As to the advisability of operating on one or both eyes at the same sitting, authorities seem to be about equally divided. It is, however, always my rule to operate upon but one eye at a time, taking at first the eye with the greatest deviation and making a free division of the muscle, and a few weeks later making a second operation upon the other eye, if needed. Previous to operating we should determine the cause of the squint, the vision, the relative power of the muscles, and the degree of the deviation in each eye. The technique of the operation is the same, irrespective of the muscle operated upon.
The result to be obtained from the operation is merely cosmetic, as the vision in the squinting eye is not improved and binocular vision is only restored in a few instances.
Tenotomy of the Internal Rectus.-As this operation is quite painful, as anaesthetic should be used. Four to six instillations of a 4 per cent. solution of cocaine at intervals of about five minutes renders the operation painless, and is to be preferred to a general anaesthetic because we are better able to judge of the effect accomplished. In young or excessively nervous subjects, ether or chloroform may have to be used. The instruments required are a speculum, fixation forceps, curved scissors and strabismus hook (Figs. 49 to 53). The lids should be widely separated by the speculum; the conjunctiva and subconjunctival tissue directly over the insertion of the muscle to be divided is seized with the fixation forceps, and with a pair of curved, blunt-pointed scissors, make a vertical cut down to the muscle, which is then separated from the subconjunctival tissue by dissecting backward with the scissors as far as it is desired to have the muscle slide for its reattachment. The strabismus hook is now to be introduced behind the muscle at its lower edge and, with the point pressed against the eyeball, turned upward beneath the tendon, which is then to be divided close to its insertion by cutting from the point to the base of the hook. The hook should then be inserted again to see if all the lateral expansions of the tendon have been divided; but too frequent and extensive excursions of the hook should be avoided, as it tends to increase the inflammatory action. Care must be exercised that too extensive dissections of Tenon’s capsule, both above and below the muscle, are not made, as the capsule of Tenon serves as a secondary attachment for the ocular muscles, and, if too freely separated from the sclerotic, the effect of the operation may be too greatly increased and the power of the muscle so much affected that it will have little or no action upon the movements of the eye. The sinking of the caruncle is also the result of a too free dissection of Tenon’s capsule.
The use of the suture to limit the effect of the operation, if too extensive, may be necessary; it is introduced though the conjunctiva at the margin of the cornea and then through the conjunctiva over the muscle. In convergent strabismus, with good vision in both eyes, the patient should be able after the operation to fixate and hold the eyes on an object at a distance of about six inches, but if the operated eye ceases to converge, or begins to diverge at eight inches, ultimate divergence may be expected. If the vision is poor, or the muscles weak, a convergence at eight or ten inches is sufficient. Diplopia, with the images near together for two or three days after the operation, is not unfavorable, as it is usually due to the inflammatory action and disappears as the inflammation subsides.
The effect of an operation for convergent squint may be increased, if desired, by a strong suture passed through a fold of the conjunctiva at the outer side near to the cornea, and then carried through the skin at the external canthus, one end above and the other below, about one-eighth of an inch apart, and then tied; or they may be fastened to the skin by strapping. The eye is thus held in the proper position for two days, when the muscles should have become reattached and the suture removed.
Subconjunctival Tenotomy is preferred by some to the operation just described. This is made by snipping the conjunctiva along the lower edge of the insertion of the muscle with blunt straight scissors (Fig. 54). The subconjunctival tissues are then separated over the muscle and the strabismus hook inserted, catching up the muscle on the hook. The scissors are now introduced, one blade in front and the other behind the muscle, which is held on the stretch by the hook, and it is divided subconjunctivally.
Advancement of the Muscle is designed to increase the power of a muscle by shortening it. This operation is useful in cases of extreme divergence and especially in those cases where the operation for convergent strabismus has resulted in a deviation in the opposite direction, and hence the internal rectus is the muscle most frequently advanced. A tenotomy of the opposing muscle is usually necessary and is generally made at the same time.
In advancement of the internal rectus the conjunctiva over the tendon is divided as for tenotomy. The conjunctiva between the cornea and the opening is separated from the sclerotic with the scissors. The tendon is then caught upon the hook and held by an assistant. A suture is next introduced from the upper margin between the tendon and the sclerotic, and passed through the tendon at the median line some distance back of its insertion. Another suture is passed through the tendon from below in the same way. Each suture is then firmly tied on the tendon, a long end being left to each. (See Fig. 55.) The tendon is now to be divided at its insertion, and the sutures passed forward under the conjunctiva flap, the upper to the upper margin of the cornea and the lower to the lower margin. The sutures are then tied separately; the tighter they are drawn the further is the tendon advanced. The operation for advancement devised by Stevens and described on page 184 under heterophoria is a particularly neat and simple operation where but little effect is desired, but where great effects are required we have found the single suture is apt to cut through from the excessive tension.
The After-Treatment.-Simple tenotomy creates no serious reaction, and the patients are allowed to return to their homes and to use their eyes as much as is desired. The use of the ice bag, bathing the eyes in cold water or a solution of calendula gives some relief of the soreness experienced for the first day or two. No bandage should be allowed (except while returning home from the operation), for with protection of the eyes there is not that incentive to parallelism of the visual axes which occurs when the eyes are being used. The advancement of a muscle is accompanied by considerable pain and swelling, which is usually controlled by keeping the patient in bed with both eyes bandaged, the ice bag applied locally and Aconite given internally.
Nystagmus (Oscillation of the Eyeballs).-These movements are involuntary, exceedingly rapid, almost rhythmical and affect both eyes at the same time. The mobility of the eye is not otherwise impaired. The oscillation is generally in the horizontal direction, but may be rotatory, vertical, or in the direction of a single muscle. It is usually permanent, but may be periodic and in some positions of the eye may have a point of rest. Nystagmus is increased in near vision and from excitement; in some cases it is complicated by similar movements of the head, but in an opposite direction. The sight is always impaired, but objects are seen as they are by the patient. Nystagmus is not infrequently associated with squint.
CAUSES.-Generally occurs in early childhood and is principally the result of amblyopia, as in congenital opacities of the cornea, congenital cataract, or total blindness. Nystagmus may be a symptom of cerebral disease, especially disseminated sclerosis.
The nystagmus of miners is a peculiar form of this affection, which first comes on while working in the darkness of the mines, and, as it progresses, lasts through the day, but increases as twilight comes on and has often associated with it night-blindness. These patients are often made dizzy and greatly annoyed by the apparent movement of objects. This form of nystagmus is due to the work done in an insufficient light and with the eyes turned in an unnatural position and often disappears on giving up their work in the mines.
PROGNOSIS.-When once developed, it generally remains, although it may diminish somewhat in advanced life.
TREATMENT.-If strabismus coexists with nystagmus, tenotomy of the contracted muscle should be made. If there is any anomaly of refraction, it must be corrected with glasses.
Agaricus.-Very useful in all spasmodic affections of the muscles of the eye, especially if associated with spasm of the lids, or general chorea. Twitchings of the lids varying from frequent winking to spasmodic closure of them. Twitchings of the eyeballs with various sensations in and around them, chiefly pressing and aching. Eyeball sensitive to touch. The spasmodic movements are absent during sleep, but return on waking and may be transiently relieved by washing in cold water.
Professor of Ophthalmology in the College of the New York Ophthalmic Hospital; Surgeon to the New York Ophthalmic Hospital. Visiting Oculist to the Laura Franklin Free Hospital for Children; Ex-President American Homoeopathic Ophthalmological, Otological and Laryngological Society. First Vice-President American Institute of Homoeopathy : President Homoeopathic Medical Society of the State of New York ; Editor Homoeopathic Eye. Ear and Throat Journal : Associate Editor. Department of Ophthalmology, North American Journal of Homoeopathy, etc.