BACKGROUND: Many corneal transplants result in significant astigmatism and corneal irregularities. As such, a gas permeable (GP) lens is needed to in order to obtain adequate vision. Of the different GP designs, the X-Cone reverse geometry lens may be considered. While the central optic zone of this design is fully vaulted to mask any irregular astigmatism and to prevent mechanical contact of the donor graft, centration and stability are maximized via the steeper secondary curve.
CASE REPORT(S): A 29 year old African American female diagnosed with bilateral keratoconus underwent penetrating keratoplasty (PKP) in 1999 presented with an unknown GP lens in the left eye. Biomicroscopy revealed corneal grafts of approximately 8mm in both eyes. She had a history of prior graft rejection in the right eye and reported being fitted unsuccessfully with various GP lenses since 10 years ago.
Corneal topography measurements revealed simulated keratometry values of 57.37@098/50.00@008 for the right eye and 46.75@090/44.87@180 for the left eye, and corneal irregularity measurements of larger than 1.1μm for both eyes. She was successfully fitted with X-Cone reverse geometry GP lens with the following parameters in the right eye: 5.82mm base curve, 5.70mm secondary curve, -19.50 sphere back vertex power and 10.50mm overall diameter, and in the left eye: 6.25mm base curve, 6.15mm secondary curve, -9.25 sphere back vertex power and 10.50mm overall diameter. Optimal fit with excellent comfort, stability and visual acuities of 20/25 were achieved in both eyes.
CONCLUSIONS: Visual debilitation due to corneal graft irregularities can significantly decrease overall quality of life for the patient. With great vision, comfort and fit, the X-Cone reverse geometry lens can be effective for those post-PKP patients whose visual goals are not met.