Influence of contact lens wear on the corneal topography of keratoconus.

PURPOSE: Corneal videokeratography is frequently used to evaluate keratoconus patients, as it is believed to allow for a more thorough appreciation of the complex curvature changes associated with the anterior corneal surface. The goal of this study was to determine the qualitative and quantitative influence of soft and rigid contact lens wear on the corneal topography of keratoconus.

METHODS

205 keratoconus patients were analyzed by computerized videokeratography for both qualitative corneal topographic patterns and quantitative indices. Fifty-six patients were non-contact lens wearers, 130 wore polymethylmethacrylate (PMMA) or rigid gas permeable (RGP) contact lenses, and 19 wore soft contact lenses. Data from the keratoconus patients were also compared to a control group comprised of normal patients with no history of contact lens wear.

RESULTS

All three keratoconus groups had a significantly increased frequency of an asymmetric bowtie/skewed radial axes (AB/SRAX) pattern compared with normals. Differences among the videokeratography patterns for the kertoconus patients included a significant shift from the AB/SRAX videokeratographic pattern to the irregular videokeratographic pattern in the rigid (PMMA or RGP) lens subgroup as well as an increased frequency of the irregular pattern in the soft contact lens group versus the no contact lens group (P < 0.0001). Additional differences between the rigid contact lens and no contact lens keratoconus groups included increased values for the quantitative indices of SAI, SRI, SIM-K, and central K in the rigid contact lens group (P < 0.05).

CONCLUSIONS

The increased frequency of qualitative and quantitative corneal irregularity in the rigid contact lens keratoconus group may reflect a mechanical effect of contact lens wear or an advanced disease state in these patients limiting them to rigid lens wear. The advanced disease is evidenced by steeper SIM-K and Central K indices in the rigid contact lens group.