The Role of Trace Elements in the Formation of Feline Corneal Sequestra

Objective: To characterize the trace element composition of feline corneal sequestra (FCS) and provide insights into their pathophysiology. Methods: FCS samples were collected from 11 eyes of 9 cats following keratectomy and compared with corneal samples from four clinically normal control cats euthanized for reasons unrelated to the study. Excised corneal tissues were immediately frozen at −80°C and analyzed using particle-induced X-ray emission (PIXE) with a 1.7 MV Pelletron accelerator to determine relative elemental abundance. Trace element levels between groups were compared using Mann–Whitney tests, and results were expressed as peak area units. Results: Affected cats were predominantly brachycephalic or predisposed breeds, including Sphynx, Persian, and British Shorthair. Lesions measured 1–8 mm in diameter and involved approximately 20%–70% stromal depth. Across all samples, sulfur demonstrated the highest elemental signal, followed by phosphorus, potassium, chloride, sodium, calcium, magnesium, zinc, iron, and bromine. Iron (median ± SEM: 751 ± 336 vs. 0 ± 0; p = 0.047) and bromine (110 ± 50 vs. 0 ± 0; p = 0.004) were consistently detected in sequestral tissue but were absent in control corneas. No statistically significant differences were observed between groups for sodium, potassium, chloride, magnesium, phosphorus, calcium, sulfur, or zinc. Conclusion: Feline corneal sequestra exhibited a distinct elemental profile characterized by the detection of iron and bromine, which were not detected in the normal corneal samples analyzed. These findings demonstrate measurable differences in trace element composition between sequestral and healthy corneas and provide novel insights into the biochemical characteristics of this disease.