An American text-book of diseases of the eye, ear, nose and throat / edited by G.E. De Schweinitz and B. Alex. Randall.

Date:
1899
Catalogue details

Licence: Public Domain Mark

Credit: An American text-book of diseases of the eye, ear, nose and throat / edited by G.E. De Schweinitz and B. Alex. Randall. Source: Wellcome Collection.

Provider: This material has been provided by the Harvey Cushing/John Hay Whitney Medical Library at Yale University, through the Medical Heritage Library. The original may be consulted at the Harvey Cushing/John Hay Whitney Medical Library at Yale University.

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    the fibers in this locality predisposes to them. When they occur there they produce an irregular blotch or oval, usually with the longer diameter vertical, and a corresponding central scotoma. Hemorrhages of large dimensions and drop-like form usually mean an extravasation between the internal limiting membrane of the retina and the hyaloid membrane of the vitreous. Recent investigations by J. Herbert Fisher indicate that the blood is poured out from a retinal vessel—probably a minute artery—and detaches the internal limiting membrane from the retinal layers, accumulating in the space thus formed. These are the so-called subhyaloid hemorrhages, which occur at the yellow spot more than at other parts of the fundus (Plate 5, Fig. IV.). Although many of the causes of retinal hemorrhage have been enumer- ated, a summary based upon Dimmer's classification may be added : (a) Hemorrhages caused by changes in the composition of the blood and the tissues of the blood-vessel walls: Pyemia, septicemia, ulcerating endo- carditis ; diseases of the liver, spleen, kidney, and atheroma of the vessels; loss of blood (menorrhagia, hematemesis), anemia (simple and pernicious), hemophilia, purpura, and scurvy; diabetes and gout; malaria and recurrent fever. (6) Hemorrhages caused by disturbances in the circulation : Hypertrophy of the heart and stenosis of the valves; thrombosis of the central vein of the retina and embolism of the central artery; suffocation, compression of the carotid, hemorrhages in the newly-born ; and menstrual disturbances. (c) Hemorrhages caused by sudden reduction of the intraocular tension —e. g. after iridectomy in glaucoma and by traumatism : Among the latter may be classed retinal hemorrhages after large cutaneous burns. Pathology.—A perivasculitis or fatty degeneration of the walls of the retinal vessel, produced by the general or local disturbance, permits rup- ture of the artery or vein and consequent extravasation. Sometimes the hemorrhage is caused by diapedesis of blood-corpuscles. In some cases the hemorrhages are superficial, and leave the retina healthy, but in other instances atrophy results and a scotoma permanently marks the spot. Hem- orrhages may take place in any layer of the retina, and by preference follow the larger blood-vessels. Sometimes they burst through the limiting membrane and pass into the vitreous. The macula, as before stated, is a favorite spot for these lesions. With the hemorrhages may be the patho- logical changes incident to the various types of serous and parenchymatous retinitis. Prognosis.—At times, as already noted, superficial retinal hemorrhages are absorbed without leaving permanent scars ; but if the macula is attacked, the visual disturbance is apt to be severe and lasting. Not only in this sense is the prognosis unfavorable, but the retinal hemorrhage, in most instances a sign of serious constitutional disturbance, may be the forerunner of extrav- asations in vital centers. Secondary changes in the optic nerve may result; sometimes glaucoma is a consequence (see page 384). Treatment.—This should be directed toward removing the cause when- ever possible to determine it. Internally, if not otherwise contraindicated, iodid of potassium may be given, ergot, small doses of pilocarpin, and bichlorid of mercury, according to various indications. Macular retinitis is a term which, though often used for only one form of retinal inflammation occurring in the macula lutea, is really more general in its application, and may include several types of inflammatory retinal change specially located in this region. The details of these alterations are not yet clearly understood, and consequently they cannot be separated from each