Forceps Injury to Descemet's membraneDefinition:
rupture of Descemet's membrane at birth due to trauma from application of delivery forceps.Etiology:
Descemet's membrane is quite thin at birth and susceptible to trauma. Forceps applied on the cornea may stretch or tear Descemet's membrane in multiple areas.Incidence/PrevalenceClinical Findings:
The resulting linear breaks in Descemet's membrane from forceps trauma may produce visual symptoms such as astigmatism, glare, and even visual loss and amplyopia. Histopathology:
Most cases of forceps injury are viewed at the time of PKP, many years after the initial injury. As in the image of a PAS stained cornea shows, the breaks may be multiple (arrows 1) and characterized by focal scrolling and intense thickening of Descemet's membrane.
Presumably this is caused by the exuberant growth of Descemet's membrane in order to heal the breaks. In addition there is hydropic change within the epithelium (arrow 2) which is seen at low magnification as the wash out of pink color in the cytoplasm. Enlarge the figure and view the microbullae (arrow 3) that have developed from the resulting bullous keratopathy. Stromal scarring accompanies the process (number 4) seen of course as a paucity of nuclei in focal regions of the stroma. Sectioning artifact, in the microtome plane of scrolled Descemet's membrane is quite common in these cases (arrow 5). Endothelium is markedly attenuated (arrows 1 and 8 below).
Higher magnification of the nodular thickening at the site of injury (arrow 6). The configuration of the nodule suggests that endothelial cells laid down layer after layer of basement membrane material (arrows 7) that were misoriented because of the gap, migrated to the edge and finally filled it at the other side. Endothelial cells are evident on the nodule (arrow 8) but are even more sparce elsewhere. Others have reported epithelial transformation of endothelium with this injury (1).Treatment:
The corneal edema resulting from the trauma can be treated symptomatically and if the initial injury was severe enough a penetrating keratoplasty may be needed eventually.References:
1. Tetsumoto, K et al. Epithelial transformation of the corneal endothelium in forceps birth-injury-associated keratopathy.Cornea, 1993;12:65-71