Which systemic condition would be MOST likely to be associated with band keratopathy?

Band keratopathy is characterized by the deposition of calcium in the corneal epithelium and Bowman's layer, resulting in a characteristic band-like appearance. This condition is most commonly seen in association with high levels of calcium, which can occur in systemic conditions that lead to increased parathyroid hormone or related hypercalcemia.

Hyperparathyroidism, which involves overactivity of the parathyroid glands, leads to elevated levels of parathyroid hormone. This hormone increases serum calcium levels by promoting calcium release from bones, enhancing intestinal absorption of calcium, and decreasing renal excretion of calcium. The excess calcium can then precipitate in the cornea, resulting in band keratopathy.

Other conditions such as hyperthyroidism or hypothyroidism are not directly associated with elevated calcium levels and hence are less likely to lead to band keratopathy. Hypoparathyroidism would result in lower calcium levels, making it highly unlikely for this condition to be associated with the deposition findings seen in band keratopathy.