Later these should be replaced by stimulant tonics and brighter light as he can tolerate it. To commence with stimulants seems to me like whipping up a tired horse instead of resting it. Mechanical.-Eye shades, blue or smoked goggles, give a good deal of relief in some cases, especially in sunlight and snow, but fail in others. I should like to see other colored goggles tried, particularly green. One man recently told me that when his eyes are very painful he gets relief only on going into a green wood or field. Proper glasses should be prescribed to correct errors of refraction. Electrical.—I have not seen any cases that I am aware of being treated by electricity. In chronic intractable cases there seems a fair field for experiment with various forms of electrical treatment. Special departments in hospitals.-Whether it would be profitable to provide green or other colored rooms and take in cases as patients and apply other special forms of treatment is uncertain. Very likely some way of cutting the disease short could be discovered, but, personally, I think better value for the money would be gained by the preventive measures I have indicated a NYSTAGMUS AS AN ECONOMIC PROBLEM. This extended account of nystagmus as a practical question of mine management seems to leave little room for further discussion. The importance of any occupational disease, however, is not to be measured by its numerical frequency but by its economic effect on the working capacity of the employee. In proportion as the disease incapacitates for work, the essential and economic consequences to the workmen and to the State are a matter of most serious concern. As under modern workmen's compensation the period of incapacity involves a considerable money payment to the employee, the question is also one of serious importance to mine managers. It is largely because of workmen's compensation law that the disease has attracted so much attention in the United Kingdom within recent years. Even in so complete a treatise as the Elements of Mining and Quarrying, by Foster, nystagmus is disposed of in less than eight lines. As yet most of the medical observations must be considered preliminary to a thorough, strictly scientific study of the subject. Every new contribution by a qualified medical authority adds materially to the existing knowledge of a question that is bound to assume importance in the future, not only as regards its economic aspects but even more more so from the humanitarian point of view. Observations and conclusions based on actual cases are, of course, of greater practical value than conclusions resting chiefly on theoretical considerations. Browne and Mackenzie have published a review of 100 cases of miners' nystagmus, with observations on the etiology and treatment of the disease. The conclusions of these authors are briefly referred to in a reference to nystagmus in the treatise on occupational diseases a Elworthy, II. S., Miners' nystagmus: Brit. Med. Jour., Nov. 19, 1910, p. 1579. b Foster, C. Le N., The elements of mining and quarrying, 1903, 321 pp. c Browne, F. J., and Mackenzie, J. R., The etiology and treatment of miners' nystagmus: Brit. Med. Jour., Oct. 5, 1912, pp. 837-840. by Thompson." The conclusions formed by Browne and Mackenzie," on the basis of 100 consecutive cases treated by them jointly, are summarized in the statement that the factors contributing to the production of nystagmus are: First, inadequate light; second, errors of refraction; third, straining of ocular muscles; and, fourth, neurotic temperament. The conclusions, in detail, are as follows: 1. Inadequate light.—That this is an important cause of miners' nystagmus is conclusively proved by the fact that 99 per cent of our cases had been using the lock lamp for a number of years. Only one case was found where the naked light was allowed, and here the nystagmus was accounted for by hypermetropia, much straining of the ocular muscles in narrow seams, and a markedly neurotic temperament with much physical debility. The lock lamp must be 9 feet from the farthest point of the mandril, and so the workman is staring into comparative darkness, whereas the naked light is attached to the workman's cap or to a post close beside. Therefore, the naked light gives a much brighter and stronger light not only because it is exposed but also because the workman has its full benefit. We have also had experience with miners in various parts of Scotland, where the naked light is used, and in these districts miners' nystagmus is practically unknown. 2. Errors of refraction.—An examination of the summary of cases of miners' nystagmus seen by us will show that 90 per cent had errors of refraction, excluding the three cases in which there was evidence of error, but owing to marked photophobia no exact estimate could be made, while 7 per cent had normal refraction. Of the 90 per cent, 48 per cent had either myopic, hypermetropic, or mixed astigmatism; 27 per cent had simple hypermetropia; and 15 per cent had simple myopia. It is interesting to note that a large number of the cases of hypermetropia were those of comparatively young men who had worked only a few years at coal cutting. 3. Straining of the extrinsic muscles of the eyeball.-This is the result of the two fore. going factors. In all our cases the workman had his eyes fixed in a staring, strained position for long periods, either downward and laterally, as in narrow seams, or upward, as in wide seams; 90 per cent of our cases were engaged in cutting coal, while 10 per cent were haulers and timbermen, and one a colliery examiner. 4. Neurotic temperament.—The inability on the part of a very large number of men with nyastagmus to concentrate their physical or mental powers in any particular line of action guides us to the conclusion that such instability is probably much more the cause than the effect of nystagmus. It most certainly appears to be a weak point in the miner's armor and would repay careful examination long before the stage of inability to work. The severe headaches and aching eyes of which these men complain are accounted for by errors of refraction and straining of the eyes; the vertigo, by incoordination of the ocular muscles; the conjunctivitis and photophobia by the sudden frequent change from darkness into dazzling light. AVERAGE AGE OF PATIENTS AND DURATION OF INCAPACITY. An extremely interesting and useful table that is appended to the paper gives in detail the age, occupation, years underground, degree of refraction, oscillation, and the necessary explanations for 100 consecutive cases. Most of the men were miners and the a Thompson, W. G., The occupational diseases; their causation, symptoms, and prevention, 1914, p. 570. b Browne, F. J., and Mackenzie, J. R., Op. cit., p. 837. exceptions are so few that it may safely be assumed that nystagmus is exceedingly rare among other underground employees. The average age was 34.95 years, the range in years being from a minimum of 18 to a maximum of 67. The average period of underground work was 19.1 years, the range in working time being from a minimum of 2 years to a maximum of 40 years. The oscillations were very slight in 2 per cent of the cases, slight in 26 per cent, marked in 48 per cent, very marked in 2 per cent, and rotatory or marked rotatory in 16 per cent. The table follows: |