Corneal and Scleral Lacerations

Corneal and Scleral Lacerations – An Overview

  • “Corneal” refers to the cornea; “scleral” refers to the sclera of the eye
  • The “cornea” is the clear outer layer of the front of the eye; the “sclera” is the white part of the eye, it is composed of a tough covering that protects the eyeball
  • “Penetrating” injury—a wound or foreign body that enters, but does not completely pass through the cornea or sclera; it also is known as a “non-perforating” injury
  • “Perforating” injury—a wound or foreign body that completely passes through the cornea or sclera; greater risk of vision loss than with penetrating injury
  • “Simple”—involves only the cornea or sclera; may be penetrating or perforating; other eye structures are intact (that is, not injured)
  • “Complicated”—a type of perforating injury; involves other eye structures in addition to the cornea or sclera; may involve the uvea (the entire middle layer of the eyeball that contains the blood vessels; it is composed of the iris [the colored or pigmented part of the eye], the ciliary body [the area between the iris and the choroid], and the choroid [located under the back part of the eye—the retina); the vitreous (the clear, gel-like material that fills the back part of the eyeball [between the lens and the retina]); or the retina (back part of the eye that contains the light-sensitive rods and cones and other cells that convert images into signals and send messages to the brain, to allow for vision); may also have trauma to the lens leading to cataracts or lacerations to the eyelids
  • The pupil is the circular or elliptical opening in the center of the iris of the eye; light passes through the pupil to reach the back part of the eye (known as the “retina”); the iris is the colored or pigmented part of the eye—it can be brown, blue, green, or a mixture of colors

Signs/Observed Changes in the Pet

  • Varies with tissues affected
  • Usually sudden (acute) onset of signs
  • Often a history of running through heavy vegetation, being hit by gunshot pellets or other projectiles, or being scratched by a cat
  • Trauma itself may not be observed
  • Common—corneal, scleral, or eyelid deformity; fluid buildup (known as “edema”) in affected tissues; bleeding (hemorrhage)
  • May see a retained foreign body
  • Lacerations often rapidly seal; may appear only as a blood-filled mass under the moist tissues of the eye (known as a “subconjunctival hematoma”)
  • May also see iris defects; pupil distortion; blood in the anterior chamber of the eye (the front part of the eye, between the cornea and the iris; accumulation of blood known as “hyphema”); cataract (opacity in the normally clear lens, preventing passage of light to the back part of the eye [retina]); bleeding in the vitreous (the clear, gel-like material that fills the back part of the eyeball); separation of the back part of the eye (retina) from the underlying, vascular part of the eyeball (known as the “choroid”; condition known as “retinal detachment”); and protrusion of the eyeball (known as “exophthalmia”)

Causes

  • Blunt or sharp trauma

Risk Factors

  • Preexisting visual impairment
  • Young, naive, or highly excitable pets
  • Hunting or running through heavy vegetation
  • Fighting

Treatment

Health Care

  • Depends on severity
  • Outpatient—if integrity of the eyeball is ensured
  • Sedation—consider for excited or fractious pets
  • When walking—apply an Elizabethan collar and use a harness to avoid increasing pressure in the affected eye

Injuries Considered for Medical Treatment

  • Penetrating or non-perforating wounds with no overriding or gaping of the wound edges—apply an Elizabethan collar; administer antibiotic and/or atropine eye solutions directly to the eye (“topical treatment”)
  • Penetrating or non-perforating wounds with mild gaping of wound edges or shelved edges—apply a therapeutic soft contact lens and an Elizabethan collar; administer antibiotic and/or atropine eye solutions directly to the eye (“topical treatment”)
  • Simple full-thickness, pinpoint corneal perforation with a formed anterior chamber and no uveal prolapse—sedentary pets; use a therapeutic soft contact lens and an Elizabethan collar; apply topical antibiotic and/or atropine ophthalmic solutions; reexamine a few hours after applying the lens and at 24 and 48 hours

Activity

  • Usually confined indoors (cats) or limited to leash walks until healing is complete
  • A harness is preferred to a collar, to reduce pressure on the neck and the risk of increased pressure within the eye (known as “intraocular pressure” or IOP) and leaking through the wound

Surgery

Injuries Requiring Surgical Exploration or Repair

  • Full-thickness corneal or scleral lacerations
  • Complicated injuries
  • Suspected retained foreign body or a scleral rupture involving the back of the eye
  • Simple, penetrating or non-perforating wound with edges that are moderately or overtly gaping and that are long or more than two-thirds the corneal thickness

Injuries Considered for Surgical Exploration or Repair

  • Small, simple, full-thickness corneal lacerations
  • Large conjunctival lacerations; the “conjunctiva” is the moist tissue lining the eye
  • Partial-thickness corneal or scleral lacerations in an active pet

Medications

Medications presented in this section are intended to provide general information about possible treatment. The treatment for a particular condition may evolve as medical advances are made; therefore, the medications should not be considered as all inclusive.

Antibiotics

  • Complicated wounds, those with retained plant material, and those caused by blunt trauma with tissue devitalization—infection common
  • Bacterial infection/inflammation of the tissues within the eyeball (known as “endophthalmitis”)—seen in 5% to 7% of pets with perforations; very rare in wounds that only penetrate, but do not perforate the cornea
  • Penetrating wound—topical (applied to the eye) antibiotics alone (such as neomycin, polymyxin B, and bacitracin) or gentamicin solution usually sufficient
  • Perforating wounds—systemic (administered by injection or by mouth) ciprofloxacin (dogs); topical (applied to the eye) cefazolin and fortified gentamicin or tobramycin
  • Topical (applied to the eye) ciprofloxacin eye solution—may be used instead of the combination of topical cefazolin and a fortified aminoglycoside

Anti-Inflammatory Drugs

  • Topical (applied to the eye) 1% prednisolone acetate or 0.1% dexamethasone solution—as soon as the wound is sutured or the surface is healing, if no infection is present
  • Systemic (administered by mouth) prednisone—for sutured or healing wounds when inflammation is severe; when the lens or more posterior structures are involved; when the wound is infected or not healing and control of inflammation is mandatory to preserve the eye
  • Topical (applied to the eye) nonsteroidal anti-inflammatory drugs (NSAIDs)—flurbiprofen or one of several other NSAIDs; may be used if topical steroids are not indicated (for example, infection is present) and control of inflammation is mandatory to preserve the eye

Medications to Dilate the Pupil (Known as “Mydriatics” and to Relieve Eye Pain)

  • 1% atropine eye solution—when significant constriction of the pupil (known as “miosis”) is present or inflammation is identified in the front chamber of the eye (known as “anterior chamber reaction”)

Medications to Relieve Pain (Analgesics)

  • Topical atropine or oral aspirin — may provide sufficient pain relief; use analgesics only as directed by your pet’s veterinarian
  • Butorphanol—dogs and cats; for mild pain
  • Carprofen
  • Tramadol
  • Oxymorphone—dogs and cats; for sudden (acute) severe pain; when sedation is required

Follow-Up Care

Patient Monitoring

  • Deep or long penetrating wounds that have not been sutured and perforating wounds—recheck every 24–48 hours for the first several days to ensure integrity of the eyeball, to monitor for infection, and to check control of eye inflammation
  • Superficial penetrating wounds—usually rechecked at 3- to 5-day intervals, until healed
  • Antibiotic therapy—altered according to bacterial culture and sensitivity results

Preventions and Avoidance

  • Take care when introducing new puppies to households with cats that have front claws
  • Minimize running through dense vegetation
  • Consider having a bottle of saline eyewash to irrigate or flush debris from the eye
  • Minimize visually impaired or blind dogs’ exposure to dense vegetation

Possible Complications

  • Loss of the eye or vision
  • Long-term (chronic) eye inflammation or pain

Expected Course and Prognosis

  • Most eyes with corneal lacerations or having a retained corneal foreign body are salvageable
  • The further back the injury is located in the eye, the poorer the prognosis for retention of vision
  • Poor prognosis—involvement of the sclera (the white part of the eye, it is composed of a tough covering that protects the eyeball) or uvea (the entire middle layer of the eyeball that contains the blood vessels); no light perception; perforating injuries involving the lens; significant bleeding into the vitreous (the clear, gel-like material that fills the back part of the eyeball); or separation of the back part of the eye (retina) from the underlying, vascular part of the eyeball (retinal detachment)
  • Penetrating injuries usually better prognosis than perforating injuries
  • Blunt trauma carries a poorer prognosis than sharp trauma

Key Points

  • The full extent of the injury (cataracts, retinal detachment, infection) may not be apparent until several days or weeks after the injury; therefore, long-term follow-up is necessary

Glaucoma

Glaucoma – An Overview

  • “Glaucoma” is a disease of the eye, in which the pressure within the eye is increased (pressure within the eye is known as “intraocular pressure” or IOP)
  • High intraocular pressure that causes characteristic degenerative changes in the optic nerve and retina with subsequent loss of vision; the “optic nerve” is the nerve that runs from the back of the eye to the brain; the “retina” is the innermost lining layer (located on the back surface) of the eyeball; it contains the light-sensitive rods and cones and other cells that convert images into signals and send messages to the brain, to allow for vision
  • Diagnosis—intraocular pressure greater than 25–30 mm Hg in dogs, as determined by specialized pressure measurements (such as applanation, rebound, or Schiötz tonometry) with evidence of changes in vision or appearance of the optic nerve or retina
  • Glaucoma may be “primary” or “secondary”; “primary” refers to a condition in which the pressure within the eye (intraocular pressure) increases without a preceding eye problem; “secondary” refers to a condition in which intraocular pressure increases as a complication or secondary to an eye disease or injury

Genetics

  • Dogs—abnormality of the structure of the eye that makes development of glaucoma more likely in some dogs is thought to be inherited; mode of inheritance uncertain

Signalment/Description of Pet

species

  • Dogs—primary and secondary glaucoma

Breed Predilections

  • Developmental abnormality of the angle between the iris and the cornea of the eye (known as “goniodysgenesis”)—Arctic circle breeds (such as Norwegian elkhounds, Siberian huskies, Alaskan malamutes, Akitas, Samoyeds); Bouvier des Flandres; basset hounds; chow chows; Chinese shar-peis; spaniels (such as American and English cocker spaniels, English and Welsh springer spaniels)
  • Narrow filtration angles—spaniels; chow chows; Chinese shar-peis; toy breeds (such as poodles, Maltese, and shih tzus)
  • Secondary to movement of the lens out of its normal location (lens luxations)—terriers (such as Boston terriers, cairn terriers, Manchester terriers, Dandie Dinmont terriers, Norfolk terriers, Norwich terriers, Scottish terriers, Sealyham terriers, West Highland white terriers, Parsons Jack Russell terriers, and fox terriers), Chinese shar-peis

Mean Age and Range

  • Primary glaucoma in dogs—any age; predominantly affects middle-aged dogs (4–9 years of age)
  • Secondary to movement of the lens out of its normal location (lens luxations) in dogs—usually affects young dogs (2–6 years of age)
  • Secondary to long-term (chronic) inflammation of the iris and other areas in the front part of the eye (uveitis)

Signs/Observed Changes in the Pet

  • Sudden closure of the angle between the iris and cornea of the eye (known as “acute angle closure”), leading to blockage of the flow of fluid and subsequent increased pressure within the eye—apparent pain (squinting or spasmodic blinking [known as “blepharospasm”], tenderness about the head, discharge from the eye(s), may be clear or may contain mucus); may note a cloudy or red eye; vision loss usually not noticed unless both eyes are involved
  • Secondary glaucoma—depends on primary disease
  • Inflammation of the iris and other areas in the front part of the eye (uveitis)—may note pain (for many days); red or bloodshot eyes, caused by dilated blood vessels (known as “scleral injection”); and cloudiness due to fluid buildup in the clear part of the eye (known as “corneal edema”)
  • Movement of the lens out of its normal location and into the front part of the eye (known as “anterior lens luxation”)—may note sudden (acute) pain; red or bloodshot eyes (scleral injection); and cloudiness due to fluid buildup in the clear part of the eye (corneal edema); may see lens in the anterior chamber (the front part of the eye, between the cornea and the iris), if corneal edema is not severe
  • Long-term (chronic) inflammation of the iris and other areas in the front part of the eye (uveitis). Enlarged, seemingly painless eye or a dilated pupil is common
  • Eyeball or globe enlargement (known as “buphthalmos”)—may be noticed first by owners

Sudden (Acute) Primary Glaucoma

  • High intraocular pressure (measured by your pet’s veterinarian)
  • Squinting or spasmodic blinking (blepharospasm)
  • Eyeball may recede into back of socket (known as “enophthalmos”)
  • Red or bloodshot eyes (scleral injection)
  • Cloudiness due to fluid buildup in the clear part of the eye (corneal edema)
  • Dilated pupil; the “pupil” is the circular or elliptical opening in the center of the iris of the eye—light passes through the pupil to reach the back part of the eye (known as the “retina”); the “iris” is the colored or pigmented part of the eye—it can be brown, blue, green, or a mixture of colors
  • Vision loss
  • Optic nerve may be depressed or cupped when the back of the eye is evaluated with specialized eye instruments by your pet’s veterinarian; the “optic nerve” is the nerve that runs from the back of the eye to the brain

Long-Term (Chronic) or End-Stage Glaucoma

  • Eyeball or globe enlargement (buphthalmos)
  • Lines that develop on the inner lining of the cornea, the normally clear part of the front of the eye (known as “Descemet’s streaks” or “Haab’s striae”)
  • Partial movement of the lens out of its normal location (known as a “lens subluxation”) with a resultant “crescent” appearing in the area of the iris (known as an “aphakic crescent”)
  • Wasting away or decrease in size of the cells in the optic nerve head (known as “optic nerve head atrophy”); the “optic nerve” is the nerve that runs from the back of the eye to the brain
  • Death of tissue in the retina (known as “retinal necrosis”)—detected increased reflectivity in the back of the eye when the veterinarian performs an examination

Glaucoma Induced by Inflammation of the Iris and Other Areas in the Front Part of the Eye (Uveitis)

  • Elevated intraocular pressure (measured by your pet’s veterinarian)
  • Red or bloodshot eyes (scleral injection)
  • Cloudiness due to fluid buildup in the clear part of the eye (corneal edema)
  • Inflammatory debris in the front part of the eye, between the cornea and the iris (anterior chamber)
  • Constricted or miotic pupil may or may not be seen; the “pupil” is the circular or elliptical opening in the center of the iris of the eye; light passes through the pupil to reach the back part of the eye (known as the “retina”); the “iris” is the colored or pigmented part of the eye—it can be brown, blue, green, or a mixture of colors
  • Scar tissue between the iris and the lens of the eye (known as “posterior synechia”) may or may not be present; the “lens” is the normally clear structure directly behind the iris that focuses light as it moves toward the back part of the eye (retina)
  • Bulging of the iris toward the front of the eye (known as “iris bombé”) may or may not be recent

Causes

  • Primary glaucoma—structural abnormalities of the eye involving the filtration angle (the “filtration angle” is the area where the cornea, sclera, and iris meet; it contains a structure that allows fluid to flow out of the eye, thus maintaining normal pressure within the eye; in primary glaucoma, the structure is abnormal so fluid does not flow adequately and the pressure within the eye increases)
  • Secondary glaucoma—blockage of the flow of aqueous humor out of the eye; the “aqueous humor” is the transparent liquid that fills the front part of the eyeball

Risk Factors

  • Inflammation of the front part of the eye, including the iris (known as “anterior uveitis”)
  • Movement of the lens out of its normal location (lens luxation)
  • Blood in the anterior chamber of the eye (the front part of the eye, between the cornea and the iris; accumulation of blood known as “hyphema”)
  • Tumor or cancer within the eyeball
  • Medications applied to the eye directly to dilate the pupil (known as “mydriatics”)—may lead to sudden (acute) glaucoma in susceptible pets
  • Primary glaucoma in dogs—consider all cases to involve both eyes, even if one eye has normal intraocular pressure at the time of evaluation; a veterinary eye doctor (ophthalmologist) should examine the apparently normal eye for filtration angle abnormalities to determine the risk for future glaucoma

Treatment

Health Care

  • Sudden (acute) glaucoma in dogs—inpatient medical care
  • After discharge from the veterinary hospital—reevaluate every 1–2 days for 1 week to monitor for return of increased intraocular pressure

Surgery

  • Cases with primary glaucoma or glaucoma due to movement of the lens out of its normal location (lens luxation) induced are best treated surgically
  • Primary glaucoma in dogs—less than 10% of affected pets undergoing medical treatment alone will have vision remaining at the end of the first year following diagnosis
  • Various surgical procedures may be performed to increase the flow of aqueous humor out of the eye; to decrease production of aqueous humor in the eye; procedures performed attempt to maintain normal intraocular pressure and vision; the “aqueous humor” is the transparent liquid that fills the front part of the eyeball
  • Surgical removal of lens that has moved forward in the eye (anterior lens luxation) may result in a visual eye, as well as help lower intraocular pressure
  • Blind, painful eyes—surgically remove the eye (known as “enucleation”); may remove the inner parts of the eye surgically, leaving the eyeball and place a prosthesis in the eye (known as “evisceration and intraocular prosthesis implantation”) in some cases

Medications

Medications presented in this section are intended to provide general information about possible treatment. The treatment for a particular condition may evolve as medical advances are made; therefore, the medications should not be considered as all inclusive.

Sudden (Acute) Primary Glaucoma in Dogs

  • Emergency medical treatment may include one or more of the following:
  • Medications applied to the eye directly to cause the pupil to constrict (known as “topical miotics”)—latanoprost 0.005% (Xalatan), travoprost 0.004% (Travatan), or bimatoprost 0.03% (Lumigan); 2% pilocarpine solution; 0.25% demecarium bromide; treatment aimed at improving aqueous outflow
  • Topical beta-adrenergic antagonists—timolol maleate 0.5%, levobunalol 0.5%, betaxolol 0.5%; reduce aqueous humor production; the “aqueous humor” is the transparent liquid that fills the front part of the eyeball
  • Carbonic anhydrase inhibitor (administered by mouth)—methazolamide; reduce production of aqueous humor
  • Carbonic anhydrase inhibitors (applied to the eye directly)—dorzolamide 2% (TruSopt), brinzolamide 1% (Azopt); reduce aqueous humor production
  • Medications to remove fluids from the body (known as “hyperosmotic agents”)—mannitol or glycerin; dehydrate the vitreous humor; the “vitreous” is the clear, gel-like material that fills the back part of the eyeball (between the lens and the retina)

Glaucoma Secondary to Movement of the Lens Out of its Normal Location Toward the Front of the Eye (Anterior Lens Luxation) or Inflammation of the Iris and Other Areas in the Front Part of the Eye (Uveitis) in Dogs

  • Treated like primary glaucoma
  • Medications to cause the pupil to constrict (miotic agents) should not be used
  • Steroids applied to the eye directly (known as “topical steroids”)—used to reduce inflammation if no changes of the cornea (the clear outer layer of the front of the eye) characterized by the presence of ulcers, with or without inflammation (condition known as “ulcerative keratitis”)

Long-Term (Chronic) Smoldering Inflammation of the Iris

  • Steroids applied to the eye directly (topical steroids)
  • Topical beta-blockers; reduce aqueous humor production; the “aqueous humor” is the transparent liquid that fills the front part of the eyeball
  • Carbonic anhydrase inhibitor diuretics or topical carbonic anhydrase inhibitors to reduce production of aqueous humor

Follow-Up Care

Patient Monitoring

  • Intraocular pressure—monitored often and regularly after starting initial therapy; if low intraocular pressure (known as “hypotensive ocular pressure”) is maintained for many weeks, slowly taper drug therapy (as directed by your pet’s veterinarian)
  • Monitor for drug reactions

Preventions and Avoidance

  • Primary glaucoma—consider all cases to involve both eyes, even if one eye has normal intraocular pressure at the time of evaluation; a veterinary eye doctor (ophthalmologist) should examine the apparently normal eye for filtration angle abnormalities to determine the risk for future glaucoma
  • Prophylactic therapy for the apparently unaffected eye—0.25% demecarium bromide or 0.005% latanoprost or 0.5% timolol maleate or 2% dorzolamide; delays onset of glaucoma in second susceptible eye

Possible Complications

  • Blindness
  • Long-term (chronic) eye pain

Expected Course and Prognosis

  • Long-term (chronic) disease that requires constant medical treatment (even with surgical intervention)
  • With medical treatment only—most affected pets ultimately go blind
  • Surgical treatment—better chance of retaining vision longer; most affected pets do not remain visual for more than 2 years after initial diagnosis
  • Secondary glaucoma due to movement of the lens out of its normal location (lens luxation)—may carry a fair prognosis with successful surgical removal of the luxated lens
  • Secondary glaucoma due to anterior uveitis—may carry a fair prognosis with control of inflammation of the iris and other areas in the front part of the eye

Key Points

  • Primary glaucoma is a disease that involves both eyes; over 50% of pets develop glaucoma in the other eye within 8 months without prophylactic therapy
  • 40% or more of dogs will be blind in the affected eye within the first year, no matter what is done medically or surgically

Conjunctivitis

Conjunctivitis – An Overview

  • Inflammation of the moist tissues of the eye (known as the “conjunctiva”); the conjunctiva is the vascularized moist tissue (mucous membrane) that covers the front part of the eyeball or globe, up to the edge of the cornea (known as the “bulbar conjunctiva”) and lines the lids and third eyelid (known as the “palpebral conjunctiva”)

Signalment/Description of Pet

Breed Predilections

  • Breeds susceptible to allergic or immune-mediated skin diseases (such as “atopy”) tend to have more problems with allergic inflammation of the moist tissues of the eye (conjunctivitis) or “dry eye” (known as “keratoconjunctivitis sicca” or KCS); “atopy” is a disease in which the dog is sensitized (or “allergic”) to substances found in the environment (such as pollen) that normally would not cause any health problems

Signs/Observed Changes in Pet

  • Squinting or spasmodic blinking (known as “blepharospasm”)
  • Redness of the moist tissues of the eye (known as “conjunctival hyperemia”)
  • Discharge from the eye(s); may be clear or may contain mucus and/or pus
  • Fluid buildup (known as “edema”) of the moist tissue covering of the eyeball (bulbar conjunctiva), around the cornea (condition known as “chemosis”)
  • Follicle formation; the “follicles” are accumulations of lymphoid tissue located at the moist tissue surface of the third eyelid and the eyelids, causing a “cobblestone” appearance; lymphoid tissue contains lymphocytes, a type of white blood cell that are involved in allergies and response to irritants

Causes

Bacterial Causes

  • Primary condition (that is, not secondary to another condition such as “dry eye” [keratoconjunctivitis sicca or KCS])—rare
  • Newborn inflammation of the moist tissues of the eye (conjunctivitis)—accumulation of discharge, often associated with a bacterial or viral infection; seen before the eyelids separate or open

Viral Causes

  • Canine distemper virus
  • Canine herpesvirus-1
  • Canine adenovirus-2

Immune-Mediated Causes

  • Allergic conjunctivitis—especially in atopic pets; “atopy” is a disease in which the animal is sensitized (or “allergic”) to substances found in the environment (such as pollen) that normally would not cause any health problems
  • Follicular conjunctivitis—inflammation of the moist tissues of the eye (conjunctivitis) characterized by accumulations of lymphoid tissue located at the moist tissue surface of the third eyelid and the eyelids, causing a “cobblestone” appearance; lymphoid tissue contains lymphocytes, a type of white blood cell that are involved in allergies and response to irritants; especially in dogs younger than 18 months of age, secondary to long-term (chronic) antigenic stimulation (that is, the substance to which the immune system is responding and producing antibodies)
  • Plasma-cell conjunctivitis—inflammation of the moist tissues of the eye (conjunctivitis) characterized by the presence of plasma cells (a specialized type of white blood cell; plasma cells are lymphocytes that have been altered to produce immunoglobulin, an immune protein or antibody necessary for fighting disease); especially in German shepherd dogs
  • Related to generalized (systemic) immune-mediated diseases—such as pemphigus, in which the body attacks its own tissues

Cancer or Pseudocancer Causes

  • Tumors involving the moist tissues of the eye (conjunctiva)—rare; include melanoma, hemangioma, hemangiosarcoma, lymphoma, papilloma, and mast-cell tumors
  • Lesions that appear to be cancer, but are not cancerous (known as “pseudocancer”)—inflammation of the border between the cornea (the clear part of the eye, located in the front of the eyeball) and the sclera (the white part of the eye, it is composed of a tough covering that protects the eyeball) characterized by the presence of nodules (condition is known as “nodular episcleritis” [also-called “fibrous histiocytoma,” “ocular nodular granuloma,” and “conjunctival pseudotumor”]; most commonly seen in collies and mixed collies; believed to be immune-mediated; usually appears as a pink mass

Secondary to Disease of the Tissues Surrounding the Eye (Known as “Adnexa,” Such as Eyelids, Third Eyelid, and Tear Glands)

  • Lack of normal tear film (known as “aqueous tear film deficiency”); “dry eye” (KCS)
  • Lid diseases (such as “entropion,” in which the eyelid curls inward, allowing facial hair to rub the eye; “ectropion,” in which the eyelid is turned outward) and lash diseases (such as “distichiasis,” in which two rows of eyelashes are present on a single eyelid; “ectopic cilia,” in which one or more eyelashes grows in an unusual location [may grow through the conjunctiva, leading to irritation of the eye])—may lead to clinical signs of inflammation of the moist tissues of the eye (conjunctivitis)
  • Secondary to blockage of the outflow portion of the drainage system that normally moves tears to the nasal passages (known as the “nasolacrimal system”), such as an obstructed nasolacrimal duct or lack of normal openings on the eyelids into the tear drainage system (known as “imperforate puncta”)

Secondary to Trauma or Environmental Causes

  • Foreign body located in the moist tissues of the eye
  • Irritation from dust, chemicals, or eye medications

Secondary to Other Eye Diseases

  • Disorder of the cornea (the clear outer layer of the front of the eye) characterized by the presence of ulcers, with or without inflammation (condition known as “ulcerative keratitis”)
  • Inflammation of the front part of the eye, including the iris (known as “anterior uveitis”)
  • Disease of the eye, in which the pressure within the eye is increased (known as “glaucoma”)

Other Causes

  • Ligneous conjunctivitis (inflammation of the moist part of the eye, characterized by thick, opaque conjunctiva)—young, female Doberman pinschers

Risk Factors

  • Exposure to dogs with canine distemper virus, herpesvirus-1, or adenovirus-2 infections

Treatment

Health Care

  • Primary—often outpatient
  • Secondary to other diseases (such as inflammation of the front part of the eye, including the iris [anterior uveitis} and corneal ulceration, with or without inflammation [ulcerative keratitis])—may need hospitalization while the underlying problem is diagnosed and treated

Activity

  • Primary—usually no restriction
  • Suspected contact irritant or sudden (acute) allergic disease—prevent (if possible) contact with the agent causing the irritation or allergy
  • Do not expose pets to other dogs to decrease risk of spread of infectious causes (such as canine distemper virus) of inflammation of the moist tissues of the eye (conjunctivitis)

Diet

  • Suspected underlying skin disease and/or food allergy—food elimination diet recommended; “elimination diet” is a diet that does not contain substances that the animal normally eats and is free of additives

Surgery

  • Blockage of the outflow portion of the drainage system that normally moves tears to the nasal passages (known as the “nasolacrimal system”), such as an obstructed nasolacrimal duct—surgical repair is difficult; treatment often not recommended
  • Cancer involving the moist tissues of the eye (“conjunctival cancer”)—may involve surgical removal of the tumor followed by radiation therapy; freezing (known as “cryotherapy”); or heating of the tissues using radiofrequency waves (known as “radiofrequency hyperthermia”); may involve surgical removal of the eyeball and associated tissues (known as “enucleation”), depending on the type of tumor and the extent of involvement

Medications

Medications presented in this section are intended to provide general information about possible treatment. The treatment for a particular condition may evolve as medical advances are made; therefore, the medications should not be considered as all inclusive.

Bacterial Infections

  • Antibiotics based on bacterial culture and sensitivity results
  • Antibiotics may be applied directly to the moist tissues of the eye (“topical treatment”) or may be given by mouth (“systemic treatment”)
  • Initial treatment—broad-spectrum topical antibiotic or specific antibiotic based on results of microscopic examination of discharge and/or conjunctival scraping, while waiting for bacterial culture and sensitivity results; may try treatment based on experience with other cases of conjunctivitis, performing a bacterial culture and sensitivity only if the pet does not respond to selected treatment
  • Topical triple antibiotic or chloramphenicol—if cocci (general type of bacteria) seen on microscopic examination of discharge and/or conjunctival scraping
  • Gentamicin or tobramycin—if rods (general type of bacteria) seen on microscopic examination of discharge and/or conjunctival scraping
  • Ciprofloxacin or other quinolone antibiotics—may be useful for severe bacterial inflammation of the moist tissues of the eye (conjunctivitis)
  • Systemic antibiotics—occasionally indicated, especially for more generalized disease (such as inflammation of the moist tissues of the eye [conjunctivitis] associated with skin infection characterized by the presence of pus [known as “pyoderma”])

New Born Conjunctivitis

  • Depends on severity
  • Topical steroids— applied directly to the moist tissues of the eye; 0.1% dexamethasone; improve clinical signs of allergic, follicular conjunctivitis (characterized by accumulations of lymphoid tissue located at the moist tissue surface of the third eyelid and the eyelids, causing a “cobblestone” appearance), and plasma-cell conjunctivitis (characterized by the presence of plasma cells); improvement often temporary
  • Treatment of any underlying disease (such as atopy) often improves clinical signs; “atopy” is a disease in which the animal is sensitized (or “allergic”) to substances found in the environment (such as pollen) that normally would not cause any health problems
  • Other steroids—1% prednisolone acetate; betamethasone; hydrocortisone

Follow-Up Care

Patient Monitoring

  • Recheck shortly after beginning treatment (at 5–7 days); then recheck as needed

Preventions and Avoidance

  • Treat any underlying disease that may make the eye disease worse—allergic or immune-mediated skin disease; “dry eye” (KCS)
  • Vaccination against canine distemper virus

Expected Course and Prognosis

  • Bacterial infection/inflammation of the moist tissues of the eye (conjunctivitis)—usually resolves with appropriate administration of antibiotics; if an underlying disease is found (such as “dry eye” [KCS]), resolution may depend on appropriate treatment and resolution of the disease
  • Immune-mediated diseases—diseases tend to be controlled, not cured; may require long-term (chronic) treatment with steroids at the lowest dose possible

Key Points

  • If a large amount of discharge is noted, gently clean the eyes before administering treatment
  • If both eye solutions and eye ointments are prescribed, apply the solution(s) before applying the ointment(s)
  • If several eye solutions are prescribed, wait several minutes between treatments
  • Call for instructions if the condition worsens, which indicates that the condition may not be responsive to treatment or may be progressing or that the animal may be having an adverse reaction to a prescribed medication
  • An Elizabethan collar should be placed on the pet, if self-trauma occurs

Cataracts

Cataracts – An Overview

  • Opacity in the lens; the lens is the normally clear structure directly behind the iris (the colored part of the eye) that focuses light as it moves toward the back part of the eye (retina); if opacity is complete, it prevents passage of light to the back part of the eye (retina), leading to blindness in the affected eye
  • “Cataract”—may refer to a lens that is entirely opaque or to a localized opacity within the lens; does not imply cause

Genetics

  • Inheritance has been established for many dog breeds; most common mode of inheritance—autosomal recessive
  • The number of individuals with genetic cataracts varies significantly between breeds; it has been reported to be as high as 10% in some breeds
  • Inheritance has been established in the Himalayan (cat)—autosomal recessive

Signalment/Description of Pet

Breed Predilections

  • Over 135 dog breeds are suspected of having increased likelihood of having hereditary cataracts

Mean Age and Range

  • Depend on cause
  • Cataracts can develop at any age
  • Genetic cataracts can develop as early as 6 months of age

Signs/Observed Changes in Pet

  • Opacity or white appearance of the lens
  • Related to the degree of vision impairment
  • Vision loss may be noticed when cataracts are present in both eyes
  • Cataract caused by diabetes mellitus (sugar diabetes)—may see signs of diabetes, such as increased urination (known as “polyuria”), increased thirst (known as “polydipsia”), and weight loss
  • Cloudiness in the eye (specifically the lens) noticed before vision impairment—may be related to sclerosis, rather than cataract formation; “sclerosis” is a normal aging change in the lens due to changes in the lens fibers, it apparently has little to no effect on vision
  • May be associated with inflammation of the front part of the eye, including the iris (known as “anterior uveitis”)—typically see cloudiness of aqueous humor (the “aqueous humor” is the transparent liquid that fills the front part of the eyeball) due to increased protein content and suspended cellular debris (condition known as “aqueous flare”); scar tissue between the iris and the lens of the eye (known as “synechiae”); and decreased pressure within the eye (known as “low intraocular pressure”)

Causes

  • Heredity—most common cause in dogs
  • Diabetes mellitus (sugar diabetes)
  • Inflammation of the front part of the eye, including the iris (anterior uveitis)—secondary to formation of scar tissue between the iris and the lens of the eye (synechia) or altered aqueous humor (the transparent liquid that fills the front part of the eyeball) composition
  • Trauma—injury to the eye, where something penetrates the outer surface of the eye and disrupts the anterior lens capsule, most commonly a cat-claw injury especially in puppies.
  • Senile—age-related; slowly progressive cataract in senior pets
  • Congenital (present at birth)—inherited cataract; damage to the developing lens or eye while the puppy is in the uterus; may be associated with other congenital eye abnormalities
  • Surgery
  • Toxic substances
  • Radiation
  • Low levels of calcium in the blood (known as “hypocalcemia”)
  • Nutrition—use of unbalanced milk-replacer diet in bottle-fed puppies
  • Electric shock—chewing electrical cords or lightning strike

Risk Factors

  • Genetics
  • Diabetes mellitus (sugar diabetes) in dogs
  • Long-term (chronic) inflammation of the front part of the eye, including the iris (anterior uveitis
  • Progressive retinal atrophy (a group of eye diseases characterized by generalized deterioration of the retina, becoming increasingly worse over time); the “retina” is the back part of the eye; the retina contains the light-sensitive rods and cones and other cells that convert images into signals and send messages to the brain, to allow for vision

Treatment

Activity

  • For safety, blind pets should not be allowed access to an in-ground swimming pool or elevated decks with open railings; use caution near stairs
  • Restrict outside activity to fenced yards or leash-walks

Surgery

  • Phacoemulsification is a surgical procedure in which ultrasonic vibrations are used to fragment and liquefy the lens, in order to remove the lens material; procedure of choice
  • Ideal time for cataract surgery is the immature or early mature cataract stageIntraocular lenses—may be implanted safely at the time of surgery, so the pet will not suffer extreme farsightedness

Medications

Medications presented in this section are intended to provide general information about possible treatment. The treatment for a particular condition may evolve as medical advances are made; therefore, the medications should not be considered as all inclusive.

  • Topical (applied directly to the eye) anti-inflammatory medication is recommended to prevent and treat lens-induced inflammation of the front part of the eye, including the iris (anterior uveitis); topical anti-inflammatory medications include flurbiprofen or diclofenac or a topical steroid, such as prednisolone 1% or dexamethasone 0.1%
  • Topical atropine for lens-induced inflammation of the front part of the eye, including the iris (anterior uveitis)
  • Non-steroidal anti-inflammatory drugs (NSAIDs) administered by mouth (oral administration) are used to treat lens-induced inflammation of the front part of the eye, including the iris (anterior uveitis); examples include carprofen, meloxicam, and tepoxalin

Follow-Up Care

Patient Monitoring

  • Early immature cataracts—monitor regularly for progression of cataracts, in order to select the ideal time for surgery and avoid complications associated with cataracts
  • Post-operative monitoring by the surgeon is critical for success

Preventions and Avoidance

  • Do not breed pets with cataracts

Possible Complications

  • Lens-induced inflammation of the front part of the eye, including the iris (anterior uveitis)
  • Secondary glaucoma (in which the pressure within the eye [intraocular pressure] is increased secondary to inflammation in the front part of the eye)
  • Separation of the back part of the eye (retina) from the underlying, vascular part of the eyeball (known as the “choroid”; condition known as “retinal detachment”)
  • Movement of the lens out of its normal location (known as “lens luxation”)

Expected Course and Prognosis

  • Long-term prognosis following cataract surgery is very good
  • Some pets have increased risk for post-operative complications, such as those with pre-existing inflammation of the front part of the eye, including the iris (anterior uveitis), even if medically controlled; genetic likelihood of developing glaucoma; retinal abnormalities

Key Points

  • Cataract surgery is performed routinely with an overall 80–90% success rate
  • Once the cataract(s) is/are removed, they cannot return
  • Artificial lens implants will restore essentially normal vision
  • Evaluation for surgery should be done early in the course of cataract development to avoid complications that may result in the cataract becoming inoperable, to allow time to plan for the surgery, and, in some cases, to eliminate the need and extra cost for an ultrasound examination of the eye and an evaluation of the electrical responses in the retina (procedure known as an “electroretinogram”)