Contact Lens Fitting in Patients with Keratoconus - A Retrospective Assessment of 200 Patients.

Abstract

Nowadays, keratoconus (KC) is very well treatable in a stage-oriented manner. A wide range of designs and materials of contact lenses (CL) are available for the treatment of KC. The aim of this study was to evaluate the possibilities, the possible challenges and the visual outcome of lens fitting in KC eyes. This retrospective study includes data from 200 patients who received a lens fitting trial in our contact lens service between 2006 and 2016. We documented ophthalmological parameters, the type of prescribed CL, the number of required trial lenses and possible causes of the failure of the lens fitting. The mean age at initial lens fitting was 33.9 ± 12.5 years. In 98.8% of the cases, the fitting was performed with rigid gas permeable lenses, in 90.1% with four-curve lenses. Of the total number of aspheric lenses prescribed, 87.5% were fitted in keratoconus stages "1" to "2" (topographic keratoconus classification; Oculus Keratograph). Back surface toric lenses or bitoric lenses were fitted to 61.7% in keratoconus stages "2 - 3" to "4". Before patients received their final CL, a median of 2 trial lenses were required (max. 16). Mean visual acuity with lens correction was 0.8 ± 0.2 at the initial fitting, mean visual acuity with glasses correction was 0.5 ± 0.3. In 7.7% of the eyes, the KC lens fitting was discontinued due to the advanced stage of keratoconus, requiring a corneal transplant. Reasons for discontinuing contact lens fitting included lens intolerance (2.3%), application problems (0.3%) or acute corneal hydrops (0.3%). Discontinuation of lens wearing due to incompatibilities or application problems occurred in only four cases (1.1%) in the further course after lens fitting. The use of contact lenses is an integral part of the stage-appropriate therapy of keratoconus. Good visual acuity can be achieved in all stages of keratoconus with a low drop-out rate. In most cases, the adjustment is carried out with rigid gas permeable lenses with a four-curve geometry. In initial stages, aspherical lenses may be sufficient. Toric lenses can be fitted in advanced stages when rotationally symmetrical lenses cannot achieve a satisfactory fit. If contact lenses have been successfully fitted, there are only a few cases in which patients abandon their contact lenses because of intolerance.