Paradigms, Paradoxes, and Controversies on Keratoconus and Corneal Ectatic Diseases

In this review/opinion article, we prospectively discuss the evolution of knowledge related to keratoconus and ectatic corneal diseases (ECDs), which is intimately related to the emergence of modern refractive surgery in the early 1980s. This is linked, but goes further beyond the need for screening candidates at risk for progressive keratectasia prior to refractive laser vision correction (LVC). In this scenario, we evolved from early diagnosis of keratoconus toward the characterization of the individual susceptibility for ectasia development. There was a paradigm shift related to the management of ECDs, which was unsophisticated and limited to spectacles, rigid contacts lens, or penetrating keratoplasty (PKP). In fact, the emergence of novel treatment modalities, such as corneal cross-linking (CXL) and intrastromal corneal ring segments (ICRS), has established conflicting situations on when, why, and how to proceed with surgery on these patients. Such paradoxes determine the need for individualized treatment planning, which should consider accurate evaluation of patient needs, advanced imaging with advanced geometric characterization, biomechanical assessment, and environmental factors. In addition, patient (and family) education has become an essential part of the management in order to allow conscious decisions and set realistic expectations. In addition, explaining patients that eye rubbing is a major factor on ectasia progression has gained its momentum with the JUNE VIOLET campaign. Such enhanced understanding has led "corneal ectasia" to be considered as a novel subspecialty in ophthalmology.