Abstract
To study clinical and histopathological findings of corneal opacification caused by thickened epithelium leading to reduced vision and topographical changes and to evaluate the outcome of its removal.
Twelve patients (17 eyes) with central, paracentral or peripheral corneal opacification were reviewed to obtain their visual acuity, describe their slit lamp (SL) appearance (depth, extent and density) and document their topographic changes before and after peeling of the epithelium under SL or surgical removal under the microscope. Specimens of six cases were available for histopathological examination and immunohistochemical staining.
Most of the eye opacifications were secondary to corneal procedures in 10 [Penetrating keratoplasty (PKP) in 7 for congenital glaucoma, keratoconus or adherent leukoma – usually over graft-host junction –, Photorefractive keratectomy (PRK) in 2 and Phototherapeutic keratectomy in one], chronic inflammation following trachoma or non-specific causes (3), and herpetic scar (1). Three cases were considered to be idiopathic. All cases presented with decreased vision, astigmatism or changes in topography or refraction. Their vision, clinical symptoms and topography improved after treatment. Histopathologically, all six cases shared findings that are similar to what have been described as peripheral hypertrophic subepithelial corneal degeneration (PHSCD) rather than Salzmann’s nodular degeneration. None of the cases showed inflammation or subepithelial pannus formation in the excised tissue. However, our cases did not fit into the diagnosis of PHSCD because of the location of the corneal opacification (being peripheral in 41% of the corneas, the presence of underlying primary etiologic factors in 82% of the eyes and the bilateral occurrence in 5 patients.
Meticulous SL examination aided by corneal imaging may accurately diagnose and determine the depth of corneal opacification as a cause for reduced vision. Histopathologically, the removed tissue is similar to PHSCD, but cases differ in their clinical profile. Peeling the thickened epithelial/subepithelial tissue is curative in most patients, improves visual and clinical outcome and avoids unnecessary corneal grafting.