A Jack Russell Terrier presents with acute painful vision loss. Examination reveals a clear circular structure in the anterior chamber and markedly increased IOP. What is the most likely diagnosis?

A Jack Russell Terrier presents with acute painful vision loss. Examination reveals a clear circular structure in the anterior chamber and markedly increased IOP. What is the most likely diagnosis?

• A. Anterior lens luxation
• B. Hyphema
• C. Glaucoma
• D. Iris bombe

Answer: (A)

Acute painful vision loss with a clear circular structure visible in the front part of the eye is classic for anterior lens luxation. When the lens becomes dislocated forward into the anterior chamber, it can be seen as a round, transparent disk floating in the aqueous. This displacement blocks normal fluid flow and often occludes the iridocorneal angle, causing a sudden rise in intraocular pressure that produces pain and rapid vision loss. Other scenarios don’t fit as well. A hyphema would present with blood filling the anterior chamber rather than a clear lens-like structure. Iris bombe involves forward bowing of the iris from posterior synechiae, leading to a shallow anterior chamber and angle closure, but you wouldn’t see a discrete, transparent circular structure floating in the chamber. Glaucoma refers to elevated intraocular pressure itself but doesn’t explain the visible lens in the anterior chamber.

Acute painful vision loss with a clear circular structure visible in the front part of the eye is classic for anterior lens luxation. When the lens becomes dislocated forward into the anterior chamber, it can be seen as a round, transparent disk floating in the aqueous. This displacement blocks normal fluid flow and often occludes the iridocorneal angle, causing a sudden rise in intraocular pressure that produces pain and rapid vision loss.

Other scenarios don’t fit as well. A hyphema would present with blood filling the anterior chamber rather than a clear lens-like structure. Iris bombe involves forward bowing of the iris from posterior synechiae, leading to a shallow anterior chamber and angle closure, but you wouldn’t see a discrete, transparent circular structure floating in the chamber. Glaucoma refers to elevated intraocular pressure itself but doesn’t explain the visible lens in the anterior chamber.