Comparison of Autokeratometry and Manual Keratometry

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Comparison of Autokeratometry andManual
Keratometry
The authors have no financial interest in the
subject matter of this poster

• Dr. A. Braganza,
• M.K. Kummelil, A. Shetty
• Narayana Nethralaya, Bangalore, India

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Incidence of Astigmatism

• 15 to 25 of the cataract patients have a
  pre-existing astigmatism of 1.50 D or more
• 9-12 have a pre-existing astigmatism of 2.00 D
  or more
• Less than 1 have a pre-existing astigmatism of
  more than 3 D
• Commonest cause of poor post-op UCVA are residual
  spherical error uncorrected pre-existing
  astigmatism

• Biometry of 7,500 cataractous eyes. Hoffer KJ.
  AmJ Ophthalmol, 1980 90360368 correction,
  890
• Prevalence of corneal astigmatism before cataract
  surgery, Ferrer-Blasco T, Montés-Micó R,
  Peixoto-de-Matos SC, González-Méijome JM, Cerviño
  A. JCRS June2009,

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Purpose

• To compare the keratometry values obtained by
  autokeratometry against those obtained by manual
  keratometry for accuracy and consistency.
• With the advent of toric IOLs and toric
  refractive IOLs to correct astigmatism we felt
  the need to see which was the more valid method
  for pre-operative assessment of patients

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Materials and methods

• Patients meeting inclusion and exclusion criteria
  for intraocular lens implantation were included
  in the study after signing the informed consent
• 100 eyes of patients posted for cataract surgery
  underwent keratometry using a hand-held
  autokeratometer (NIDEK) and a manual keratometer
  (Bausch and Lomb) using a standardized protocol.
• Repeat measurements were taken 5 minutes later to
  check for consistency.

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Materials and methods

• All patients underwent routine phacoemulsification
  through a clear corneal incision.
• Manifest refraction was performed at 6 weeks post
  op and the post operative refraction was analysed
  to assess the accuracy of the k readings
  obtained by the 2 instruments.

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Results
Manual Automated T-test
Steep K 44.09 1.22 44.18 1.32 0.74
Flat K 43.43 1.28 43.52 1.35 0.74
Mean K 43.76 1.23 43.85 1.31 0.74
Correlation coefficient 0.97 0.99
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Conclusion

• There was no statistical difference between
  Manual and Automated Keratometry values
• The repeatability of the tests was good when
  performed in a standardized fashion (correlation
  coefficient0.97 0.99)
• Steep axis of the post-operative K by both
  techniques correlated well with the refractive
  cylinder. (correlation coefficient0.98 0.98)

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