Treatment of the cornea with riboflavin and UVA significantly stiffened the cornea only in the anterior 200 microm. This depth-dependent stiffening effect may be explained by the absorption behavior for UVA in the riboflavin-treated cornea. Sixty-five percent to 70% of UVA irradiation was absorbed within the anterior 200 microm and only 20% in the next 200 microm. Therefore, deeper structures and even the endothelium are not affected.

Collagen cross-linking leads to a stiffening of the anterior parts of the corneal stroma. The increase of biomechanical stability can stop the progression of a keratectasia after LASIK by means of a simple procedure.

The biochemical study showed that the treatment of the cornea with riboflavin/UVA leads to significant collagen cross-linking not only in the anterior slice of 200 microm but also in the following 200 microm. This locally limited cross-linking effect may be explained by the absorption behavior for UVA of the riboflavin-treated cornea; 65% of UVA irradiation is absorbed in the first 200 microm and only 25-30% in the next 200 microm. Therefore, deeper-lying structures and especially the endothelium are not affected.

Backgrounds:To report 2 cases of multidrug-resistant fungal keratitis caused by Fusarium solani. The patients underwent a different conservative and surgical therapy including in both of them a keratoplasty à chaud. Methods and Findings:A 21-years-old male and a 26-yearsold female patient, who both used soft contact lenses developed corneal infiltrates. In the first case the diagnosis was delayed because multiple microbiological examinations of corneal scrapings were initially negative for fungi. A combined empirical therapy against Acanthamoeba and bacteria resulted in no improvement of the clinical findings. The patient underwent a keratoplasty à chaud and the histopathologic analysis of the corneal button yielded Fusarium solani multiresistant to all antifungal agents. In the second case, Fusarium solani was detected in the initial microbiological examination of the corneal scrapings. Although the fungus was multiresistant to all antifungal agents, an aggressive multiple topical antifungal therapy as well as lyposomal Amphotericin B i.v was applied successfully after the keratoplasty à chaud combined with application of Polyvidon-Iodine on the infected cornea and cryocoagulation circular at limbus. Results:Although a therapy with topical Amphotericin B and systemic lyposomal Amphotericin B was applied by the first case the infection progressed to an endophthalmitis. Unfortunately an enucleation was unavoidable. The multiple conservative antifungal therapy in the second case was successful, and the corneal transplant remained free from new infiltrations. Conclusion:We consider the fast diagnosis of multidrug resistance of great importance. Secondly, a penetrating keratoplasty early on the course of the disease increases the chances of a successful outcome.

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