If there is hyperphoria present, it may be relieved. The immediate effects desired by 1 degree or 2 degree. It is highly important that the operation be made with the least possible disturbance of the tissues surrounding the muscle, so that there may be as little restriction of motion following it as is consistent with the correction of the heterophoria. The patient will commonly complain of diplopia in looking to the extreme limit of the field in the direction of the tenotomized muscle, and it may be many months, or even a year or two before this will disappear. If the operation has not been too extensive, normal mobility will be eventually recovered.
In many cases of lateral heterophoria, a tenotomy is unnecessary. The muscular balance, when but slightly deranged, will often be restored by the gymnastic use of prisms. This method of treatment will require numerous and frequent sittings. I prefer to add to the office treatments the gymnastic use of prisms by the patient several minutes daily, increasing the strength of the prism as the adduction or adduction becomes greater. This exercise with prisms is to be recommended in all cases where the convergence is abnormal, even though an operation be in view, and should be continued until as nearly a normal balance of power as possible is secured.
Therapeutics-The sphere of action of remedies in the treatment of heterophoria is not well defined. The reason for this, lies in the fact already alluded to, that specialists are usually unwilling to restrict themselves to internal medication, but must correct by mechanical or surgical, or by other accessory means, obvious defects in the eyes. Thus errors of refraction and accommodation must be corrected, and the use of systematic exercise and electricity are at least very common accompaniments of the indicated remedy. This compounding of remedial measures, together with the somewhat uncertain knowledge in our possession as to the natural history of eye strain, combine to increase the scepticism in the value of drugs, which the specialist seems naturally to possess.
Speaking simply from my own experience, candor compels me to say that evidences of beneficial effects from medicine in heterophoria are very obscure. Still there are many men in our school who think otherwise, and this failure on my part may be a personal fault. Even among those who are the most sanguine in the use of remedies, however, it is fair to say that their employment is made to play a secondary part to the other methods we have considered. They are held to be useful adjuvants, rather that the principal factors in the cure, and are often resorted to, chiefly when other means have failed.
It is far free my intention to disorders, and certainly when we are called upon to avail ourselves of their help, or law of therapeutics gives us the most satisfactory guide; yet it cannot be denied that surgical, mechanical and empirical local and constitutional methods are the stock-in-trade of the great majority of even those oculists ‘who call themselves “homoeopaths” If it were less so, perhaps it would be better, but we are called upon to face the facts as they are, not as we think they ought to be.
If we have any better success in the practice of any branch of medicine than our Old-School colleagues, it is due directly or indirectly to our law of therapeutics. We cannot afford then, to indulge in too much scepticism as to the value of drugs.
Of the remedies likely to be of benefit in heterophoria, the following may be mentioned as among the most important: Onosmodium, Gels., Senega, Stram., Bry., Phos., Natr. mur., Ruta., Calc. phos., Argent. nit.
DISCUSSION.
JOHN E. PAYNE, M.D.: This admirable paper has so covered the ground of our present knowledge of this subject as to leave but little opportunity for other than a statement of our individual experience in such cases. That heterophoria does exist there can be no doubt, but tests of positive demonstration have been so inadequate as to deter the cautious observer from the application of any remedy that can not be readily annulled should occasion demand. We will look forward with much expectancy to the workings of Dr. Wilson’s improved instrument, a description of which he has been so kind as to give us.
All prism tests heretofore devised have had the disadvantage of being inaccurate when used over strong convex or concave lenses improperly centered. Rapid work is manifestly impossible under these conditions, especially when testing for small degrees of heterophoria. A strong cylinder lens decentered in the meridian of its greatest curvature may upset all our elaborate measurements, and lead us into errors of treatment.
We know that the persistent use of prisms has power to induce simulated heterophoria; why not therefore the same of strong convex or concave spherical or cylinder lenses improperly centered. As a preliminary therefore to all tests for heterophoria we must make accurate adjustments of all lenses correcting errors of refraction. Then as to times for making measurements; I have found that innervation of the recti is greater in early morning and in evening hours, the maximum of control being during the middle of the day. This I have been accustomed to ascribe to the temporary muscular inactivity that is an integral part of our existence after prolonged repose in sleep, in case of the morning hours, and to the fatigue that follows a day’s exertion, in the evening hours.
I have found a difference of as much as four degrees in exophoria. Surely this must have an important bearing on our final diagnosis. Again, who can say from our present methods of examination that a case of heterophoria that presents itself to us is not quite as much due to a spasm of one of the recti muscles as to an insufficiency, or innervation, of its opponent? My experience would head me to suppose that such is the fact in some cases at least, if not in a majority.
During my early study of heterophoria I had occasion to operate on several cases of exophoria, and to my surprise I found that a very careful tenotomy performed on one of these by the Stevens’ method (without the use of strabismus hook, and making the conjunctival opening very small and exactly over the tendinous insertion) was followed by a swinging in of the eye to an over convergence of 16 degrees from an over-divergence of 10 degrees, and by a decided diplopia. The eye seemed literally to “snap” inwards, such force was used by the internus. This case presented, previous to the operation, a very limited adduction with an exaggerated abduction. I have since had the experience repeated.
If the trouble had been due to an innervation of the internus, as, previous to the operation, I had supposed it to be, whence came its sudden accession of strength when freed from the restraint of its opponent? It seems more reasonable in ascribe the whole trouble to a tonic spasm of the externus, causing limited adduction and decided exophoria, than to place it in the usual category of weakened interni. These cases also suggest that our present methods of testing the actual strength of the muscles are misleading, and that a limited adduction or a limited abduction are merely such relatively, and not sufficiently positive in demonstration of individual strength as to allow us to apply such radical treatment as tenotomy.
Dr. Wilson has mentioned Dr. Seguin’s observation of a ” tinnitus, or noise in the head,” accompanying esophoria due to “paresis of the 6th cerebral nerves.” I can bear testimony to a like experience, in two cases of exophoria. In these, the noise was described as a singing, like crickets or grasshoppers in a field, apparently located in the ears themselves, and coming on after prolonged use of the eyes.
One patient said that he considered the advent of this symptom a warning to desist from the use of his eyes, which, if neglected, would result in a severe occipital headache the following day. An examination of his tympanic membranes disclosed a progressive subacute catarrh of the tympanic cavity and membrane, with some thickening of the latter, and a perceptible diminution of the acuteness of hearing. The other case was not examined with reference to this.
Regarding treatment, my experience has not as yet led me to place much reliance in the efficacy of internal medication, but rather to prefer mechanical methods, such as prisms and gymnastic exercise combined with general hygienic measures.
The use of low degree of prisms (the 1 degree or the 2 degree before each eye) in exophoria and in esophoria, even in high degrees of aberration, combined with gymnastic exercise at intervals of two to three days, under personal observation and manipulation, has done more than anything else to secure a restoration of painless vision to the patient. Prisms of high degree do not accomplish more in such cases, and they eventually become an element of dependence that will, in the end, cause an exaggeration of the symptoms.
