A multifocal lens effect as a complication of radial keratotomy.

A corneal topography analysis system evaluated a patient who after bilateral radial keratotomy complained of disabling visual distortion in each eye even when spectacle correction improved vision to 20/20. The patient showed an excellent spectacle corrected Snellen visual acuity over an extended refractive range, the so-called 'multifocal lens effect.' Topography analysis showed a highly irregular surface in each eye with a central area of corneal flattening with power below 30 diopters. Between the central island of low power and the most peripheral extent of the cornea analyzed, corneal power increased by more than 15 diopters in some hemimeridians. The findings in this case suggest that some patients with a 'multifocal lens effect' and good Snellen visual acuity after radial keratotomy have enough corneal surface distortion and image degradation to properly describe the phenomenon as a complication of surgery.