Vector analysis of cross cylinder LASIK with the NIDEK EC-5000 excimer laser for high astigmatism

J Refract Surg. 2009 Dec;25(12):1075-82. doi: 10.3928/1081597X-20091117-06.

Abstract

Purpose: To evaluate visual outcomes of LASIK in eyes with high astigmatic refractive errors with low spherical component.

Methods: We prospectively evaluated cross cylinder LASIK in patients with high astigmatic eyes with low spherical component over a 2-year period. All laser surgeries were performed with the NIDEK EC-5000 excimer laser. We used power vectors (M [spherical equivalent] and J(0), and J(45) [cylinder]) to analyze the astigmatic results. Main outcome measures were uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), manifest refraction, and complications.

Results: Thirty-four eyes of 22 patients were included. Patients were followed for 21.8+/-3.7 months. At the last examination, UCVA of 20/40 or better was observed in 33 (97.1%) eyes. Best spectacle-corrected visual acuity after LASIK improved significantly in comparison to BSCVA before surgery (P<.005). Mean preoperative cylinder was -4.73+/-0.89 diopters (D) (range: -4.00 to -7.00 D), which decreased to -0.29+/-0.47 D (range: 0.00 to -1.50 D) at last follow-up (P<.001). Reduction in the magnitude of power vectors was 92.4% for M, 103.2% for J(0), and 76.4% for J(45). No cases of post-operative astigmatic regression or corneal haze were observed.

Conclusions: Cross cylinder LASIK with the NIDEK EC-5000 excimer laser is a successful procedure for correcting high astigmatism and improving vision.

MeSH terms

  • Adult
  • Astigmatism / physiopathology
  • Astigmatism / surgery*
  • Follow-Up Studies
  • Humans
  • Keratomileusis, Laser In Situ*
  • Lasers, Excimer / therapeutic use*
  • Patient Satisfaction
  • Prospective Studies
  • Refraction, Ocular / physiology
  • Reoperation
  • Visual Acuity / physiology*