Clinical Application and Decision-making

Abstract

It is accepted that progression of keratoconus (KC) should be treated by cross-linking (CXL). The accepted indications for progression of KC include: increase of 1 D of maximum K-reading (Kmax) or of manifest cylinder and/or deterioration of corrected distance visual acuity (CDVA) within 1 year, as well as contact-lens-dioptric changes which require replacement every 2 years or less. Some consider a spherical equivalent (SE) increase of ≥0.50 D or when corneal thickness decreases by ≥5 % as progression of KC which justifies CXL. At the present time, many KC patients are diagnosed earlier and referred immediately to experts without long-term topographic or refractive history to support progression of KC. It is a common bias/dilemma of waiting for progression of KC and further functional deterioration versus CXL without a delay. Decisions should consider the high-risk groups where the progression may be fast or when even small progression may cause significant functional damage. This group includes KC patients younger than 20 years old, unilateral KC, and patients with CDVA of 6/12 or with very advanced KC in which functional vision is dependent upon use of scleral lenses. KC in steroid users may also advance faster. In these groups, clinical judgment per individual case should consider the risk of functional vision loss versus the risks of the CXL procedure.