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M. van der Mooren, H. Weeber, P. Piers; Verification of the Average Cornea Eye ACE Model . Invest. Ophthalmol. Vis. Sci. 2006;47(13):309.
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© ARVO (1962-2015); The Authors (2016-present)
To verify the validity of the ACE model used for assessing the image quality of intraocular lenses.
Modulation Transfer Function (MTF) measurement in a physical eye model is a well–known and useful tool to assess the image quality of intraocular lenses. The best known example is the ISO eye model which is essentially aberration–free. However, corneas of a normal population of pseudophakic eyes exhibit positive spherical aberration. Two different ACE models were developed simulating the average refractive power and average spherical aberration of the human aphakic eye. MTF measurements of intraocular lenses in the ACE model were compared to clinical data.
Five studies found independently that the average corneal spherical aberration is approximately 0.285µm for a 6mm pupil. Based on this value, many different eye models could be designed and built. The ACE model is essentially the same as the ISO eye model, only the aberration–free cornea of the ISO model is replaced with a lathe–cut, convex–plano PMMA lens. The convex side has an aspheric surface yielding the average amount of corneal spherical aberration. Another possibility for the artificial cornea is a spherical, equi–biconvex BK7 lens. Because the standard glass manufacturing process is used, stability and surface optical quality can be improved. The BK7 lens is designed such that the same speed and amount of spherical aberration were obtained. Although higher–order aberrations are absent in the ACE model, MTF measurements can be related to clinical results of spherical lenses and aspherical lenses correcting the average corneal spherical aberration.
The validity of the ACE model is verified, based on the corneal clinical data. The MTF results of intraocular lenses in the ACE model in relation with obtained clinical results are also supportive of the validity of this model. Another possibility is to use an equi–biconvex BK7 glass lens with spherical curvatures as an artificial cornea in the ACE model instead of an aspherical, lathe–cut PMMA lens.
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