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K. Scholz, A. Langenbucher; Topography-Based Assessment of Corneal Asphericity for Planning of Aspherical IOLs. Invest. Ophthalmol. Vis. Sci. 2007;48(13):3533.
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© ARVO (1962-2015); The Authors (2016-present)
In the last decade a series of aspherical intraocular lenses were launched to the market for improvement of retinal image quality. The exact shape of the cornea including curvature and corneal asphericity (CA) is required for an adequate correction of the pseudophakic eye with an aspherical lens. The purpose of the study was to assess CA and to study the influencing factors.
A sequence of 3 topographic measurements (EyeSys Vista topographer/VFA Tracey, EyeSys Vision Inc., Texas) were taken under standardized conditions from 493 eyes of 248 individuals (age 17 to 81, 45.12±17.1 years) and included consecutively in this cross-sectional study. Patient’s eyes were grouped for age (up to 29 years (I), 30 to 39 years (II), 40 to 49 years (III), 50 to 59 years (IV), 60 to 69 years (V) and 70 years and older (VI)), sex (205 male/288 female) or refraction (165 myopic (mean SE -2.60±1.97 D, range +0.5 to +6.50 D) and 162 emmetropic).
Mean CA of the anterior corneal surface ranged in between -0.47 and 0.36 (-0.10±0.09). In the subgroups mean CA was -0.09±0.08/ -0.13±0.08/ -0.09±0.10/ -0.11±0.11/ -0.08±0.12/ -0.09±0.11 in I/II/III/IV/V/VI; -0.11±0.10/ -0.09±0.10 in male/female and -0.08±0.10/ -0.11±0.09/ -0.11±0.11 in hyperopic/emmetropic/myopic. No significant correlation could be found between CA and age. CA did not differ significantly between age groups. However, CA differed significantly between male and female (p=0.004) and between hyperopic and emmetropic/myopic eyes (p<0.0001/ <0.0001), but not between emmetropic and myopic eyes (p=0.850).
In general aspherical intraocular lenses are optimized on a model eye with a spherical or aspherical cornea. Our findings demonstrate a high amount of interindividual variations of CA. Thus the proper correction of spherical aberrations in pseudophakic eyes requires the selection of suitable aspherical intraocular lenses based on biometric data and the individual CA.
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