[Correlation intervals between the power values of artificial lenses deduced from theoretical formulae and regression formulae].
We give a precise theoretical formula used to calculate the power of implants. A spatial representation is shown. It exhibits Dc (power of the cornea) and l (axial length) values which induce a good fit between the power of artificial lens deduced from theoretical and statistical (S.R.K.) formulae. These values are situated on a look like parabolic curve (C) centered on a 26.13 mm or 27.2 mm l value according to anterior or posterior implants. We show the existence of area of (Dc, l) points giving a fit between theory and statistic within a given uncertainty delta DI. This fit is depicted on a chart (Dc, l, delta DI) on which the different curves which correspond to various delta DI, are deduced from the curve of equal power (C) by single translations. We indicate that an uncertainty near 1 dioptre on the power of the cornea induces a deviation near 0.21 dioptre on the powers of the anterior implant when calculated using the two methods. Moreover, we establish that the power SRK is always higher than the theoretical power for axial lengths situated in the 24 to 28.5 mm range.
Petrakian
J P
JP
Laboratoire de Physique Générale, Faculté des Sciences et Techniques, Marseille.
D006801:Humans; D007910:Lenses, Intraocular; D008433:Mathematics; D012044:Regression Analysis
Espace de corrélation entre les valeurs de puissance de cristallins artificiels déduites de formules théoriques et de formules de régression.