Neuralgia of the fifth nerve may cause it, as does also irritation decayed teeth. Attacks are often precipitated by hysteria, convulsions, nervous excitement, anxiety, mental disturbances, anger, fear, etc. any condition causing vascular turgescence may cause it, as in gout, acute rheumatism, atheroma, climatric changes, intoxication, indigestion, fever, sleeplessness, etc. The use of atropine in some eyes will cause it. It has often occurred after an iridectomy for glaucoma in the other eye.
Priestley Smith concludes, from a study of the immediate causes of increased intra-ocular tension, that it may result from three conditions, viz:” Hypersecretion by the ciliary processes serosity of the fluids and obstruction at the filtration angle.”
Hypersecretion may be expected from irritation of the fifth nerve or from dilation of the ciliary vessels, and, while these conditions may serve to act as a exciting cause, he considers it a pure hypothesis.
The serosity of the intra-ocular fluids is probably a supplementary cause of increased tension, for, whenever the circulation of the blood is obstructed, serum is apt to escape from the capillaries. In a mild from of serous inflammation of the uveal tract there is a serous exudation, the aqueous is cloudy, punctate spots on the posterior surface of the cornea, dilated pupil and an increased tension, which may result in glaucoma from the serous nature of the intra-ocular fluids.
To an obstruction in excretion he chiefly attributes the cause of increased intra-ocular pressure. This obstruction at the iritic angle in glaucoma was first demonstrated by Knies Von Graefe’s Archiv. Vol. xxii., 3. and Weber plus Von Graefe’s Archiv. Vol. xxiii., I. in 1876. Since then Priestly Smith has examined over eighty eyes having had various varieties of glaucoma and found obstruction of the filtration angle in all but three or four. As predisposing causes to this obstruction he considers the rigidity of the sclera that increases with age and the extra rigidity of the sclera found in Jews (who as a race are found to have a greater liability to glaucoma. The smallness of the eyes, as demonstrated in the Egyptians, who, as a race, have small eyes and are especially prone to glaucoma, may be considered another feature. The increasing size of the lens in age, as demonstrated by him, seems, however, to be the most important predisposing factor in the causation of obstruction at the iritic angle with resulting glaucoma. His measurements further show that a small cornea belongs to a small eye, that the horizontal diameter of the cornea in glaucomatous eyes is less than that in healthy eyes, and that the size of the lens in small eyes is not proportionately small. The increase of the size of the lens in age without proportionate increase in the other structures of the eye causes it to encroach upon the surrounding pats; its margins press upon the ciliary processes, its anterior surface approaches nearer the cornea and in this way the depth of the anterior chamber is decreased. Priestley Smith summarizes as follows:
“The causes of primary glaucoma., then, are various and complex, and are not yet completely known; but they are alike in this-they all lead to compression of the filtration-angle. With that compression the actual glaucoma process begins. The escape of fluid is retarded and the intra-ocular pressure rises;l this, in its turn, increases the compression of the filtration-angle. The fluid which still exudes from the turgid ciliary body is albuminous and less diffusible than the normal secretion; it tends to accumulate behind the lens, and this latter, being pressed forward, intensifies the mischief. thus cause and effect react upon each other in a vicious circle.”
The theory of Priestley Smith does not satisfactorily explain all the phenomena of glaucoma, hence many other theories have from time to time been presented. the latest, that of Abadie Ophthalmologische Klinik, November, 1897., of Paris, presents features worthy of careful consideration. He argues that persistent changes at the iritic angle would necessarily cause persistent and not transitory symptoms. We know that we frequently have transitory attacks of both acute and sub-acute glaucoma, and he claims therefore that the nervous system must be interested in these transitory attacks that disappear without leaving a trace behind them. The old theory that the fifth nerve played this important role, in the light of recent investigations, must be abandoned, as it is a nerve of sensation only, and that the trophic influence which this nerve was claimed to have upon the nutrition of the eye must be attributed to the sympathetic branch which accompanies it.
He then claims that the true origin of the disease is an excitation, at times transitory, again permanent, of the vaso- dilator nerve-fibres of the blood-vessels in the eye resulting in either the increased blood-pressure in the vessels, which perhaps also increases the intra-ocular secretions. He cities the action of mydriatics and myotics as the most positive proof that glaucoma is due to dilatation of the blood vessels. Atropine producing dilation of the vessels aggravates the glaucomatous symptoms. Eserine on the contrary constricts the vessels and lessens the intensity of the glaucoma.
He further claims that the good results of an iridectomy in glaucoma substantiates his theory and says that the success of the operation rests solely upon breaking up the circular set of excitor nerves which regulate the dilatation and constriction of the blood vessels,. These nerves are situated in the middle part of the iris, and Abadie says that only this portion of the iris need be removed, and that even a simple slit without excision would be sufficient. That the reason the removal of either the iris, or sclerotomy, is only a partial success is because this ring plexus of nerves in the centre of the iris is not removed.
Galezowski Rec. d’Oph., July, August, 1894. considers glaucoma to be due to an alternation of nutrition through an obliteration of the lymph-vessels and distension of the lymph- canals, plastic exudation around the canal of Schlemm, hyaline degeneration of the walls of the vessels of the iris, rigidity of the lamina cribrosa, and concentration of lymph at the entrance of the optic nerve.
The causes of secondary glaucoma are those of some previous disease of the eye which obstruct the excretion.
Annular Posterior Synechia, by partially or totally obstructing the passage of the fluids from the posterior to the anterior chambers, causes glaucoma because the secretion going on, the iris becomes pushed forward and closing up the filtration-angle increased tension sets in. Iridectomy may be advisable in annular synechiae to prevent glaucoma.
Anterior Synechia, from some perforating wound or ulcer of the cornea, causes an insufficient access to the filtration- angle.
Dislocation and injuries of the Lens will often be the cause or glaucoma. When dislocated into the anterior chamber it causes a stoppage of the filtration-angle, a lateral dislocation causes by pressing forward the iris and ciliary process. An injury of the lens by the keratome in iridectomy, needling of a soft cataract, or penetrating wounds of the eye injuring the lens, causes swelling with pressure upon the iris and glaucoma. The lens should be immediately removed in these cases. Glaucoma occurs in some cases after extraction of the lens and also after discission for secondary cataract. Intra-ocular tumors and haemorrhages also cause increased tension. In serous exudation from the uveal tract, glaucoma results from diminished filtration power of the fluids. Glaucoma has also been seen in eyes with a detached retina.
DIAGNOSIS- The importance of an early diagnosis in this disease cannot be over-estimated, and the most usual prodromal symptoms are, a frequent changing of the reading glasses, the halos around a light and periods of obscuration of vision. In all cases, the chief symptoms to be looked for are the enlarged ciliary veins, anaesthesia and haziness of the cornea, irregularity of the pupil contraction of the field of vision, pulsation of the retinal arteries, cupping of the optic disc and increased tension.
Acute glaucoma has frequently been mistaken for iritis, and in some cases the differential diagnosis, which practically rests upon the increased tension and dilatation of the pupil in glaucoma, is extremely difficult. The inflammatory symptoms of both give the same appearance, the fundus is often not to be seen in either, there may be haziness of the cornea in both, and the iridescent vision may occur at the same age, that Atropia may have been used in the eye with partial dilatation of the pupil and the difficulty to accurately determine the tension in an acutely inflamed eye may render the deferential diagnosis extremely uncertain. the two disease may even exist together. for the deferential diagnostic signs se page 290.
Glaucoma simplex and optic nerve atrophy are, according to Schweigger, Archiv. Ophthal., vol. xx., 4, 1891. often mistaken for each other. The essential diagnostic point seeming to rest upon a comparison of the field of vision in the two diseases, which would, of course, be aided by the presence of any or all of the following symptoms of glaucoma. The history, halos, pain, increased tension, more rapid progress depth of the cup and arterial pulsation. The peripheral color sense is not so markedly defective in glaucoma as in atrophy. We have also seen cases where the failing vision has been attributed to cataract, but the mistake could hardly be made by any careful observer. Other cases we have seen attributed to a cold in the eye, the pain said to be neuralgia, and instillation of Atropia used. This inexcusable error could not have been made had the tension of the eye been examined.
Professor of Ophthalmology in the College of the New York Ophthalmic Hospital; Surgeon to the New York Ophthalmic Hospital. Visiting Oculist to the Laura Franklin Free Hospital for Children; Ex-President American Homoeopathic Ophthalmological, Otological and Laryngological Society. First Vice-President American Institute of Homoeopathy : President Homoeopathic Medical Society of the State of New York ; Editor Homoeopathic Eye. Ear and Throat Journal : Associate Editor. Department of Ophthalmology, North American Journal of Homoeopathy, etc.