March 2012
Volume 53, Issue 14
ARVO Annual Meeting Abstract  |   March 2012
Preliminary Results of Intrastromal Femtosecond Astigmatic Keratotomy
Author Affiliations & Notes
  • Julie M. Schallhorn
    Ophthalmology, UCSF, San Francisco, California
  • Jan Venter
    Ophthalmology, Optical Express, San Diego, California
  • Steven C. Schallhorn
    Ophthalmology, UCSF, San Francisco, California
    Ophthalmology, Optical Express, San Diego, California
  • Footnotes
    Commercial Relationships  Julie M. Schallhorn, None; Jan Venter, Optical Express (F); Steven C. Schallhorn, AMO (C), Optical Express (F)
  • Footnotes
    Support  None
Investigative Ophthalmology & Visual Science March 2012, Vol.53, 1504. doi:
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    • Get Citation

      Julie M. Schallhorn, Jan Venter, Steven C. Schallhorn; Preliminary Results of Intrastromal Femtosecond Astigmatic Keratotomy. Invest. Ophthalmol. Vis. Sci. 2012;53(14):1504.

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      © ARVO (1962-2015); The Authors (2016-present)

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Purpose: : To describe a new technique for the treatment of astigmatism using the femtosecond laser to perform intrastromal astigmatic keratotomy.

Methods: : 110 eyes of 93 patients with astigmatism post cataract surgery had intrastromal femtosecond astigmatic keratotomy (IFAK) performed to improve their uncorrected visual acuity. Arcuate intrastromal incisions were made with a 150KHz femtosecond laser from 60 microns below the anterior surface to 80% corneal depth. The initial nomogram varied the arc length of the incision according to the amount of attempted cylinder correction. Patients were examined and refracted at 1 week, 1 month, and 3 months postoperative.

Results: : The preoperative mean manifest spherical equivalent (MSE) of -0.06D +/- 0.42 (range -1.50 to +0.88) did not change after surgery, with a 3 month postoperative mean MSE of -0.02D +/- 0.44(range -1.38 to +1.25). The mean preoperative astigmatism of -1.28D +/- 0.59 (range -3.50 to -0.50) was reduced to -0.60D +/- 0.53 (range -2.75 to 0.00) at 3 months postoperative. Sixty percent of eyes had <= 0.50D of cylinder at 3 months postoperative, as compared to 6% before surgery. The uncorrected distance visual acuity was 20/20 or better in 53% of eyes at 3 months as compared to 17% before surgery. The vector analyzed correction ratio (surgically induced refractive correction (SIRC) divided by the intended refractive change (IRC)) was 0.78, indicating an overall under-correction. The cylindrical refraction was stable from 1 week to 3 months postop with a mean cylinder of -0.62 and -0.63D at the 1 week and 3 month examination, respectively.

Conclusions: : Intrastromal femtosecond astigmatic keratotomy can safely and effectively reduce moderate amounts of astigmatism and improve uncorrected distance acuity. Undercorrection of astigmatism indicates a need for nomogram refinement.

Keywords: refractive surgery • astigmatism • cornea: clinical science 

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