I-site newsletter frequently reports on corneal ectasia, one of the most common indications for specialty lens fitting in our practices. This links directly to a still fairly new technique, corneal cross-linking (CXL). Lately, I have been quite stunned by the early results in keratoconus patients undergoing CXL. The latest techniques are 'epi-on,' which means that the epithelium does not have to be removed before applying the Ribovflavin and UV-A, two eyes are treated at the same time and the treatment itself takes only 30 minutes. CXL seems to halt the progression of keratoconus in the vast majority of cases (more than 90% in some studies), and improvement occurs in more than just a few anecdotal cases (40% to 60% of patients showed improvement in some studies). This means we can potentially 'turn back the clock' one step in many patients, according to Roy Rubenfeld MD, eye surgeon in Washington DC and the lead investigator of a large clinical trial in the US on the topic. This means that instead of a corneal transplant, contact lenses may still suffice, and instead of a scleral lens, a corneal (R)GP lens or evena soft lens may work. Many (long term) questions have yet to be answered (including: does the technique actually 'cross-link' the collagen fibers, or is it just shrinkage and/or hardening of the fibers?). For more see: The Future of CXL - Cataract & Refractive Surgery Today Europe Jan 2011. But in the meantime, some suggest that the procedure should be performed in every single keratoconus patient (the sooner the better, 10 years of age is not uncommon), and this kind of treatment may become more common after (or with!) refractive surgery to stabilize the cornea. I-site newsletter will keep you informed going forward on the progression of CXL in ectasia: quite literally.

 Eef van der Worp

Much of our work revolves around the toric cornea - and how to best correct it. Where soft lenses fail, (R)GP lenses continue to provide patients with excellent vision. Somehow, fitting toric (R)GP lenses always seems very complicated to students, while in fact it is no more complicated than fitting two (R)GP lenses in one eye: just fit the two meridians in alignment to the cornea just as you would fit your normal lens. It is best not to worry about induced astigmatism, etc at this point: just do an over-refaction, and apply that to the front surface if desired by the patient. Still too complex? Recently, the gas permeable lens institute (GPLI) has made a toric calculator available. Just fill in the refraction and keratometry values to get started. For patients manifesting between 0.75D and 2D of corneal cylinder it will suggest a spherical lens, for patients with >2D of corneal astigmatism an (R)GP toric lens will be recommended and the toric lens powers provided. In orthokeratology, corneal astigmatism has been a limitation for some time, and still may be to some degree. However, toric orthokeratology lenses are widely available. Michael Baertschi and Michael Weiss from Switzerland report in the journal Optometry on an orthokeratology toric lens that in theory can correct up to 7D of corneal astigmatism. The case they present involves a patient with -3D of corneal astigmatism.