Archiv. f. Ophthal., III, pt. III. p.350. considers unilateral mydriasis occurring at short intervals, first in one eye than the other, as a premonitory sign of mental derangement. Mydriasis occurs as a paralytic affection of the third nerve or as result of some irritation of the sympathetic. It causes a dimness of vision from too much light and an increase of the circles of diffusion. This functional disturbance of the pupil is, therefore, usually merely a symptom of deeper and more serious trouble and requires remedies adapted to that condition. It is, however, sometimes found uncomplicated with other disorders, being dependent upon cold, trauma, etc., in which case Arnica, Belladonna, Causticum and a score of remedies may be indicated. The instillation of sulphate of Eserine is often also of great service. As mydriasis is generally associated with paralysis of one or more of the ocular muscles, disuse from the possible danger of sympathetic ophthalmia.
Anatomy.-The iris is the beautiful, colored and contractile membrane which is seen through the transparent cornea. It is attached at its periphery to the sclera through the fibres of the ligamentum pectinatum, and is perforated at about its centre by round opening, the pupil. It rests posteriorly on the capsule of the lens, while its anterior surface is free. The iris is continuous with the ciliary body and choroid, and together they form the vascular tissue of the eye known as the uveal tract, which secretes the aqueous humor and nourishes the lens and the vitreous. Between the iris and lens is a circular space known as the posterior chamber, while between the iris and cornea is found the anterior chamber. Both anterior and posterior chambers contain the aqueous humor, in which fluid floats the iris. The anterior surface of the iris is lined with a layer of endothelial cells which is continuous with that on the posterior surface of the cornea. On the back of the iris is a much thicker layer of epithelium containing much pigment and which is continuous with that of the ciliary body and choroid. The substantia propria consists of connective tissue fibres and cells, many of which, is dark eyes, contain pigment, and within the stroma are found the muscular fibres, blood-vessels, lymphatics and nerves. The muscular fibres are flat, found in bundles, and are of the unstriped variety. Some are arranged in curves about the pupil, nearer the posterior than the anterior surface, and constitute the sphincter pupillae, while others, more deeply situated, run in a radial direction from the centre to the circumference and are called the dilator pupillae.
The blood supply of the iris is derived from the circulus iridis major, which is formed by two long posterior ciliary arteries uniting at the ciliary region with the branches of the anterior ciliary arteries, these then give off branches that pass radially toward the pupil, where they form by anastomosis another ring called the circulus iridis minor (Fig. 65). Capillary networks are given off
Diagrammatic representation of the ocular vessels. The veins are represented black, the arteries clear. a, short posterior ciliary arteries; b, long posterior ciliary arteries; cc. anterior ciliary artery and vein; dd’, posterior conjunctival artery and vein; e’e, central artery and vein of the retina; f, cosae; i. short posterior ciliary vein; k, branch of the posterior short ciliary artery to the optic nerve; l, anastomoses of the choroidal and optic nerve vessels; m, chorio- capillaris; n, episcleral branches; o, arteria recurrens choroidalis; p. circulus arteriosus iridis major; q, vessels of iris; r, of the cilliary processes; s, branch from the ciliary muscle to the venae vorticosae; u, circulus venosus; v, marginal loop plexus of the cornea; w, anterior conjunctival artery and vein. that terminate in veins, which return the blood in a similar course to that followed by the arteries. The iris contains no lymphatic vessels, the lymph being conveyed in sinuses in the sheaths of blood-vessels. The nerves of the iris are very numerous and follow the same course as the vessels. The action of the pupil is controlled by two antagonistic mechanisms-the sphincter muscle supplied by the third nerve and the dilator muscle, by the sympathetic system. Hence, in division of the third nerve, contraction ceases and dilatation results from the unopposed action of the sympathetic. On the other hand, division of the sympathetic causes contraction from an unopposed action of the third nerve. Stimulation of the third nerve causes contraction by overcoming the dilating action of the sympathetic, and, when the sympathetic is stimulated, any contracting influence of the third nerve is overcome and dilatation follows.
PHYSIOLOGY.-The eyes of newly born children are always blue- pigmentation taking place after birth. The iris serves as a curtain to shut off peripheral rays, to regulate the amount of light entering the eye and acts as an aid to accommodation. Contraction of the pupil occurs, from stimulation of the retina by bright light or electricity; when the eyes are accommodated for near vision; in poisoning by morphia, eserine, etc., in deep sleep and after the local application of eserine or other myotics. Dilatation of the pupil occurs when going from a bright into a dim light, when the eye is adjusted for distant vision, in violent muscular efforts, in poisoning by Atropia and other drugs, and after the local application of Atropine or other mydriatics. In examining the mobility of the pupil the eye should be shielded from the light, when a gradual dilatation ensues, then a bright light is suddenly thrown into the eye, when, if normal, the pupil will quickly contract, followed by a very slight dilatation. The pupil is usually larger in children than in adults or old age. Myopes often have larger pupils. The pupil is frequently large in nervous, excitable people.
Hyperaemia Iridis.-Congestion of the vessels in the iris is frequently a symptom of other irritation or inflammations of the eye. It is met with as a result of the irritation from over use of the eyes or from a foreign body lodged in the cornea. It is also found in inflammations of other coats of the eye, the cornea, sclera, choroid, etc., and it is, of course, the first change in either a primary or secondary inflammation of the iris itself. It is diagnosed by the ciliary injection, a fine pinkish or rosy zone surrounding the cornea; by a change in the color of the iris, it loses its normal lustre and brilliance becoming of a dull hazy appearance; and by a sluggish contracted pupil, there are no adhesions, but it is simply slow of action. The change in the color of the iris results from the reddish tinge, due to the congestion, which when combined with the normal color of the iris, gives to a blue iris a greenish hue, to the black a reddish brown color, etc.
Iritis.-Inflammation of the iris, of whatever form of variety, presents certain characteristic features which are found in varying degrees in the different pathological or clinical classifications of iritis, and hence it is thought best to make a general study of the disease as a whole, with brief allusions to the different sub-divisions. There are frequently cases of what might be termed intermediate forms; a serous iritis may change to a plastic; and posterior synechiae, the diagnostic sign of plastic, may occur in any form.
PATHOLOGY.-Iritis may be divided pathologically into three classes viz.: Plastic, parenchymatous or purulent, and serous. In plastic iritis there is first a hyperaemia, followed by an increase of the stroma cells, which become swollen and turbid, together with a fibrinous exudation. This exudation first appears at the pupillary edge and later upon the posterior surface of the iris, but is very rarely found on the anterior surface. The exudation consists of an amorphous, fibrinous coagulum containing some pigment and round cells. The process may be arrested at this period with an absorption of the fibrin. If not arrested at this stage, the fibrinous exudation becomes changed into a delicate membrane, and later into tough, fibrous, connective tissue (containing blood-vessels), which forms the adhesions between the iris and the lens capsule.
In purulent iritis the hyperaemia is at once followed by a considerable immigration of round cells and proliferation of the stroma cells. The iris becomes rapidly swollen with an inflammatory product rich in pus cells, which saturates its tissue and overflow into the anterior chamber. If the disease progresses, all the tissues of the iris become gradually destroyed and the condition is apt to extend, resulting in purulent panophthalmitis.
In serous iritis, following the hyperaemia, there is an infiltration of serous fluid and a few cells into the tissue of the iris and upon the surfaces. This serous exudate is glutinous in character and serves to cause adhesions between the iris and lens capsule, but does not contain the cellular elements found in plastic iritis-the adhesions are much less firm. A variety of serous iritis is the sero-fibrinous iritis. In this the characteristics are numerous haemorrhages into the stroma of the iris, the fluid parts of the blood transude into the anterior chamber and the cellular elements remaining in the iris undergo fatty degeneration.
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.