# Conjunctivitis

The primary manifestation of conjunctival disease in cats is conjunctivitis.
The big three:
- Herpes
- Chlamydia
- Mycoplasma
Age:
- Neonates and juveniles
Generalities that may help distinguish among them:
- Herpes - Often accompanied by URT disease
- Chlamydia - More likely to produce whopping chemosis
- Mycoplasma - Occasionally produces a pseudo-diphtheritic membrane on surface of conjunctiva.
Latency and recrudescence:
- Herpes latent in trigeminal, perhaps cornea. Recrudesces when stresseds.
- Secondary infections frequently manifest as keratitis.
Diagnosis:
- Cytology of conjunctival scrapings
- PCR test of conjunctival scrapings (esp. Herpes and chlamydia).
- Very common NOT to arrive at a definitive diagnosis, so you end up treating empirically.
Treatment:
- Herpes – Herpetic conjunctivitis is usually self-limiting. May need specific antiviral therapy in extremely refractory cases (will discuss antivirals in detail under “Herpetic Keratitis”).
- Chlamydia - Topical tetracycline or chloramphenicol
- Mycoplasma - Topical tetracycline or chloramphenicol

# Keratitis

# Herpetic keratitis

Clinical signs / history
- Usually manifests in adults following initial URT illness and conjunctivitis as a kitten
- Recall that this virus remains latent in the trigeminal ganglion and, to a lesser extent, the corneal stroma
- Keratitis
- Dendritic ulceration
- Generally have concurrent conjunctivitis
- Frequently have decreased STT as well.
Diagnosis:
- Dendritic ulceration is pathognomonic
- History of URT disease in cat with keratitis should always arouse suspicion of herpes
- PCR test of conjunctival swab
Treatment:
- Antiviral drugs
  - Trifluorothymidine (topical) - Solution only, so frequent therapy, but 95% effective. Very expensive
  - Cidofovir (topical) – Concentrates in corneal epithelium, so can get away with BID therapy
  - Famciclovir (oral) – The most in vogue therapy in 2015, but very expensive. I’m not convinced the literature is conclusive that it’s any better than topical cidofovir
  - All are nucleic acid analogues, result in creation of proteins that virus can’t use, and ultimately virus fails to replicate (thus they are virostatic).
  - All capable of inducing intense chemosis due to sensitivity to drugs.
- Topical antibiotics (tetracycline)
- Oral lysine – May reduce the frequency and severity of recrudescences
- +/- Topical atropine
Prognosis:
- Response to antivirals is pretty good, but recurrence is very common.
- Need to warn owners of this possibility

# Feline corneal sequestrum (nigrum)

Maxim: If it’s a cornea, and it’s black, and it’s a cat, its a SEQUESTRUM!!
Definition: Area of focal corneal stromal necrosis in center of cornea. Only seen in cats, with some predisposition for brachycephalics.
Etiology:
- Unknown; possible relationship to tear film abnormalities, decreased corneal sensitivity, herpesvirus infection, chronic corneal trauma.
Diagnosis:
- Clinical appearance.
Treatment:
- Aggressive - Lamellar keratectomy, followed by NM flap. Subsequently treat as ulcer. Usually choose this tx if painful.
- Conservative - Most sequestra will slough spontaneously given enough time (months).

# Eosinophilic Keratitis

Keratitis syndrome of pinkish fleshy proliferation at limbus, unkown etiology, diagnose by cytology, resonds to steroids.

# Exposure Keratitis due to Eyelid Agenesis (also called Eyelid Coloboma)

Definition: Congential absence of portion of lid, usually superotemporal.
Clinical signs / history:
- Keratitis changes
- Blepharospasm
- Portion of lid, usually superotemporal, absent
Treatment:
- Medical - Topical lubricants
- Surgical - Tarsal pedicle graft

# Anterior Uveitis

Definition: Inflammation of iris and ciliary body.
Clinical signs / history:
- Same as for dog
- Flare, miosis, hyperemia, fibrin, etc.
- Cats somewhat more prone to development of pre-iridial fibrovascular membranes (PIFMs) in anterior chamber.
- As with dogs, anterior uveitis in cats is sometimes associated with systemic disease, so you may have clinical signs / history referable to such disease.
- Lens induced uveitis uncommon in cats.
Etiology:
- Systemic infectious disease (toxo, FIP, systemic fungal, FeLV, FIV)
- Intraocular neoplasia (melanoma, lymphoma)
- Idiopathic (about 70%)
Diagnosis:
- Clinical signs
- Good physical exam to delineate systemic illness
- Minimum data base (CBC, profile, FIV, FeLV, toxo)
Treatment:
- Treat any underlying disorder
- Topical steroids, atropine
- Oral aspirin (1/2 baby twice weekly) for chronic cases
Sequelae / prognosis:
- High incidence of secondary glaucoma.

# Ocular Neoplasia

Lid Tumors
- Squamous cell carcinoma
  - Clinical signs / history:
    - Usually older, white cats.
    - Pinkish mass, sometimes ulcerated, of lids (can also see on NM, conjunctiva, cornea)
- Treatment:
  - Surgical resection; due to the infinite varieties of tumor location and size, there is no single “preferred technique.” Often involve rotational skin grafts.
  - Brachytherapy (i.e., intralesional radiation)
  - Cryotherapy
Intraocular tumors
- Anterior Uveal Melanoma
  - Most common primary intraocular tumor of cats. Iris affected more commonly than ciliary body.
  - Clinical signs / history:
    - Diffuse form - Most common in cats. Rather than a discrete tumor mass, animal presents for hyperpigmentation of iris.
      - Sometimes present primarily with signs of anterior uveitis.
    - Nodular form - Discrete black nodule.
  - Benign or malignant? - There definitely is malignant potential. Difficult to say for sure about a benign form. Some say there is a benign “variant” termed melanocytoma or diffuse benign iris melanosis. Others say these supposedly benign pigmentary disorders have malignant potential, while still others say they are always pre-malignant.
  - Metastatic potential - Considered high (50-ish%) to regional lymph nodes then viscera. Can be long delay between diagnosis of ocular tumor and metastatic disease.
  - Secondary glaucoma common.
  - Diagnosis:
    - Tentatively diagnosed based on clinical appearance alone; definitive diagnosis made on histopathology of enucleated globe.
  - Treatment:
    - One opinion - Observation, then enucleate if secondary glaucoma or ocular pain occur.
      - Another opinion - Early enucleation
- Lymphosarcoma of the Iris
  - Clinical signs / history:
    - Tan-pink mass in anterior chamber
    - Ocular pain if uveitis is present
    - Secondary glaucoma common.
  - Etiology:
    - Since there’s no lymphatic tissue in the eye, this should always be considered a secondary tumor.
  - Diagnosis:
    - Clinical appearance, while not as classic as the melanoma, is still quite suggestive.
    - If mass is large enough can aspirate via the limbus.
  - Treatment:
    - Search for primary tumor site.
    - Enucleation.
- Feline Post-traumatic Ocular Sarcoma
  - Definition: Intraocular sarcoma (fibro-, anaplastic, or osteo-) that can seemingly arise diffusely within the globe following traumatic insults, and perhaps even following chronic anterior uveitis.
  - Clinical signs / history:
    - Trauma
    - Usually older cats
    - Usually do not see a discrete mass; present with glaucoma, phthisis, or signs of chronic inflammation. Therefore diagnosis is often made on histopathologic exam of enucleated globe.
  - Treatment:
    - Enucleation due to aggressive nature of tumor.
    - Often fatal

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