Auto Refraction & Auto Keratometry

Auto Refraction

  • Done to estimate the amount of far-sightedness or near-sightedness a patient has.
  • This instrument measures how light is reflected from the back of the eye to find the refraction that will give the clearest vision.

This is an estimate of the patient’s refraction or the amount of hyperopia, far-sightedness, myopia, near-sightedness, or astigmatism a patient has. The instrument measures how light is reflected from the retina at the back of the eye in order to determine the refraction.

As auto-refraction is not precise, it is necessary for the optometrist to do additional testing. With the patient’s assistance, the optometrist determines the final refraction which will give the patient the clearest vision.

Auto Keratometry

  • Measures the curvature of the eye by reflecting light on the front “window” of the eye.
  • This instrument allows professionals to determine the refraction, detection of eye diseases, and the fitting of contact lenses.

This is a measurement of the corneal curvature using light reflected from the cornea, the front “window” of the eye. Some corneas are steeply curved, others can be more flat, toric, or egg-shaped. Most commonly the vertical meridian is more steeply curved and the horizontal meridian more flat but other variations are possible.

Auto-keratometry gives information on the topography of the eye; this helps eye care professionals determine the refraction, fitting contact lenses as well as information about corneal diseases such as keratoconus.

*These tests are performed by a technician before seeing the optometrist, during your “Pre-Test”.

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