Assessing Keratoconus Progression

Abstract

A variety of methods have been described to both evaluate and document keratoconus progression. In a clinical practice, the ophthalmologist usually evaluates two scans of a patient performed a few months apart to estimate if there is a progression of the disease. Today, besides corneal keratometry, there are many other parameters that are also examined in order to evaluate if the keratoconus is progressing, including change in best-corrected distance visual acuity (CDVA) or uncorrected distance visual acuity (UDVA), manifest refraction, change on the posterior elevation maps, reduction in apical corneal thickness, increase in anterior corneal asymmetry, index of surface variance (ISV), the index of height decentration (IHD), and the maximum anterior saggital curvature (Kmax). In this chapter, we describe in more detail the possible options of markers or indices that can be used to identify keratoconus progression. We also present the reasons why Belin ABCD progression display can be a good option for the diagnosis of keratoconus change. The advantage of using such a wide number of indexes is to provide reproducible and comparable measurements at different time intervals. We support what many authors have just recently published regarding performing more than one imaging at a time to create reliable results (minimal 3 images, ideally 5 images) and recommend evaluating at least two parameters. Only a deep knowledge of the meaning of all these indexes and values increases reliability in the evaluation of keratoconus progression. Further prospective studies are needed to confirm the importance, applicability, and consistency of each index. © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG 2022.