EYE RESEARCH APPLICATIONS 



m 



Fig. 3. X-ray image spectrograph for microanalysis by fluorescent emission (von Hamos). Q, x-ray 

 tube; 0, sample to be analyzed; F , photographic film; 6162 , diaphragms; C, bent crystal; B\Bi , spectral 

 images of specimen from focused monochromatic rays. 



copper primary x-radiations ; and a similar 

 amount of iron in a spleen section 80 [i thick 

 exposed to chromium radiation. Thus mi- 

 croscopy and microanalysis are possible both 

 by the emission and diffraction analysis with 

 bent crystals of characteristic radiation, and 

 by the absorption in the specimen of mono- 

 chromatic or polychromatic beams. 



REFERENCES 



1. Barrett, C. S., AIME Tech. Pubis., 1865; 



Metals Technol., April, 1945. 



2. Cauchois, Y., "Sur la formation d'images des 



rayons X," Rev. opt., 29, 151 (1950). 



3. Clark, G. L., "Applied X-rays," 4th ed., Mc- 



Graw-Hill Book Company, N. Y., pp. 107, 

 702, 1955. 



4. VON Hamos, L. and Engstrom, A., Acta 



Radiol., 25, 325 (1944). 



G. L. Clark 



EYE RESEARCH APPLICATIONS 



X-ray microscopy has been applied to the 

 eye in order to delineate the eye's two main 

 types of channels: the vascular system and 

 the aqueous outflow apparatus. 



The Vascular System 



The technique of x-ray microscopy has 

 been useful in examining the blood vessel 

 patterns in the relatively thick and opaque 

 sections necessary for their demonstration. 

 Many have contributed to this field which 

 has been called historadiography, microra- 



diography and microangiography. The main 

 development work has been at the Nuffield 

 Institute for Medical Research, Oxford, 

 England, by the late Alfred Barclay (1) and 

 in the Department for Physical Cell Re- 

 search, Karolinska Institutet, Stockholm, 

 Sweden, under the direction of Arne Eng- 

 strom (2). 



Because of the transparency of the retina, 

 its vascular pattern may be studied in the 

 light microscope after injection of an opaque 

 material such as India ink. Such a method 

 is not feasible with the thicker and more 

 opaque tissues of the eye. In such areas x-ray 

 microscopy is probably the most suitable 

 method. Francois, Neetens and Collette (3, 

 4) applied this method to the eye. Thorotrast 

 was injected as a contrast medium. They 

 used a Machlett A2 tube with an iron target 

 and a beryllium window. "Lippman" emul- 

 sion film (Gavaert) was used. The parts of 

 the eye taken for examination were dis- 

 sected under the dissecting microscope and 

 the fixed wet samples were supported be- 

 tween thin plastic sheets. 



Studies were made of the retina, choroid, 

 ciliary body, iris (3) and optic nerve (4). 

 Some of the major findings were: 



(1) At the level of the peripapillary por- 

 tion of the retina anastomoses exist between 

 capillaries originating from the optic nerve 

 and the retinal capillaries proper. 



(2) The intraocular portion of the short 

 ciliary arteries nourishes the choroid only. 



571 



