Evaluation of rigid gas permeable lens fitting in keratoconic patients with optical coherence tomography

To assess fitting of rigid gas permeable (RGP) lenses in patients with keratoconus, using spectral domain optical coherence tomography (SD-OCT).

The study was conducted on 30 eyes of 30 keratoconic patients fitted with RGP lenses, namely Rose K2 lens. Biomicroscopic examination with and without RGP lens was done. Fluorescein pattern was examined to determine the fitting, if ideal (three-point light touch), steep (central fluorescein pooling) or flat (central heavy bearing touch). Post-lens tear film thickness was measured centrally and at the lens edges using SD-OCT. Patient's comfort was assessed and graded.

Mean central post-lens tear film thickness was 35.1 ± 7.3 μ in patients with ideal fitting. Mean post-lens tear film thickness of 50.4 ± 8.2 μ and 25.3 ± 6.1 μ was noted in patients with steep and flat fitting, respectively. Mean post-lens tear film thickness of 102.5 ± 12.1 μ, 85.4 ± 11.4 μ, 135.6 ± 13.3 μ was demonstrated in eyes with ideal, steep and flat edge lift, respectively. Tear film thickness under the edges was significantly (p=0.04) lower in patients unsatisfied with their contact lenses.

SD-OCT can image and measure the tear film thickness in keratoconic patients with different fitting patterns of RGP lenses. OCT- guided fitting can be used to evaluate and modify the lens parameters to increase patient satisfaction. Lens intolerance may be related to edge lift rather than central fitting.