DISOEDERS IN RELATION TO THE EYE T69 



control in the eye, due either to infection or to pathological inflammatory 

 change, as in herpes, in the nerve itself. 



Hypotony or loss of tension is generally a serious symptom pointing to 

 progressive loss of vitality and deterioration of the eye. It is observed 

 most frequently, if we disregard the purely mechanical hypotony of 

 retinal detachment, in chronic or relapsing affections of the uveal tract. 



Neuroparalytio keratitis, keratomalacia, and reticular keratitis are 

 associated with hypotony. 



Degenerative 'changes in the cornea, congenital or experimentally pro- 

 duced by feeding with devitaminized food, are generally associated with 

 a decidedly reduced intra-ocular tension. 



Herpetiform eruption, disturbances of sensibility with injuries or after 

 alcohol injections of the Gasserian ganglion are often associated with 

 marked increase in tension. 



Malarial keratitis is, clinically, very similar to the above, suggesting 

 at least a trophic disturbance, and this is borne out by the negligible effect 

 of quinin on the corneal process. Endocrin treatment with adrenal and 

 mixed glands should be beneficial. 



Neuro-endocrin Control of Intra-Ocular Tension. Theory. Vagus 

 control would involve a contracted pupil and uveal arteries and, ceteris 

 paribus, a lowered or at least not increased tonus. Narrowing of the 

 pupil by meiotics does not cause increased tension in normal eyes. Sym- 

 patheticotonia would provide a more active secretion of aqueous, and by 

 dilatation of pupil and rolling up of the filtering area conduce mechanic- 

 ally to a diminution of drainage, and consequent rise in tension. 



Clinical. Ocular tonus, the relation between secretion and elimi- 

 nation, probably depends on a double control, vagotonic and sympathetico- 

 tonic. The former undoubtedly tends to lower tension, the latter to raise 

 it. However this may be under physiological conditions, clinical ob- 

 servations in acute glaucoma undoubtedly indicate a marked sympathetic 

 irritation as one, at least, of the causal factors, while the symptoms are 

 in accord with this view, and the beneficial or curative drugs and pro- 

 cedures are, without exception, those which stimulate the vagus system or 

 depress the already overstimulated sympathetic. 



Predisposition to glaucoma was postulated for middle age or beyond, 

 in hyperopes, by a theory which laid stress on the mechanical factors of a 

 shallow anterior chamber, large lens, and, correspondingly small circum- 

 lental space, a narrow filtration angle, and a pupil which tended to dilate 

 unduly under even a weak solution of a mydriatic. For this reason it 

 was that oculists feared instillations of atropin, say for refraction tests, 

 or even its internal administration in older patients. 



Provocative instillations of cocain were used to determine the above- 

 mentioned susceptibility to mydriatics which indicated a predisposition 

 to glaucoma. 



