One of the most common visual side effects of Post LASIK patients is halo’s and ghosting which is more pronounced during low light levels. These visual disturbances are called higher order aberrations (HOA). In the opinion of contact lens fitters, many patients find relief of the higher order aberrations and improvement of their visual acuity when they wear Rigid Gas Permeable (RGP) lens fitted over the Laser treated corneal area.
I recently read this research paper titled ‘Changes in wave-front aberrations after rigid gas permeable contact lens fitting in post-laser in situ keratomileusis patients with visual complaints’ published in Can J Ophthalmol. 2010 Jun;45(3):264-8.
The authors were Tan G, Yang J, Chen X, He H, Zhong X
To evaluate the effect of rigid gas permeable (RGP) contact lenses in reducing wave-front aberrations in post-laser in situ keratomileusis (LASIK) myopic patients.
Cross-sectional study.Participants: Thirty patients with visual complaints after conventional LASIK procedure for correcting myopia.
The 30 patients were fitted with RGP contact lenses. Wave-front measurements were taken before and after RGP contact lens wearing.
Compared with bare eye examinations, root mean-square values of higher-order aberrations (HOAs) significantly decreased with RGP contact lens use. Among these, spherical aberration decreased from 0.507 (SD 0.304) microm to 0.164 (SD 0.121) microm (t = 7.186, p < 0.001); coma decreased from 0.470 (SD 0.312) microm to 0.165 (SD 0.090) microm (t = 5.566, p < 0.001); secondary coma decreased from 0.079 (SD 0.050) microm to 0.044 (SD 0.027) m (t = 4.118, p < 0.001); and total HOAs decreased from 0.782 (SD 0.449) microm to 0.307 (SD 0.140) microm (t = 6.710, p < 0.001).
Fitting RGP contact lenses effectively decreased higher-order aberrations HOAs induced by conventional myopic LASIK surgery. Possible reasons may be the elimination of irregularity and dissymmetry on the corneal anterior surface, relief of the aspherical extent of the central corneal surface, and enlargement of the effective optical zone.