Question of the Week

You are a resident on the cornea service when a 60-year-old woman is referred to your clinic for evaluation of corneal edema in the right eye and possible surgical management. Three years ago, she underwent cataract extraction of a dense nucleus with IOL implantation in the right eye. She tells you that her vision in that eye has progressively worsened since the time of surgery. Her eye is uncomfortable, but she denies new floaters, flashes of light, and any history of ocular trauma. Vision is CF at 3 feet OD and 20/20 OS. Pachymetry is notable for a corneal thickness of 710 μm OD and 550 μm OS. The right cornea has subepithelial bullae on the superior third of the cornea, an irregular surface, and 2-3+ corneal edema. Slit lamp photograph is shown below.

What is the most likely diagnosis?

A. Fuchs’ endothelial dystrophy

B. Band keratopathy

C. Pseudophakic bullous keratopathy

D. Limbal stem cell deficiency

Answer

Correct answer: C

Given the timeline of symptoms (emerging post-cataract surgery) and the corneal decompensation with superior subepithelial bullae, the most likely diagnosis is pseudophakic bullous keratopathy (PBK), which generally presents with symptoms of pain, redness, and progressive blurring of vision after cataract surgery with signs of epithelial and subepithelial bullae, stromal haze, edema, and scarring (option C). The pathophysiology of PBK involves dysfunction of endothelial cells found in the innermost corneal layer. These cells have sodium-potassium ATPase pumps to keep the cornea in a dehydrated state, which allows the tissue to maintain its transparent property. Any intraocular surgery can damage the endothelial cells, and the ultrasonic energy of phacoemulsification needed to disassemble very dense cataracts is a well-known cause of endothelial injury, leading to PBK. Treatment options for PBK include conservative medical management with topical hyperosmotics or topical corticosteroids. However, if the condition continues to progress, surgical management with penetrating keratoplasty (PKP) or endothelial keratoplasty (DSEK or DMEK) may be necessary. Although Fuchs’ endothelial dystrophy can also cause endothelial dysfunction, symptoms would likely manifest bilaterally (option A). Band keratopathy is a form of corneal degeneration that results in a band-shaped opacity in the cornea due to subendothelial calcium deposits. It is often a sequela of inflammation and may occur after uveitis (option B). Limbal stem cell deficiency results in dysfunction of the corneal epithelium. Patients experience ocular pain and decreased vision from stromal scarring (option D); however, the history of this patient is more consistent with PBK.