Evaluation of Soft Contact Lens Power Effects on the Piggyback Lens System in a Keratoconic Population

Title

Evaluation of Soft Contact Lens Power Effects on the Piggyback Lens System in a Keratoconic Population

Author

Catarina M. Jang, O.D.

Purpose

This study sought to investigate the relationship between different soft contact lens powers (+6.00D, +0.50D and-6.00D) and its effect on the total effective power of the piggyback lens system (PBLS). The change in best corrected visual acuity was also studied between the rigid lens regimen and piggyback lens regimen.

Method

Thirteen subjects diagnosed with keratoconus wearing a habitual right gas permeable lens (RGP) were identified. Visual acuity and over-refraction measurements of the habitual RGP lens and in each of the three PBLS cases were recorded.

Results

The results of this investigation indicate no statistical significant effect of the soft contact lens power on the total effective power of the PBLS. As well, no statistical significance was observed in visual acuity improvement from RGP lens wear when compared to PBLS wear, although there was a suggestion of improvement in 38% of our subjects.

Conclusion

This preliminary investigation probes the optical properties of the PBLS and further supports the use of piggyback lenses to correct for keratoconus-induced irregular astigmatism and refractive error in RGP lens intolerant patients.