Corneal cross-linking is widely used to treat keratoconus. However, to date, only limited data from randomized trials support its efficacy. The efficacy and safety of corneal cross-linking for halting progression of keratoconus were investigated in a prospective, randomized, blinded, placebo controlled, multicentre trial. Twenty-nine keratoconus patients were randomized in three trial centres. The mean age at inclusion was 28 years. Longitudinal changes in corneal refraction were assessed by linear regression. The best corrected visual acuity, surface defects and corneal inflammation were also assessed. These data were analysed with a multifactorial linear regression model. A total of 15 eyes were randomized to the treatment and 14 to the control group. Follow-up averaged 1098 days. Corneal refractive power decreased on average (+/−standard deviation) by 0.35 +/− 0.58 dioptres/year in the treatment group. The controls showed an increase of 0.11 +/− 0.61 dioptres/year. This difference was statistically significant (p = 0.02). Our data suggest that corneal cross-linking is an effective treatment for some patients to halt the progression of keratoconus. However, some of the treated patients still progressed, whereas some untreated controls improved. Therefore, further investigations are necessary to decide which patients require treatment and which do not. NCT00626717 , Date of registration: February 20, 2008.

Millions of people in Germany wear contact lenses every day. Deficient contact lens hygiene can lead to corneal infection. Contact lens–associated keratitis usually has a highly acute presentation and can cause long-term visual loss. This review is based on pertinent publications retrieved by a selective search in PubMed, as well as on relevant meta-analyses, Cochrane reviews, and reports by national and international health care authorities. 23–94% of contact lens wearers report associated discomfort and eye problems. The annual incidence of contact lens–associated keratitis is 2–4/10 000. It is due to bacteria in 90% of cases, and much less commonly to acanthamoebae and fungi. The pathogens generally arrive with the contact lens on the surface of the eye and can penetrate into the corneal tissue because the tear film under the lens is not swept away from the ocular surface by the eyelids, and corneal epithelial changes are often present as well. Corneal infiltration that is diagnosed early is often self-limited, but advanced bacterial infection usually requires intense topical antibiotic treatment. Some severe infections can only be eradicated by emergency corneal transplantation; this is the case in 20–30 % of fungal and acanthamoebic infections. The wearing of contact lenses, particularly soft ones, is associated with a risk of microbial keratitis if proper contact lens hygiene is not exercised. Contact lens–associated keratitis very rarely causes permanent damage to eyesight (0.6 cases per 10 000 contact lens wearers per year). The use of contact lenses always calls for meticulous care.

Technical innovations in corneal transplantation have now made it possible to replace only the diseased part of the cornea, rather than the entire cornea as in penetrating keratoplasty (PKP). Patients with endothelial insufficiency due to Fuchs endothelial dystrophy, bullous keratopathy, or endothelial failure after keratoplasty can be treated with the new methods of posterior lamellar corneal transplantation: Descemet stripping automated endothelial keratoplasty (DSAEK) and Descemet membrane endothelial keratoplasty (DMEK). It remains unclear which of these methods is better in the individual case. We review the pertinent literature retrieved by a selective search in Medline and the Cochrane Library employing the terms "DMEK," "DSAEK," "DSEK," and "posterior lamellar keratoplasty." The publications considered in this article are those that contain important clinical information on the operative techniques. No randomized controlled trials of these techniques have been published to date. Numerous case series have shown that patients who undergo DSAEK (postoperative visual acuity ≥0.5 in 38-100%), and especially those who undergo it in early or intermediate stages of endothelial insufficiency, achieve a better functional result more rapidly than patients treated with PKP (postoperative visual acuity ≥0.5 in 47-61%). Only 23-47% of DSAEK patients achieve a visual acuity of 0.8 or more, compared to 36-79% of DMEK patients. Moreover, transplant rejection is seen in only 1-3% of cases of DMEK, compared to 0-8% after DSAEK and 1-23% after PKP. Numerous case series show clear advantages of DMEK over DSAEK, which, in turn, has better results than PKP. Nonetheless, randomized controlled trials are needed to determine which operative method is best in each stage of corneal disease.

To describe an outbreak of toxic anterior segment syndrome (TASS) following penetrating keratoplasty (PK) and to examine its possible causes. Owing to a series of TASS following PK between June 6, 2007, and October 2, 2007, we reviewed the records of all patients who had undergone PK during that time. In addition to routine microbial tests on organ culture media, we looked for specific pathogens and endotoxins in all of the materials used for organ culture or PK. Furthermore, we analyzed all of the perioperative products and instrument processing. Of the 94 patients who underwent PK, we observed 24 cases of postoperative sterile keratitis. Causal research revealed that the accumulation of cleaning substances or heat-stable endotoxins on the surface of the routinely used guided trephine system was most likely responsible for the TASS. To our knowledge, this is the first report on TASS following PK. Suboptimal reprocessing of surgical instruments may be an important cause of TASS as in this series the TASS-like symptoms resolved after modified instrument-cleaning procedures. The standardization of protocols for processing reusable trephine systems might prevent outbreaks of TASS following PK.