1'2 PHILOSOPHICAL TRANSACTIONS. [aNNO 1724. 



An Account of the Dissection of an Eye with a Cataract. Bij Mr. John 

 Ranby,* Surgeon. N^aSl, p. 30. 



Sept. 21, 1723, one William Sollars, aged 50, complained of a decay in his 

 sight. On examining his eyes, there were two cataracts, that in his right eye 

 almost ripe, the other just forming. Before the operation however was performed, 

 the man fell ill of a fever, and died the 2d of March. Having procured the 

 right eye, in which the cataract was most confirmed, in order to make an exact 

 dissection of it : in examining it, the aqueous and vitreous humours were in 

 their natural state, but the crystalline humour was opaque, and of a foul pearl 

 colour, and more solid substance than in its natural state. The aqueous hu- 

 mour had its natural transparency, nor could there be observed any thing pre- 

 ternatural, either on the iris or uvea, except too great a contraction of the pupil. 

 This very much strengthens the opinion of Maitrejan, Brisse, Heister, and 

 Valsalva, who have severally asserted, that a cataract is only an opacity of the 

 crystalline humour, and that it naturally proceeds from a serous acid, which so 

 far astringes and corrodes its substance, as to destroy its transparency. This 

 Maitrejan confirms by an experiment, of immerging the crystalline humour in 

 a composition of 3 parts water and one of aquafortis, by vvhicli he says it may 

 be rendered hard and opaque ; but in this point I cannot help siding with the 

 learned Dr. Pitcairn, who has sufficiently proved, that there is no such serous 

 acidity in an animal body. To me nothing seems more easy than to deduce this 

 opacity of the crystalline humour from an inflammation in the blood, or an in- 

 creased momentum in the fluids, with which it is supplied : for in that case, 

 grosser particles, inconsistent with the transparency, may be impelled into the 

 lymphatic vessels of which it is composed; and that there is an inflammation is 

 sufficiently demonstrated from hence ; first, the patient feels often a pungent 

 pain in the eye, which, as it is generally the forerunner of a cataract, so it 

 certainly indicates an inflammation of the part. 2dly, Those maculae, which 

 appear as it were swimming in the air, plainly prove that there are opaque parti- 

 cles already entered the lymphatic vessels, which compose the vitreous humour. 

 3dly, The iris, whose colour arises from the blood vessels, as it changes from 

 a lighter to a darker colour, shows the violence of the inflammation, and is 

 therefore esteemed a symptom of the worst consequence. 



* Mr. John Ranby bestowed considerable attention on human and comparative anatoniy. on wliich 

 he published several papers in the 3.3d, ,34th, 36tli, and 37th Vols, of the Phil. Trans. He was in 

 high repute as a practising surgeon, and was among the most active and most successful promoters 

 of the inoculation of the small-pox, soon after its introduction into this countr}'. 



