| Popis: |
A 44-year-old man with bilateral keratoconus was referred for Intacs implantation (Addition Technology, Inc.) because of progressive discomfort and contact lens intolerance in the left eye. The procedure was performed under topical anesthesia. The tunnel was created with the IntraLase laser using the following settings: channel depth of 400 mm (70% of the peripheral corneal pachymetric values), entry incision length of 1.5 mm and width of 1.0 mm, channel inner diameter of 6.8 mm and outer diameter of 7.6 mm. One week postoperatively, the patient began to show signs of focal corneal edema around the Intacs segments (Figure 1). Despite an intensive course of topical steroids and suture removal, the corneal edema did not improve. Intraocular pressure was 10 mm Hg bilaterally. At 1 month, slitlamp examination revealed worsening of the initial focal edema surrounding the Intacs segments. At 2 months, there was no improvement in the corneal stromal edema. A decision to explant the Intacs was made. The procedure was uneventful, and the Intacs segment cultures were negative. The corneal edema gradually resolved over the following month. There are several possible/postulated mechanisms for this post-Intacs complication. Although pathologic changes in keratoconus have been shown to involve the anterior layers of the cornea primarily, alterations in the size and shape of the endothelial cells have also been reported. It has been demonstrated that the endothelium of keratoconic corneas show striking abnormalities, with increases in polymegathism and pleomorphism. 1 Furthermore, it has been postulated that the use of certain types of tight-fitting contact lenses can cause hypoxic strain to an already dysfunctional endothelium, permanently worsening stromal edema. 2 In combination with the previous observations, the endothelial distress caused by laser ablation during tunnel creation with the femtosecond laser could temporarily increase endothelial permeability and exacerbate a previously impaired endothelium. In our case, segment explantation led to resolution of the corneal stromal edema. It seems the presence of Intacs segments in combination with abnormal endothelial function is a crucial factor in the development of this complication. |
