The “Red” Conjunctiva: Making the Correct Diagnosis

The “Red” Conjunctiva:
Making the Correct Diagnosis
Jennifer Hyman, VMD, MA, DACVO
Eye Care for Animals
Annapolis, MD
The “red eye” is a common complaint and presentation in veterinary ophthalmology. It may present for many different reasons.
Periocular trauma, episcleral inflammation, scleral injection, corneal vascularization, intraocular hemorrhage, uveitis, and ocular
surface disease, including keratoconjunctivitis sicca (KCS) may all lead to the complaint of a “red eye”. Aside from intraocular
hemorrhage clients notice changes in the conjunctiva in their pets, especially if discharge accompanies the color change. Examination
of the eye should lead to localization of the abnormality and standard ophthalmic testing should be performed, including Schirmer tear
testing, fluorescein staining, intraocular pressures, and qualitative tear film assessment. If cytology and/or culture and sensitivity need
to be submitted this should be done prior to instillation of topical fluorescein.
Several different types of tear measurement are available. The most common test is the Schirmer tear test that measures combined
basal and reflex tearing. This needs to be performed prior to instillation of proparacaine or fluorescein. The strips should be handled as
little as possible since the oils from our hands may affect the absorption of tears. Many people crimp the strip at the lower indent prior
to placing it in between the globe and lower lateral eyelid to facilitate stable placement. The strip should stay in the eye for 60
seconds. Normal values for the dog are over 15 mm wetting/minute and for the cat over 5 mm wetting/minute. Some patients have
enough pain associated with their KCS resulting in high reflex tearing and a falsely normal STT reading. This is not infrequent in dogs
with blepharophimosis, such as the Miniature Pinscher and rat terrier. A STT with topical anesthesia is needed to diagnose these
patients. Proparacaine is instilled and after 30-60 seconds the instilled proparacaine and lacrimal lake are removed from the lower
conjunctival fornix by WekCells. Then a STT strip is placed in the lower conjunctival fornix and the tears measured. A value that is
less 10 mm wetting/minute or less than half of the standard STT value is consistent with KCS.
The phenol red thread test is another way to measure tear production. The thread is placed in between the globe and lower eyelid in
the conjunctival fornix. Reflex tearing appears to be decreased in the author’s experience using this method, due to the softness of the
material and the time of the test is only 15 seconds, however the threads are flimsy and that can compromise correct placement in the
eye.
Other patients may present with keratoconjunctivitis sicca-like signs but have normal tear production. These patients may have a
qualitative tear film abnormality and the best way to diagnose this is by tear film break-up time. After instilling fluorescein drops or
making a solution of fluorescein in saline and placing a drop on the cornea the eyelids should be manually closed and then held open.
The fluorescein should coat the cornea for 20 seconds or more. Splotching or inconsistency in the fluorescein prior to 20 seconds is
consistent with a compromised tear film. A blacklight or slitlamp biomicroscope/direct ophthalmoscope using the cobalt filter is
needed to make this diagnosis. Rose Bengal staining can also be used to diagnose tear film abnormalities. Rose Bengal stains mucin
and “sick” corneal and conjunctival epithelial cells. The rose Bengal stain should coat the cornea evenly and last for over 20 seconds.
Examination of the “red” conjunctiva should include evaluation of the eyelids for induration, erythema, alopecia, broken hair
shafts, color change and focal lesions. Skin scraping and fungal culture may be needed. The eyelid skin is more sensitive than other
areas so gentle compression or “pinching” of a small section of the skin and then plucking a few hair shafts from the area is often an
easier way to evaluate for mites than an actual skin scraping. Mite and fungal infection should be treated as an infection elsewhere on
the skin. Generalized thickening and inflammation may require impression cytology, culture/sensitivity, and/or biopsy. Bacterial
infection should be treated according to biopsy results with antibiotic treatment for 4-8 weeks. Immune-mediated inflammation should
be treated with immunosuppressants; prednisone, oral cyclosporine, azathioprine are options. Apoquel, the recently released antiinflammatory may be tried, but more data is needed to evaluate its effectiveness for immune-mediated blepharitis. Topical treatment
such as hydrocortisone ointment, prednisolone acetate applied to the eyelids, and warm compressing may be prescribed as needed.
The Meibomian glands and opening to the ducts should be examined next. Inspissated meibum, “tipping” of the Meibomian gland
duct openings, and inflammation of the palpebral conjunctiva in the area, or even of the overlying skin are all signs of meibomianitis,
chalazion, or hordeolum formation. Treatment by warm compressing, then cleaning the eyelid margin with dilute Johnson’s no more
tears baby shampoo, Lid and Lash cleanser, or Ocusoft eyelid cleanser are products that the author often recommends. This should be
performed once or twice daily. Usually meibomianitis is immune-mediated or an infection associated with another ocular surface
disease, such as KCS. Cephalosporins or doxycycline or minocycline are recommended to empirically address meibomianitis.
Alternatively, meibum may be expressed from the plugged ducts and cultured. Doxycycline also has an immunomodulating effect that
may be beneficial in treating the inflammation. Doxycycline may be utilized with niacinamide to control immune-mediated eyelid
disease as a maintenance regimen. Due to the altered immune system of the KCS eye intermittent treatment for meibomianitis may be
indicated.
Chalazion formation may be treated surgically by local anesthesia, such as lidocaine:sodium bicarbonate infiltration and then
curettage of the chalazion. Sedation may be needed if the patient is painful, scared or too active. Chronic chalazion or hordeolum
formation may need to be addressed by excision. If this is needed biopsy of the material is recommended.
Conjunctivitis is present when the underlying sclera and/or episclera are inflamed. Episcleritis is usually diagnosed by clinical
examination, however biopsy and histopathology are needed for definitive diagnosis. The biopsy and treatment of scleral disease is
best handled by a veterinary ophthalmologist. Glaucoma and retinal detachment are the worst sequelae of this disease. Cocker spaniels
are the most commonly affected breed in the author’s experience. Necrotizing episcleritis, a variant of episcleritis, may be globethreatening. Topical, as well as systemic treatment may be required to control the disease process. Treatment may be for a finite period
with resolution or maintenance treatment may be needed if the condition recurs during drug taper. Typically topical anti-inflammatory
and immunosuppressant medications are prescribed to address the efferent and afferent arms of the immune system, respectively. A
subconjunctival injection of a steroid may also aid in treatment. If topical medications are not efficacious additional systemic
medication may be required, such as prednisone, azathioprine, cyclosporine/cyclosporine oral microemulsion, or a
doxycycline:niacinamide combination. Cryotherapy may be needed if medical therapy is not effective. Episcleritis may present as a
focal abnormality or diffuse disease, and may be uni- or bi-lateral.
Primary conjunctivitis occurs due to infection, immune-mediated disease, trauma or neoplasia. Secondary conjunctivitis occurs
with KCS, corneal abnormality, systemic metabolic disease, and as an ocular manifestation of systemic disease (OMSD). Treatment
may be empiric after diagnostic testing or based on cytology, culture/sensitivity, and biopsy. Certainly non-responsive conjunctivitis
needs more in-depth diagnostics.
Primary conjunctivitis in the feline is often caused by the feline herpes virus (FHV-1) and Chlamydophila; Calicivirus and
Mycoplasma are generally lesser players in the etiology of feline conjunctivitis. Other bacteria, parasites, fungi, and viruses can be
causative agents. An immune system abnormality is associated with eosinophilic conjunctivitis; FHV-1 may also be involved leading
to a multiple etiology. First line antibiotic therapy utilized by the author for a mixed bacterial and viral infection is ofloxacin and
idoxuridine or cidofovir. Other antibiotics such as tobramycin and cefazolin fortified tears may be prescribed. Trifluridine is another
topical antiviral, however it stings and compounding it to an ointment form is recommended. Although trifluridine is stronger, it needs
to be applied 3-6 times daily; cidofovir only needs to be applied twice daily, resulting in increased client compliance and decreased
patient stress. Usually topical antibiotics are applied 3-4 times daily. Recent studies have demonstrated an effect on tear film quality
after a corneal ulcer in the feline and infection with FHV-1. Maintenance use of a topical lacrimomimetic, such as Genteal or Refresh
should decrease the rate and risk of recurrence. Topical immunosuppressants such as Optimmune (0.2% cyclosporine), 1-2%
cyclosporine, or 0.02%-0.03% tacrolimus may be useful in treating eosinophilic conjunctivitis. Many cats dislike ointments so the
author generally tries to prescribe drop formulations. If an ointment is utilized the owner should be educated to apply a “grain of rice”
size amount. A last note; due to the rare reports of neomycin sensitivity in cats the author does not prescribe neomycin containing
antibiotics for cats.
For the canine, treatment of primary conjunctivitis is similar, however viral disease is not as common in the dog; a few cases of
viral keratitis and conjunctivitis have been reported. First line antibiotics include triple antibiotic ointment or drops, tobramycin or
gentocin, and oxytetracycline. Second line antibiotics may be utilized for refractory cases or based on culture/sensitivity such as
ofloxacin and cefazolin fortified tears. Vigamox, a third line antibiotic is usually utilized for malacic corneal ulcers, but not for
conjunctivitis. Ointments generally have a longer retention time and can help with ocular surface disease, so if the patient tolerates an
ointment it would be beneficial to prescribe it. If a corneal ulcer such as a descemetocele or corneal rupture is also an issue only drops
should be prescribed. For conjunctivitis that is not associated with a corneal ulcer a steroid such as hydrocortisone or dexamethasone
may be beneficial. Tobradex or Neopolydex may be prescribed. Other antibiotic/anti-inflammatory combinations are available,
depending on the diagnosis and causative agent. Some dogs may be neomycin sensitive so if a neomycin containing medication was
prescribed and the patient is not improving or seems to have increased sensitivity and eyelid involvement a different medication
should be tried.
The use of cyclosporine and tacrolimus is primarily for quantitative and qualitative KCS in dogs and sometimes cats. The majority
of KCS cases are immune-mediated and T cells have been documented on histopathology of affected glands. These
immunosuppressants are available as the FDA-approved Optimmune and in compounded form. Aqueous, oil-based and ointment
forms are available. Some patients may be sensitive to the oil base, so if blepharitis develops after instituting an oil-based product it
should be discontinued and an ointment or aqueous base utilized. Generally, corn or olive oil is utilized for compounding cyclosporine
and tacrolimus. Even aqueous based solutions may cause irritation due to the preservatives and underlying disease process. Lastly, the
patient may be hypersensitive to the cyclosporine or tacrolimus itself. When this occurs utilizing a lower concentration or applying it
less frequently may resolve the issue; alternatively a different medication could be prescribed, such as changing to cyclosporine if
tacrolimus is not tolerated. Client education is important when prescribing these products. Some ophthalmologists instruct the owner
to wear gloves when applying these ointments, due to the reports of neoplasia in lab animals when treated with high doses of these
agents. Also, a recent report was published on the development of corneal neoplasia in dogs being treated for KCS with these
immunosuppressant medications. However, the role of the underlying disease process and the severe keratitis in these patients may
also be involved in the development of the neoplasia.
Cyclosporine and tacrolimus also have tear stimulating properties that are not related to the immunosuppressive properties of these
drugs. They improve the health of the goblet cell population and decrease mucus production. Another benefit is the decrease in
pigment deposition and even dissolution of it. For patients with KCS-related conjunctivitis that are non-responders to the drug, i.e.,
tear production does not increase, it is still advisable to maintain one of them for their beneficial effects on the conjunctiva. A typical
medication schedule for a KCS patient may include: 1. A lacrimostimulant such as cyclosporine, 2. A topical lacrimo- and
mucinomimetic such as Genteal, and 3. A topical anti-inflammatory such as hydrocortisone ointment. Severe cases may also require
rotating topical antibiotics, and/or pulse oral antibiotics. The author recommends referral and management by an ophthalmologist for
non-responsive cases that require involved medication schedules and significant client education and contact. Mucomist or 5%
acetylcysteine may help with remodeling of the ocular surface and decrease mucus production. Some patients have a negative
response to this, but it is something to try in situations of copious mucus production.
Topical tear and mucin replacement/supplementation is an important part of treating ocular surface disease. Patients with
pancreatitis or other systemic disease may suffer from suppression of tear production associated with decreased metabolism. Tear
supplementation may also be helpful in cases of allergic conjunctivitis. Vaccine-related conjunctivitis has been documented in the
canine and ongoing research on allergic conjunctivitis indicate OTC mast cell inhibitors, such as Zaditor may also help decrease
conjunctivitis and improve comfort. Topical tear/mucin supplementation is available OTC with and without preservatives. If one
brand does not seem to be improving patient comfort another one should be tried. I-Drop Vet, Optixcare, and other veterinary products
are also available for stocking in the clinic.
Patients with KCS should have baseline labwork, including a full thyroid panel performed. Hypothyroidism can be related to the
onset of KCS. Possible exposure to drugs and other medical history should also be collected; sulfa drugs and Etogesic are two know
etiologic agents of lacrimal gland destruction. Client education and communication is very important in managing this disease as it can
very frustrating for the client to treat and to experience their pet in discomfort. Current publications on liposome-encapsulated
lacrimostimulants and antibiotics, as well as additional aqueous based lacrimostimulants hold promise for future therapy. Parotid duct
transposition is recommended for patients that are significantly painful, that are non-responders to cyclosporine or tacrolimus, and that
respond to an atropine stimulation test. This surgery is not without complication, so client education is again critical. There are many
other causes of red conjunctiva, e.g., ligneous conjunctivitis, and reference to an ophthalmic text is recommended for further
investigation of less common disease entities.
References
Veterinary Ophthalmology, 4th ed., Gelatt KN, editor, Blackwell Publishing, Ames IA 2007.
Veterinary Ophthalmology (2011) 14, 3, 161-168.
Veterinary Ophthalmology (2011) 14, 4, 248-256.
Veterinary Ophthalmology (2011) 14, Supplement 1, 54-59.
Veterinary Ophthalmology (2012) 15, 5, 299-306.

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