[Construction of a model eye for simulation of Purkinje reflections for determining the radii of curvature and the position of the crystalline lens].
Specular reflections at the optical interfaces of the eye, the Purkinje reflections, are used in physiologic optics and ophthalmology for biometric measurements. To date, there is no standard in the measurement of crystalline lens radii of curvature and position. To that end model eyes were designed.


METHODS
The most important goal was to simulate the Purkinje reflections I, III, and IV, in the human eye as realistically as possible. The casing of the model eye was made of brass; the optical components were made from contact lens material.


RESULTS
Several variants of components were manufactured to reproduce the range of variations in human eyes. By combining different components it was possible to vary the radii of curvature of the cornea and of the crystalline lens, axial separations, crystalline lens rotations and decentrations independently and reproducibly. First applications included devices for biometry of the crystalline lens (phacometry), validation of methods for eye alignment measurement, and refractometry.


CONCLUSIONS
The properties of the specular reflections of the model eye are very close to the target values in human eyes. One of the advantages of the model eye is the compact design. This model eye is the first measuring standard for phakometry.
Kirschkamp
T
T
Medizinische Fakultät, RWTH Aachen.
Jöckel
M
M
Wählisch
G
G
Barry
J C
JC
D000886:Anthropometry; D004867:Equipment Design; D005137:Eye, Artificial; D006801:Humans; D007908:Lens, Crystalline / Q000033:anatomy & histology*; D008953:Models, Anatomic; D019721:Ophthalmoscopes; D012029:Refraction, Ocular