The paradigm change in keratoconus therapy

Abstract

Until not even 15 years ago, the therapy of keratoconus was relatively simple: Once the diagnosis was established, the patient was supposed to live with rigid contact lenses and glasses as long as possible until the penetrating keratoplasty became necessary as a final solution for the disease, typically at an age of 30–40 years. However, this plan had some flaws: (1) Penetrating keratoplasty is in more than 10% of the cases not the final solution because of graft rejection and so called recurrency of keratoconus, (2) even in a nicely healed graft the resulting astigmatism may be up to 10 D and more, and (3) penetrating keratoplasty is an “open-sky surgery” with vision-threatening risks. During the past 10 years this simple world became much more complicated with the advent of crosslinking (CXL) to stop the progression, intrastromal rings, toric phakic intraocular lenses (IOLs) and topography-guided photorefractive keratectomy (PRK) for visual rehabilitation, and deep anterior lamellar keratoplasty (DALK) in desperate cases. These changes also implicate new challenges. Strategically, CXL should be performed as early as possible, but can we really treat children at the current state? Is topography-guided PRK better than intrastromal rings? Can toric IOLs be used in any keratoconus case or shall we implant such IOLs only in pellucid marginal degenerations? These questions can be answered only by means of prospective studies and the current problem is that we do not have good prospective studies available. New techniques open, however, the field for speculations, proposals, and assumptions; which are sold as new techniques. Whenever you hear the sentence “in my hands, this gives excellent results” your alarm clock should ring: This is not a scientific proof, this is merely a personal note. The best example is the high intensity CXL (>15 mW/cm2) proposed several years ago as a new technique. Today, at least 4 years after its introduction, we are still waiting for good clinical data that prove the safety and efficacy of the technique. Moreover, we are now seeing patients with stromal central scars which may be singular cases but may also occur more frequently in high intensity treatments. Only prospective studies can answer this question. In this issue, the whole spectrum of the innovations and problems of modern keratoconus therapy is addressed. Many questions, however, remain open and will be subject of more studies. In summary, quite calmly a change in paradigms regarding the management of keratoconus has happened during the past 10 years, and we should be proud to participate in this change.