A manual and atlas of medical ophthalmoscopy / by W.R. Gowers.

  • Gowers, W. R. (William Richard), 1845-1915.
Date:
1882
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Licence: Public Domain Mark

Credit: A manual and atlas of medical ophthalmoscopy / by W.R. Gowers. Source: Wellcome Collection.

Provider: This material has been provided by the Francis A. Countway Library of Medicine, through the Medical Heritage Library. The original may be consulted at the Francis A. Countway Library of Medicine, Harvard Medical School.

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    macula lutea, in which a small extravasation may cause per- manent loss of central vision. A ring of haemorrhage around the macula may cause considerable central amblyopia (PI. XI. 2). Occasionally the patient is conscious of the red colour of the extravasated blood. At the moment of extrava- sation there may be no symptoms, or there may be sudden dimness of sight, or there may be ocular spectra. Causes.—Haemorrhage into the retina, as elsewhere, depends on one or both of two causes—increased intravascular pressure, decreased strength of vascular wall. Local increased blood pressure is a common cause. In optic neuritis with much constriction of the veins, the whole fundus may be covered with extravasations (PI. YI. 1). Similar extravasations may attend all forms of retinitis. They may be large and abundant in thrombosis of the retinal vein, as Michel has shown (see p. 28). General increased blood pressure is an occa- sional cause. High arterial tension may often be traced in eases of retinal haemorrhage in which no other cause can be discovered. But it is, on the whole, a rare accident, consider- ing the frequency with which high tension exists. Its rarity may be due to the efficient support of the retinal vessels, as explained in the description of the effects of passive congestion. It is sometimes seen when hypertrophy of the left ventricle can tell unduly on the vascular system. In the peculiar vascular condition which attends arrested menstruation, hsernorrhages occasionally occur; more rarely in suppression of some other habitual discharge. Mr. Spencer Watson1 has recorded an instance of extensive retinal extravasation in a woman at the climacteric period, in whom there was high arterial tension, which was ultimately relieved by a copious epistaxis. In some cases of heart disease, especially when conjoined with degenerated vessels, numerous extravasations occur into the retina, with signs of parenchymatous retinitis, venous distension, and diffuse cloudiness. This condition has been called hsemorrhagic retinitis. It may occur without any recognizable cardiac disease in apparently healthy persons