Inaccuracy of intraocular pressure measurement in congenital corneal opacity: three case reports

BACKGROUND: To report three cases of congenital corneal opacity where intraocular pressure (IOP) readings were high despite the use of multiple anti-glaucoma eye drops and normalized after corneal transplantation. CASE PRESENTATION: Three Korean infants presented with bilateral dense stromal opacification which had been present since birth. IOPs measured by rebound tonometer were high despite administration of multiple anti-glaucoma medications. One eye of each patient underwent penetrating keratoplasty (PK) because corneal opacity impaired visual development. Immediately after PK, IOPs were normalized and maintained normal without medication, whereas they remained high in the contralateral unoperated eye. On histology, stromal fibrosis was observed in the removed corneal button, and molecular assays revealed increased levels of type 1 and 5 collagens. CONCLUSION: The IOP measurement using the conventional applanation-based tonometry can be inaccurate in congenital corneal opacity which is marked by corneal fibrosis. Therefore, IOP values should be interpreted with caution in these patients, and the possibility of false-positive diagnosis of glaucoma considered.