Chapter 4
_Electricity._ The credit of first using high frequency currents in the treatment of glaucoma belongs to Truc, Imbert and Marques, and Roure's experiments indicate that this current suitably applied appears to have an influence not only in reducing the arterial tension, but also the ocular tension. Thus, in an interesting series of experiments he has been able to reduce an arterial pressure of 200 mm. to 140 mm., and an ocular tension of plus 2 to the normal after eighteen applications of the high frequency current. The current is applied for ten to fifteen minutes at a time twice a week. Some surgeons, for example, Würdemann, have suggested the use of electricity combined with massage, and have apparently achieved satisfactory results.
The constant current has also been much employed for the purpose of reducing intra-ocular tension. Coleman quotes Le Prince's observations, who applies the negative pole to the eye and the positive pole to the neck, gradually passing a current of 30 to 40 ma. during a quarter of an hour, and who reports notable diminution of tension. Coleman points out that in his own experience he has not found any patient who would willingly tolerate more than 19 ma. of current with an ordinary sized electrode, although he grants that it is possible that Le Prince used a very large electrode. Unfortunately he does not mention its size. Ziegler of my own city, who has studied most scientifically and intelligently the use of electricity in diseases of the eye, announces this rule: The positive pole should be used in all inflammatory processes of the eye, glaucoma excepted, and with this rule Coleman agrees. Now, although the negative pole is a stimulant and therefore not generally indicated in inflammation, as Coleman points out, the object in view is to diminish the density of the ocular capsule and its tension, hence the negative rather than the positive pole should be used, inasmuch as the former, according to him, while it is a sedative, hardens tissue and would tend to increase intra-ocular tension by diminishing excretion. Moreover, in chronic glaucoma the ordinary inflammatory processes are not present, indeed, primary acute glaucoma itself is not an inflammation.
I have no personal experience in the use of the constant current with negative pole application to the eye in the reduction of increased intra-ocular tension, but quote for our general benefit the opinions of those who have employed it. I have always been very frankly pessimistic in regard to the therapeutic value of electricity in ocular disorders. Perhaps I am wrong; I am willing to be enlightened. There seems little doubt that Truc and Imbert's observations that high frequency currents can temporarily reduce intra-ocular tension is correct, that they are able to relieve the pain of primary and of secondary glaucoma would seem to be proved by many observations, some of which I have myself made, and other very accurate and excellent ones have been made by Risley in Philadelphia.
A word might be said in regard to _diathermy_. According to Zahn, the method of applying diathermy to the human eye is to take a layer of cotton wool 1 cm. thick soaked in a 2 per cent solution of sodium chlorid, which is applied close to the outside of the lids. On this is put an electrode 15 cm. in size with a large indifferent electrode applied to the back of the neck. It is not germane to the subject to name the various ocular diseases which were treated in this manner, but Clausnizer has made an investigation of the influence of diathermy on intra-ocular tension. In a number of diseases, for example, iridocyclitis, the method produced distinct rise of pressure. In one, a patient with secondary glaucoma, prior to the diathermic application the tension was 37½ mm., after the passage of the current it had fallen to 28 mm., but the next morning the tension rose to 45 mm. In a patient with chronic glaucoma no definite alteration of tension could be found. This observation is mentioned, not because it puts us in possession of a valuable therapeutic measure, but largely because it is a good example of how in this disease it is wise to investigate any method which furnishes a hope of relief.
In a few instances endeavor has been made to reduce the intra-ocular tension, or at least to relieve glaucomatous symptoms, by galvanism of the cervical sympathetic, for example, by placing one electrode along the whole length of this nerve in the neck and one on the back of the neck on the opposite side, 15 to 20 ma. of current being used. Good results have been reported by an observer named Allard. I confess that I am entirely faithless in regard to any results that may be reached in this manner. It is possible that as the positive pole is a sedative, if there were any influence, the influence of sedation would be present, but certainly it has over and over again been experimentally proved that irritation of the cervical sympathetic quite rapidly produces elevation of intra-ocular tension of 2 to 4 mm. In some experimental work the primary elevation of intra-ocular tension was followed by a secondary drop.
3. _Indirect reduction of increased intra-ocular tension brought about by lowering general vascular pressure._ Much has been written in regard to the association between increased vascular pressure and increased intra-ocular pressure. It is not my province to analyze observations often contradictory and not infrequently inaccurate. This much seems to be established: First, that at corresponding ages there is usually a higher average blood pressure in glaucomatous subjects than there is in non-glaucomatous subjects; second, that arteriosclerosis and therefore usually increased blood pressure, with all its concomitant conditions, is correctly classified as an exciting cause of glaucoma; and third, that the regulation of this increased blood pressure is part of the advantageous management of increased intra-ocular pressure, although it may be too much to say, as Gilbert has, that blood pressure and intra-ocular pressure rise and fall together. It may be true, as Thomas Henderson says, that the intra-ocular pressure is influenced by changes in the general arterial or general venous pressures, whereby a rise in general arterial pressure induces a proportionate rise in the intra-ocular pressure, but it would seem that future investigations must confirm this statement before it can be entirely accepted, as well as his further statement that the effect of an increased general venous pressure is a direct one, producing millimeter for millimeter a corresponding increase in the intra-ocular pressure.
Now, it goes without saying, if these data are correct, or even only partly correct, that part of the treatment of the increased intra-ocular pressure state must be constitutional in that the vascular pressures should be lowered in order that the beneficial effect of their relationship to the intra-ocular pressure shall be established. It is further a great mistake to drive down a high arterial pressure simply because that exists. In other words, it is often necessary from the general standpoint that a certain amount of plus pressure shall remain if the patient's general well-being is to be maintained. There must always be a differential diagnosis between plus pressure and what may be called over plus pressure. That is to say, a man may be perfectly comfortable and properly need, for example, a pressure of 160 or 165 mm., which is above the physiologic limit, but which is a plus pressure, while some disturbance in his general life may add to that 10, 15 or 20 mm. more of pressure, which is then the over plus amount. This over plus amount may be in association with a rise of intra-ocular pressure, and must be eliminated if the latter is to be controlled by a non-operative procedure, or, indeed, by an operative one.
It is no easy matter to determine the presence of increased venous pressure, although there are tolerably accurate instrumental technics, and yet, as Henderson points out, it is just this increased general venous pressure which is often detrimental. Therefore the perfunctory use of such drugs as nitrite of amyl and the other nitrites may not be in the least indicated when, for example, the venous pressure depends upon inability of the right heart to perform its functions, and the drug needed may, for example, be digitalis. Far better than pressure-reducing drugs like nitrite of amyl, urgently indicated in some instances and for some purposes, is the regulation of life and the restoration to their normality of the metabolic processes, the elimination of the worry which is usually the exciting agent that brings about the over plus pressure, which may have as one of its expressions an acute rise of intra-ocular tension. I believe that in the management of a case of glaucoma, whether it be chronic or chronic with sub-acute exacerbations, the greatest care with the aid of an expert clinician must be exercised to find out exactly what mean pressure of the arterial and venous system best conforms with the patient's general welfare, and I am bitterly opposed, and I think with right, to the sudden reduction of tensions, except in emergencies, without a perfect understanding of the facts I have ventured to indicate. This does not for a moment mean that prior, for example, to operative work it is not necessary to get rid by means of drugs of an over plus tension, for surely the elimination of such an over plus tension may be the means of preventing, for example, an intra-ocular hemorrhage, and in this emergency we must not lose sight of Gilbert's recent investigation, who has found that blood withdrawn to the extent of 8 grams to each kilogram of the body weight always produces lowering of the intra-ocular tension, appearing in six to eight hours and lasting to the next day in simple glaucoma, and in inflammatory glaucoma commencing the day after the venesection and lasting two to three days. It is not necessary for me to point out the value of free purgation and diaphoresis in this respect.
In most instances the successful maintenance of a glaucomatous life, exclusive of operative interference, in addition to sustained myosis, demands the investigation of the patient's metabolism, which must be kept at the normal standard, the removal of the evil effects of auto-infection, as we are wont to call it, and especially the elimination of the cause which is responsible for the over plus tension of the arteries and of the veins. This is best secured by just such regulation of life as has been referred to, aided when necessary by the ordinary drugs which the patient's condition indicate, and the success of all treatments, be they operative or non-operative, is enhanced if such a happy state of affairs can be brought about.
I am firmly convinced that every glaucomatous patient, and I now refer to those who are the subjects of chronic progressive glaucoma, should be carefully studied from the general standpoint by the oculist with the aid of an expert internist, just as I am convinced that the modern expert internist should not study his cases of cardio-vascular disease without the help of the oculist. Perhaps I am going a little far afield, but in justification of my statement I want to quote the opinion of Dr. Hobart Hare, one of America's most expert clinicians, on blood pressure, because it seems to me much harm has been done by the more or less brutal knocking down of blood pressure simply because blood pressure above the normal existed. "Concerning the matter of high blood pressure," writes Hare, "independent of cerebral lesions, the longer I study the matter the more convinced I am that this blood pressure is devised by nature to compensate for fibroid changes in peripheral vessels, in order that tissues which would otherwise be cut off from adequate blood supply may receive plenty of blood, and I consider it one of the most vital points to ascertain whether a pressure is what may be called the patient's pathological norm, that is, the pressure which is required in the face of vascular changes, or whether this pressure is in excess of his pathological norm. If it is in excess, measures directed to bring it to the pathological norm should be instituted, but if the pressure found proves to be the pathological norm it is a bitter mistake to lower it, be the pressure what it may. If it is lowered below the pathological norm, all manner of disturbed cardiac action, etc., may result. There is no more reason for reducing a blood pressure below his pathological norm than there is for reducing it below his physiological norm. The adjustment of a man's blood pressure to his pathological norm often has to be as correctly done as the adjustment of a watch which is losing or gaining time."
I shall not quote Hare's elaborate methods for determining these various points because they do not belong to a paper of this character, but I quote his admirable advice because it emphasizes what I believe to be an essential in the treatment of chronic glaucoma, exclusive of operative work, that is, the intelligent co-operation of the oculist and the internist.
Some such thought was in the mind of Ibershoff, who quotes Sterling and Henderson's views that the rate of secretion depends upon and varies with the difference in the blood pressure and the tension of the eyeball, and that the specific gravity of the secretion increases directly with the blood pressure and inversely with the ocular tension. Should the blood pressure be very high, paracentesis, for example, would apparently not be the proper procedure, and the resulting difference produced between the blood pressure and the eye tension would cause a rapid reformation of fluid with higher specific gravity and higher osmotic coefficient. The proper procedure in these circumstances is first properly to reduce the blood pressure, or what I have, quoting Hare, ventured to call the over plus pressure.
4. _The relation of osmosis, lymphagogue activity, absorption of edema, capillary contractility and decreased affinity of ocular colloids for water to the reduction of increased intra-ocular tension._ We are all familiar with the attention which was directed some years ago to the statements coming from French clinics that the treatment of glaucoma should include the administration of osmotic substances as adjuvants in the reduction of increased intra-ocular tension. Particularly was this treatment advocated by Cantonnet in the administration of daily doses of 3 grams of chlorid of sodium, preceded, of course, by a careful urinary examination and the estimation of the amount of urine and its contained chlorids. Carefully this dose was increased in proper circumstances to 15 grams per diem, and in Cantonnet's original paper good results were achieved in 12 of the 17 patients so treated. I have myself experimented somewhat, not with the administration of sodium chlorid by the mouth, but with the introduction by the bowel of fairly large quantities of physiologic salt solution in patients with glaucoma whose quantity of urinary secretion was markedly below the normal, and in one or two startling instances, which have been reported, achieved success in the rapid reduction of the intra-ocular tension when by this technic the urine secretion rose to the normal amount. To be sure, myotics were also used, but these myotics were insufficient, totally so in the two instances noted prior to the enteroclysis.
Very interesting are the observations on the subconjunctival injections of various substances, notably the citrate of sodium, because of its power of decreasing the affinity of ocular colloids for water. This method of treating increased intra-ocular tension, introduced, as you know, by Thomas and Fischer, has met with confirmation from a number of sources in spite of the fact that Happe's experimental study failed to confirm Fischer's observations; indeed, he even reports in several instances a rise of tension.
As you will remember, the strength of ordinary crystallized sodium citrate in water should be from 4.05 to 5.41 per cent. Of this five to fifteen minims are injected, the eye having been previously cocainized and adrenalinized. With frequent injections the weaker of the two solutions is mixed with 2 to 4 parts of physiologic salt solution. These authors in no sense claim to cure glaucoma, but to ameloriate it and reduce the tension. Weekers has used the salts of calcium, 3 grams a day, with success in so far as lowering of tension is concerned, although it must be stated, as a reviewer of his work has said, that his recommendation of this drug in these respects is poorly supported. On the other hand, Tristiano seems to have proved that calcium chlorid is capable of lowering ocular tension and clinically may be used as an adjuvant in the treatment of glaucoma for this purpose, largely because he believes that he has proven that it facilitates the absorption of edema. Darier has reported that a single subconjunctival injection of a milligram of iodate of sodium has cleared the cornea and lessened the intra-ocular pain in glaucoma.
What shall be said in regard to certain medicinal agents which stimulate the lymphagogue activity of the eyeball in their relation to the reduction of intra-ocular tension, notably of dionin? Toczyski's experiments with this drug on the normal eye indicate that it produces first a rise of tension, which shortly falls to the normal and sometimes below it, the tension being high as long as the primary narrowing of the pupil is maintained, but more than one author, particularly A. Senn, holds an opposite view and reports acute glaucoma following its instillation into a chronic glaucomatous eye. He believes that dionin not only does not reduce the tension but hinders the filtration through the anterior lymph channels by the pressure of the edema which is produced on the veins and by the increased secretion of the ciliary processes. In spite of this statement, most of us must agree with Karl Grossman's observations that certainly in acute and particularly in chronic secondary glaucoma, this is a most valuable agent, especially if it is combined with holocain, which Paul Knapp in his well-known research has proved can reduce the tension even of the normal eye. I cannot think that anybody who has systematically used dionin with holocain, the former in gradually increasing strength, beginning with 2 per cent and going up to 8 per cent, in various types of acute glaucoma, particularly of the secondary variety, can fail to have noted a favorable influence.
Many authors, for example, Darier, Grandclement and others, are strong in their recommendation of adrenalin, particularly if this drug is added to the various myotic mixtures, and yet adrenalin is certainly not without danger in the treatment of glaucoma. McCallan has seen a number of instances of striking increase of intra-ocular tension following this instillation in the conjunctival sac. Harmon has had a similar experience, as also has Senn. It is possible that in these circumstances the solution was too strong. Should the rise of tension occur, and I have seen it myself, it is doubtless due to the fact that this drug dilates the pupil, which would be especially dangerous if the dilatation should occur before contraction of the ciliary vessels; also the narrowing of the ciliary veins by the adrenalin might by virtue of this narrowing obstruct the gate of outflow. I have never been able to persuade myself that, except as an adjuvant to operative work, there was any real therapeutic value in the instillation of adrenalin.
A word in regard to the effect of general narcosis on intra-ocular tension. Thus, Neuschuler has observed that narcosis causes an elevation of the intra-ocular tension of from 2 to 6 degrees as measured with Fick's tonometer. These observations were made while he was experimenting on irritation of the sympathetic as a method of producing increased intra-ocular tension. This is not in accord with Axenfeld's recent observations. It is well known, this observer points out, that after the period of excitation and muscular rigidity disappears, there is a lowering of blood pressure in chloroform narcosis and coincidently a sinking of the intra-ocular pressure. Not only this, the intra-ocular tension of normal eyes during this narcosis drops several millimeters. Only such eyes as have high hypertony, for example, in absolute glaucoma, are unaffected during chloroform narcosis. In the light of this observation it will be interesting to measure the tension both of normal and glaucomatous eyes during narcosis in a large series of cases, and if it is confirmed there will be an additional reason why in many circumstances general narcosis is advantageous in glaucomatous patients. Formerly I thought it was essential, if iridectomy was to be performed, lest some sudden movement on the part of the patient might bring the point of the knife in contact with the lens. I have rarely employed it in corneo-scleral trephining, and yet if there is this temporary reduction of intra-ocular pressure, it is not without a certain therapeutic value, and the matter is mentioned as a suggestion that additional observations along this line shall be made.
Dr. George Edmund de Schweinitz' Paper on Concerning Non-Surgical Measures for the Reduction of Increased Intra-ocular Tension
Discussion,
NELSON MILES BLACK, M.D.,
Milwaukee.
It seems almost useless to attempt any discussion of Dr. de Schweinitz' most terse and comprehensive paper. However, Dr. de Schweinitz mentioned the close relationship which should exist in the non-surgical treatment of increased intra-ocular tension between the internist and the ophthalmologist, but neglected to mention a corresponding relation which should exist between the rhinologist and the ophthalmologist, and possibly between the dental surgeon and the ophthalmologist.
I would like to refer to the _now_ recognized close relationship which exists between disease of the nasal accessory sinuses and diseases of the eye. The definition of glaucoma found in Dr. Wood's system of therapeutics gives rise to an hypothesis as to why disease of the nasal accessory sinuses may be a factor in producing increased intra-ocular tension and why treatment directed toward obtaining free drainage from the sinuses gives good results in so many cases, especially if the relationship is recognized sufficiently early. "Glaucoma proper is essentially a damming or blocking of the drainage from the interior of the eye. The chief lymph stream flows from the posterior chamber past the margin of the lens, through the zonula of Zinn, beneath the iris, through the pupil into the anterior chamber, thence through the tissue at the junction of the iris and sclera into the circular canal of Schlemm and from this space into _the external lymph channels_. _Obstruction to the steady escape of the intra-ocular fluids at any point in this drainage system or any undue increase of the fluids themselves may produce glaucoma._ Probably the most important obstruction to the exosmosis is at the angle close to Schlemm's canal."