Hypoglobus following orbital decompression for dysthyroid ophthalmopathy.

Hypoglobus following orbital decompression is not a rare complication. Hypoglobus requiring surgery to elevate the globe following orbital decompression is considered clinically significant hypoglobus. A retrospective analysis of 157 consecutive patients who had their orbits expanded by removing the medial wall and floor of the orbit found seven patients (4.5%) who required further surgery to elevate the globe. The seven patients who developed clinically significant hypoglobus following orbital decompression all developed a set of distinct clinical signs. These included a "setting sun" appearance of the globe, eyelid malposition, orbital volume loss, and strabismus. These clinical signs can be explained by the inferior movement of the globe and the orbital contents following the loss of support structures on the orbital floor. A two-wall orbital decompression performed on a cadaver reproduced the physical signs of hypoglobus. The dissection suggested that the periorbita is the most important structure supporting the globe in the orbit.