REATIVE SOIE> 



377 



of the optic nerve, the choroid coat, the retina, the vitreous 

 humour, tho crystalline lens, the aqueous humour, tho cornea, 

 the sclerotic coat, the irw, tho pupil, ami, last of all, the eye- 

 lid*, tin- doors that open and close this superlative piece of 

 mi'cliuiiiMii. How 



.harming t. be able to 

 say with the bard of 

 :n " Much Ado 

 i.ing " 



A L 



11 1 hare a rood eye, uncle; 

 I can mt a i-huivh li\ 



Hut there are eome 

 unfortunate person* 

 who cannot oven atter 

 Mi'-li a truixm as that, 

 because nature has by 

 disease been over- 

 turned, and the organ 

 <>f vii.it. ii refuses to 

 ml to the will of 

 tin' mind. 



There is no branch 

 of surgery requiring 

 more refined scientific 

 thought or delicacy of 

 touch than that repre- 

 1 by the skill 

 of an accomplished 

 oculist. Take, for 

 instance, Mr. Robert 

 Brudenell Carter's 

 drawing of the vessels, 

 the healthy Papilla, 

 Nervi Optici, or optic 

 disc as examined by tho 

 ophthalmoscope, an in- 

 strument of remark- 

 able ingenuity. 



The entrance of the 

 optic nerve presents, 

 within normal limits, 

 considerable diversities 

 of shape and colour. 

 "With regard to shape, 

 it is in most cases 

 round, but seldom per- 

 fectly circular, often 

 cval, with the longer 

 diameter perpendicu- 

 lar ; angular in almost 

 all cases of convergent 

 squint: never oval, with 

 the longer diameter 

 horizontal. In many 

 cases the ophthalmo- 

 scope exhibits round 

 the entrance a dark 

 rhig or crescent, which 

 depends on a collection 

 of pigment in the cho- 

 roid in the immediate 

 neighbourhood of the 

 nerve,and has no patho- 

 logical signification. 

 At the point where tho 

 lamina cribrosa ceases, 

 tho nerve is contracted, 

 and the opening in tho 

 choroid is narrow, and 

 in a certain measure 



compresses the trunk. For this reason a sort of double border 

 is often wen around the nerve-entrance, and between the 

 limits of this border it is still surrounded by tho choroid, in 

 which at tins part Donders, by careful inspection, has seen a 

 choroidal vessel. 



Tho colour is either white, yellowish, reddish, bluish, or greenish 



Fig. 4. 



admixture. The glistening whiteness described by OHM obswrcr* 

 (tendinous glistening of Coceiu*) is not found in healthy eyes, 

 but is prMnt, M we shall Me hereafter, in many condition* of 

 disease. Among the eanses of the variation in colour within 



normal limit*, may be 

 mentioned the age of 

 the individual, the 



i:. i: :.<-r '. '. -\r.\i\i\.- I: 



of the vessels upon 

 the optic disc, the 

 illumination and the 

 colour of the surround- 

 ing field. In eye* rich 

 in pigment the illumi- 

 nated dUc is compared 

 by Desmarres to the 

 moon in a fine summer 

 night, and contrasts 

 strongly with the neifh- 

 boorinf part*. It is 

 onetimes surrounded 

 by a margin of pig- 

 ment granule*, often 

 perceptible a* a dark 

 ring. In eyes with 

 lees pigment the dUo 

 cannot be to conspicu- 

 ously illuminated or 

 sharply defined, and 

 presents) usually a more 

 reddish tint. 



It is in the considera- 

 tion of the cane* which 

 are attended to and 

 relieved by oculist* 

 that the knowledge of 

 the structure of th* 

 human eye becomes so 

 valuable. The non- 

 professional reader is 

 startled when he reads 

 that portions of the 

 iris may be removed 

 from the living being, 

 who experiences com- 

 fort and relief from 

 the operation. 



"In 1860," Mr. 

 Carter says, "I was 

 consulted by a hale 

 man, sixty-five years 

 of age, on account of 

 pain and blindness of 

 his left eye. The at- 

 tack had commenced 

 three days before I 

 saw him, and his suf- 

 ferings were very great. 

 The globe was of stony 

 hardness, the conjunc- 

 tiva much injected, th 

 cornea steamy, the 

 aqueous turbid, the 

 pupil somewhat di- 

 lated, fixed, and of an 

 oval outline. With the 

 affected eye the pa- 

 tient could barely dis- 

 cern the position of the 

 window before which 

 he was seated. A large 

 piece of iris was imme- 

 diately excised, and his recovery was speedy and complete. 

 Ten days after the operation he could read pearl type with the 

 affected eye, and it has ever since remained in an equally good 

 condition.' ' 



The same eminent authority says: "A few months ago I 

 saw a young man whose eye had been punctured by a thorn 



