518 



PHYSIOLOGY 



of epithelial debris in the anterior chamber. The intraocular pressure under 

 these circumstances becomes very high, the disease being known as glaucoma. 

 The principal symptoms of glaucoma are pain and impaired vision. 

 The chief diagnostic signs are a stone- hard eyeball, sluggish rather dilated 

 pupils, and the retina when examined through the ophthalmoscope is found 

 to show cupping of the optic disc, and vessels which are thin and show pulsa- 



!']<;. 259. Arrangement of apparatus for measurement of intraocular 



(HENDERSON and STARLING.) 

 o is a piston -recorder for recording graphically the changes in pressure. 



tiou. In treating glaucoma operative measures to lower the pressure 

 should be taken immediately, because the high pressure interferes with 

 the proper blood supply to the eye. Since all hypermetropes (persons with 

 long sight) have a tendency to suffer from glaucoma, care should be taken 

 against giving drugs such as atropine which cause dilatation of the pupil, 

 since this increases the resistance to the escape of fluid at the nitration angle, 

 and therefore predisposes to an attack of glaucoma. 



MALNUTRITION OF THE EYE shows itself in many ways: (l)as phlyetenulur 

 conjunctivitis in young children; (2) as myopia in school children in whom tin- sdei.i 

 lii-inn ill nourished is unable to withstand the intraocular pressure, so that the sphericity 

 of the eyeball is destroyed ; (3) as night blindness in middle age, the rod elements of 

 llu- retina being affected ; (4) as cataract in old age. In this condition the nutrition 

 of the crystalline lens is impaired, and as a result it loses its normal transparency. Tin- 

 opacity develops sometimes at the centre (nuclear), sometimes in the cortex. The condi- 

 tion is trrjited by removing the lens (e\t ra.-t ion of cataract). 



