PROGNOSIS AND TREATMENT. — In thrombosis the recovery of vision is very improbable. In a few cases of embolism some vision is recovered. Either spon taneously or under treatment the em bolus may be broken up and pass on ward into some branch of the artery, and even into such peripheral branches that its effects are no longer noticed. To favor such a termination the inhala tion of nitrite of amyl may be pushed to a decided physiological action, and active massage of the eyeball employed. These should be repeated daily for sev eral days before abandoning hope of im provement. If the embolus is dislodged, strychnine may be indicated to promote restoration of the retinal function.
Thrombosis of the central retinal vein causes blindness, less sudden and com plete than that due to the obstruction of the artery. It is attended with dila tation of the retinal veins and hfemor rhages throughout the retina, and may be followed by hemorrhagic glaucoma. The treatment is that of the general con dition accompanied by the retinal dis ease.
Detachment of the retina is a dis placement of the retina from its normal position. This may be caused by a tumor or by a displacement of the cho roid. But the term is commonly under stood to mean a separation of the retina from the choroid by serous fluid.
SYMPTOMS.—Then is impairment of vision, usually sudden. and affecting but a portion of the visual field. Commonly the subretinal effusion settles to the lower part of the eye, so that the upper part of the field of vision is lost. The detached portion of the retina may float in front of some part still normal, caus ing sudden temporary loss of vision. With the ophthalmoscope a gray veil is detected, hiding more or less completely the normal red of the eyeground. It presents rounded folds, which float, as the movements of the eve disturb the fluid beneath. These folds are more hyperopic or less myopic than the un detached parts of the retina that may be seen above them. On the folds may be traced the retinal vessels, appearing very small and dark in color.
—The rounded gray folds with the retinal vessels on them are un mistakable. It is sometimes more diffi cult to decide if the case is one of simple detachment or one of detachment due to new growth. Movement of the folds of retina, after moving the eye, indi cates that it is floating freely on serous fluid. When attached to a choroidal growth no such movement occurs; and the vessels of the growth, resembling choroidal vessels, may be seen through the retina. When a new growth exists,
but the retina is separated from it by serous fluid, the growth may be per ceived through the retina by making the ophthalmoscopical examination with di rect sunlight. The tension of the eye ball may throw some light on the case, being normal or below in simple detach ment and sometimes elevated in cases of tumor. The recognition of detached retina accompanying cataract is impor taut as influencing the prognosis regard ing the results of operation. It must depend chiefly upon the careful testing of the field of vision.
—Blows on the eye or head may cause detachment of the retina, either primarily or as the result of other changes in the eye. Very myopic eyes are especially liable to it, and the lia bility increases with age. Extensive changes in the vitreous, especially cica tricial contraction, may pull the retina away from the choroid. Sometimes a tear may be recognized in the detached retina, apparently due to such traction. Through it the choroid may be clearly seen with the ophthalmoscope.
—A small proportion of cases recover spontaneously. This most frequently occurs in traumatic cases. In a large proportion of cases no treatment will effect the permanent replacement of the retina and restore sight. There is no hope of care for eyes having ex cessive myopia or great alterations of the vitreous.
— An opening through the sclera permitting the subretinal fluid to escape externally, with or with out an opening through the detached portion of the retina to allow it to pass freely into the vitreous, has usually caused a temporary improvement in the detachment; in a very few eases it has afforded permanent relief. But in most cases the detachment has recurred, and there has been no permanent benefit. The burning with the galvanocautery of one or two holes in the sclera that will close only after several days or weeks is claimed to be more efficient. The greatest chance of permanent res toration is given by prolonged rest in bed, with the eyes covered most of the time by a pressure bandage; and the use of pilocarpine-sweats and potassium iodide or salicylic acid internally. But this must be persisted in for several weeks to render the benefit permanent; and in a large proportion of eases it fails to do good.