Cataract. Opacity of the Lens or Its Capsule. 435 



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

 between the margin of the iris and the shadow reflected by 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 

 unsightliness of the dense white cataract is largely done away 

 with. ■ 



Discissipn. 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 

 absorption of the lens so that in the course of a week or two the 

 whole may be removed. It is not, however, unattended by 

 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), or colargolum, and is then ren- 

 dered anaesthetic by cocaine (5 to 10 per cent, solution) or in the 

 large animals general anaesthesia is produced by ether or chloro- 

 form. The eyelids are held apart by the lid speculum, the nic- 

 titans held if necessary by forceps, and the bulb steadied by seiz- 

 ing 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 capsule about two-thirds the diameter of the lens. If 

 the toughness of the capsule threatens to endanger the ciliary 

 body by dragging upon it, two needles or fine hooks may be in- 

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

 and the capsule may be torn without throwing any strain on sur- 

 rounding parts. The pupil must thereafter be kept dilated by 

 atropia to obviate adhesion of the iris to the wound and the eye 

 must be kept in comparative darkness 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 extracted. 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. 



