8 LANDMARKS MEDICAL AND SURGICAL. 



14. Eyelids and eyes The opening between the eyelids 

 varies in size in different persons ; hence more of the eyeball 

 is seen in some than in others, and the eye appears larger. 

 Although human eyes do vary a little in size, yet the actual 

 difference is by no means so great as is generally supposed. 

 The size of the fissure has much to do with the apparent 

 size of the eye. Contrast the narrow fissure of the Chinese 

 and Mongolian races, and the apparent smallness of their 

 eyes with those of Europeans. As a rule the external 

 angle of the lid is higher than the internal. When not 

 exaggerated, it gives the face an arch and pleasing ex- 

 pression. 



Evert the lids to see the Meibomian glands ; observe 

 their perpendicular arrangement, in the substance of the 

 tarsal cartilages. 



The free borders of the lids are not bevelled, as described 

 by J. L. Petit and most anatomists, ' so as to form with the 

 globe of the closed eye a triangular canal for the flow of the 

 tears.' On the contrary, it is easily seen that the lid margins, 

 when closed, come into accurate contact. Their plane is not 

 exactly horizontal, but slightly inclined upwards. 



Every time the eye is shut, the ball turns upwards and 

 inwards, so that the cornea is completely covered by the 

 upper lid. This may be well seen by raising the lid of a 

 sleeping infant ; also in cases of low fever when the lid is 

 not completely closed. This up-turning of the eye obviously 

 clears the cornea, and protects it from the light. 



A careful examination of the motion of the lower lid in 

 the act of shutting the eye proves that it is a double motion. 

 The lid is not only slightly raised, but drawn inwards about 

 -jL- of an inch. This second movement sweeps any particles 

 of dust as well as moisture towards the inner canthus. 



1 5. Puncta lachrymalia. The puncta lachrymalia are 

 distinctly visible at the inner angles of the lids. The lower 

 punctum is larger and a little more external than the upper, 

 so that they are not exactly opposite. The direction, too, of 

 the puncta deserves notice. Their open mouths look a little 

 backwards, ready to imbibe the tears. When their proper 



