OPTIC NERVE DISEASE.
Inflammation attacking the terminal portion of the optic nerve is known as optic neuritis or papillitis, and its treatment must be directed to the removal of the primary cerebral cause, as tumour, internal hydro cephalus, sinus thrombosis, cerebral abscess, meningitis, &c. Trephining is urged by IIorsley and Risien Russell in every case of cerebral pressure in which choked disc is present; after the removal of bone a free incision should be made in the dura mater. In this way blindness may be pre vented even when the primary disease is incurable.
The treatment of the optic neuritis following various blood conditions as seen in Bright's disease, clalorosis, lead poisoning and diphtheria, which is more amenable to drugs, will be found discussed under the heading of the primary affections.
Retrobulbar neuritis of secondary nature is due to the action of toxins operating upon the nerve behind the eyeball and causing pallor of the temporal half of the disc with some atrophic change. This produces amblyopia with a central scotoma for red and green or a central loss of vision from axial neuritis. The treatment of this toxic amblyopia is discussed under its own heading, and consists mainly in the removal of the exciting causes—viz., tobacco, alcohol, lead, salicylates and quinine.
" Reflex " amblyopia arising from irritation of the fifth nerve causing trigeminal neuralgia yields to remedies directed to the primary cause as discussed under Neuralgia, and the various types of disturbance of vision met with in hysteria yield to agents directed to the general neurotic con dition.
" Primary " atrophy of the optic disc, as seen in tabes, general paralysis of the insane and disseminated cerebrospinal sclerosis, like the " consecu tive " atrophy which follows optic neuritis (choked disc), is usually beyond the reach of remedial agents. The same remark unfortunately holds with regard to disease of the chiasma and optic tract producing the various forms of hemianopia, unless when the primary cause is syphilis and energetic antis•philitic treatment is commenced at an early stage.
various forms of retinitis demand measures suitable to the primary blood or bloodvessel conditions. Thus the treatment of albuminuric retinitis is that of the underlying type of Bright's disease, often associated also with arteriosclerosis.
Syphilitic retinitis is usually complicated with choroiditis, and yields when energetically attacked by Mercury. Retinitis pigmentosa is a congenital affection occasionally met with in hereditary syphilis, and being of a degenerative type is little influenced by mercury, though hypodermic medication with Strychnine and the application of a weak continuous current may retard its progress, and I)oyne reports good results from the administration of the uncooked retina of sheep with oxygen inhalation.
I hemorrhagic retinitis independent of renal disease occurring in chronic valvular disease and arteriosclerosis can only be met by remedies directed against the primary cause—as saline purgatives and vasodilators when the tension is high, and large doses of Iodides in the absence of high tension. The retinitis occurring in diabetes and leukemia calls for agents indicated by the primary disease.
The " Blinding of the Retina " by strong sunlight, the electric arc, or the reflected light from snow is preventable by the use of dark smoked or coloured glasses. Powerful electric light should be cut off by several layers of red or by a combination of red and blue glass.
When the exposure to strong electric light has already occurred absolute rest to the eye in a darkened room is essential, after which Strychnine hypodermically, following cupping of the temples and suhconjunctival saline injections, should be resorted to. At a later stage the use of a weak continuous current is indicated.
Snow-blindness speedily yields to rest in a darkened room or to the use of smoked glasses, but the pain and smarting of the conjunctiva call for Cocaine instillation and astringent eye-washes.