Ocular emergencies (Proceedings)

Ocular emergencies [ER] have been written about extensively and there are many good texts to access. This discussion will serve as a reminder of the most common ER conditions with many photos to assist in recognition, some new and standard therapies, and indications for referral to a specialist.

Many of the flow charts illustrating what to do with a red eye are excellent and good references to review periodically. It's harder to mistakenly miss major problems if ophthalmic examinations are performed systematically.

The number one rule of ocular emergencies is to not forget the body to which the eyeball is attached. Look at the pet as a whole animal especially in cases of suspected trauma such as car accidents or dog fights. Pets that have disappeared for a few days and come home with an ocular problem also need to be evaluated systemically. Are they dehydrated, are they suffering from other systemic injuries, do they have normal temperature, pulse, respiration?

We will discuss ocular ER cases most commonly seen:

Laceration

Ulceration

Glaucoma

Orbital Cellulitis

Uveitis

Proptosis

Lens Luxation

Sudden Blindness

Laceration: eyelids: The time from injury affects the healing ability and the bacterial load. As eyelids are well vascularized, only minimal debridement, even a couple of days after a laceration, is required. Culture and sensitivity may be warranted if more than a few days after the incident or if purulence is obvious. Owners may use an over the counter triple antibiotic ointment until the pet is examined. Cool pressure on the laceration may be tolerated to diminish hemorrhage and swelling. The degree of eyelid margin loss will determine if primary closure can be accomplished or if a rotational flap to compensate for margin loss will be required. Carefully evaluate medial eyelid lacerations for the potential for lacrimal puncta trauma. If a laceration is close or debridement may involve this area, place a stent of 2-0 nylon into the adjacent nasolacrimal duct until complete. This will allow identification if the duct is lacerated and may remain in place for a week post repair to maintain the duct integrity. It is important to evaluate the entire globe if the laceration crossed the eyelid margin. Concussive injuries causing uveitis, lens luxation, or retinal detachment may need to be addressed. If severe, the potential for intracranial damage may also need to be monitored and a full neurologic examination should be performed. Laceration of the globe itself may necessitate suturing of the cornea or sclera in addition to the possible need for further diagnostics such as ultrasound.

It is important while suturing the eyelid margin that attention to proper alignment is observed. Large or hemorrhagic lacerations may benefit from palpebral conjunctival sutures with 6-0 vicryl. Eyelid margins may be sutured with a figure 8 or simple interrupted pattern as long as care is taken to tuck away the suture ends such that corneal rubbing is impossible. The use of Elizabethan collars is of benefit with atopy dogs, young dogs, or nervous dogs. Take care though to not ignore pruritis that may indicate sutures were tied overly tightly with excessive swelling, foreign bodies were missed, or sutures are rubbing.

Laceration: Cornea: If foreign bodies [FB] are present use 2-3 doses of topical anesthetic over 10-15 minutes to assure anesthesia. Superficial FB may be elevated with a 25g needle, bevel up, and care not to penetrate the cornea. Malacic corneal stroma should have cytology and culture and sensitivity performed. Topical fluroquinolone solution such as Ocuflox, Vigamox, or Zymar should be used at 1 drop every 6 hours. Autologous serum may also be of benefit in these cases with suspected melting. It may be of benefit to sedate to prevent further trauma if a foreign body is large, if it is penetrating into the eye, in preparation for referral. Systemic antibiotics and, if not contraindicated, prednisone, should be prescribed. Removal of a FB that penetrates the globe should be avoided until the pet is under general anesthesia and a veterinarian trained in intraocular surgery is available. Topical atropine once to twice daily initially may help decrease the chance of synechia but should be used with caution in breeds predisposed to goniodysgenesis and a risk of glaucoma. I rarely use this drug for more than one or two days. A short acting mydriatic such as tropicamide may be used for the first week twice a day instead.

Keep in mind, the cornea is only 0.5-1mm thick. Proper suturing of this thin, unique tissue requires years of practice. If a lesion is greater than 50% through the corneal thickness it needs grafting and/or suturing and referral of your patients to an ophthalmologist should be offered as soon as possible.

Periodically we evaluate pets who have a small puncture to the cornea with massive intraocular damage. Ultrasound is the best diagnostic in this situation and yet if not available, radiography may reveal metallic FB if a pellet is present. If pellets have clearly traveled through the lens and back of the eye, enulceation may be the only option. A case of a pellet through the cornea, lens, and retina with associated detachment has been successfully treated.

Ulceration: These may be acutely painful and require immediate therapy if they are 1. rapidly progressing which may indicate an aggressive micro-organism or 2. if they are deep and a dent into the cornea can be viewed with the naked eye. If a deep hole is not present with the risk of rupture, all corneal cases should have a tear test performed. May of these cases progress rapidly and/or heal poorly due to undiagnosed dry eye. Cytology and culture and sensitivity from the ulcer margins should be performed after topical anesthetic. Fluorescein stain should then be applied. Shallow epithelial erosions should heal within 3-5 days with a broad spectrum antibiotic 3-4 times daily. Any erosion or ulceration lasting longer should be re-evaluated for complicating factors. Evaluate for missed FB, indolent erosion, chemical burn with alkali, nonresponsive bacteria, or eyelid margin involvement such as entropion.

Proptosis: Evaluate the whole pet. If the pet requires stabilization first, lubricate the cornea with antibiotic or tear lubricant ointment. If the globe appears strangulated, some animals will tolerate a quick snip of the lateral canthus after local anesthetic block to relieve intraocular pressure. Bleeding is usually minimal and this may allow for improved circulation to the eye until anesthesia can be induced safely. Replacement of the globe requires pulling the eyelids out and up and over the globe as gentle pressure is placed on the cornea with a lubricated finger or a scalpel handle. This may be accomplished with the use of forceps grasping the eyelid margin or placement of sutures. The sutures should not exit through the conjunctival surface of the eyelid, but just in front of the meibomian gland opening. Once the globe is in place, a temporary tarsorrhaphy with 4-0 nylon in a vertical mattress suture pattern is performed to close the opening 80% of the way across. A small opening medially may be left for antibiotic ointment. Assure the conjunctival fornices are flushed free of debris prior to closure. Systemic broad spectrum antibiotic therapy and a week or so of low dose prednisone may be prescribed.

Prognosis varies and may not be determined immediately. Certainly some globes that are dangling by a few muscles or pieces of conjunctiva, should be enucleated. But in many cases I instruct owners that we can always remove the eye later if needed. Offer them to give it a chance. Many eyes, even those with dramatic strabismus at initial presentation, will eventually rotate to a more normal position given weeks to heal. Vision may not always return yet many owners are happy to keep the eye. Pupil size is not always a good prognosticator and again, if in doubt, reposition the eye. An important point to keep in mind is that it requires a lot more force to proptose a tightly fitting eye than that in a Brachycephalic. Dolicocephalic dogs and cats, therefore, who sustain a proptosis typically have a poorer prognosis for return of vision, let alone avoiding phthisis due to diminished vascular supply.

These do need to be monitored for the possibility of decreased tear production, KCS, and decreased blinking, lagophthalmos. If a blink response is not noted, leave the sutures in place. These may be well tolerated if positioned properly for weeks to months. If a pet has an eyeball/skull conformation that easily led to a proptosis, a canthoplasty procedure in both eyes may be suggested to prevent future proptoses.

Glaucoma: If primary, closed angle glaucoma, treat with one drop of Xalatan [0.005% latanoprost], 30 minutes apart. If the pressure does not come down in one hour consider IV Mannitol therapy at 1g/kg over 30 minutes. At the same time methazolamide 2.2-4.4mg/kg PO BID should be started. Referral to an ophthalmologist within hours should be recommended if owners want to attempt preservation of vision. If owners are not wanting to consider immediate LASER and/or goniovalve surgery, they do need to be educated about four points:

1. medical therapy will not 'cure' angle closure glaucoma.

2. the response to medical therapy is typically short lived although there are rare exceptions.

3. the pressure elevation will permanently destroy the retina within about 24-48 hours.

4. the 'GOOD' eye is at HIGH risk for glaucoma developing in the next 12 months although prophylactic therapy may delay that onset.

Do NOT use Xalatan therapy if the lens is luxated as this causes significant miosis in the dog. This may further elevate the pressure with a papillary block of the lens. Carbonic anhydrase inhibitors (CAI) topically, Azopt, and systemic methazolamide maybe used until referral. Again educating the owners about the 'good' eye is imperative especially in high risk breeds such as Jack Russell Terriers.

Uveitis: Uveitis may be very painful and patients may be presented on ER. Keep in mind this disease reflects a vasculitis, it may have chronic blinding and painful complications, and may represent systemic disease. Examine the whole pet to determine if any infectious, neoplastic, immune mediated or metabolic etiologies are present elsewhere. Carefully examine both eyes as one may be mild in comparison and not noted to be a problem.

Hemorrhagic uveitis with bleeding into the iris stroma or anterior chamber (hyphema) will require evaluation of history of trauma, investigation systemically for coagulopathies, hypertension, toxins. Ultrasound may be warranted if intraocular neoplasia is suspected ie. an older dog, no history of trauma, not painful, no other issues listed above. These need to be monitored long term for secondary glaucoma which may occur at any time even months down the road. Topical +/- systemic steroids (prednisilone acetate 1% 3-4 times daily and 0.5 mg/kg PO BID) are warranted if fluorescein negative. If inflammation is severe, topical non steroidal anti-inflamatories such as diclofenac or flurbiprofen, can be added to synergistically aid in steroid therapy. Antibiotics may be used if ulceration is present or systemically if trauma or puncture is suspected. Atropine is rarely used in my clinic. Pain control is better managed with drugs like Tramadol and the atropine may be contraindicated in goniodysgenesis patients where hyphema and inflammatory debris may further compromise the drainage angle. Intraocular pressure should be low normal in these cases therefore if pressures are in the teens, topical CAI should be initiated. These are cases that may be forming a preiridial fibrovascular membrane and monitoring for control of the inflammation and secondary glaucoma will be critical.

Acute Blindness: Sudden acquired retinal degeneration (SARDS), optic neuritis, cerebral hypoxia after general anesthesia, acute cataract, toxicities such as ivermectin, enrofloxacin, retinal hemorrhage, acute uveitis, retinal detachment, or glaucoma are all indications for a conversation with your ophthalmologist. This will be further discussed as to how you can diagnose and potentially treat.