A six year old neutered male Golden Retriever was presented to the ophthalmology service at Bronte Road Animal Hospital with what the referring veterinarian described as "bleeding in the iris" of the left eye.

Ophthalmic examination revealed moderate conjunctival hyperemia in the left eye, normal Schirmer tear test values and no uptake of flourescein dye in either cornea. Pupillary light reflexes and menace response were normal. Intraocular pressure, measured with the MacKay Marg Applanation tonometer, revealed an intraocular pressure of 18mmHg in the right eye and 12 mmHg in the left eye.

Examination of the left eye revealed six or seven blood filled iris cysts, extending into the pupillary space from behind the iris. Some of the cysts were completely filled with blood, others were partially filled with the blood gravitating ventrally within the individual cyst, while others were clear. There were no abnormal finding in the posterior segment.

Mydriatic (Mydriacyl 1% - Alcon) was applied to both eyes to dilate the pupils. This revealed even more iris cysts behind the iris which had been hidden. Two iris cysts were also noted in the right eye following mydriasis.

Discussion

Iris cysts are seen not uncommonly in the Golden Retriever and the Boston Terrier amongst other breeds. It is not known if there is a relationship between uveitis and the development of iris cysts. Certainly most dogs presenting with iris cysts do not have overt uveitis, but there has been speculation that a very low grade festering uveitis may indeed be present and associated with iris cyst development. In this case the conjunctival hyperemia and the reduced IOP are suggestive of uveitis, but no flare was seen with slit lamp examination. The presence of blood in the iris cysts is unusual, but has been reported in the past by several ophthalmologists. The cause of the bleeding is not known, but it would not be unreasonable to assess platelet function and clotting factors in such cases.

When numerous iris cysts are present to the point that the visual axis is compromised, some ophthalmologists recommend that the iris cysts be deflated using the diode laser. This would not be recommended in cases where the iris cysts are blood filled. Others may drain the iris cysts via a small limbal incision. This is effective when the iris cysts are free floating which was not the case here.

There has been some discussion that the presence of iris cysts may lead to glaucoma. It is not my experience to see dogs with iris cysts going on to glaucoma, however pathologists report that amongst their cases of end stage glaucomatous eyes which were enucleated from Golden Retrievers, the presence of iris cysts are not uncommon. It is not clear if a cause and effect relationship exists.

In this particular case, the dog was treated with topical dexamethasone alcohol eyedrops (Maxidex - Alcon). Subsequent examination revealed less inflammation, and clearing of the blood from the iris cysts.