Abstract

Aqueous misdirect syndrome or malignant glaucoma has been reported as a rare post-surgical complication in people,^1,2 or as an idiopathic condition in both cats and people.³ This condition occurs when aqueous humor is diverted into the posterior segment causing anterior displacement of the lens and narrowing of the iridocorneal angle and anterior chamber. This causes an increase in intraocular pressure due to the narrowed iridocorneal angle. Some cases respond to medical management, some surgical management, and some develop end-stage glaucoma.⁴ A yearling female Guadalupe fur seal stranded due to malnutrition and was admitted to The Marine Mammal Center in Sausalito, CA for assessment. Bilateral enlarged globes were noted seven weeks into her rehabilitation. Ophthalmic exam revealed buphthalmos with elevated intraocular pressures (IOPs) (57 mmHg OD, 33 mmHg OS, TonoVet®) and very narrow anterior chambers OU. The iris and lens were touching the corneal endothelium OS causing a focal area of corneal edema. Ocular ultrasound revealed marked anterior displacement of the lens and iris. Repeated IOPs worsened OS (47 mmHg) and remained high OD with persistent buphthalmos despite topical carbonic anhydrase inhibitor and beta blocker (dorzolamide-timolol) treatment. Due to concern for permanent optic nerve damage, extracapsular lens extraction with posterior capsulectomy was performed OU. Three months post-operatively, she is visual and comfortable, and her intraocular pressures have been stable (26–28 mmHg OU) for months off glaucoma medications. This represents a case of probable congenital malignant glaucoma in a pinniped that was successfully managed with extracapsular lens extraction and vision was retained.

Acknowledgements

We thank Dr. Dane Whitaker and the staff and volunteers at The Marine Mammal Center as well as Dr. Todd Schmitt and the staff at SeaWorld^® San Diego for their excellent care of the animals; we also thank the staff and management at Veterinary Vision for their assistance with this case. The work was conducted under National Marine Fisheries Service permit #18786.

Literature Cited

1.  Luntz, MH, Rosenblatt, M. 1987. Malignant glaucoma. Survey of Ophthalmology. Volume 32, Issue 2, Pages 73–93.

2.  Von Graefe A. 1869. Beitrage zur pathologie und therapie des glaucoms. Arch Fur Ophthal. 15:108–252.

3.  Czederpiltz, JMC, La Croiz, NC, van der Woerdt, A, Bentley E, Dubielzig RR, Murphy CJ, Miller PE. 2005. Putative aqueous humor misdirection syndrome as a cause of glaucoma in cats: 32 cases (1997–2003). JAVMA, Vol 221:9.

4.  Atkins, RM, Armour MD, Hyman JA. 2016, Surgical outcome of cats treated for aqueous humor misdirection syndrome: a case series. Veterinary Ophthalmology 19(Sup1): 126–132.