Management of Common Orbital Problems

Transcription

1 Management of Common Orbital Problems Rachel A. Allbaugh, DVM, MS, Diplomate ACVO Iowa State University Department of Veterinary Clinical Sciences, Ames, IA The obit functions to protect the eye and houses many important structures including muscles, glands, blood vessels and nerves. Knowledge of basic orbital anatomy is important when assessing clinical signs of patients with orbital disease and is imperative when considering orbital surgery. Orbital Cellulitis and Abscess Orbital inflammation (cellulitis) or abscess formation results in increased space occupation within the orbit and causes anterior displacement of the globe (exophthalmos) and third eyelid elevation. Common etiologies include penetrating injury through the roof of the mouth (e.g. from chewing on a stick or bone), a tooth root abscess, and potential hematogenous spread of an infectious agent. In addition to exophthalmos and an elevated third eyelid, globes will be resistant to retropulsion and animals may demonstrate pain on orbital palpation or mouth opening manifesting as anorexia and decreased water intake. Fever may or may not accompany the condition. Oral examination may demonstrate a swelling or draining site behind the last upper molar on the affected side, but not always. Orbital ultrasound can be used to look for evidence of a foreign body as well as a fluid pocket suggestive of an abscess. If an abscess is present, drainage can be performed via an oral approach while under general anesthesia with samples collected for culture and cytology. Patients with consistent clinical signs but without a fluid pocket likely have orbital cellulitis and should not undergo probing exploration given the risk for iatrogenic introduction of additional bacteria from the mouth. In either case extended therapy with an appropriate systemic antibiotic (e.g. Clavamox ) for 4-6 weeks is recommended as well as a systemic anti-inflammatory. A corticosteroid injection (e.g. Dexamethasone 0.2 mg/kg IV) can quickly alleviate discomfort and improve appetite in affected animals to facilitate subsequent oral medication administration. Systemic corticosteroids can be continued at an anti-inflammatory dose for a few days then gradually tapered. If inflammation recurs when off medication an inciting cause may remain or another condition may exist (e.g. neoplasia or immune-mediated disease). If a patient cannot completely blink to protect the cornea while exophthalmic an ocular lubricant should be used QID to prevent corneal ulceration, or if a corneal ulcer is already present an ophthalmic antibiotic ointment (e.g. Neomycin/PolymyxinB/Bacitracin) should be used QID to help prevent ulcer infection and provide ocular lubrication. Canned food may be needed for anorexic dogs for the first few days but the prognosis is generally very good for orbital cellulitis and abscessation.

2 Masticatory Muscle Myositis Masticatory muscle myositis is an immune-mediated disease that involves autoantibodies directed at the unique myofiber composition and is more commonly seen in certain large breed dogs. Clinical signs include bilateral exophthalmos with third eyelid elevation, resistance to retropulsion, resistance and/or pain on mouth opening and possibly visibly swollen temporalis muscles. Testing for antibodies against type 2M muscle fibers can be performed (UC Davis lab) or a biopsy of the temporal muscles is usually diagnostic. Treatment needs to be initiated in the acute stage of the disease to prevent irreversible muscle fibrosis which restricts jaw movements and predisposes to aspiration pneumonia. Corticosteroids at an immunosuppressive dose are used to treat the disease and prevent muscle fibrosis with an initial dosage of Prednisone 2 mg/kg PO SID for 1 month then if clinical signs are controlled gradual reductions by 25% intervals every 3-4 weeks are continued until every other day dosing is completed. Azathioprine or other immunomodulating drugs can be used in addition if needed but on-going monitoring is needed and side effects may preclude their use. Patients diagnosed at the advanced stage of disease with muscle atrophy and muscle fibrosis will have enophthalmos and restricted jaw movements that cannot be influenced medically so timely diagnosis and treatment is imperative. Other Causes of Orbital Disease A patient with exophthalmos, elevated third eyelid, resistance to retropulsion with no or little pain on mouth opening is less likely to have orbital cellulitis or abscessation and instead may have an orbital tumor (especially if an older patient), vascular anomaly (especially if a younger patient), zygomatic mucocele, parasitic cyst, orbital hematoma (highly suggestive of rodenticide toxicity if extensive subconjunctival hemorrhage is present), or another problem. Further diagnostics will be needed depending on the patient to help identify the exact cause and direct appropriate therapy. Ocular Proptosis Proptosis occurs when the eyeball moves forward so far that the eyelids become locked behind the equator of the globe. This occurs due to trauma, but may only require minor force in brachycephalic breeds with shallow orbits and large eyelid openings. The prognosis will vary with the severity of trauma (e.g. very poor prognosis in cats, horses, and dolichocephalic dogs that require extreme force to result in proptosis) and status of the globe on presentation. Salvage of the eye is much more likely than saving vision; however, many owners will still value a blind eye that is cosmetic. If numerous extraocular muscles are torn (3 or more), the optic nerve is transected, or the globe is ruptured it should simply be removed. Otherwise, replacement should be attempted as soon as the patient is systemically stable.

3 Following proptosis the globe should be lubricated as frequently as possible to prevent desiccation and corneal ulceration until the globe is surgically replaced. The eyelids can be carefully clipped and prepared with eyewash and dilute betadine solution (1:50 dilution; do NOT use betadine scrub, chlorhexidine, and/or alcohol as they are toxic to the corneal epithelium). A lateral canthotomy may be needed to relieve eyelid tension prior to globe replacement and should be performed with scissors instead of a blade to avoid globe damage. Once the globe is back in the orbit the eyelids are sutured closed with horizontal mattress sutures as a temporary tarsorrhaphy ensuring appropriate suture passage to prevent corneal irritation. The medial eyelids should be left open so ophthalmic medications can be applied at the medial canthus. Post-replacement an e-collar should be placed to prevent self-trauma and medications prescribed to prevent infection (topical +/- systemic antibiotic), reduce inflammation (systemic anti-inflammatory), and relieve pain (topical atropine, systemic tramadol or other narcotic). Recheck can be performed within one week to assess suture position and ensure none are rubbing on the cornea as eyelid swelling decreases, though it is optimal to leave tarsorrhaphy sutures in place for up to 3 weeks so orbit swelling has ample time to subside. Following suture removal a complete ophthalmic exam should be performed, including STT, fluorescein staining, and assessment of complete eyelid closure. Possible complications post-proptosis are KCS due to lacrimal gland inflammation or duct damage, lagophthalmos and exposure keratitis due to eyelid stretching, and lateral strabismus due to medial rectus muscle damage. Some of these complications may resolve with time but in the interim globes will require supplemental ocular lubrication BID-QID (e.g. GenTeal gel or Optixcare). Orbital Surgery The most common orbital surgeries performed are enucleation and exenteration with lesser performance of orbital fracture repair and orbitotomy. Enucleation, or removal of the eye and associated secretory structures, is indicated in any case of an irreversibly blind, painful eye and may be performed via a transconjunctival or transpalpebral approach. It is also appropriate for ocular tumors not amendable to other therapies. Exenteration involves removal of the all of the orbital contents and is utilized for patients with orbital tumors. In general exenteration should not be performed when a simple enucleation would suffice to prevent unnecessary soft tissue removal and hemorrhage. A silicone orbital prosthesis can be placed following enucleation to provide space occupation and avoid sinking of the skin over the orbit. Possible Enucleation-Associated Complications Though enucleations are fairly simple surgeries complications may arise and can be minimized with good surgical skills and knowledge of normal anatomy. Extensive hemorrhage may occur

4 in some exotic species or pocket pets due to disruption of the orbital plexus or sinus so only a transconjunctival approach should be used in these species and care must be taken to stay close to the globe during removal. Secretory tissues such as the third eyelid gland, eyelid margins with associated meibomian glands and conjunctival tissues should all be removed to prevent postoperative orbital cyst formation. When removing a globe excessive force should not be used to avoid traction on the optic nerve which could cause damage at the level of the optic chiasm and blind the opposite eye (especially concerning in cats). Seromas and orbital emphysema may also occur following surgery but can typically be managed conservatively without further consequence. To reduce the risk of seroma or abscess formation orbital prostheses are not typically placed in cats nor in patients with potential infectious disease (e.g. ruptured infected corneal ulcer eyes). Recommended Veterinary Ophthalmology Textbooks: Slatter s Fundamentals of Veterinary Ophthalmology, 5th edition. David J Maggs, Paul E Miller and Ron Ofri. Saunders Elsevier Essentials of Veterinary Ophthalmology, 2nd edition. Kirk N Gelatt. Blackwell Publishing Veterinary Ophthalmic Surgery. Kirk N Gelatt and Janie P Gelatt. Saunders Elsevier Ophthalmic Disease in Veterinary Medicine. Charles L Martin. Manson Publishing Ltd. 2010

5 Management of Common Adnexal Diseases Rachel A. Allbaugh, DVM, MS, Diplomate ACVO Iowa State University Department of Veterinary Clinical Sciences, Ames, IA Adnexal tissues include the eyelids and the third eyelid. These structures are important for ocular protection, tear spread and ultimately corneal health; therefore abnormalities must be addressed to help prevent ocular problems or even vision compromise. Eyelid Masses Eyelid masses are common in older dogs and most are benign. Tumors may include those involving skin tissues (papilloma, melanoma, mast cell tumor) or more commonly glandular tissue with meibomian gland adenomas being the most frequent canine eyelid neoplasm. Small tumors may be monitored over time but if they abrade the cornea they can cause irritation and even corneal ulceration. Eyelid wedge or house (4-sided) resection is a simple procedure that removes full thickness eyelid tissue with keys to the surgery including not removing more than 30% of the eyelid length, making sure the margin to apex distance of the excision is twice the width of margin removed, and ensuring accurate eyelid margin apposition with no sutures allowed to contact the corneal surface. However, this surgery is typically not needed for adenoma removal and these tumors are better managed by debulking and cryotherapy or carbon dioxide laser excision through the palpebral conjunctival surface. These therapies minimize eyelid margin and skin impact, prevent surgical eyelid shortening and can also be used to address chalazion formation. For larger masses or potentially malignant neoplasms referral for grafting procedures and adjunctive therapy may be necessary. Eyelid Lacerations Eyelid wounds may occur from animal fights, car accidents or other trauma and though general principles of skin wound treatment and healing still apply there are some important considerations periocularly. Artificial tear ointment or lube should be applied to the eye prior to clipping to prevent hairs from irritating the cornea. Dilute betadine and saline solution should be used to gently clean the wound instead of chlorhexidine or alcohol as they are toxic to the corneal epithelium. Wounds should not be debrided, or only very minimally with 4x4 gauze, as eyelids have wonderful vascular supply and healing potential. Eyelid margin apposition is most important to ensure proper function and can be achieved with a symmetrically placed figure of eight suture or simple interrupted sutures with suture ends engaged in subsequent skin suture knots to direct them away from the corneal surface. Soft, braided suture (e.g. Vicryl ) is optimal to further minimize the risk of corneal abrasion. Longer lacerations may require twolayer closure with buried sutures placed prior to eyelid margin apposition while being sure not to penetrate the palpebral conjunctiva. Postoperative management includes topical ophthalmic

6 antibiotic +/- corticosteroid TID, oral antibiotic, a systemic anti-inflammatory +/- other pain control and an Elizabethan collar to prevent self-trauma until suture removal in days. Macropalpebral Fissure/Lagophthalmos This occurs with overly large eyelid openings and is most common in brachycephalic dog breeds with shallow orbits and resultant conformational exophthalmos. These dogs may be at a higher risk of traumatic ocular proptosis also. Some of these patients may not be able to blink their eyelids closed completely (lagophthalmos) and have chronic exposure of the central cornea. Others may have concurrent conformational issues, such as medial lower lid entropion and trichiasis, which further irritate and may result in damage of the cornea. Patients with evidence of corneal pathology (e.g. pigmentation, vascularization, ulcers) benefit from surgical shortening of the eyelids. A medial canthoplasty surgery is most appropriate to shorten the eyelids, allow complete blinking, as well as address medial lower lid entropion and medial canthal or nasal trichiasis. Careful eyelid margin apposition is necessary (magnification required) to prevent iatrogenic entropion following canthus closure. An additional medial temporary tarsorrhaphy suture helps to protect the surgical site during the postoperative healing stage. Regardless of surgery, ocular lubrication BID-QID is beneficial to help minimize ocular exposure and irritation while Tacrolimus ophthalmic medication BID may help to reduce corneal pigmentation. These therapies should be started early in an effort to prevent vision compromise which can occur in any patient with macropalpebral fissure and lagophthalmos. Entropion and Ectropion Entropion is inward rolling of the eyelid margin while ectropion is eversion of the eyelid margin. Both may occur due to tight medial and/or lateral canthal attachments and/or an overly long eyelid and affect certain breeds of dogs more frequently than others. Entropion can result in corneal irritation, vascularization, scarring and even ulceration while ectropion rarely causes more pathology than simple irritant-induced conjunctivitis. Entropion in young animals should be addressed with temporary nonabsorbable vertical mattress tacking sutures to evert the eyelid margin (repeated q. 3-4 weeks as needed). Some patients will outgrow their entropion while others may require permanent surgical correction when they are more skeletally mature (e.g. 6 months or older). The most common entropion surgery is the Hotz-Celsus procedure with or without eyelid wedge resection to shorten eyelid length and/or lateral canthal tenotomy. Keys to Hotz-Celsus surgery include making the incisions long enough to extend beyond the entropic area, incising within 2 mm of the eyelid margin (at the haired/nonhaired border), removing sufficient subcutaneous tissue to allow natural skin closure while not taking too much total tissue, and closing by the law of bisection. Though large breed dogs are best treated with the above procedure small breed dogs with medial lower eyelid entropion (and sometimes nasal trichiasis that results in tear wicking) could undergo small Hotz-Celsus or medial

7 canthoplasty surgery to address the issues. Ectropion that causes persistent conjunctivitis can be managed conservatively with daily eye rinsing to remove microscopic debris that settles in the resultant tear pool/conjunctival pocket or with surgery if corneal pathology or cosmetic concerns occur (e.g. with eyelid wedge resection, V to Y blepharoplasty, or more advanced procedures). Third Eyelid Gland Prolapse The third eyelid gland encompasses the base of the third eyelid cartilage and can prolapse to become visible extending beyond the edge of the third eyelid margin due to weakened connective tissue attachments. This occurs more commonly in certain dog breeds and typically at a young age. Glands that remain out of place become inflamed, enlarged, and are unsightly. Aqueous tear production can also be impacted which is of great consequence given its normal lacrimal role and the fact that many affected breeds are also predisposed to keratoconjunctivitis sicca (KCS or dry eye disease). Prolapsed glands should be repositioned using any one of a variety of techniques based on the individual surgeon s preference and rate of personal success as no technique is 100% effective. The Morgan pocket technique is utilized commonly and if suture knots are tied on the anterior/palpebral surface of the third eyelid it reduces the risk of iatrogenic corneal trauma from suture material. Bulldogs with third eyelid gland prolapse can be particularly difficult to manage and may warrant referral to a specialist to maximize surgical success. Third eyelid glands should never be removed for this condition. Everted Third Eyelid Cartilage Cartilage eversion is a problem that may affect one or both third eyelids of some young large breed dogs. The third eyelid cartilage stem generally folds near the neck of the T, allowing the leading edge of the third eyelid to inappropriately evert outward away from the cornea or, less commonly, inward toward the cornea. This is easily differentiated from a prolapse of the third eyelid lacrimal gland by the glistening cartilage convexity visible through the conjunctival surface. Though folded cartilage does not typically cause corneal pathology or visual compromise, the inappropriate third eyelid margin position impairs optimal tear film distribution and drainage, may contribute to conjunctivitis and exposure keratopathy, and is unsightly to most pet owners as the third eyelid no longer conforms to the ocular surface. Patients are treated by surgical resection of the bent portion of cartilage, cartilage removal and homotransplantation, or careful application of thermal cautery to remodel the cartilage and return the third eyelid to a normal position. The medial and lateral tips of the cartilage may also be affected and can be similarly treated with cautery being my personal treatment preference for this condition.

8 Recommended Veterinary Ophthalmology Textbooks: Slatter s Fundamentals of Veterinary Ophthalmology, 5th edition. David J Maggs, Paul E Miller and Ron Ofri. Saunders Elsevier Essentials of Veterinary Ophthalmology, 2nd edition. Kirk N Gelatt. Blackwell Publishing Veterinary Ophthalmic Surgery. Kirk N Gelatt and Janie P Gelatt. Saunders Elsevier Ophthalmic Disease in Veterinary Medicine. Charles L Martin. Manson Publishing Ltd. 2010

9 Management of Common Corneal Conditions Rachel A. Allbaugh, DVM, MS, Diplomate ACVO Iowa State University Department of Veterinary Clinical Sciences, Ames, IA The cornea is a smooth, clear, physically tough window into the eye. A healthy cornea is imperative to normal vision. To maintain corneal health external protection is required (orbit, eyelids, third eyelid) as is a constant source of lubrication (precorneal tear film). Pathologic responses are limited in this highly organized, avascular structure with many changes potentially leading to vision loss. Corneal Ulceration A corneal ulcer results from a loss of epithelial cells and allows exposure of the underlying corneal stroma which stains positive with sodium fluorescein (highlighted by cobalt blue light). Ulcers can occur due to trauma, foreign bodies, chemical or thermal insult, conformational issues (entropion, macropalpebral fissure, lagophthalmos), hair/eyelash disorders (distichiasis, ectopic cilia, nasal fold trichiasis), or acquired conditions (KCS, facial nerve paralysis, eyelid masses, indolent ulcers). Infectious organisms are typically secondary invaders which complicate compromised corneas. The appearance and location of an ulcer may suggest the underlying etiology and help direct therapy so always look for and address all underlying causes! Simple, uncomplicated ulcers should be managed in a way that prevents infection/complication, reduces pain and aids healing (which should occur in a matter of days) while not impeding it (e.g. with topical steroids/nonsteroidals/anesthestics). Therapy includes an E-collar, a topical ophthalmic antibiotic TID-QID, +/- ophthalmic atropine SID-BID, +/- systemic nonsteroidal anti-inflammatory drug or tramadol PO for a few days. A recheck is warranted in 3-5 days to ensure ulcer healing without complication. Complicated, melting and/or infected ulcers require more aggressive management with culture and cytology helpful to guide therapy. Treatment may include topical ophthalmic antibiotics (e.g. ofloxacin 0.3%, tobramycin 0.3%, and/or compounded cefazolin 5%) every 1-4 hours, plasma/serum every 1-4 hours, atropine BID, a systemic NSAID +/- tramadol, and a systemic antibiotic (e.g. doxycycline or Clavamox ) with an E-collar still imperative to prevent injury of a fragile eye. Eyes should be rechecked in hours to assess patient comfort and ensure the eye is not worse. Ulcers 50% deep or greater are candidates for surgery as well as those that worsen or fail to improve with appropriate medical therapy. Ruptured corneal ulcers may be able to seal and heal on their own with aggressive medical therapy but surgery is usually recommended. Surgical options for complicated ulcers include a conjunctival graft, corneo-conjunctival transposition, corneal transplant, collagen or amnion graft. Indolent Corneal Ulcer

10 Indolent ulcers are also known as refractory ulcers, Boxer ulcers (given the breed predilection) or superficial chronic corneal epithelial defects (SCCEDs). These ulcers occur in middle aged to older dogs and are superficial epithelial defects only with no corneal stromal loss. Epithelium fails to adhere to underlying stroma so a loose epithelial margin is commonly noted on examination. Sometimes fluorescein staining will appear negative at recheck visits due to loose epithelium completely covering a defect but signs of patient discomfort and ocular redness remain to indicate the persistent ulcerative disease. A cotton-tipped applicator may be used to gently test the lesion and see if epithelium is able to be easily removed. Other causes of non-healing ulcers MUST be ruled out (KCS, foreign body behind third eyelid, conformation issues, eyelash disorders, etc.) for an ulcer that fails to heal with appropriate management before specific indolent ulcer treatment should be attempted. Therapy for indolent ulcers is the same basic management for a simple ulcer (noted above) as well as sterile cotton tip applicator debridement under topical anesthesia to remove loose epithelium. Debridement alone results in a healing rate of 30-40% so grid, punctate, or diamond burr keratotomy may be needed to improve the odds of healing (to 80-90%). Surgical superficial keratectomy is nearly 100% successful and may be needed in select cases. Tetracycline antibiotics (oxytetracycline topically or doxycycline systemically) may aid healing as well as other topical therapies (serum, ophthalmic sodium chloride, PSGAGs) or a soft contact lens. Corneal Foreign Bodies Plant material is the most common type of foreign body that may become stuck on the corneal surface or even get embedded. Superficial foreign bodies can commonly be removed following topical anesthesia with irrigation (hydropulsion) or a sterile cotton-tipped applicator. Deep and penetrating foreign body patients should be referred to an ophthalmologist for management as linear corneal foreign bodies may require a needle to be carefully inserted adjacent to the foreign body to enable removal and penetrating cases need surgical removal and corneal suturing. Following removal most corneas heal very rapidly if not infected but patients should still be managed with topical antibiotics, atropine, pain control and an e-collar. Chronic Superficial Keratitis (Pannus) Chronic superficial keratitis is a progressive, bilateral immune-mediated condition that affects the cornea of dogs. Corneal disease typically starts temporally or nasally with vascularization, cellular infiltration and superficial pigmentation, but without treatment can progress to involve the entire cornea and even cause blindness. The third eyelid can be affected with or without corneal changes as a lymphocytic-plasmacytic conjunctivitis resulting in margin depigmentation and an irregular surface. Greyhounds, German Shepherds and associated breeds are more commonly affected and ultraviolet light exposure exasperates the disease. Young animals tend to have more severe disease that may be more challenging to control;

11 while middle-aged to older dogs have a better prognosis. Diagnosis is typically based on clinical signs and signalment though cytology showing lymphocytes and plasma cells is supportive. Topical ophthalmic corticosteroids (prednisolone acetate or dexamethasone TID- QID) and immunomodulators (cyclosporine or tacrolimus BID) along with UV light reduction (provide shade, tinted Doggles, etc) are the basis for therapy, with gradual tapering of topical steroids (dose reduction every 2-3 weeks) and only immunomodulator use SID long term if possible. Keratoconjunctivitis Sicca Keratoconjunctivitis sicca (KCS) or dry eye disease is due to decreased aqueous tear production and is easily diagnosed by use of a Schirmer tear test strip (normal mm/min in dogs). Values of mm/min may indicate KCS if consistent historic client observations and/or clinical signs are also present (conjunctivitis, intermittent mucoid or mucopurulent discharge, corneal changes), while values less than 10 mm/min are diagnostic for KCS. Causes of KCS are numerous including infectious/inflammatory disease processes, trauma, iatrogenic damage, systemic metabolic diseases, congenital acinar hypoplasia, lacrimal gland neoplasia, neurologic dysfunction, and drug toxicity; however, immune-mediated lacrimal gland adenitis is the most common cause. Tear production can be transiently lowered by debilitation, dehydration, anesthetic drugs (topical or systemic) and parasympatholytic drugs (e.g. atropine) but will not permanently result in KCS. Treatment of KCS involves tear stimulant therapy lifelong, tear replacement therapy until tear values improve, and supplemental treatments on an individual case basis. Client education is the most important tool in managing KCS as diligent treatment is required, results may not be immediate (can take 1-3 months), and lifelong treatment is necessary. Lacrimostimulant drugs used for treatment of KCS include cyclosporine and tacrolimus. Cyclosporine is available as Optimmune 0.2% ophthalmic ointment or can be compounded (1% or 2%) as drops or ointment. Tacrolimus must be compounded with 0.03% most common; however, stronger concentrations have been attempted for refractory cases. For compounded formulations a reputable pharmacy is recommended. Cyclosporine or tacrolimus is used every 12 hours for most cases of KCS; however, severe, refractory patients may need more frequent treatment (every 8 hours) or use of both medications in combination. If a positive response is seen maintain on that frequency of medication and do not decrease or discontinue use as tear values can quickly drop and may not respond when treatment is resumed. Quality tear substitutes, such as I-Drop Vet, Optixcare, GenTeal Severe gel, etc., are recommended until the STT improves and should be used as frequently as needed for the individual patient (range 2-3 times to 8-10 times daily). An ointment formulation can be used before bedtime/naptime. Additional therapies may include eye wash to remove excessive ocular discharge, n- acetylcysteine 5% BID-QID short term to help remove severe mucoid secretions, topical ophthalmic antibiotics (TID-QID) short term if bacterial conjunctivitis is present or if there is a

12 corneal ulcer, systemic doxycycline and/or omega-3 fatty acid supplementation to help reduce inflammation and improve tear film quality/stability. Topical corticosteroids are NOT recommended for patients with KCS due to the high risk for corneal ulceration. Lacrimostimulants have anti-inflammatory properties that will reduce keratitis and conjunctivitis, but it is the improved tear production and supplemental lubrication that will be most important in improving the clinical signs of KCS. Patients nonresponsive to aggressive medical therapy for KCS may benefit from parotid duct transposition surgery. Though this surgery does provide saliva as an ocular lubricant, it rarely obviates the need for topical medications and may result in postop complications. Other surgeries under investigation include episcleral cyclosporine implant placement and buccal mucosal graft transplantation surgery. Preliminary results are encouraging but long-term follow-up is still needed. Qualitative Tear Deficiency Qualitative tear deficiency is due to an abnormality in the mucin or lipid layer of the tear film. Clinical signs may appear similar to KCS but are typically more subtle. The key difference is a normal STT (>15 mm/min) with a qualitative tear deficiency since aqueous tear production is unaffected. Rose Bengal staining may be of value to highlight corneas with poor mucin coverage and/or dead epithelial cells. To document a deficiency in the lipid component of the tear film meibomian gland secretion (mebum) analysis is performed, while a mucin deficiency is evident by reduced goblet cell numbers in a conjunctival biopsy. More commonly a tear film break-up time (TBUT) is performed to highlight general tear instability. A TBUT involves application of concentrated fluorescein to an eye (without rinsing). The lids are blinked to spread tears and then held open while a cobalt blue light illuminates the corneal surface and allows for timed evaluation of dark windows or fissures developing within the tear film. Normal tear film should remain homogenous and stable for 20 seconds or longer. Break-up noted in 10 seconds or less is diagnostic, with values of less than 5 seconds suggestive of a mucin deficiency. If impacted or infected meibomian glands are evident to suggest a lipid deficiency treatment of the specific issue (e.g. manual gland expression and warm compresses for impacted glands, medications for meibomianitis, surgical curettage of chalazia) and application of lipid substitutes is necessary. If a mucin deficiency is suspected topical cyclosporine is used twice daily long-term for its mucinogenic properties and viscous artificial tears are used until the tear film improves. Topical antibiotics may also be needed if a corneal ulcer is present or a secondary bacterial conjunctivitis exists. Topical steroids should NOT be used to reduce inflammation (status will improve with lubrication) given the risk for ulceration. Many patients with poor tear quality have confounding ophthalmic or conformational issues that may also need addressed (e.g. medial lower lid entropion, trichiasis, macropalpebral fissure, lagophthalmos, etc.).

13 Exposure Keratitis Exposure keratitis is due to a disorder of corneal coverage or tear distribution and may manifest with a roughened corneal surface, ingrowth of blood vessels, resultant corneal edema and/or pigmentation, corneal scarring, corneal ulceration and even globe perforation. Though the cornea can only respond in a limited number of ways, the causes of this corneal pathology can be numerous (exposure during anesthesia, eyelid agenesis, acquired eyelid margin defects, facial nerve paralysis, lagophthalmos, macropalpebral fissure, exophthalmos, buphthalmos). In order to determine the definitive cause a complete ophthalmic exam must be performed (including cranial nerve testing and globe retropulsion) along with baseline diagnostic tests (STT, fluorescein stain for ulcers +/- TBUT, and tonometry). Patients with any form of exposure keratitis require ocular lubrication using a viscous product (e.g. Optixcare or GenTeal severe gel) to improve corneal health; however, diagnosis and treatment of the underlying problem is necessary to permanently resolve the situation. Eyelid defects can be surgically corrected with eyelid margin apposition most important to ensure proper function. Facial nerve paralysis results in an inability to blink the eyelids and therefore cover the cornea. Patients with concurrent neurogenic KCS have the worst prognosis; however, if parasympathetic stimulation to the lacrimal gland remains, globe retraction and third eyelid elevation may allow adequate tear spread and globe protection. A temporary tarsorrhaphy may be performed for select patients to help retain moisture and protect the cornea while awaiting the return of nerve function. If the facial nerve remains paralyzed long-term and the eye is very painful with recurrent problems (e.g. ulceration/perforation) enucleation may be considered. Macropalpebral fissure and lagophthalmos can be corrected with medial canthoplasty surgery as previously discussed. Exophthalmic eyes need the underlying condition addressed (e.g. orbital cellulitis, abscess, neoplasia, cystic disease, etc.); however, a temporary tarsorrhaphy may be used to partially close the eyelids and protect the globe in the short term. Buphthalmic globes typically have chronic glaucoma and are irreversibly blind so end-stage treatment should be considered (e.g. enucleation, evisceration, or chemical ablation). Pigmentary Keratitis Pigmentary keratitis develops secondary to chronic corneal irritation and is more prevalent in certain breeds of dogs (e.g. Pugs). Treatment is directed at halting the progression of pigmentation and correcting the inciting cause such as surgery to address trichiasis, entropion, lagophthalmos, etc. Topical tacrolimus 0.03% or cyclosporine 0.2-2% BID may be helpful to reduce corneal pigment or prevent further pigment extension. Ophthalmic lubrication (e.g. Optixcare or GenTeal severe gel) is imperative to reduce irritation and can be used as prevention in patients at risk. Topical steroids are generally not recommended given the risk of corneal ulcers in brachycephalic breeds or other dogs with chronic ocular irritation.

14 General Eye Medication Tips Teach clients how to administer eye medications before they leave the clinic in order to reduce frustration and improve compliance. When giving small animal patients eye medications it is easiest to support the chin with one hand and direct the nose upward, then hold the medication bottle/tube in the opposite hand and elevate the eyelid to apply to the ocular surface. Once medication is on the cornea or conjunctiva the eyelids are blinked to distribute the drug. When solutions or suspensions are used only 1 drop is needed and with ointments 1/8 is sufficient (grain of rice). Liquid medications should be given at least 5 minutes apart to allow time for absorption. Aqueous drops should be given before oil based drops which should be given before gels or ointments if all are being used in sequence. Multiple ointments should be spaced 30 minutes if possible. Recommended Veterinary Ophthalmology Textbooks: Slatter s Fundamentals of Veterinary Ophthalmology, 5th edition. David J Maggs, Paul E Miller and Ron Ofri. Saunders Elsevier Essentials of Veterinary Ophthalmology, 2nd edition. Kirk N Gelatt. Blackwell Publishing Veterinary Ophthalmic Surgery. Kirk N Gelatt and Janie P Gelatt. Saunders Elsevier Ophthalmic Disease in Veterinary Medicine. Charles L Martin. Manson Publishing Ltd. 2010

15 Management of Common Intraocular Problems Rachel A. Allbaugh, DVM, MS, Diplomate ACVO Iowa State University Department of Veterinary Clinical Sciences, Ames, IA Intraocular problems may include inflammatory diseases, glaucoma, lens abnormalities or fundic lesions. A thorough ocular examination is necessary to identify abnormalities so that an accurate diagnosis can be made and appropriate management planned. Uveitis Uveitis is inflammation of the vascular tunic of the eye, the uveal tract, and may be separated into anterior uveitis (affecting the iris and ciliary body) or posterior uveitis (affecting the choroid and commonly also the retina chorioretinitis). Clinical signs and findings of uveitis are numerous and variable depending on the cause and associated ocular issues, but consistent features are signs of pain, aqueous flare, conjunctival/episcleral vessel injection, miosis, and hypotony (low IOP). If uveitis is causing a secondary glaucoma mydriasis and elevated or inappropriately normal intraocular pressure may occur instead. Causes of uveitis include infectious diseases, immune-mediated diseases, neoplasia, trauma, lens-induced inflammation and others. A complete physical exam and various diagnostic tests are warranted for patients with uveitis to help guide treatment. Therapy is aimed at the underlying cause when known though many cases remain idiopathic. A topical ophthalmic corticosteroid (prednisolone acetate or neomycin/polymyxin/dexamethasone) QID or more is used to decrease anterior segment inflammation with or without a topical nonsteroidal anti-inflammatory drug (diclofenac, flurbiprofen, or ketoprofen). Topical atropine is warranted SID-BID in patients with appropriately low intraocular pressures to decrease ciliary spasm, prevent posterior synechia and stabilize the blood-aqueous barrier. Systemic anti-inflammatory medication is commonly employed with the choice of a corticosteroid or nonsteroidal anti-inflammatory drug based on the presumed cause and individual patient status. Doxycycline 10 mg/kg PO SID may be employed if tick-borne illness is suspected or for its anti-inflammatory effects. Treatment should be continued for 2-4 weeks past the resolution of clinical signs with gradual tapering of anti-inflammatory medication. Glaucoma Glaucoma is the general term for elevation of intraocular pressure (>25 mmhg) that results in retinal and optic nerve damage. Clinical signs of acute glaucoma may include signs of pain (though not always obvious and possibly more subtle dull migraine-like pain), injected episcleral blood vessels, corneal edema, mydriasis, blindness, possibly other changes and is an ocular emergency. Patients with chronic glaucoma may have globe enlargement (buphthalmos), lens luxation or subluxation and retinal degeneration. Primary glaucoma is caused by an inherited malformation in the iridocorneal drainage angle which predisposes both

16 eyes to glaucoma, while secondary glaucoma may be due to uveitis, hyphema, intraocular neoplasia, or lens luxation/subluxation. Distinguishing between acute and chronic glaucoma as well as primary and secondary glaucoma is important for determining the potential for vision and guiding treatment. Immediate emergency treatment and/or referral to a veterinary ophthalmologist is imperative for potentially visual eyes. Therapy for dogs with primary glaucoma may include the following: a topical prostaglandin analogue (latanoprost or travoprost) SID-BID, topical carbonic anhydrase inhibitor (dorzolamide or brinzolamide) BID- TID, beta-blocker (timolol or betaxolol) BID, or a parasympathomimetic (compounded demecarium bromide) BID. Some therapies are contraindicated in certain patients (e.g. do not use timolol in patients with cardiac disease or asthma) or with some of the secondary glaucomas (e.g. do not use a prostaglandin analogue if an anterior lens luxation is present as miosis will worsen the situation). In addition to the therapies mentioned, emergency treatment with a hyperosmotic agent (mannitol IV or glycerin PO) may be needed in an acute case to rapidly reduce pressure or aqueocentesis can be performed if a patient is refractory to emergency medical therapy. End-stage surgery (enucleation, evisceration, or chemical ablation) is appropriate for irreversibly blind, painful glaucomatous eyes. Cataracts Inherited cataracts are the most common cause of vision threatening lens opacities in dogs, affecting certain purebred dogs more than others. Diabetes mellitus is another common cause with 80% of dogs developing cataracts due to the osmotic pull of water by sorbitol locked in the lens. Currently there is no medical therapy proven to treat cataracts and surgical removal remains the only way to restore vision to dogs blinded by cataracts. Pupil dilation with tropicamide is needed to allow thorough lens examination and monitoring of cataract progression. Early referral to a veterinary ophthalmologist is best for any clients potentially interested in cataract surgery as cataract surgery success is greater when operated at the immature stage and also because advancing cataracts may result in lens-induced uveitis, glaucoma, and/or retinal damage that could prevent the option for surgery. Diabetic patients, those with hypermature cataracts, or any patient with apparent lens-induced uveitis should be managed long term with a topical ophthalmic anti-inflammatory drug (e.g. diclofenac). Patients with active uveitis will need additional treatment with a topical corticosteroid until the inflammation is under control. Eyes with cataracts should be examined regularly for cataract progression, signs of intraocular inflammation and IOP should also be monitored if possible. Diabetic cataract prevention is currently being studied with an aldose reductase inhibitor eye drop TID (Kinostat ), though an ocular supplement with the antioxidant grape seed extract has also shown good results in a small study (OcuGLO PO SID) and is commercially available (

17 Lens Luxation/Subluxation Lens luxation (complete movement) or subluxation (partial shifting) may occur due to a primary abnormality in the supporting lens zonules affecting a number of terrier breeds. Partial lens shifting may manifest as asymmetric anterior chamber depth, an aphakic crescent or pupil abnormalities. Complete luxation that is posterior is not the surgical emergency that an anterior lens luxation is due to the lens blocking aqueous humor flow in the eye and causing secondary glaucoma. Anterior lens luxation patients should be referred to a veterinary ophthalmologist immediately for lens removal surgery. If IOP is elevated carbonic anhydrase inhibitors and mannitol can be administered. If a lens is subluxated or posteriorly luxated surgical lens removal can be considered or topical medications that cause long-acting miosis can be used BID to help keep the lens from shifting anteriorly (e.g. demecarium bromide or a prostaglandin analogue). If one eye is affected in a breed with the confirmed/presumed genetic zonular mutation the other eye should be monitored and possibly prophylactically treated as well. If lens luxation or subluxation occurs due to chronic glaucoma lens removal is not recommended, and many of these eyes are already irreversibly blind due the prolonged high pressure causing irreversible retinal/optic nerve damage while resulting in buphthalmos and subsequent zonular rupture. Blindness General causes of blindness include anything that obscures the optical axis (e.g. severe corneal pigmentation, complete cataract, intraocular hemorrhage, etc.), retinal dysfunction, optic nerve dysfunction or cortical disease affecting the occipital lobe of the brain. If the fundus can be visualized the retina should be evaluated for appropriate location, blood vessel caliber/extent/branching, optic nerve head appearance, and tapetal reflectivity. Signs of retinal degeneration include vascular attenuation, optic nerve head pallor and tapetal hyperreflectivity. A common cause of retinal degeneration in dogs is progressive retinal atrophy (PRA), an inherited condition that manifests first as difficulty seeing in dim light. There is no proven therapy for this condition and vision loss is expected to progress to complete blindness but nutritional supplementation (lutein or OcuGLO PO SID) can be attempted to possibly halt the disease. Sudden acquired retinal degeneration syndrome (SARDS) is another disease that causes blindness due to retinal dysfunction but occurs rapidly and initially without observable signs of retinal degeneration. Diagnosis is made by documenting no retinal activity on electroretinogram. Experimental therapy with intraocular injections and oral immunosuppressive drugs may restore some degree of vision in a minority of patients treated early, but most dogs adapt well to blindness within a few months with ongoing good quality of life. Blindness not due to observable optical axis impediment or retinal disease may be due to optic nerve or central nervous system inflammatory disease, neoplasia, vascular accidents, or toxicity and may require more advanced testing for a diagnosis.

18 Recommended Veterinary Ophthalmology Textbooks: Slatter s Fundamentals of Veterinary Ophthalmology, 5th edition. David J Maggs, Paul E Miller and Ron Ofri. Saunders Elsevier Essentials of Veterinary Ophthalmology, 2nd edition. Kirk N Gelatt. Blackwell Publishing Veterinary Ophthalmic Surgery. Kirk N Gelatt and Janie P Gelatt. Saunders Elsevier Ophthalmic Disease in Veterinary Medicine. Charles L Martin. Manson Publishing Ltd. 2010

19 Management of Common Feline Ophthalmic Issues Rachel A. Allbaugh, DVM, MS, Diplomate ACVO Iowa State University Department of Veterinary Clinical Sciences, Ames, IA Though cats may get many of the same eye problems as other species it is important to remember that they are not small dogs and that some of their ocular issues require different management strategies or that simply they can get diseases that other species do not get. Awareness of these considerations and knowledge of certain feline ophthalmic issues is important in small animal practice. Conjunctivitis Conjunctivitis is a common ophthalmic problem in feline patients and a frequent cause for presentation to veterinarians. Clinical signs include blepharospasm, epiphora or discolored ocular discharge, conjunctival hyperemia and possibly chemosis. Infectious etiologies are the most common cause of conjunctivitis in cats, including Feline Herpesvirus-1 (FHV-1), Chlamydophila felis, Mycoplasma spp., and calicivirus. The specific agent may be difficult to identify so empiric therapy is commonly used to treat patients while avoiding drugs that may suppress the immune system or worsen clinical signs. Antibiotic agents used include topical erythromycin, oxytetracycline, or chloramphenicol ointment TID-QID and/or systemic doxycycline 10 mg/kg PO SID to address possible bacterial agents. Antiviral therapy (compounded ophthalmic cidofovir 0.5% BID and/or famcyclovir 90 mg/kg PO BID) +/- adjunctive therapy with L-lysine is commonly used to manage FHV-1. Antibiotic and antiviral therapy is typically continued for 2 weeks past the resolution of clinical signs, while lysine can be given long term to possibly reduce the severity and frequency of FHV-1 recurrence. Corneal Ulceration Corneal ulcers in cats may be most commonly caused by FHV-1 or trauma, but eyelid or eyelash abnormalities may also cause ulcers. Dendritic ulcers are pathognomonic for FHV-1 infection; however superficial geographic ulcers are a more common presentation. Bacterial organisms are typically secondary invaders which complicate compromised corneas. Simple, uncomplicated ulcers should be managed in a way that prevents infection/complication, reduces pain and aids healing (which should occur in a matter of days) while not impeding it (e.g. with topical steroids/nonsteroidals/anesthestics). Therapy includes a topical ophthalmic antibiotic TID-QID, such as tetracycline, erythromycin, chloramphenicol, tobramycin or a fluoroquinolone. Antibiotics containing neomycin and polymyxin are not recommended in cats due to poor susceptibility of feline infectious agents, potential topical hypersensitivity, and rare anaphylactic reaction risk. If discomfort is noted with ulceration ophthalmic atropine SID-BID

20 +/- a pain relieving drug can be used for a few days. A recheck is warranted in 3-5 days to ensure ulcer healing without complication. Any nonhealing feline superficial ulcer with no other obvious cause should be treated as a herpetic ulcer with an antiviral +/- lysine in addition to a topical antibiotic to prevent secondary bacterial infection. Ulcers with loose epithelial lips that are superficial are also likely due to FHV-1 and may require sterile cotton-tip applicator debridement or other therapies to encourage healing (e.g. diamond burr or superficial keratectomy). Complicated, melting and/or infected ulcers require more aggressive management with culture and cytology helpful to guide therapy. Treatment may include topical ophthalmic antibiotics (e.g. Ofloxacin 0.3%, Tobramycin 0.3%, and/or compounded Cefazolin 5%) every 1-4 hours, plasma/serum every 1-4 hours, atropine BID, a pain relieving drug, and a systemic antibiotic. An E-collar may be needed to prevent injury of a fragile eye. Eyes should be rechecked in hours to assess patient comfort and ensure the eye is not worse. Ulcers 50% deep or greater are candidates for surgery as well as those that worsen or fail to improve with appropriate medical therapy. Ruptured corneal ulcers may be able to seal and heal on their own with aggressive medical therapy but surgery is usually recommended. Surgical options for complicated ulcers include a conjunctival graft, corneoconjunctival transposition, corneal transplant, collagen or amnion graft. Corneal Sequestrum Sequestra may form in the corneas of cats due to chronic irritation (e.g. exposure, entropion) or due to FHV-1 infection. They may develop at the site of chronic corneal ulcers as well. Brown to black discoloration is present representing necrotic collagen. Though lesions may slough on their own, surgical removal via a superficial keratectomy is recommended to prevent inadvertent globe rupture. Use of topical lubricants long term may minimize the risk of recurrence or development in the opposite eye in predisposed cats as well as oral lysine supplementation. Eosinophilic Keratitis Eosinophilic keratitis is an immune-mediated disease which manifests as a pinkish-white superficial or proliferative lesion of the feline cornea due to blood vessel ingrowth and inflammatory cell infiltration. Lesions commonly start near the lateral or medial limbus but can progress to involve the entire cornea and cause blindness. It is typically nonpainful and may be unilateral or bilateral. Diagnosis is made by consistent clinical appearance and surface cytology which shows eosinophils among other inflammatory cells. Treatment with topical ophthalmic dexamethasone sodium phosphate or prednisolone acetate QID followed by gradual decreasing and/or immunomodulating drugs (e.g. cyclosporine) BID is generally