![]() Zernike modes or pyramids are fundamental forms that show different distortions using polynomial equations. These basic components were expressed mathematically many years ago by Fritz Zernike (a Dutch physicist and nobel laureate for the invention of contrast-phase microscopy) which became known as the Zernike modes, which are arranged in a special pyramidal order ( 7). But since the results of the aberrometry have a complex and mixed form of aberration that is unclear to the physician, measurement aberrometry has to be broken down into basic components that usually have a simpler form and that the physician can make it easier to interpret and find a cure. For example, correcting them by prescribing glasses, or by prescribing lenses, or correcting by excimer laser or other methods. Now a clinician or refractive surgeon should be able to interpret and analyze the data obtained from the aberrometry to provide a therapeutic solution. It also device shows the aberrometry qualitatively with a map the green areas correspond to areas of the reference surface in the pupil range that do not deviate from the wavefront (the deviation from the wavefront is in the zero micron range) and the yellow and red zones are the zones of positive deviation and the blue and purple zones are the zones of negative deviation ( Figure 1C).Ī, the concept of abrasion in diagrams B, root mean sqare or RMS. The device reports the sum of statistics and because the numbers obtained may also be negative, the second power of them is added together, and then the second root of this sum (root mean sqare or rms) is reported as the determinant of the aberration ( Figure 1B). Because the wavefront values are quite variable compared to the reference level, they give different values for each wavefront ( 5, 6). When it is positive, the wave front is ahead of the reference level (such as myopia) and when the wavefront is behind the reference level (back), it has a negative sign (such as hyperopia). the value of the deviation of the wavefront from the reference surface is shown in micrometers. If there are aberration on the wavefront that is out of eye their light focus will shift from the center of these squares and the sensor will sense and measure them and will show the deviation of each point on the wavefront quantitatively in microns and qualitatively with the map. In the outgoing method, such as the Hartman shack, the infrared beam of laser light travels over the retina the reflex light that will be parallel to normally passes through the lenseset and then focuses on a sensor called a charged coupled device, the surface of the sensor contains several rows of squares, the center of each of which will be the focal point of the optical lens ( 4). In the incoming aberrometry method, such as ray tracing or Tscherning, the infrared light is trace on the retina it is then compared with a photodetector pointing point on the retina with a pointing point on the retina reference compared that has no aberration ( 1- 3). Introductionĭifferent methods are used for aberrometry which are divided into two groups: (1) outgoing, and (2) incoming. Zernike Modal Aberrometeric Analysis Wavefront 1. ![]() Some modes of high-order Zernike have sentences of low-order This can cause abnormal analysis. There are no strong clinical reasons for Zernike modes to be a fully accurate description of aberromerty, so clinicians should consider other clinical data and findings in their interpretation. When we say refractive surface, we do not mean a specific place like the cornea because other than the cornea other factors such as crystalline lens, vitreous, retin even tear layer they are involved in creating aberrations, but usually the pupil range is considered as the reference surface. Therefore, aberration is the creation of the distance of the wavefront in a certain phase from the refractive surface or reference surface. the wavefront is a two-dimensional surface perpendicular to a bunch of parallel light rays, that all these rays have the same phase on this surface (because light emits sinusoidally and therefore has multiple identical phases) whenever these rays pass through a refractive surface, it is also called the reference level this refractive index will be ideal if the homogeneity of these rays is maintained and the rays of this bunch of light will be able to focus at one point, but if the by passing light through the refractive surface the wavefront will be disturbed and the lights on this surface have different phases than the reference surface then it is said there is a discrepancy or deviation between the reference surface and the wavefront. One of the methods for studying optical systems is the aberrometry of wavefront. ![]()
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