Turner Jennifer M, Le Chi Hieu, Murphy Paul J
Cardiff University, School of Optometry and Vision Sciences, Maindy Road, Cardiff, CF24 4HQ, UK.
University of Greenwich, School of Engineering, Central Avenue, Medway, ME4 4TB, UK.
Heliyon. 2025 Feb 10;11(4):e42601. doi: 10.1016/j.heliyon.2025.e42601. eCollection 2025 Feb 28.
To develop a method for accurate 3-dimensional (3D) representation of the anterior ocular surface (AOS) based on ocular impression and reverse engineering of an AOS plaster biomodel.
An AOS plaster biomodel was fabricated using ocular impression and a developed casting support device (CSD) and landmark registration element (LRE) to stabilise and consistently fix the impression casting tray within the casting support during the casting process. The touch-trigger probe on a co-ordinate measurement machine (CMM) digitised the AOS plaster biomodel to represent the AOS shape. The CSD and LRE were manufactured using an Additive Manufacturing selective laser sintering (SLS) process. A single stainless-steel ball (diameter: 22 mm) was cast as a surrogate AOS biomodel using polyvinylsiloxane impression material. The surrogate biomodel which was used to evaluate material selection and stability of the AOS biomodels fabricated using the CSD and LRE, and to evaluate repeatability and reproducibility of the point cloud data collection methods. The points of circular profiles were measured at different Z values in mm: z = -1 mm, z = -2 mm, z = - 3 mm, z = -4 mm and z = -5 mm.
The measurements were highly repeatable with an acceptable tolerance. For the typical case of the surrogate AOS biomodel, the average distance of the digitised points to the best-fit sphere of all the digitised points from four measurements ranges from 0.002 to 0.010 mm. The shrinkage study of the surrogate AOS biomodels was conducted, with measurements taken one month apart for comparison. The analysis results showed that most of the surrogate AOS biomodels reduced in size but within an acceptable tolerance, in which the mean error is from 0.005 to 0.010 mm for the 2D circular profiles measured at Z = -4 mm.
The Cardiff Eye Shape Analysis Protocol (CESAP) provides a repeatable and consistent method for producing solid, white-plaster, representations of a plaster cast AOS biomodel. Casting an impression in white plaster (Novadur™) produces a consistent surrogate AOS biomodel of a single stainless-steel 22 mm diameter ball. CESAP can be used as a framework for consistently converting an ocular impression into a 'real' AOS model that can be reverse-engineered to create 3D CAD models of the AOS shape for potential applications in optical image (topographer) calibration, prosthetic shell and scleral lens design, and AOS database development.
基于眼印模和眼前节（AOS）石膏生物模型的逆向工程，开发一种准确的眼前节三维（3D）呈现方法。
使用眼印模和开发的铸型支撑装置（CSD）及地标注册元件（LRE）制作AOS石膏生物模型，以便在铸造过程中稳定并始终如一地将印模铸造托盘固定在铸型支撑内。坐标测量机（CMM）上的接触式触发探头对AOS石膏生物模型进行数字化处理，以呈现AOS形状。CSD和LRE采用增材制造选择性激光烧结（SLS）工艺制造。使用聚乙烯基硅氧烷印模材料铸造单个不锈钢球（直径：22 mm）作为替代AOS生物模型。该替代生物模型用于评估使用CSD和LRE制造的AOS生物模型的材料选择和稳定性，以及评估点云数据采集方法的可重复性和再现性。在不同的Z值（单位为mm）下测量圆形轮廓的点：z = -1 mm、z = -2 mm、z = -3 mm、z = -4 mm和z = -5 mm。
测量具有高度可重复性且公差可接受。对于替代AOS生物模型的典型情况，四次测量中数字化点到所有数字化点最佳拟合球的平均距离在0.002至0.010 mm之间。对替代AOS生物模型进行了收缩研究，相隔一个月进行测量以作比较。分析结果表明，大多数替代AOS生物模型尺寸减小，但在可接受的公差范围内，其中在Z = -4 mm处测量的二维圆形轮廓平均误差为0.005至0.010 mm。
加的夫眼形分析方案（CESAP）提供了一种可重复且一致的方法，用于制作石膏铸型AOS生物模型的实心白色石膏模型。用白色石膏（Novadur™）浇铸印模可制作出直径22 mm的单个不锈钢球的一致替代AOS生物模型。CESAP可作为一个框架，用于将眼印模一致地转换为“真实”的AOS模型，该模型可进行逆向工程以创建AOS形状的3D CAD模型，用于光学图像（地形图仪）校准、假体外壳和巩膜镜设计以及AOS数据库开发等潜在应用。
