A comprehensive long-term follow-up study of Brown-McLean syndrome

This report aims to document a long-term follow-up of a rare case of Brown-McLean syndrome where high-density central corneal endothelial cells (CECs) were maintained, yet the peripheral area developed corneal edema.

A 72-year-old Japanese male was referred to our hospital. He had a history of three instances of rhegmatogenous retinal detachment in the right eye, requiring three intraocular surgeries. While the circumferential corneal peripheral regions, predominantly in the nasal and temporal areas, exhibited corneal edema, the central region remained clear. The central corneal thickness was measured at 541 μm, and the thickness in the nasal and temporal regions exceeded 700 μm. CEC density at the center was determined to be 2499 cells/mm² using a non-contact specular microscope, but imaging of the nasal and temporal cornea was obscure due to corneal edema. Panoramic images of the corneal endothelial layer, captured via slit-scanning wide-field contact specular microscopy, showed a high-density and uniform distribution of cells across the clear corneal region, close to the border between edematous and non-edematous areas. Twelve years after the initial visit, the central cornea maintained its transparency and a CEC density of 2456 cells/mm². Despite the entire peripheral corneal edema, there was no noted deterioration from twelve years prior. The annual reduction in central cornea CECs was a mere 0.09 %.

This case implies the unintended formation of a biological barrier at the border or a possible lack of CEC affinity of centrifugal movement, among other unidentified factors. Such factors may hinder the migration of CECs from the central to the peripheral regions of the cornea, a discovery that is crucial for advancing our knowledge of corneal endothelial biology and exploring new treatment options.