatic conjunctivitis with
subconjunctival hemorrahgesubconjunctival hemorrahge
Traumatic conjunctivitis withTraumatic conjunctivitis with
conjunctival emphysemaconjunctival emphysema
39. Actinic ConjunctivitisActinic Conjunctivitis
Occurs following chronicOccurs following chronic
UV-light exoposureUV-light exoposure
Diagnosis: ulcerativeDiagnosis: ulcerative
conjunctivitis adjacent toconjunctivitis adjacent to
lid margins, develops inlid margins, develops in
areas of conjunctiva thatareas of conjunctiva that
are not pigmentedare not pigmented
40. Actinic ConjunctivitisActinic Conjunctivitis
Precursor to squamous cellPrecursor to squamous cell
carcinomacarcinoma
Treatment: shade (flyTreatment: shade (fly
mask, stabling), monitormask, stabling), monitor
for neoplasiafor neoplasia
developmentdevelopment
41. Conjunctival NeoplasiaConjunctival Neoplasia
Conjunctival neoplasia mayConjunctival neoplasia may
masquerade as conjunctivitismasquerade as conjunctivitis
initiallyinitially
Most common types:Most common types:
squamous cell carcinoma,squamous cell carcinoma,
lymphoma, hemangioma,lymphoma, hemangioma,
hemangiosarcoma, papilloma,hemangiosarcoma, papilloma,
and melanomaand melanoma
Diagnosis based uponDiagnosis based upon
excisional/incisional biopsy,excisional/incisional biopsy,
scrapings, or aspiratesscrapings, or aspirates
42. Conjunctival NeoplasiaConjunctival Neoplasia
Treatment:Treatment:
Surgical excision (alwaysSurgical excision (always
treatment of choice whentreatment of choice when
complete excision possible)complete excision possible)
Ancillary therapies oftenAncillary therapies often
indicated based upon tumorindicated based upon tumor
type, location, extent:type, location, extent:
Diode laser ablation,Diode laser ablation,
cryotherapy, radiation,cryotherapy, radiation,
chemotherapychemotherapy