Navarro Rafael, González Luis, Hernández-Matamoros Jos L
ICMA, Consejo Superior de Investigaciones Cientificas, Universidad de Zaragoza, Zaragoza, Spain.
Optom Vis Sci. 2006 Jun;83(6):371-81. doi: 10.1097/01.opx.0000221399.50864.c7.
The purpose of this study is to develop and analyze a method to obtain optical schematic models of individual eyes. Each model should be able to reproduce the measured monochromatic wave aberration with high fidelity.
First, we choose a generic eye model as the input guess and then apply a two-stage customization procedure. Stage 1 consists of replacing, in the initial generic model, those anatomic and optical parameters with experimental data measured on the eye under analysis. The set of experimental data was that provided by a standard clinical preoperative examination, namely lens topography, ultrasound biometry, and total wave aberration. Then, the second stage is to find the unknown lens structure that would reproduce the measured wave aberration through optical optimization. Two totally different initial eye models have been compared; one considers a simpler constant refractive index for the lens, whereas the second model has a gradient-index (GRIN) lens.
This automatic customization method has been applied to 19 eyes with different degrees of spherical ametropia (from +0.4 D to -8 D). Two models have been obtained for each eye (constant and gradient index lens). The results were highly satisfactory, with 100% convergence, and with average RMS prediction errors approximately lambda/100. This is one order of magnitude lower than typical measurement errors. The models with a constant refractive index lens tended to overestimate surface curvatures, whereas for the GRIN model, lens surfaces were too flat.
The proposed method is highly efficient and robust giving a high-fidelity reproduction of the wavefront in all cases attempted so far. Limitations found in reproducing the geometry of the lens seem to be associated with the use of inaccurate models of its refractive index.
本研究的目的是开发并分析一种获取个体眼睛光学示意图模型的方法。每个模型都应能够高保真地再现测量得到的单色波像差。
首先，我们选择一个通用眼睛模型作为输入猜测，然后应用两阶段定制程序。第一阶段包括在初始通用模型中，用在被分析眼睛上测量得到的实验数据替换那些解剖学和光学参数。实验数据集是由标准临床术前检查提供的，即晶状体地形图、超声生物测量法和全波像差。然后，第二阶段是通过光学优化找到能够再现测量得到的波像差的未知晶状体结构。比较了两种完全不同的初始眼睛模型；一种模型考虑晶状体具有更简单的恒定折射率，而第二种模型具有渐变折射率（GRIN）晶状体。
这种自动定制方法已应用于19只具有不同程度球面屈光不正（从 +0.4 D到 -8 D）的眼睛。每只眼睛都获得了两种模型（恒定折射率和渐变折射率晶状体）。结果非常令人满意，收敛率为100%，平均均方根预测误差约为λ/100。这比典型测量误差低一个数量级。具有恒定折射率晶状体的模型往往高估表面曲率，而对于GRIN模型，晶状体表面过于平坦。
所提出的方法高效且稳健，在迄今为止尝试的所有情况下都能高保真地再现波前。在再现晶状体几何形状时发现的局限性似乎与使用不准确的折射率模型有关。
