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Ocular Tuberculosis
250
EDITORIALS
sents a particular problem. Definitions we must have; but no definition can take the place of careful, intelligent study of the individual case, in its dif ferent aspects. Edward Jackson. OCULAR TUBERCULOSIS For many years, in European clinics, tuberculosis has been regarded as a ma jor etiological factor in the production of diseases of the eye. Practically all ob servers agree that ocular tuberculosis is more prevalent in Europe than in the United States. But sufficient attention has not been paid in this country to ward the elimination of tuberculosis as an etiological factor in diseases of the eye, particularly those of the anterior segment and uvea. When proper in vestigations are carried out, one will often be astounded to find that the in cidence of ocular tuberculosis in his private practice is much higher than he had anticipated. One of the difficulties associated with the diagnosis and treatment of tuber culosis of the eye has been the eye physician's lack of understanding and fear of the use of tuberculin. When tu berculin treatment or diagnostic meas ures are carried out by the specialist in tuberculosis at the eye physician's re quest, the patient is put to an unneces sary amount of expense and inconveni ence in having to visit the two physi cians for each observation. There is ab solutely no reason why the treatment and diagnosis of eye infections with tu berculin should not be done by the eye physician if he will observe certain pre cautions. First of all, it must be remembered that those patients exhibiting tubercu lous lesions of the eye rarely have an active pulmonary tuberculosis. But in order to be sure that tuberculin is not used upon a patient where active tu berculous lesions other than those in the eye may be present, each patient should have a thorough examination by the specialist in tuberculosis before diagnostic tuberculin tests are made by the eye physician. If the temperature chart, x-ray photographs, and other ex aminations of the tuberculosis special
ist show no active foci then the eye physician may proceed without fear of doing harm. Consensus of opinion still seems to favor the use of old tuberculin for diag nostic purposes, administered either intradermally or subcutaneously. Gifford, in his book on ocular therapeutics, gives detailed information as to the prepara tion of dilutions. Unless the retina is involved, it is· safe to start with a first diagnostic dose of one ten thousandth of a milligram of old tuberculin. A local reaction at the site of injection and a temperature reaction would make one suspicious that the ocular lesion might be due to tuberculosis, but when a focal reaction is produced in the eye itself, the evidence is conclusive. Even in the diagnostic procedure it is safer to start with small doses, and any dose should definitely not proceed beyond that which produces the slightest focal re action. If diagnostic doses up to one milligram are given without either a lo cal or focal reaction, tuberculosis as a cause of the eye lesion may be elimi nated. Authorities differ widely when con sidering the type of tuberculin to be used for treatment. Gifford thinks the majority opinion still favors old tuber culin, and certainly satisfactory results are obtained in many cases with it. Schieck in a recent monograph, which is well worth reading by anyone inter ested in the treatment of ocular tuber culosis, states that at the clinic in Würzburg the bacillus emulsion has been used for many years. He thinks it less likely to provoke unfavorable re actions than old tuberculin, and the end results are just as satisfactory. H e recommends an initial therapeutic dose of 0.1 cc. of a 1:10,000 dilution. Succeed ing doses are increased progressively by 0.1 cc. until 1 cc. of a 1 to 10 dilution is reached. He advises treatment every other day with the smaller doses, cut ting the time down to twice a week as the dose increases. Some observers de sire an interval of at least two days or longer between doses, in order to avoid giving the next injection during the negative phase of immune reaction. This appears logical, and certainly it is
EDITORIALS better to have a longer period between doses than too short a one. The controversy concerning the type of tuberculin to be used is considered by Schieck as follows, "In my judg ment the dose of the "injection is the main point, for much more depends upon what concentration one chooses than which tuberculin one injects." If a focal reaction is produced at any time during the treatment, one drops back to a smaller dose and again in creases it gradually. Schieck states that in the Vienna clinic as directed by Mei ler, tebe protein is used. This is milder in its effect than even the bacillus emul sion, and may be used in cases where the bacillus emulsion is not well borne. At the Würzburg clinic Schieck has never seen irreparable damage pro duced in an eye by the use of tubercu lin. In this monograph, in addition to tu berculin therapy, emphasis is placed upon hygienic and dietetic measures for the patient, similar to those used in the treatment of pulmonary tuberculosis. Ultraviolet radiation used locally is us ually unable to penetrate to the lesion because of its depth, but used as a gen eral measure may be considered bene ficial. In tuberculous iritis and uveitis, Stock recommends twenty percent of a skin erythema dose of x-ray to the eye, not to be repeated in less than six weeks. The stimulation thus produced may lead to a beginning of the healing process. Schieck has observed that in certain cases hemorrhages into the anterior chamber are followed by beneficial re sults, and attributes them to antibodies carried in by the blood. H e goes so far as to advise the injection into the an terior chamber of fresh blood drawn from a vein in tuberculosis of the iris. Experience would seem to indicate that the focal reaction produced by an overdose of tuberculin where the dis ease is limited strictly to the cornea may, after the inflammation subsides, produce a beneficial affect, but focal reaction produced where the uvea is in volved causes a definite setback in the healing process, and increases the pe riod necessary for treatment. To be on
2Sl
the safe side it is wise to observe the general rule of avoiding the production of focal reactions. The use of small, gradually increasing dosages, over a a longer period of time will in the end give the best result. The recent work of Urbanek in isolat ing the organism of tuberculosis from the blood of patients affected with tu berculosis of the eye, and the culture by Meiler of the organism directly from an enucleated eye, would tend to indi cate that in some cases ocular tubercu losis is caused by the localization of the organism itself in the eye. In other cases sensitization of the eye to tuberculous toxins arising from foci located else where in the body, may be the cause of the inflammation. Either type of in flammation should be amenable to treatment by tuberculin which the eye physician, observing proper precautions should not hesitate to administer. M. F. Weymann.
OCULAR IMAGES It has long been known that with eyes of high refractive differences such as monocular aphakia, binocular single vision is a rare occurrence. Disregard ing the prismatic effects introduced by correcting such a pair of eyes, the in ability to use them together is ex plained by the disparity in size of the two retinal images. The image formed by the correcting lens on the retina of an aphakic eye may be as much as thirty percent larger than the image in the fellow normal eye. In this case, the fo cal length of the lens system of the nor mal eye is the shortest and the image formed consequently is the smallest. An exaggeration of this idea may be obtained by considering the use of the telescope. Viewing a distant object with one eye through a telescope will pro duce a larger image on that retina than the image on the other retina, and it is easily understood that fu sion under such a circumstance would be impossible. Besides this overall size difference, vertical or horizonal mag nification or even more complex varia tions in size and shape can be demon-
EDITORIALS
sents a particular problem. Definitions we must have; but no definition can take the place of careful, intelligent study of the individual case, in its dif ferent aspects. Edward Jackson. OCULAR TUBERCULOSIS For many years, in European clinics, tuberculosis has been regarded as a ma jor etiological factor in the production of diseases of the eye. Practically all ob servers agree that ocular tuberculosis is more prevalent in Europe than in the United States. But sufficient attention has not been paid in this country to ward the elimination of tuberculosis as an etiological factor in diseases of the eye, particularly those of the anterior segment and uvea. When proper in vestigations are carried out, one will often be astounded to find that the in cidence of ocular tuberculosis in his private practice is much higher than he had anticipated. One of the difficulties associated with the diagnosis and treatment of tuber culosis of the eye has been the eye physician's lack of understanding and fear of the use of tuberculin. When tu berculin treatment or diagnostic meas ures are carried out by the specialist in tuberculosis at the eye physician's re quest, the patient is put to an unneces sary amount of expense and inconveni ence in having to visit the two physi cians for each observation. There is ab solutely no reason why the treatment and diagnosis of eye infections with tu berculin should not be done by the eye physician if he will observe certain pre cautions. First of all, it must be remembered that those patients exhibiting tubercu lous lesions of the eye rarely have an active pulmonary tuberculosis. But in order to be sure that tuberculin is not used upon a patient where active tu berculous lesions other than those in the eye may be present, each patient should have a thorough examination by the specialist in tuberculosis before diagnostic tuberculin tests are made by the eye physician. If the temperature chart, x-ray photographs, and other ex aminations of the tuberculosis special
ist show no active foci then the eye physician may proceed without fear of doing harm. Consensus of opinion still seems to favor the use of old tuberculin for diag nostic purposes, administered either intradermally or subcutaneously. Gifford, in his book on ocular therapeutics, gives detailed information as to the prepara tion of dilutions. Unless the retina is involved, it is· safe to start with a first diagnostic dose of one ten thousandth of a milligram of old tuberculin. A local reaction at the site of injection and a temperature reaction would make one suspicious that the ocular lesion might be due to tuberculosis, but when a focal reaction is produced in the eye itself, the evidence is conclusive. Even in the diagnostic procedure it is safer to start with small doses, and any dose should definitely not proceed beyond that which produces the slightest focal re action. If diagnostic doses up to one milligram are given without either a lo cal or focal reaction, tuberculosis as a cause of the eye lesion may be elimi nated. Authorities differ widely when con sidering the type of tuberculin to be used for treatment. Gifford thinks the majority opinion still favors old tuber culin, and certainly satisfactory results are obtained in many cases with it. Schieck in a recent monograph, which is well worth reading by anyone inter ested in the treatment of ocular tuber culosis, states that at the clinic in Würzburg the bacillus emulsion has been used for many years. He thinks it less likely to provoke unfavorable re actions than old tuberculin, and the end results are just as satisfactory. H e recommends an initial therapeutic dose of 0.1 cc. of a 1:10,000 dilution. Succeed ing doses are increased progressively by 0.1 cc. until 1 cc. of a 1 to 10 dilution is reached. He advises treatment every other day with the smaller doses, cut ting the time down to twice a week as the dose increases. Some observers de sire an interval of at least two days or longer between doses, in order to avoid giving the next injection during the negative phase of immune reaction. This appears logical, and certainly it is
EDITORIALS better to have a longer period between doses than too short a one. The controversy concerning the type of tuberculin to be used is considered by Schieck as follows, "In my judg ment the dose of the "injection is the main point, for much more depends upon what concentration one chooses than which tuberculin one injects." If a focal reaction is produced at any time during the treatment, one drops back to a smaller dose and again in creases it gradually. Schieck states that in the Vienna clinic as directed by Mei ler, tebe protein is used. This is milder in its effect than even the bacillus emul sion, and may be used in cases where the bacillus emulsion is not well borne. At the Würzburg clinic Schieck has never seen irreparable damage pro duced in an eye by the use of tubercu lin. In this monograph, in addition to tu berculin therapy, emphasis is placed upon hygienic and dietetic measures for the patient, similar to those used in the treatment of pulmonary tuberculosis. Ultraviolet radiation used locally is us ually unable to penetrate to the lesion because of its depth, but used as a gen eral measure may be considered bene ficial. In tuberculous iritis and uveitis, Stock recommends twenty percent of a skin erythema dose of x-ray to the eye, not to be repeated in less than six weeks. The stimulation thus produced may lead to a beginning of the healing process. Schieck has observed that in certain cases hemorrhages into the anterior chamber are followed by beneficial re sults, and attributes them to antibodies carried in by the blood. H e goes so far as to advise the injection into the an terior chamber of fresh blood drawn from a vein in tuberculosis of the iris. Experience would seem to indicate that the focal reaction produced by an overdose of tuberculin where the dis ease is limited strictly to the cornea may, after the inflammation subsides, produce a beneficial affect, but focal reaction produced where the uvea is in volved causes a definite setback in the healing process, and increases the pe riod necessary for treatment. To be on
2Sl
the safe side it is wise to observe the general rule of avoiding the production of focal reactions. The use of small, gradually increasing dosages, over a a longer period of time will in the end give the best result. The recent work of Urbanek in isolat ing the organism of tuberculosis from the blood of patients affected with tu berculosis of the eye, and the culture by Meiler of the organism directly from an enucleated eye, would tend to indi cate that in some cases ocular tubercu losis is caused by the localization of the organism itself in the eye. In other cases sensitization of the eye to tuberculous toxins arising from foci located else where in the body, may be the cause of the inflammation. Either type of in flammation should be amenable to treatment by tuberculin which the eye physician, observing proper precautions should not hesitate to administer. M. F. Weymann.
OCULAR IMAGES It has long been known that with eyes of high refractive differences such as monocular aphakia, binocular single vision is a rare occurrence. Disregard ing the prismatic effects introduced by correcting such a pair of eyes, the in ability to use them together is ex plained by the disparity in size of the two retinal images. The image formed by the correcting lens on the retina of an aphakic eye may be as much as thirty percent larger than the image in the fellow normal eye. In this case, the fo cal length of the lens system of the nor mal eye is the shortest and the image formed consequently is the smallest. An exaggeration of this idea may be obtained by considering the use of the telescope. Viewing a distant object with one eye through a telescope will pro duce a larger image on that retina than the image on the other retina, and it is easily understood that fu sion under such a circumstance would be impossible. Besides this overall size difference, vertical or horizonal mag nification or even more complex varia tions in size and shape can be demon-