Mechanisms for Acute Corneal Hydrops and Perforation

Acute corneal hydrops (ACH) and perforation in corneal thinning diseases are the consequences of exposure to distending intraocular pressure (IOP) forces that are in excess of corneal resistance to them. Apart from thinning, resistance to these forces may be reduced by disease-related tissue changes, such as corneal scarring, which could lower resistance to IOP. Eye rubbing trauma has sometimes been found to be associated with ACH and perforation. This association is not surprising given that the combination of rubbing-related mechanical tissue trauma and the associated increased distending stress of higher IOP seem likely to increase the risk of complications. Many cases of ACH and perforation are described as spontaneous, but this classification may be the consequence of not considering the multiple potential mechanisms for IOP elevation such as coughing, sneezing, nose blowing, and sneeze suppression in addition to those related to eye rubbing/wiping/massaging/touching as well as changes in body orientation, strenuous exercise, and wearing swimming goggles for example. Classification of ACH or perforation as spontaneous may lead patients to assume that nothing can be done to avoid these complications. Patients with corneal thinning diseases who are counseled regarding the potential precipitating mechanisms for IOP elevation will have the opportunity of reducing exposure to them and the risk of the associated complications. In addition, when ACH or perforation occur, faster resolution of edema and wound healing may depend on reducing potentially exacerbating exposures to mechanisms for IOP elevation.