Page:Encyclopædia Britannica, Ninth Edition, v. 17.djvu/846

Rh 782 OPHTHALMOLOGY region. small brown specks will be seen in the pupil. The whole free edge (exclusion), or the whole posterior surface (total posterior synechise), may adhere to the lens-capsule, and the pupil may be completely covered with a film of lymph (occlusion). These three last conditions are apt to cause secondary glaucoma. Coloboma of the Iris is a congenital defect in the iris. The defect is always in the lower part, and gives the pupil a balloon shape. It may or may not be accompanied by a similar defect in the choroid and retina. Diseases From the intimate association of their vascular supply, of the th e ciliary body, iris, cornea, sclerotic, and choroid are iliary frequently affected together. Diseases in this region all agree in their tendency to relapse frequently during a very chronic course, and to involve separate patches. Sclerotitis (episcleritis) forms a low painful swelling, of a peculiar rusty colour, under the conjunctiva in the ciliary region. It lasts for months, with frequent relapses. The subjects of this disease are mostly rheumatic or anaemic women. Internally, iodide of potassium is some times useful. If that fail small doses of mercury should be given. Locally, atropine, blistering the temple, or massage of the swelling through the upper lid may be tried. Irido-cyclitis, inflammation of the iris and ciliary body, is characterized by congested patches of a violet colour in the ciliary region, cloudy areas in the cornea, and attacks of iritis with much plastic exudation. There is great pain and intolerance of light, It relapses frequently, each attack leaving more cloudiness of cornea and more iritic adhesions, till ultimately the sclerotic presents a bluish bulging in the ciliary region (ciliary staphyloma), the cor nea is opaque, its curvature irregular, and the sight gone. Irido-choroiditis resembles a mild attack of iritis ; there is little pain or photophobia. Small deposits form on the back of the cornea (keratitis punctata). Recent choroid- itis and sometimes opacities in the vitreous may be seen with the ophthalmoscope if the pupil be clear. This also relapses frequently, with the formation of much iritic adhe sion, and sometimes of secondary glaucoma. This occurs mostly in delicate young persons, and generally involves both eyes. The treatment consists of atropine locally, disuse of the eyes, and tonics with iodide of potassium internally ; only in mild cases is a good result obtained. The iritic exudation is generally too plastic to be absorbed. Wounds or Diseases in the Ciliary Region are extremely liable to involve the other eye sympathetically. There are two affections of very different moment. In sympa thetic irritation the eye is tender and irritable, cannot bear a bright light, and is easily fatigued by continued strain of the accommodation, as in reading or other close work. This condition usually yields speedily when the other eye is removed, which should be advised without hesitation. Sympathetic inflammation is of much more serious mo ment. It may begin quite insidiously, or with acute pain and intolerance of light. Once begun, it becomes an inde pendent disease, little influenced by treatment directed to the exciting eye, and usually ending at last in irrepar able blindness. The symptoms are deposits on the back of the cornea (keratitis punctata), violet-coloured ciliary congestion, often great tenderness of the ciliary region, the iris muddy and in severe cases buff- coloured, and with many large blood-vessels on its surface. Extensive iritic adhesions form which cannot be absorbed. The process is an irido-cyclitis or irido-choroiditis. It may be set up two months or many years after the injury ; the eye is never safe. Treatment must evidently be mainly preventive. All blind eyes liable to cause sympathetic inflammation should be at once removed. If some vision be left in the wounded eye, and the patient can be kept under observation, it may be left, the patient being warned of the danger to the other eye. The inflam mation once arisen, the exciting eye, if blind, must be removed ; but not if there be any sight in it, as it may be eventually the better eye of the two. The patient must be kept in a dark room and not allowed to use his eyes. Atropine solution must be applied locally. After the in flammation is quite quiescent removal of the lens with a portion of the iris may be of use in giving an artificial pupil. Cataract. Cataract is an opacity of the crystalline Diseases lens. It is due to some alteration in the structure and of the relationship of its fibres, as the result either of some senile fP 8 *, change or defect of development, of local interference with its nutrition (as in glaucoma), of some general diseases such as diabetes, or of local injury to the lens or its capsule. For practical purposes all cataracts are classified under three categories. (A) They may be hard or soft below the age of thirty-five, and in diabetes of any age, cataracts are soft. (B) They may be general or partial, according to the amount of lens involved in the opacity. General cataract may be nuclear (beginning from the centre) or cortical (spreading inward from the periphery) ; or both conditions may coexist. Partial cataract may be (1) lamellar, where one or several of the concentric layers in an otherwise transparent lens becomes opaque. This form is often congenital. It is said to be frequently caused by infantile convulsions. (2) Pyramidal cataract is a small white spot on the lens-capsule in the centre of the pupil. This is the result of corneal perforation in purulent oph thalmia. The cornea falls against the lens-capsule when the aqueous humour is evacuated, and becomes adherent to it, The aqueous, refilling after the healing of the per foration, tears away the cornea and leaves the spot of lymph. on the capsule. (3) In posterior polar cataract the opacity begins at the posterior pole of the lens. It indicates deep-seated disease. (C) Cataract may be primary or secondary, according as it arises in an eye otherwise healthy or depends on some other disease in it. Cataracts arising from injury to the lens are called traumatic. Symptoms and Treatment of Cataract. Vision becomes gradually impaired. If the cataract be small and central, vision improves in a dull light or when the eyes are shaded. On ophthalmoscopic examination (see below) the opaque parts appear either as dark striae converging towards the centre or as a dark central mass. The fundus, if visible, appears red. An attempt should be made to ascertain if it is healthy. On oblique illumination by a convex lens the opaque parts now appear white and the rest of the pupil black. When the cataract is ripe the pupil is filled by a homogeneous pearly- white or amber-coloured opacity. The rest of the eye is healthy if the pupil reacts to light, and the patient can tell the direction of a candle-flame at four feet distance. As a palliative atropine may be used if it be found to improve vision. To remove the cataract operation is required. Operation is undesirable in pyra midal, secondary, and immature cataract, and usually if, while the cataract in one eye is ripe, the other eye remains good, unless the patient specially desires the operation. The Operation. In the soft cataract of infancy, youth, and diabetes the needle operation should be chosen. The pupil having been dilated by atropine, a fine needle is passed through the cornea near its margin, and lacerates the lens-capsule freely. The lens, acted on by the aqueous humour, swells up and gradually dissolves, the process of solution taking from two to three months, and generally needing one or two repetitions of the needling. In hard cataracts the lens must be extracted entire. The follow ing is the most usual operation. With a narrow knife an incision is made through the upper part of the cornea at its junction with the sclerotic, in length somewhat less