Coleman A L, Haller J A, Quigley H A
Department of Ophthalmology, UCLA School of Medicine, USA.
J Glaucoma. 1996 Dec;5(6):433-5.
The purpose of this research was to study the accuracy of measurements that rely on Littmann curves to determine the real size of fundus images.
Retinal tacks of known dimensions were placed near the optic disc in one eye of each of two cynomolgus monkeys. Images of the retinal tack and optic nerve head of these two eyes were then obtained with a Zeiss Fundus camera. The dimensions of the retinal tacks and optic discs were measured directly on the film from the Zeiss fundus camera. These measurements were then corrected with Littmann's mathematical approximations.
In the cynomolgus eye with 19.9 mm axial length, Littmann's mathematical approximations of the real sizes of the retinal tack and optic disc from measurements on the Zeiss film had median percent bias [(calculated size-real size)/real size] of -0.2% (range, -3.2% to 3.9%). In the other eye with 17.9 mm axial length, the median percent bias was 14.7% (range, 5.1% to 29.7%).
The estimation of the real size of fundus images with Littmann's mathematical approximations from images on Zeiss film have < 4% bias if the eye's dimensions fall in the range over which Littmann's curves were produced.
本研究旨在探讨依靠利特曼曲线来确定眼底图像实际大小的测量方法的准确性。
在两只食蟹猴的每只眼睛的视盘附近放置已知尺寸的视网膜定位钉。然后用蔡司眼底相机获取这两只眼睛的视网膜定位钉和视神经乳头的图像。视网膜定位钉和视盘的尺寸直接在蔡司眼底相机拍摄的胶片上进行测量。然后用利特曼的数学近似方法对这些测量值进行校正。
在眼轴长度为19.9 mm的食蟹猴眼睛中，根据蔡司胶片上的测量值，利特曼对视网膜定位钉和视盘实际大小的数学近似值的中位偏差百分比[（计算尺寸-实际尺寸）/实际尺寸]为-0.2%（范围为-3.2%至3.9%）。在另一只眼轴长度为17.9 mm的眼睛中，中位偏差百分比为14.7%（范围为5.1%至29.7%）。
如果眼睛尺寸落在产生利特曼曲线的范围内，利用利特曼的数学近似方法根据蔡司胶片上的图像估计眼底图像的实际大小，偏差小于4%。
