Corneal disease in dogs: there is a hole in my cornea (Proceedings)

Topics

Dermoids, Corneal Ulcers, Trauma-induced corneal lesions, Lipid Keratopathy, Pigmentary Keratitis, Endothelial Degeneration

Corneal Ulcers

    1) Superficial Ulcers

    2) SCCED (superficial chronic corneal epithelial defect)

          • Indolent Ulcers

          • Boxer ulcers

          • Non-healing ulcers

     3) Complicated Ulcers

Superficial Ulcers

     – Duration

          • Uncomplicated ulcer will heal in 2 days

          • If doesn't behave "typically" consider underlying conditions

     – Age

          • Young dog: distichia, ectopic cilia, entropion

          • Old dog: indolent/non-healing ulcer

     – Work-Up

          • Fluorescein Stain

          • Close look at eyelids and conjunctiva for hairs or foreign bodies

     – Treatment for uncomplicated, superficial ulcers

          • Topical Antibiotic

               o BNP ointment/ Neo-Poly-Gramicidin

               o Tobramycin drops

          • Atropine

               o One drop in office should be sufficient

          • E Collar

     – Recheck 2 - 3 days

Indolent Ulcers

     – Must Haves:

          • Older patient (at least 5yrs)

          • Epithelial undermining (lipping edges)

          • No depth – always superficial

          • 1 week+ duration

     – These will get smaller and larger during treatment

     – Treatment options

          • Corneal debridement (cotton tipped applicator)

          • Linear Grid Keratotomy

          • Anterior Stromal Puncture

          • Diamond Burr

          • Contact lens

     – Medications

          • Tobramycin or Ofloxacin

          • Atropine

          • E Collaran

          • Tramadolan

     – Recheck

          • 2 weeksan

          • Do not re-debride before 2 weeks

     – Mistakes I see:

          • Debriding deep ulcers

          • Deep linear grid lacerations

          • Treating with one antibiotic and then changing because the ulcer didn't heal ... the scarring is going to get worse and worse

          • Debriding young dogs .... There is an underlying cause for young dogs not healing

Complicated Ulcers: Deep Stromal Ulcers / Perforations / Melting Ulcers

     – These are Corneal Emergencies

     – Descemetocele is a impending perforation: ulcer to the depth of endothelial basement membrane, Peripheral Fluorescein uptake with clear center. Rarely see bulging of membrane, usually deeeeeep crater

     – Perforation, especially if leaking, is a definite emergency if globe is to be saved. Perforation typically has a fibrin plug, blood, iris adhered to cornea, collapsed anterior chamber, aqueous humor leakage

     – These cases can rupture in the exam room!

     – They don't all look the same

     – Acute perforations usually very painful

     – Treatment: Prompt, careful, thorough exam, avoid excessive restraint, look for underlying cause

          • Dry eye, Distichiasis, trichiasis, ectopic cilia, entropion, Foreign body (esp. behind third eyelid)

          • Mineral degeneration, Facial nerve, trigeminal nerve disease, Corneal sequestrum (cat)

          • Numbing the surface of the eye with topical anesthetic can be very helpful

          • Examine non-painful eye first: may give clues to inciting cause of painful eye (i.e. Dry eye, extra hairs, etc.)

          • Slow, careful examination of affected eye if possible

          • Proper diagnostics to rule out underlying dry eye, assess depth of ulcer, etc.

     – Prognostic clues:

          • Presence of direct or consensual PLR

          • Clear view into eye

          • Size of ulcer

          • Integrity of cornea

          • Presence of other ocular disease such as cataracts, retinal disease, glaucoma

     – Treatment - Complicated Ulcers

     – These ulcers typically need surgery, True ocular emergency

     – Medical Management

          • Ofloxacin q 2 h

          • Serum q 2 h

          • Oral Antibiotics

          • Oral Anti-inflammatory

          • Tramadol

          • Atropine BID

          • E Collar

     – Recheck – 24 hours

     – Surgical repair options: Conjunctival pedicle flap, Corneoconjunctival transposition flap, Direct suture if lesion < 2mm, Conjunctival island graft, Conjunctival hood flap, Corneal graft, Other tectonic grafts (scleral, small intestinal sub mucosa (BIOSIS))

Melting Ulcers

     – Corneal perforation within 12-24 hours if not treated aggressively

     – Causes usually bacterial

          • Pseudomonas aeroginosa

          • Beta-hemolytic streptococcus

     – Fungal uncommon in dog; common in horse

     – Melting due to collagenases either from organism or self

     – Examination and diagnostics: Look for underlying causes (Dry eye, lid abnormalities, hairs, ear/ skin infection, etc.), Schirmer tear test, Culture and sensitivity, Cytology, Fluorescein stain, Tonometry

Treatment and follow up

     – Topical antibiotics every 1-2 hr

          • Avoid ointments in case it ruptures

          • Fluoroquinolones

     – Topical anti-collagenase every 1-2 hr

          • Serum (aseptically prepared, keep refrigerated, discard after 5 days)

          • EDTA, N- acetylcysteine

          • Mucomyst, tetracyclines

     – Topical mydriatics

     – Systemic antibiotic

     – Systemic steroid or NSAID

     – Pain Management

     – E- COLLAR

     – Treatment protocol

     – Ofloxacin, ciprofloxacin q 1-2 hours

          • good against gram- bacteria

          • good corneal penetration

     – Neomycin, polymyxin w/ bacitracin or gramicidin q 4-6 hours

          • good broad spectrum activity

          • poor penetration

          • won't touch pseudomonas

     – Atropine 1% or tropicamide 1%

          • prevent synechia, ciliary spasm, stabilize blood aqueous barrier

     – May need hospitalization if client unable to treat round the clock

     – Follow up within 24-48 hours

Trauma Induced Corneal Lesions: Penetrating Corneal Wounds, Lacerations / Punctures, Penetrating Corneal Lacerations

     – Signs: Aqueous leakage (seidel), Fibrin seal or iris prolapse, Scleral lacerations

     – Avoid manipulation

     – Corneal lacerations

          • Lacerations that are leaking are best treated surgically ASAP

          • Degree of intraocular damage and integrity of cornea will determine type of surgical treatment

          • If surgery must be delayed due to other injuries, long traveling distance, etc. treat medically

     – Medical treatment

          • Topical antibiotic solution (NO ointments)

          • Topical mydriatic solution if miotic

          • Systemic anti-inflammatory to treat intraocular inflammation

          • Systemic antibiotics to prevent intraocular infection

          • Pain management

          • E-collar

     – Surgical treatment: Direct suture, Conjunctival flap, Corneal transplant with or without flap

     – Complications of lacerations: Anterior/posterior synechia, Chronic uveitis, Phthisis bulbi, Secondary glaucoma, Cataract, Blindness

Crystalline Keratopathy

     – Corneal Dystrophy: inherited

     – Lipid Keratopathy: secondary to systemic lipid abnormalities

     – Corneal Degeneration: secondary to local inflammation or irritation

     – Causes

          • Inherited propensity: Shetland Sheepdog, Siberian Husky, Beagles, Cavalier, Airedale, Rough Collie

          • Hypothyroid dogs: do not metabolize fats appropriately

          • Diet

     – Work Up

          • Blood work with thyroid panel, Calcium, Cholesterol, Triglyceride levels

     – Treatment:

          • Correct underlying problem if you find one

          • Low fat diet, ask about treats!

          • If stable, visual, and comfortable: leave it

     – If visual deficits or chronic ulcerations refer for

          • Superficial keratectomy, TCA, grafts

Pigmentary keratitis

     – Brachycephalics predisposed

     – Cause: chronic corneal irritation, Medial canthal entropion, KCS, Distichia, Nasal fold trichiasis, Excessive corneal exposure

     – Treatment

          • Address underlying cause

               o Medial canthoplasty

               o Tear stimulants

               o Cryotherapy for distichia

          • Medical Therapy

               o Topical Tacrolimus

               o Topical steroids

Endothelial degeneration

     – Diffuse corneal edema

     – Rule Outs: Glaucoma, Lipid Aqueous, Anterior Lens Luxation

     – Diagnostics: Intraocular pressure, Corneal stain

     – Treatment

          • Sodium Chloride Ointment

          • Early → Keratoleptnysis

          • Late →Thermokeratoplasty