26 PRACTICE OF PHYSIC. 



CCLXXIX. The inflammation of the membranes of the 

 eye affects especially, and most frequently, the adnata, appear- 

 ing in a turgescence of its vessels ; so that the red vessels 

 which are naturally there, become not only increased in size, 

 but there appear many more than did in a natural state. This 

 turgescence of the vessels is attended with pain, especially upon 

 the motion of the ball of the eye ; and this, like every other 

 irritation applied to the surface of the eye, produces an effusion 

 of tears from the lachrymal gland. 



This inflammation commonly, and chiefly, affects the adnata 

 spread on the anterior part of the bulb of the eye ; but usually 

 spreads also along the continuation of that membrane on the 

 inside of the palpebrae ; and, as that is extended on the tarsus 

 palpebrarum, the excretories of the sebaceous glands opening 

 there are also frequently affected. When the affection of the 

 adnata is considerable, it is frequently communicated to the sub- 

 jacent membranes of the eye, and even to the retina itself, 

 which thereby acquires so great a sensibility, that the slightest 

 impression of light becomes painful. 



CCLXXX. The inflammation of the membranes of the 

 eye is in different degrees, according as the adnata is more or 

 less affected, or according as the inflammation is either of the 

 adnata alone, or of the subjacent membranes also ; and, upon 

 these differences, different species have been established, and 

 different appellations given to them. But I shall not, however, 

 prosecute the consideration of these, being of opinion that all 

 the cases of the Ophthalmia membranarum differ only in degree, 

 and are to be cured by remedies of the same kind, more or less 

 employed. 



The remote causes of Ophthalmia are many and various ; as, 



1. External violence, by blows, contusions, and wounds, ap- 

 plied to the eyes ; and even very slight impulses applied, while 

 the eye-lids are open, to the ball of the eye itself, are some- 

 times sufficient for the purpose. 



2. Extraneous bodies introduced under the eye-lids, either of 

 an acrid quality, as smoke and other acrid vapours, or of a bulk 

 sufficient to impede the free motion of the eye-lids, upon the 

 surface of the eye-ball. 



