Ocular Melanosis in Cairn Terriers

Ocular Melanosis is an eye condition that most commonly affects Cairn Terriers, though it has been reported occasionally in other breeds such as the Boxer. It is also called Pigmentary Glaucoma because this condition often results in glaucoma (which is a high pressure in the eye that can cause discomfort and blindness). Ocular Melanosis is inherited, although the specific genes and mode of inheritance is not completely understood.
The condition causes pigmented (i.e. brown) cells to accumulate in the eye and eventually block the drains that are responsible for removing fluid from the eye.  These “clogged” drains will cause the pressure inside the eye to increase.  The high pressure in the eye will damage the retina (the layer in the back of the eye that senses light) and the optic nerve (the nerve that sends the signal from the retina to the brain).  Dark pigment may also be deposited on the sclera (white part of the eye).

Unfortunately, despite ongoing research, there is currently no cure for this condition. Treatment is aimed at controlling inflammation with topical anti-inflammatory medications.  Dogs with Ocular Melanosis typically require routine eye exams and intraocular pressure monitoring. If intraocular pressures start to increase, then anti-glaucoma medications can be initiated in an attempt to decrease the pressure.  Unfortunately, glaucoma surgeries to preserve vision, such as ECP (endocyclophotocoagulation), have a very low success rate with this condition.  In the event that the glaucoma is no longer responsive to anti-glaucoma therapy, alternative surgeries, such as eye removal, may be necessary to ensure long-term comfort.

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