Contact lens fitting in keratoconus

Keratoconus is a progressive, bilateral but typically asymmetric, non-inflammatory ectasia of the cornea of undetermined etiology characterized by central corneal stromal thinning, apical protrusion, irregular astigmatism, and variable degrees of scarring. Beginning at puberty in most cases, the disease has a highly variable course in which periods of relative stability are interspersed with episodes of progression. The modes of visual correction in keratoconus vary depending on the stage of the disease. In the very earliest stages, most patients are corrected with myopic, astigmatic spectacles. However, with progression of the disease and distortion of the corneal surface, spectacle correction may no longer suffice, and contact lenses become the primary method of visual rehabilitation. For most patients with keratoconus, contact lens correction becomes the dominant therapeutic mode for the course of their disease. When corneal curvature becomes too steep for lenses to be fit with stability or comfort, or when central scarring no longer permits good central acuity even with an adequate lensfit, opthalmologists turn to some form of surgical therapy for the disease. Surgical treatment may include flattening the apex of the cone by thermal or electrocautery, epikeratoplasty, or, most commonly, keratoplasty. Approximately 10-20% of keratoconus patients come to keratoplasty. In this review, we will discuss past and current approaches to the contact lens correction of keratoconus.