The effect of cold is to cause a loss of the little reserve nervous energy which such a person may possess, and also if the effect of cold is upon a single part of the body to cause a demand for a readjustment of the disturbed balance of nervous energy.

Such a waste of nervous energy as we have supposed is a sufficient cause of the anæmia which is supposed to act as an inducement to neuralgia, and again with reduced nervous energy there may be disturbance or delay in the process of digestion or of assimilation.

Indigestion and anæmia are regarded as prolific causes of nervous troubles, but they are themselves symptoms and generally manifestations of the same irritation from which the other symptoms arise.

Let us still suppose our case of insufficiency of the internal recti in which the reserve energy is unduly expended. If such a person indulges in the use of certain classes of food or too much food, there is at once an increased demand for nervous force with which to carry on the now unusually difficult function of digestion. Unless this is furnished, there is distress in the hypogastric region; but if it is furnished, other disturbances arise, and headache, neuralgia, or even epilepsy occur.

Nerve-wounds, foreign bodies or tumors pressing in the course of a nerve, or other mechanical sources of irritation, may act as original and independent sources of disturbance, or they may unite their influence with a more permanent one.

Anstie* mentions as "one of the most powerful "Neuralgia," 1872, p. 169.

sources of peripheral irritation tending to set up neuralgia" the "functional abuse of the eyes." "This," he says, "is one of the very few peripheral influences which occasionally we see producing neuralgia by hereditary predisposition."

The learned writer and acute observer makes little practical account of what he evidently regards as among causes "altogether accidental and factitious."

If we inquire to what extent the natural or acquired difficulties in performing the visual act influence the disposition to neuralgia, we shall find it very great.

Eight hundred and fifty cases in private practice have been examined with reference to the ocular conditions, a large proportion of which have been under observation a sufficient time to enable the writer to judge of the result of treatment in this direction.

Without attempting to make an analysis of the result in all these cases, one hundred consecutive cases are selected, as in the class of cephalalgia, as fairly representative of the whole number.

It is proper to add that these were all typical and chronic cases of several years' duration. Nearly all were people of ample means, who had spared no expense in their endeavors to free themselves from their malady. Nearly all had tried the virtues of drugs, baths, and electricity, while a large proportion had spent much time in foreign travel and in seeking for aid at celebrated spas.

Temporary relief had generally been found from some of these means, but the speedy return of the

complaint after discontinuing medical treatment, or after returning from a delightful journey amid new and interesting scenes, had demonstrated clearly that the relief had not been gained by the removal of the radical cause of the evil.

The one hundred cases selected were examined between the dates May 1, 1881, and August 30, 1882. Of the number, twelve were not subject to important ocular defects or were not seen after the first examination, and may be rejected from this present inquiry. Three placed themselves under treatment but soon discontinued without accepting the advice rendered in their

cases.

Eighty-five were treated for the relief of unfavorable ocular conditions with greater or less success in the correction of these anomalies, and with the following results relating to the neuralgic affection:

Of the eighty-five cases, seventy-one were permanently relieved of neuralgia. In ten cases the condition was materially improved, but entire relief was not obtained, while in four cases no relief was gained. There were, then,

It may be of interest to study the condition of some of those where no relief or where only some improvement was obtained; and an example of each is given. Mrs. P., aged forty-nine. For twenty years sub

ject to intense neuralgia, mostly tri-facial. Has frequent fainting-turns, and is in many respects out of health.

Right eye compound myopic astigmatism, corrected by a glass, spherical 2.25 D, with cylindrical 1 D, axis 180°.

Left eye hypermetropic, corrected by spherical +1.25 D.

There is homonymous and vertical diplopia which a prism of 8° with its base out, and another of 2° with its base down, corrects, at a distance of twenty feet, uniting the images.

Glasses

With a full understanding on the part of the patient that an attempt to produce perfect and easy binocular vision was well-nigh a hopeless task, she determined to make the attempt as a last resort. were prescribed, and the muscular irregularities so far corrected as to permit binocular vision, but the vast difference in the refractive states of the two eyes rendered the attempt to produce perfectly united action too difficult. Marked temporary improvement in the patient's condition followed the first relief to the diplopia, but the unpleasant symptoms returned after about two months.

Every oculist will recognize the difficulty in attempting to induce any harmonious action between so differently constituted organs, and, assuming that the neuralgia was the outcome of the ocular errors, the attempt could only be regarded in the light of an experiment.

Would it not in such a case be eminently conserv

ative to remove one of these offending organs rather than to permit all this suffering to continue indefinitely?

The next case shows how the neuralgic habit may be in some measure modified, while some of the important ocular defects on which the neuralgia is supposed to depend may continue:

Mrs. H., aged forty-nine. Subject during the past nine years to neuralgia. Pains located along various nerves. Sometimes manifesting themselves as sciatica, at others as cervico-brachial, and at others as still different forms of neuralgia.

She has astigmatism 1.25 D, with insufficiency of the external recti muscles, and is accustomed to see double very often. There is well-marked mydriasis of the left eye, a condition which has existed for one or two years.

The astigmatism was relieved by cylindrical glasses, and their use was followed by a very marked improvement in the patient's condition. The paresis of the accommodative muscle, however, remains as a permanent and irritating factor for which there is no remedy.

Hence, while a certain amount of relief has been secured, complete recovery is scarcely to be hoped for.

Turning, now, to the more successful class of cases, it will be seen that various conditions which are calculated to create difficulties or perplexities in the use of the eyes are in each of them sufficient to induce the phenomena of neuralgia in different parts of the body. 6