OCULAR EMERGENCIES

ocular emergencies and bulla osteotomy in dogs

1. OCULAR EMERGENCIES ECTROPIAN BULLA OSTEOTOMY Dr . Naveen kumar verma DIVISION OF SURGERY ON P R E S E N T A T I O N

2. Ocular emergencies and management Acute exophthalmos including globe prolapse (globe prolapse commonest in Dog Breeeds (Brachycephalic With Shallow orbit) Orbital inflammation – abscess and cellulitis (all species, but commonest in dog) Foreign bodies (all species) Gross trauma to globe and/or adnexa (all species) Complicated corneal ulceration and corneal infection (all species) Thermal and chemical injuries (all species) Acute uveitis (mainly dog and horse) Acute glaucoma (mainly dog, but other species can be affected) Sudden loss of vision (all species) Sudden onset of ocular pain (all species)

3. ACUTE EXOPHTHALMOS (PROPTOSIS) Forward displacement of the globe , GLOBE PROLAPSE( dislocation of the globe beyond the plane of the eyelids ).

4. MANAGEMENT

5. ORBITAL INFLAMMATION Orbital cellulitis and Orbital abscess may be identical, and both can be a cause of proptosis . Orbital cellulitis is diffuse inflammation, whereas a retrobulbar abscess (orbital abscess ) is characterised by localised inflammation . CAUSES: Acute inflammation of the lacrimal (dacryoadenitis ) or zygomatic gland ( sialoadenitis ) . Acute masticatory myositis and acute extraocular polymyositis . MANAGEMENT Anti-inflammatory therapy may also be required if the inflammation fails to respond to antibiotics. For acute masticatory myositis and acute extraocular polymyositis , immunosuppressive levels of systemic corticosteroids(prednisolone 2 mg/kg) are indicated initially and then slowly tapered off.

6. FOREIGN BODIES Foreign bodies are associated with acute onset of ocular pain, blepharospasm and lacrimation .

7. Treatment Foreign bodies require removal if they are causing irritation or are capable of causing irritation . Organic foreign bodies are the commonest necessitating this approach. Superficial foreign bodies can be removed a few minutes after application of topical local anaesthetic (e.g. proxymetacaine hydrochloride 0.5%) using a foreign-body spud , a surgical spear, or cotton wool wound round the tips of fine mosquito forceps. Patience is required. Flat foreign bodies in particular (e.g. plant material, flakes of metal or paint) can be quite difficult to remove as they become embedded in the superficial cornea where they set up a considerable reaction. Foreign bodies that have penetrated the cornea and are accessible are best removed using a 25-gauge needle or a foreign-body needle, inserted at 90° into the protruding tip of the foreign body. The foreign body is removed slowly and carefully in the direction exactly the reverse of the angle of entry. Attempt to grasp the foreign body with tissue forceps, this may cause it to penetrate more deeply and is better avoided. It is sometimes necessary to undermine corneal foreign bodies with a 15-gauge scalpel blade or a Beaver blade to facilitate removal .

8. TRAUMA CORNEAL ULCER LIQUEFACTIVE STROMAL NECROSIS (‘MELTING’ ULCER)

9. MANAGEMENT Surgical intervention is not normally required unless foreign material is present. Reconstructive surgical repair is indicated when the wound is large In the majority of animals, medical therapy with broad-spectrum systemic antibiotics and anti-inflammatory agents is required, as is some form of topical ocular lubricant if exposure keratopathy is a likely complication primary repair under general anaesthesia is required. Sutures, usually in simple interrupted pattern, are placed so that they do not damage the cornea. Few cases require suturing, as healing is so rapid and uncomplicated, always provided that the damage is limited to the conjunctiva and does not involve deeper structures . On occasions, minimal debridement is required to remove loose flaps of tissue , sometimes combined with suturing using buried absorbable 6-0 to 7-0 sutures of polyglactin 910 .

10. . Burns may be a consequence of both accidental and non-accidental injury. Eye itself is less commonly damaged than the eyelids because of the rapidity of the blink response. Corneal damage is usually typified by diffuse corneal haze and fluorescein Uptake Treatment Topical antibiotic ointment and systemic analgesic are usually sufficient If pain is more severe bcoz of secondary iridocyclitis , a short-acting cycloplegic should also be used. Occur in any species, but guard dogs, police dogs and horses are at increased risk. Acids precipitate protein and unless they are particularly strong (i.e. pH 2.5 or less) they do not penetrate beyond the corneal epithelium . Alkalis react with fats to form soaps, which damage cell membranes. They thus have the capacity to penetrate the eye, so that their damaging effects are widespread Managed by water irrigation.

11. ACUTE UVEITIS Eye is reddened and painful with the classical signs of blepharospasm , lacrimation and photophobia . The whole cornea is mildly oedematous, hyphaema is present, iris detail is lost and the pupilis constricted . When viewed from the side it was possible to see that the anterior chamber was shallow as a result of profound iris inflammation.

12. ACUTE GLAUCOMA Pain, photophobia, blepharospasm and lacrimation Corneal oedema (if the IOP is greater than 40–50mmHg ) Dilated ( mydriatic ), non-responsive pupil, but when a previous uveitis has caused extensive posterior synechiae (adhesions), the pupil will be immobile and constricted ( miotic ). No direct or consensual pupillary light response High intraocular pressure (in excess of 30mmHg ) Abnormal anterior chamber depth – iris inflammation cause the anterior chamber to be shallower than normal, posterior lens luxation will cause the anterior chamber to be deeper than normal . Reduced vision or blind: affected animals can become acutely blind within hours of the onset of glaucoma.

13. SUDDEN LOSS OF VISION Some types of acute visual loss benefit from early intervention if sight is to be restored . Electroretinography(ERG ) is a critical tool in the evaluation of vision loss . Causes- Acute-onset pancorneal opacity (e.g. panstromal oedema) Uveitis (anterior, posterior and panuveitis ) Acute glaucoma (mainly dog) Globe rupture Haemorrhage Retinal detachment and Sudden acquired retinal degeneration (SARD) in the dog When the blood supply to the optic-nerve head is severely disrupted, ischaemic optic neuropathy can result . Optic neuritis and retrobulbar neuritis (e.g. associated with distemper virus )

14. Toxic damage (e.g. toxic hepatic encephalopathy, quinolone antibiotics, anthelmintics like ivermectin , salt poisoning and lead poisoning ) Metabolic disease e.g. hypoglycaemia in all species Intracranial lesions such as brain tumours (e.g. optic chiasma compression by neoplasm ), haemorrhage, hydrocephalus, tentorial herniation Post-ictal (epilepsy ) Management Accurate case assessment is crucial, as it helps to determine if the damage is reversible or irreversible Rest of the treatment depend on probable cause diagnosed A case of blindness due to enrofloxacin toxicity

15. SUDDEN OCULAR PAIN Reduction of ocular pain after the application of topical local anaesthetic ( e.g. proxymetacaine hydrochloride0.5 %) implies external eye disease (e.g. ocular surface disease, ulcerative keratitis)rather than an intraocular problem (e.g. uveitis, glaucoma ). Successful treatment depends upon establishing and eliminating the cause

16. Ectropion Ectropion is eversion of the lower eyelid . Signalment . The predisposition to having excessive eyelid length and droopy eyelids is seen in breeds such as Saint Bernards , Bloodhounds, Cocker Spaniels, and Basset Hounds . Other frequently affected breeds include GreatDanes , Newfoundlands , and Bull Mastiffs . History . Developmental ectropion is usually breed associated (St . Bernard, Bloodhound, Cocker Spaniel) and may be seen in dogs with loose facial skin. Intermittent or physiologic entropion is seen in large hunting breeds ( GoldenRetriever , Irish Setter, Labrador Retriever). These dogs appear normal in the morning but have droopy eyelids late in the day.

17. SURGICAL TREATMENT Wedge Resection: Wedge resection is used for mild to severe cases of ectropion . Technique: Resect a triangular full-thickness wedge of skin from the lateral aspect of the lower eyelid near the lateral canthus. Mark the site of incision laterally by nicking or crushing, then manipulate the redundant lid laterally with thumb forceps to determine the amount of lid margin to be resected Make the sides of the excised triangle twice the length of the base of the triangle to facilitate apposition. Excise this segment of skin as a triangle with its base at the lid margin. Align and accurately appose the eyelid margin with a simple interrupted or cruciate suture , then place additional skin sutures (4-0 to 5-0 absorbable Vicryl or nonabsorbable silk) while positioning and cutting suture ends so they do not rub on the cornea.

18. V-Y Correction Make a V -shaped incision distal to and slightly wider than the area of the ectropion . Begin the incision about 2 to 3 mm from the eyelid margin. Undermine the flap to near its base on the eyelid and remove any scar tissue. Beginning at the most distal aspect of the V incision, begin placing sutures (4-0 to 5-0 absorbable Vicryl or nonabsorbable silk) from medial to lateral , creating the stem of the Y The length of the stem of the Y depends on how much elevation the lid margin requires to return it to a normal position (estimated as defect + 2 to 3 mm). When the desired position of the lid has been obtained, appose the arms of the Y A temporary tarsorrhaphy may be needed to help prevent contracture along the suture lines during healing.

19. BULLA OSTEOTOMY INDICATION: Performed in conjunction with TECA in animals with chronic otitis external and middle ear disease. 2 types:- Lateral bulla osteotomy Ventral bulla osteotomy Although a lateral bulla osteotomy affords less exposure to the tympanic cavity than a ventral bulla osteotomy. It does not require that the animal be repositioned and is preferred when performed in conjunction with TECA.

20. Lateral Bulla Osteotomy TECHNIQUE:- Bluntly dissect the tissue from the lateral aspect of the bulla using a small periosteal elevator . Avoid damaging the external carotid artery and the maxillary vein, which travel just ventral to the bulla. Rongeur the lateral and ventral aspects of the bulla until the caudal aspect of the middle ear canal is exposed. Extend the bony excision as needed to fully visualize the contents of the tympanic cavity, but avoid sharp dissection and curettage of the rostral aspect of the osseous ear canal to reduce the risk of retroauricular vein damage. Use a curette to remove infected material, but avoid curetting in the rostral ( dorsal) or rostromedial area of the tympanic cavity so as not to damage the auditory ossicles or inner ear structures. Gently irrigate the cavity with saline to remove all remaining debris .

21. Ventral Bulla Osteotomy Allows increased exposure of the tympanic cavity and can be performed alone or in conjunction with lateral ear resection. It is the technique of choice when middle ear neoplasia is suspected in cats that have nasopharyngeal polyps. This technique provides better drainage of the bulla than does lateral bulla osteotomy and allows both bullae to be opened without the need to reposition the animal.

22. TECHNIQUE:- Place the patient in dorsal recumbency , and prepare area surrounding the angle of the mandible for aseptic surgery. Palpate the bulla immediately caudal and medial to the vertical ramus of the mandible . Draw an imaginary line connecting the mandibular rami and a second imaginary line along the long axis of the ventral aspect of the head. In dogs, make a 7 to 10 cm incision (3 to 5 cm in cats) parallel to the midline of the animal and centered 2 cm toward the affected side from where these imaginary lines intersect. Incise the platysma muscle, retract the linguofacial vein if necessary, and deepen the incision by bluntly dissecting the digastricus muscle (lateral) from the hyoglossus and styloglossus muscles (medial). Avoid damaging the hypoglossal nerve , located on the lateral aspect of the hypoglossus muscle . Confirm the location of the bulla and use self-retaining retractors (e.g., Gelpi , Weitlaner ) to spread the digastric and glossal muscles and retract them from the bulla.

23. Palpate the bulla craniomedial to the cornu process of the hyoid bone and caudomedial to the angle of the mandible. Bluntly dissect tissues from the ventral surface of the bulla and use a Steinmann pin to make a hole in its ventral aspect. Enlarge the opening witha small rongeur (e.g., Lempert ). Examine the interior of the bulla for inflammatory debris, neoplastic tissue, or foreign bodies, and obtain samples for culture, sensitivity, and histopathologic examination. In cats, be sure to examine both compartments of the bulla. Flush the cavity with warm saline; if evidence of infection is noted or, if continued drainage is anticipated, place a small, fenestrated drain tube in the cavity and exit it through a separate stab incision. Suture the fenestrated portion of the drain tube to the bulla with small chromic gut suture (4-0 to 6-0). Depending on the amount of exudation, remove the drain in 3 to7 days.

24. COMMON COMPLICATIONS Superficial wound infection, Facial nerve paralysis, Vestibular dysfunction, Deafness, Chronic fistulation or abscessation Avascular necrosis of the skin of the pinna Facial nerve damage may result in loss of the blink response and parasympathetic innervation to the lacrimal glands . The eye should be kept moistened with artificial tears or an ophthalmic lubricant to prevent corneal ulceration.

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