Corneal ectasia after PRK - Clinicopathologic case report

Purpose: To describe the clinical and ultrastructural features of a prominent ectasia of the cornea that occurred 9 years after excimer laser photorefractive keratectomy (PRK). Methods: Analysis of corneal topography and ultrastructural examination by transmission electron microscopy (TEM) were used to assess the ectatic cornea. Results: The intended laser ablation in the left eye was 74 mu m, and the preoperative ultrasonic pachymetry was 536 mu m. Orbscan II (V 3.00; Orbtek, Salt Lake City, UT) observations revealed inferior topographic steepening and protrusion of the anterior and posterior corneal surfaces 13 years after the patient underwent PRK. The least thickness of the cornea was 456 mu m. TEM showed that the epithelial basement membrane had degenerated into subepithelial stroma, and apoptotic keratocytes with cell debris on the extracellular matrix were observed in the stroma. However, the endothelial cells were normal. Conclusion: Clinical examination of an eye that had developed corneal ectasia 9 years after PRK showed forward protrusion of both anterior and posterior corneal surfaces. Ultrastructural examination also revealed a degenerated stroma. However, there was no abnormality of the corneal endothelium.