Ocular Emergencies

Chapter 19 Ocular Emergencies

MATERIALS REQUIRED

PROPTOSIS OF THE GLOBE

CORNEAL LACERATIONS

LID LACERATIONS

SEVERE OCULAR AND ADNEXAL CONTUSIONS AND CONCUSSION

PENETRATING INJURIES OF THE GLOBE

SEVERE CORNEAL ULCERATION

DESCEMETOCELE OR IRIS PROLAPSE

ACUTE ANTERIOR UVEITIS

SUDDEN BLINDNESS

The conditions discussed in this chapter are the most important disorders for which early action is necessary to prevent severe or permanent damage to the eye. Emergency treatment is outlined separately for ready clinical reference, followed by further discussion for those conditions not covered elsewhere in the text.

MATERIALS REQUIRED

PROPTOSIS OF THE GLOBE

At initial presentation it is often preferable to try to salvage the globe rather than to remove it.

Emergency treatment for proptosis of the globe (Figure 19-1)

1. Replace the globe as soon as possible to prevent severe corneal damage. If treatment is delayed because the animal is far away, advise that the owner keep the eye moist with saline, water, petroleum jelly (Vaseline), or antibiotic ointments and avoid additional trauma when moving the animal.

2. Carefully examine the patient for systemic injuries and provide appropriate supportive care.

3. Protect the surface of the cornea with antibiotic ointments.

4. When the patient is stable, induce anesthesia.

5. The basic procedure is to lift the lid margins over the equator of the globe while pushing the globe back into the orbit at the same time.

6. Flush the conjunctival sac free of extraneous debris with sterile lactated Ringer’s solution.

7. Roll out the lid margins with hemostats or forceps and place a temporary tarsorrhaphy suture. In general, three or four simple interrupted or horizontal mattress sutures of 4/0 nylon are used as shown in Figure 19-2, A and B. Sutures should emerge from the lid margin (in line with the meibomian gland openings) rather than on the conjunctival surface so as to prevent sutures rubbing on the cornea.

8. Apply a suitable antibiotic ointment (e.g., neomycin, polymyxin B, bacitracin) to the eye.

9. Place a scalpel handle over the cornea, which is well lubricated with either an antibiotic or artificial tear ointment, and draw up on each of the sutures simultaneously, as shown in Figure 19-2, C and D. This maneuver prevents forward movement of the globe while pulling the eyelids up and over the cornea. Once the cornea is protected, tie the sutures (Figure 19-2, E). If necessary (i.e., if pressure is extensive), additional sutures may be placed between the original sutures. Usually the medial canthus is left open for a few millimeters so topical medications may be applied.

10. Give dexamethasone 0.1 mg/kg IV to control secondary uveitis. Systemic steroids may then be used to treat optic neuritis if present.

Figure 19-1 Proptosis in a young Boston terrier after a dog bite injury.

(Courtesy University of Wisconsin–Madison Veterinary Ophthalmology Service Collection.)

Figure 19-2 Procedure for replacement of a proptosed globe. A, Globe proptosis. B, Placement of simple interrupted traction sutures of 4/0 nylon. Alternatively, a series of modified horizontal mattress sutures may be used. Sutures should enter and exit at the lid margin and not on the conjunctival surface. C, Placement of scalpel handle on a cornea lubricated with an artificial tear ointment. D, Traction on the sutures and replacement of the globe. E, Completion of the sutures.

Prognosis

If there is any doubt as to whether the globe can be salvaged, an attempt should be made to replace it back into the orbit. The sooner the eye is replaced, the better the prognosis, both for saving the eye and for shortening the convalescent period. Unfortunately, some eyes are inevitably lost despite early and vigorous treatment. Enucleation as the initial therapy should be considered if (1) the owner is unwilling or unable to provide what may be potentially long-term postoperative care, (2) the eye has ruptured, (3) three or more extraocular muscles are torn, or (4) the eye is completely filled with blood. The following are useful prognostic indicators.

Avulsion of Extraocular Muscles

The medial and inferior (ventral) recti and inferior (ventral) oblique muscles rupture first. Because branches of the ciliary artery to the anterior segment enter the globe with the extraocular muscles, complete avulsion of three or more muscles indicates an unfavorable prognosis. In eyes with only a few of the muscles ruptured, temporary postoperative deviations (usually lateral or superolateral) of the globe occur (Figure 19-1 and 19-3). These deviations often diminish over weeks to months (up to 6 to 9 months), or the exposed conjunctiva becomes pigmented, thereby improving the cosmetic appearance of the eye. Surgical repair of the extraocular muscle tears may be indicated in select cases.

Figure 19-3 Superolateral deviation of the globe after proptosis suggests damage to the medial rectus and inferior oblique extraocular muscles.

Hyphema

Marked hyphema is an unfavorable sign, because it is usually associated with severe damage to the uveal tract or rupture of the globe, which leads to ocular hypotension and phthisis bulbi.

Pupils

The size of the pupil is not associated with the ultimate visual outcome, but the presence of an intact direct and consensual pupillary light reflex is generally a good prognostic sign. The absence of a direct or consensual pupillary light reflex, however, does not indicate that the prognosis is invariably poor. The reason is that mydriasis can result from damage to either the afferent limb of the pupillary light reflex (the retina or optic nerve) or the efferent limb (the oculomotor nerve or the iris sphincter muscle), and miosis may result from iridocyclitis attributable to the injury or loss of sympathetic innervation of the pupil. A midrange pupil may occur if the tone of both the sympathetic and parasympathetic nerves is lost, or if the optic nerve is severed only in 1 eye. The most favorable set of prognostic indicators are as follows:

• Presence of vision at initial presentation

• Minimal damage to extraocular muscles (none, one, or two injured)

• Absence of hyphema

• Normal findings on fundus examination

Skull Conformation

Proptosis occurs most frequently in brachycephalic breeds with shallow orbits (e.g., Pekingese, Boston terrier, pug). It is extremely important that excessive pressure around the neck of these breeds be avoided, especially after proptosis. Because more force is required to produce proptosis in cats and mesocephalic and dolichocephalic dogs, its presence in these animals warrants a less favorable prognosis than proptosis in brachycephalic dogs. Concurrent facial fractures also warrant a poor prognosis.

Maintenance Therapy

1. Systemic oral antibiotics for at least 7 to 14 days

2. Application of topical antibiotic ointments every 6 hours (neomycin/bacitracin/polymyxin B or gentamicin) and 1% atropine ointment every 12 hours through the medial canthus if the patient is tractable

3. Initial sutures are left in place for up to 3 weeks. If some degree of lagophthalmia is present, it may be better to remove the sutures sequentially rather than all at once. If after 3 weeks the lids still do not close well over the globe, the sutures should be replaced and maintained for an additional 2 to 3 weeks to allow residual orbital swelling to regress and to prevent corneal desiccation and ulceration. In some cases sutures may be left in place for 3 to 6 months.

Keratoconjunctivitis sicca and corneal ulceration secondary to exposure are common in the postoperative period. Supplemental artificial s tears or topical antibiotic ointments are often required for several weeks or longer after proptosis to lubricate the eye and prevent infection. Additionally, many severely traumatized eyes demonstrate a deep corneal vascularization that proceeds from the limbus to the center of the cornea before gradually regressing over 4 to 8 weeks. If the cornea is not ulcerated or subject to exposure, topical corticosteroids (0.1% dexamethasone or 1% prednisolone acetate) may be used every 6 to 12 hours in an effort to moderate this vascular response.

In some patients chronic partial exophthalmos and chronic corneal exposure continue to be problems. Usually this situation results from facial nerve palsy, damage to extraocular muscles that retain the globe in the orbit, organized blood/scar tissue within the orbit, or eyelid retraction. In affected patients further surgical intervention, such as extraocular muscle repair, permanent medial or lateral tarsorrhaphy, or, in extreme cases, enucleation, should be considered. Mild cases usually do not need surgery and may be managed with supplemental artificial tear ointment to prevent corneal drying.

Only gold members can continue reading. Log In or Register to continue

Related

Stay updated, free articles. Join our Telegram channel

Tags: Slatters Fundamentals of Veterinary Ophthalmology

Aug 11, 2016 | Posted by admin in INTERNAL MEDICINE | Comments Off

Full access? Get Clinical Tree

Get Clinical Tree app for offline access

Get Clinical Tree app for offline access