WAVEFRONT... What is WAVEFRONT?

In addition to standard visual errors, Bausch & Lomb's "new" WAVEFRONT also measures and treats small vision errors (higher order aberrations) that scatter light in a pattern that is unique to you. These are evident in dim light where a point of light is seen as scattered. Thes could cause shading to be seen around one edge of a perfectly round light, and they are certainly an important cause of poor quality night vision. About 70% of people with these vision problems could benefit from WAVEFRONT treatment.

Principles of high-resolution Shack-Hartmann Sensor in the WAVEFRONT Analyzer:

• A low-power, invisible, plane laser-wave is directed into the eye.
• It is focused on the retina by the refractive power of the cornea and the lens.
• The retina absorbs part of this light, the other part is reflected and goes back through the optical media of the eye.
• The optical aberrations along the light path within the eye lead to distortions of the wavefront exiting the eye.
• The distorted wavefront hits the Shack-Hartmann Sensor consisting of an array of 1,500 micro-lenses and a low-light CCD sensor in the focal plane of the lenses.
• The deviations of all spots from their regular positions (in reference to an incident wave) are measured and from these values the optical aberrations are computed in the form of Zernike polynomials.

Advantages:

• High resolution
• High accuracy and reproducibility
• Fast measuring & analysis
• Wide dynamic range
• High resolution data need powerful software and hardware tools for evaluation of aberrations 

Disadvantages:
Wavefront may not be suitable for all patients.  In order to determine if you are a good candidate for the wavefront treatment, come in for a pre-operative evaluation at our Clinic.


Tscherning Aberrometry 

Tscherning Aberrometry analyzes the ingoing light, which forms an image on the retina. A grid pattern formed by multiple spots is projected through the optical system of the eye and forms an image on the retina. This image is observed and evaluated by a method similar to indirect ophthalmoscopy and captured on CCD camera. The distortion of the grid pattern enables calculation of the aberrations of the optical system of the eye.

their regular positions are measured and  from these values the optical aberrations are computed in

• Principles of Tscherning Aberrometry:

  • A collimated laser beam illuminates a mask with a regular matrix of 168 pinholes to form a bundle of thin parallel rays
  • These rays form a spot pattern on the retina that is more or less distorted according to the optical errors of the eye
  • This retinal spot pattern is imaged onto the sensor of a low light CCD camera by indirect ophthalmoscopy
  • The deviations of all spots from  the form of Zernike polynomials

Advantages:

• Fast measuring

Disadvantages:

• Time-consuming set-up
• Time-consuming analysis
• Low resolution
• Diffraction of the laser radiation at the small pin holes disturbs the result
• Complicated mechanical and optical arrangement
• Patient disturbed by visible flash (green, 532 nm)
  

OVERVIEW

The images received by the Bausch & Lomb WAVEFRONT Workstation are of superior quality and provide a much better wavefront image, thanks to the higher resolution and greater number of data points measured. This allows the surgeon a better idea of attainable post-operative visual acuity.  Although the Tscherning is fast measuring, it is still lower resolution and time consuming.