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Home |Glossary|Aberrometer


What is an Aberrometer?

An aberrometer is a diagnostic device that measures refractive aberrations of the eye. It is used in laser eye surgery to ensure high accuracy. What this device does is pass light through the eye and then measures that light as it exits the eye. This enables an ophthalmologist to measure wavefront - the change in the shape of the front of the light waves as they exit the cornea.

What a wavefront aberrometer does

A wavefront aberrometer measures every variation of the eye, from the cornea to the retina, helping eye care practitioners to diagnose and cure eye ailments. An aberrometer helps to quantify glare, halos, and night visual disturbances and help doctors screen patients whose vision may be compromised by these conditions. It also allows physicians to measure highly distorted eyes.

A wavefront aberrometer records data from several spots on the surface of the cornea, producing a map of imperfections there. Information from the aberrometer is used to provide customized laser eye surgery.

Other uses of wavefront aberrometry

Wavefront aberrometry is not only used to determine causes of visual disturbances, it is also utilized to program ablations in wavefront-guided procedures. Using wavefront aberrometry to conduct such procedures is becoming increasingly common, since they are much more effective than conventional methods. Wavefront aberrometers are also used therapeutically sometimes to correct spherical aberration in patients with night vision disturbance.

Types of aberrometers

Different aberrometers measure different numbers of spots, ranging from as low as 60 to as high as 650. Types of wavefront aberrometry include the Harmann-Shack principle, the Tscherning principle and Ray tracing. Most aberrometers are based on Hartmann-Shack wavefront sensors, which transform the light coming out of the eye into a set of spots ("data points") on the digital camera. The spots are created when microlenses focus the light onto a camera placed in the lenses' focal plane.

Tscherning aberrometers, on the other hand, measures light as it enters the eye. A Tscherning aberrometer shines a fine bundle of red laser beams into the eye. These beams form a pattern on the retina. As the beams traverse through the eye's optical system, they are bent or distorted by the optical aberrations in the lens and cornea. An image of the laser grid pattern on the retina is captured by a highly sensitive video camera and then analyzed.

Wavefront aberrometers have brought about sea change in the way eye ailments are treated. Now it is possible to diagnose eye problems early on and tackle them in a more efficient manner.