Options for a young patient with considerably high, topographically stable, astigmatism: December consultation #1

Abstract

A 21-year-old woman was referred for a refractive surgery evaluation. She has no relevant allergies or medical or family history of keratoconus or corneal transplantation. Spectacle dependence is her chief complaint. She occasionally wears contact lenses but wants to have surgery performed. The corrected near visual acuity and the corrected distance visual acuity (CDVA) are 20/20 in both eyes. The manifest refraction is 5.75 3.25 178 in the right eye and 5.00 3.50 170 in the left eye. The intraocular pressure and the results from a slitlamp examination and a fundus retinoscopy are normal. The ultrasound pachymetry shows the central corneal thickness (CCT) to be 505 mm in the right eye and 508 mm in the left eye. Among all devices used tomeasure the CCT, the thinnest measured point is 504 mm in the right eye and 503 mm in the left eye. Placido-disk corneal topography shows a high regular symmetric astigmatism that was stable over 1 year of follow up, with an insignificant change in keratometry (K) values (Figure 1). The 5 topographies were obtained at 3-month intervals. Scheimpflug and dual Scheimpflug tomography (Figures 2, 3, and 4) are normal with no suspicious pattern except a high regular astigmatism. The pachymetry maps show corneas that, although slightly thin, are within normal limits across the diameter. An excimer laser system predicts a stromal ablation of approximately 127 mm in the right eye and 121 mm in the left eye. For laser in situ keratomileusis (LASIK) with a 110 mm flap thickness, the percentage of tissue altered (PTA) would be 47% in the right eye and 46% in the left eye. The residual stromal bed (RSB) would be 267 mm in the right eye and 272 mm in the left eye. For photorefractive keratectomy (PRK), the PTA would be 25% in the right eye and 24% in the left. What kind of refractive surgery (if any) would you recommend to this patient? If none, why? Would you consider LASIK with a thin, predictable LASIK flap? What data helped you most in making your decision? Did the stability shown by the Placido disk–based corneal topography over 1 year significantly affect your surgery decision?What are your limits for treating a cornea with high regular symmetric astigmatism? If you recommend proceeding with surgery, was age a significant factor in that decision?