Corneal Calcification Associated With Preservative Free Eye Drops and Persistent Epithelial Defects

Abstract

Purpose:: To describe the formation of calcareous degeneration of the cornea, associated with the use of preservative free eye drops, in patients with a persistent epithelial defect and active ocular surface inflammation. Phosphate levels in preservative free preparations causing calcareous degeneration, were measured with a standardized analyzer(Roche ^TM phosphorus reagent and 217 analyzer) .

Methods:: A retrospective case note review and clinical photographs of six cases of calcareous corneal degeneration. Six patients with persistent epithelial defects (diabetic, two penetrating keratoplasty, two herpes zoster.) who subsequently developed corneal calcareous degeneration whilst on topical medications. Data regarding underlying etiology, diagnosis, clinical findings, medications used and phosphate levels of topical medications (as measured independently by Roche ^TM phosphorus reagent and 217 analyzer) used were collected. This study did not require IRB/Ethics committee approval. All drug complications and side effects have been reported to the Medicines and Healthcare Products Regulatory Agency.

Results:: All six cases of calcareous degeneration of the cornea had persistent epithelial defects,treated with preservative free medications (timolol (MSD^TM),dexamethasone (minims^TM Chauvin and prednisolone (minims^TMChauvin)),in the presence of active inflammation on the ocular surface.The mean levels of phosphate were 130,42.9,and 22.9 mmol/l in timolol,dexamethasone and prednisolone.All six patients had some degree of corneal opacification caused by calcareous degeneration and reduced visual acuity.

Conclusions:: The common link in our case series seems to be the use of preservative free medications in persistent epithelial defects.The preservative free medications have high levels of phosphate which may not be common knowledge.

Keywords: cornea: clinical science