Cataract. Opacity of the Lens or Its Capsule. 433 



portion is unripe there is a clear zone of greater or less depth 

 between the margin of the iris and the shadow reflected b}' the 

 opaque portion of the lens. 



In the lower animals the question is less important as we 

 do not aim at securing perfect vision, and the danger of in- 

 flammation is therefore the main consideration. Escaping this, 

 the aqueous humor may be expected to dissolve and remove 

 the greater part of the still adherent lens .substance, and the 

 un.sightliness of the dense white cataract is largely done away 

 with. 



Discission. Tearing of the capsule .so as to admit the aqueous 

 humor to the lens may be admissible in the young with soft cat- 

 aract. The liquid causes gradual swelling up, solution and 

 ab.sorption of the lens so that in the course of a week or two the 

 whole may be removed. It is not, however, unattended bj' 

 danger, as the rapid swelling of the lens will sometimes determine 

 an inflammation which will lead to complete destruction of the 

 eye. The eye is first thoroughly washed with aseptic cotton and 

 a sublimate solution (i : 1000), and is then rendered ansesthetic 

 by cocaine (5 to 10 per cent, solution ) or in the large animals 

 general anaesthesia is produced by ether or chloroform. The 

 eyelids are held apart by the lid speculum, the nictitans held if 

 necessary by forceps, and the bulb steadied by seizing it with 

 hooked forceps. A cataract needle is passed through the cornea 

 close to its border, and carried through the pupil, previously 

 dilated with atropia, so as to tear an opening in the anterior cap- 

 sule about two-thirds the diameter of the lens. If the toughness 

 of the capsule threatens to endanger the ciliary body by drag- 

 ging upon it, two needles or fine hooks may be introduced 

 through opposite borders of the cornea (inner and outer) and the 

 capsule may be torn without throwing any strain on surrounding 

 parts. The pupil must thereafter be kept dilated by atropia to ob- 

 viate adhesion of the iris to the wound and the eye must be kept 

 in comparative darkne.ss and aseptic. If active inflammation sets 

 in, cold, astringent or iced dressings may be called for, while if 

 the swelling of the lens is threatening it should be at once ex- 

 tracted. If the eye becomes unduly tense, puncture of the cornea 

 is indicated, and the relief of tension will sometimes start a tardy 

 solution into renewed activity. 

 28 



