Undetected development of glaucoma after radial keratotomy.

Purpose: To report a case of advanced glaucomatous optic atrophy years after bilateral radial keratotomy.

Methods: Multiple intraocular pressure (IOP) measurements of both eyes in a 40-year-old woman who underwent previous bilateral radial keratotomy were obtained using Goldmann applanation tonometry as well as air-puff and Schiotz tonometry. In addition to regular eye examinations, corneal thickness, surface, and shape were examined using Orbscan and C-Scan.

Results: The cornea of both eyes did not show signs of corneal thinning, but flattening of the corneal surface was observed. The decreased corneal curvatures precipitated a misjudgment of IOP readings measured by central applanantion tonometry (12 to 18 mmHg), whereas impression and non-contact tonometry revealed elevated IOP values (21 to 27 mmHg).

Conclusions: Changes of the corneal shape without corneal thinning can lead to falsely low IOP values. Therefore, in eyes that have undergone corneal refractive surgery, non-Goldmann measurement of IOP and continued examination of the optic nerve and possibly visual fields are recommended.