CORNEA 



61 



referred to. When a very thin optical section of the cornea — 

 more particularly of its peripheral region near the limbus — is 

 approaching the angles at which the epithelial and the endothelial 

 bounding edges will be seen by D.I.S.R., a change occurs in the 

 appearance of the intra-corneal portion of the beam (Fig. 28) 

 which lies between their specularly observed areas — it changes 

 from its normal relucent grey-white appearance to a finely and 

 vertically striated almost scintillating faint bronze or golden tinsel 

 colour ; this must presumably be due to a succession of multiple 



J/cnimr/JL Sec/ion. [ 



Fig. 28. Fig. 29. 



Scintillating sheen in the optical section of the cornea. 



regular reflections of a sort occurring from the laminated structural 

 principle on which the cornea is built (Fig. 29) (7). Under similar 

 conditions, in the thin optical section of the lens-cortex, both 

 anteriorly and posteriorly, particularly in elderly persons, an 

 area (Fig. 30 X, X') comes to assume a metallic lustre, sometimes 

 faint and golden, sometimes rich and copper-bronze. The 

 explanation must be the same (Fig. 31) as in the case of the cornea 

 — a summation of regular interior reflections due to meridional 

 stratification of a medium which is not optically homogeneous (8). 

 The anatomical surfaces of discontinuity in the lens are each 

 capable of causing regular reflection in very slight degree because 

 their visibility in the thin optical section of the lens is best when 



