A 22-year-old male has bilateral Krukenberg spindles. What is the most likely diagnosis?

The presence of bilateral Krukenberg spindles is strongly indicative of pigmentary dispersion syndrome. This condition involves the shedding of pigment granules from the iris, which can lead to increased intraocular pressure and eventually glaucoma. The Krukenberg spindle is characterized by a vertical spindle-shaped deposit of pigment on the corneal endothelium, which occurs as a result of the pigment released from the iris in individuals with pigmentary dispersion.

In the context of a 22-year-old male, this diagnosis aligns with the demographics often affected by pigmentary dispersion syndrome, as it typically presents in younger individuals, particularly males. The bilateral nature of the spindles reinforces this diagnosis because pigmentary dispersion syndrome usually affects both eyes.

Other conditions such as Salzmann's nodular degeneration and pseudoexfoliation syndrome do not typically present with Krukenberg spindles. Posner-Schlossman syndrome is characterized by episodes of elevated intraocular pressure but does not manifest with this specific pigment deposition pattern. Understanding the associations and clinical features of these conditions helps clarify why pigmentary dispersion syndrome is the most appropriate diagnosis in this case.