Ocular Melanosis (OM)/Secondary Glaucoma
(Formerly referred to as Pigmentary Glaucoma)

Ocular Melanosis is an inherited condition that occurs predominantly in Cairn Terriers, although there are some unconfirmed reports of a similar condition in other breeds. Pigment deposits accumulate and decrease the eyes’ ability to drain fluid out of the anterior chamber. This fluid accumulation leads to an increase in pressure in the eye known as secondary glaucoma. The condition generally affects both eyes. If the elevated pressure goes undiagnosed and/or untreated, the dog will not only go blind, but also suffer from pain because of increased pressure in the eye.

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Onset of the more obvious changes usually occurs between 7 to 12 years of age, which make this a vital time to closely watch each eye for small spots or patches of very dark pigmentation within the sclera (white part of the eye). Visits to the veterinarian when Cairns are this age should include an examination of the anterior chambers of the eyes for pigment deposits as well. It is important that all Cairns be checked regularly for the early signs of Ocular Melanosis (pigmented scleral patches and thickened iris roots) especially those dogs who are related to dogs that have, or that are suspected to have Ocular Melanosis.
 
If caught early, the damage that glaucoma causes can be slowed, and vision maintained longer by use of medications. If allow to persist, the condition may require removal of the eye due to the pain caused by a build-up of pressure.
 
Awareness of this condition in the United States is fairly recent, as the first known cases were diagnosed in 1984.

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If your Cairn has been diagnosed with Ocular Melanosis and you would like more information, you may contact Dr. Petersen-Jones at peter31@cvm.msu.edu. He can also be contacted through the Comparative Opthalmology laboratory at MSU by telephone at (517) 353-3278.

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