Central Toxic Keratopathy

Excimer laser ablation is an increasingly popular option for the correction of mild to moderate refractive errors in the United States. It is generally regarded as safe, with an overall annual complication rate of less than 0.8% since 2010. Central toxic keratopathy (CTK), first described in 1998, has numerous alternative descriptive names including stage IV diffuse lamellar keratitis, central lamellar keratitis, central flap necrosis, central necrosis lamellar inflammation, and keratinocyte-induced corneal micro edema (KME). This rare clinical syndrome classically presents as a central or paracentral, amorphous corneal opacification with associated striae, stromal loss, and hyperopic shifts that usually present within nine days of excimer laser ablation (i.e., laser-assisted keratomileusis (LASIK) or photorefractive keratopathy [PRK]). It is believed to be non-inflammatory, but its cause is still unknown. Though initially thought of as a progression, or severe form, of diffuse lamellar keratitis (DLK), there is significant support that CTK is a distinct and separate entity from DLK. In addition to cases in other refractive surgeries, there are proposals that CTK exists as an entity outside of the refractive surgery literature: there have been reports of CTK associated with contact lens use with and without recent mechanical debridement, idiopathically, as well as potentially with selective laser trabeculoplasty or topical anesthetic use.[11]