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208 Corneal Sequestration, Cats

Corneal Sequestration, Cats Client Education
Sheet
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• FHV-1 ulceration is linked to sequestrum
BASIC INFORMATION
formation, particularly in nonbrachycephalic • Eliminate ocular pain.
• Minimize corneal scarring.
Definition cats (p. 464).
Corneal sequestration is a disease unique to • Tear film deficiencies (e.g., keratoconjuncti- Acute General Treatment
cats, characterized by an area of necrotic cornea vitis sicca, qualitative tear film abnormalities) • Prophylactic topical antibiotic therapy
that is variably pigmented. have been reported in cats with sequestra. (ointment or solution formulation), such as
• Source of pigment unknown; cats with oxytetracycline/polymyxin B, ciprofloxacin,
Synonyms sequestra may have pigmented tears. Contact or neomycin/polymyxin/gramicidin q 6-8h,
Corneal mummification, corneal necrosis, lenses placed in cats with sequestra (see Acute particularly if fluorescein-positive
corneal sequestrum, corneal nigrum, necrotizing General Treatment below) often become • If sequestrum appears small and superficial
keratitis discolored. and eye is comfortable, observation is a
treatment option:
Epidemiology ○ Sequestrum may slough, resulting in
SPECIES, AGE, SEX DIAGNOSIS minimal scarring; however, sequestra can
Cats of any age; average age of 5 years in Diagnostic Overview take months to years to slough. Corneal
retrospective studies The diagnosis is based on physical appearance rupture may occur if sequestrum is deep.
of the lesion. • If sequestrum is chronic, large, or eye is
GENETICS, BREED PREDISPOSITION painful, keratectomy is indicated (sequestrum
All breeds, but Persian, Himalayan, and Differential Diagnosis excision using a corneal dissector; generally
Burmese appear predisposed. Corneal rupture with iris prolapse (should a referable procedure)
have dyscoric/misshapen pupil and uveitis if ○ No postoperative pigmented corneal
RISK FACTORS this has occurred) tissue should remain; a contact lens may
• Feline herpesvirus type 1 (FHV-1 [p. 464]), be placed for protection for 2 weeks.
particularly in domestic short hairs and long Initial Database ○ Very deep sequestra may require conjunc-
hairs • Complete ophthalmic exam (p. 1137) to assess tival or frozen donor corneal grafting.
• Any corneal insult for underlying causes of corneal irritation
• Brachycephalic cats are predisposed. • Fluorescein dye application (sequestrum itself Chronic Treatment
• Grid keratotomy performed for nonhealing/ often does not retain fluorescein dye; there Treat underlying contributing factors/causes,
indolent corneal ulcers in cats. may be positive fluorescein dye retention such as entropion or lagophthalmos (p. 296)
around the sequestrum) and FHV-1 (p. 464).
Clinical Presentation
HISTORY, CHIEF COMPLAINT Advanced or Confirmatory Testing Possible Complications
• Black spot on eye • Consider testing for FHV-1 (p. 464) if there • Recurrence of the sequestrum after surgery
• Blepharospasm is a chronic history of ocular disease. • If the sequestrum is allowed to slough,
• Ocular discharge • Tear film break-up time (p. 1137) descemetocele formation or corneal rupture
• “Red eye” is possible (p. 209).
TREATMENT
PHYSICAL EXAM FINDINGS Recommended Monitoring
• Circular to oval pigmented lesion in central Treatment Overview • If the lesion is not treated surgically, owners
to paracentral cornea is pathognomonic. Treatment goals: should monitor carefully for sequestrum
• Pigmentation varies from subtle tan discol- • Completely remove the sequestrum and sloughing, and return to the veterinarian
oration of cornea to a dense, black, opaque prevent recurrence. immediately after the sequestrum sloughs
lesion.
• Lesion may form a slightly raised, irregular
corneal plaque.
• Corneal neovascularization or granulation
tissue with chronicity
• Variable corneal edema and inflammation
surrounding sequestrum
• A rim of loose, edematous corneal epithelium
may develop around the sequestrum.
• Depth of corneal involvement (i.e., extent
of lesion) is difficult to ascertain because
sequestra are often opaque.
Etiology and Pathophysiology
• Associated fundamental problems are 1) pain,
2) obstruction of vision, and 3) cosmetic
appearance.
• Chronic corneal irritation, such as that
found with entropion and/or lagophthalmos
(incomplete closure of the eyelids), is a CORNEAL SEQUESTRATION Corneal sequestrum in a cat (arrows). Note its dark appearance and paracentral
common feature. location.

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