Pigmentary Keratitis

Rhea V. Morgan, DVM, DACVIM (Small Animal), DACVO

BASIC INFORMATION TREATMENT AND FOLLOW-UP Description Pigmentary keratitis is the migration of brown (melanin) pigment Treatment Options into the cornea. The pigment usually affects the surface of the cor- The first priority of treatment is to correct any underlying causes. nea, and one or both eyes may be involved. The pigment may or Eyelid abnormalities and extra eyelashes may require surgery. may not be accompanied by inflammation. Pigmentary keratitis Medications for dry eye, pannus, and glaucoma are started when occurs most often in the dog; it is rare in cats. indicated. Causes If the pigment is present in one of the flat-faced breeds of dog Pigment usually invades the cornea as a result of chronic irritation. and is secondary to the typical anatomy of these breeds (large, prom- Causes of irritation include the following: inent eye; lashes or hair growing near the eye; large eyelid opening), • Extra or abnormal eyelashes or hair rubbing on the cornea then conservative therapy with topical lubricants may be started. • Exposure of the cornea in dogs with prominent eyes and large • If the pigment affects the central cornea or progressively wors- eyelid openings, especially in the flat-faced breeds of dogs ens, then prolonged therapy with cyclosporine or tacrolimus • Dry eye (keratoconjunctivitis sicca) from lack of tear may be helpful. These drugs increase tear production and production encourage the pigment to thin and disperse over time. • Inability of the eyelids to protect the eye because of decreased • If the pigment threatens vision or does not respond to medica- blinking or enlargement of the eye from glaucoma tions in these breeds, then surgery (canthoplasty) may be con- • Corneal ulceration sidered to remove hair from near the cornea and to make the • Chronic corneal inflammation (keratitis), such as pannus in the opening of the eyelids smaller. dog • Surgery to remove the pigment from the cornea is no longer per- formed in most cases, because the pigment is likely to return and Clinical Signs may be accompanied by postoperative scarring of the cornea. Depending on the underlying cause, the dog may show no clinical signs except for the development of a dark brown film on the eye. Follow-up Care This film may cover only a small portion of the cornea and only Periodic recheck visits are used to monitor both the pigmenta- be detected by your veterinarian during an examination. If the pig- tion and the underlying cause. If the pigmentation visibly worsens ment progresses to cover most of the cornea, then decreased vision despite therapy or any new signs develop, notify your veterinarian. may be noted. Other signs usually pertain to the underlying cause Following re-examination, the frequency or types of medications and can include pain; tearing; increased thick, ropey discharge; may be changed. enlargement of the eye; redness; and other ocular symptoms. Prognosis It is easier to prevent pigment from spreading than it is to make it Diagnostic Tests recede. When pigment does recede, the process can be slow and The presence of corneal pigment is confirmed by examination take many months. Stopping the progression of the pigment often of the eye, often with the use of magnification. Other diagnostic depends on whether the underlying condition can be successfully tests, such as tear testing, fluorescein staining, and glaucoma test- treated. If the pigment does not cover the pupil or is not very thick, ing, are used to determine the underlying cause. The eyelids, blink it may have minimal effects on vision. Thick, widespread pigmen- responses, and position and shape of the eye are also thoroughly tation can result in blindness. Prolonged treatment and diligent examined. monitoring may be required for the life of the dog.