Elder Keshia S, Benjamin William J
University of Alabama at Birmingham School of Optometry, 1530 3rd Avenue South, Birmingham, AL 35294-0010, USA.
Optometry. 2009 Mar;80(3):131-7. doi: 10.1016/j.optm.2008.08.005.
With the disappearance of the radiuscope, alternative methods must be developed to accurately measure gas-permeable (GP) lenses. The purpose of this study was to design, manufacture, and test a novel attachment for the evaluation of spherical base curves of GP rigid contact lenses using a corneal topographer.
A topographer attachment was devised with the intent of measuring the surface radii of GP lenses. A front-surface mirror was fixed at a 45 degrees angle above a hemispherical GP lens mount taken from a radiuscope. The device was set in the chin rest of a Humphrey Atlas topographer (Carl Zeiss Meditec, Inc., Jena, Germany) such that the image from the back of a GP surface was focused. The base curve radii of 9 rigid polymer buttons nominally ranging from 5.00 mm to 9.00 mm in 0.5-mm steps were measured 3 times with a Neitz Auto CG (Neitz Instruments Co., Ltd., Tokyo, Japan), Reichert Radiuscope (Reichert Ophthalmic Instruments, Depew, New York), and Humphrey Atlas topographer using the base curve (BC) attachment.
An analysis of variance with replication and without interaction, using the main effects of measurement method (n = 5) and nominal button radius (n = 9), found that there was no statistically significant effect of the base curve measurement method (F[4, 122] = 1.23; P = 0.303), although there was a statistically significant effect of nominal button radius (F[8, 122] = 4.70; P = 0.003).
Although the optical system of the corneal topographer was designed for measurement of convex surfaces, measurement of base curve radii from concave surfaces was performed without a correction factor using the prototype attachment. The mean SimK and Axial radii were within the tolerance for GP base curve radius, 0.05 mm, cited in ANSI Z80.20-2004 and ISO 18369-2:2006. Thus, the clinical feasibility of this prototype BC attachment to support measurement of spherical base curve radii for GP lenses by a corneal topographer was demonstrated.
随着弧度计的消失，必须开发替代方法来精确测量透气性（GP）镜片。本研究的目的是设计、制造并测试一种新型附件，用于使用角膜地形图仪评估GP硬性接触镜的球面基弧。
设计了一种地形图仪附件，用于测量GP镜片的表面半径。一个前表面镜以45度角固定在从弧度计取下的半球形GP镜片座上方。该装置安装在汉弗莱阿特拉斯角膜地形图仪（德国耶拿卡尔蔡司医疗技术公司）的颏托中，以便聚焦GP镜片表面背面的图像。使用Neitz Auto CG（日本东京Neitz仪器有限公司）、Reichert Radiuscope（纽约迪皮尤Reichert眼科仪器公司）和汉弗莱阿特拉斯角膜地形图仪，通过基弧（BC）附件，对9个标称半径从5.00毫米到9.00毫米、步长为0.5毫米的刚性聚合物纽扣的基弧半径进行了3次测量。
采用测量方法（n = 5）和标称纽扣半径（n = 9）的主效应，进行有重复且无交互作用的方差分析，结果发现基弧测量方法没有统计学显著效应（F[4, 122] = 1.23；P = 0.303），尽管标称纽扣半径有统计学显著效应（F[8, 122] = 4.70；P = 0.003）。
虽然角膜地形图仪的光学系统是为测量凸面而设计的，但使用原型附件在不使用校正因子的情况下对凹面的基弧半径进行了测量。平均SimK和轴向半径在ANSI Z80.20 - 2004和ISO 18369 - 2:2006中引用的GP基弧半径公差0.05毫米范围内。因此，证明了这种原型BC附件在支持角膜地形图仪测量GP镜片球面基弧半径方面的临床可行性。
