Phosphate buffer in alkali eye burns as an inducer of experimental cornealcalcification

Corneal calcification is a common problem in severe inflammation, chronic g laucoma, renal disorders and other diseases with disturbed calcium and phos phorus metabolism. The pathogenesis of corneal calcifications in ocular dis eases is not yet completely understood. We present a model of an induced co rneal calcification by local treatment, In a double-masked experiment 16 ra bbits underwent eye burn of one cornea followed by immediate rinsing (160 m l) with isotonic phosphate buffer (n = 8) or saline solution (n = 8) three time a day for 16 days. Tissues were excised, shock frozen and cut into 10 mum slices, freeze dried and coated with evaporated carbon. In the phosphat e buffer group an early onset of corneal opacification occurred resulting i n completely white corneas after 16 days, combined with corneoscleral ulcer ation. The other group showed similar corneal erosion and a little corneal ulceration, but no opacifications. The opacifications of the phosphate buff er group could be identified as calcifications by direct measurements of ca lcium and phosphate (by energy dispersive X-ray analysis on corneal samples ). In conclusion, inappropriate application of phosphate leads to uncontrol led calcifications of the cornea after severe burns to the eye. This reflec ts clinically observed calcifications after eye burns and possibly the adve rse side effects of phosphate buffered eye drops being applied in ophthalmo logy. (C) 2001 Elsevier Science Ltd and ISBI. All rights reserved.