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Practical Use of the Ophthalmometer.'
By LORENZO BURROWS, M. D., Buffalo, N. Y.
Attending Ophthalmologist, Buffalo General Hospital. NASMUCH as most of the difficulties experienced in getting I favorable results with the ophthalmometer arise from improper handling, I have undertaken to describe and give the reasons for my own method of operating it, which for a good many years has yielded as nearly perfect satisfaction as any one test can.
POSITION. With the table and chin rest so adjusted that the patient can comfortably keep the head in position with the eyes at the height of the white marks on the sides of the frame, the chin is set firmly on its rest; then from behind, the operator grasps the patient's head and tips it forward, with the chin as a fulcrum, guiding with the fingers, so that when the forehead touches its rest, there will be the same space on either side, between the temples and the sides of the head frame; and the skin of the forehead will lie smoothly in its normal position and not drawn in any direction. The patient must maintain a steady pressure with both the chin and the forehead. This is the only way to get the head straight. Bringing the eyes to a level by sighting through the horizontal slit in the disc, as is usually advised, is entirely wrong, because, generally they are not at the same level in the head and tilting it sidewise to make them so, is not the natural way of carrying it; and if the reading is taken in that position, the axis will be at fault, unless the tilting is so slight that it can be overcome by tortion, and the fact that the axis as indicated by the instrument, after leveling the eyes, so often agrees with that indicated by the trial lenses, is a strong argument against the statement that there is no such movement as tortion; without it, the two findings would disagree whenever the patient's face was asymmetrical, that is to say, almost always.
FOCUSING. When using the old instrument that tilts forward or backward, to bring the telescope in line with the eye, it is necessary to refocus it after the mires are moved to the secondary position; because the primary position being say, with the mires in the horizontal plane, and the whole instrument standing at an appreciable angle, with the top nearer the eye than the bottom; when the mires are rotated to the vertical plane, the upper one
1. Read before the Buffalo Ophthalmological Club, January 12, 1905.
will lie inside the original focus and the lower one outside, and an accurate reading will be impossible because of the resultant blurred images. The newer instruments, adjusted to raise and lower by a screw, leaving the disc in the same plane, should be focused in the primary position and not changed.
READING. If possible, the amount of overlapping must be read with the lids opened naturally; because their pressure upon the eyeball often makes a marked difference in the amount of astigmatism ; sometimes as much as one diopter. This fact is used as the basis for the statement that the patient's eyes should be kept wide open in order to avoid an artificial showing; whether it is or is not artificial, it is a condition that is constant and the ciliary muscle has to meet it; therefore, it must be corrected as it stands and not as it theoretically should be.
APPLICATION OF READING. The general rule is, to substract from the reading a quarter or half diopter, when the astigmatism is with the rule, and add a quarter or half diopter when against the rule, the result representing the amount of correction the eye will accept. This is ordinarily applicable, but is subject to variations ranging from nothing up to one diopter and occasionally it will be found necessary to reverse the order and add when the astigmatism is with the rule, etc. Allowing for lenticular astigmatism, is the reason commonly given for making these reductions or additions; an asymmetry of the curvature of the posterior surface of the cornea and fundus astigmatism have also been suggested. Whatever may be the reason for it, the fact stands, that it must be done, and the point to keep in mind is that it must not be done arbitrarily; it is not less elastic than any other rule governing refraction. Some operators seem to disregard it entirely, and look upon the showing of the instrument as absolute which is a grievous mistake, because when the reading is less than one-half diopter with the rule, the astigmatism is nearly always against the rule, perhaps as much as one diopter.
AXIS-PRIMARY AND SECONDARY POSITION. In a large proportion of eyes, the meridians of greatest and least curvature are not exactly ninety degrees apart; that is, the astigmatism is irregular.
Roughly stated, about one-third of all cases show this irregularity in one or both eyes. The variation may be anywhere between five and forty degrees, and is most frequently found associated with astigmatism of less than one diopter, although quite
an appreciable number may be noted with astigmatism of one to two diopters. A difference is rarely seen in the higher degrees.
In applying this part of the finding, it must be remembered that the axis indicated by the long pointer, when the mires are in the primary position, i. e., at or near the horizontal plane,-is that for a minus cylinder if with the rule or a plus cylinder if against the rule; and the axis indicated by the long pointer when the mires are in the secondary position,-i. e., at or near the vertical plane,-is that for a plus cylinder if with the rule or a minus cylinder if against the rule; this is because the axis indicated in the primary position is obtained by exactly aligning the mires in the horizontal meridian and this can be done only at the horizontal axis; and the axis indicated in the secondary position is obtained by exactly aligning the mires in the vertical meridian and this can be done only at the vertical axis. This interpretation of the finding is almost invariably correct.
REASONS FOR DISAGREEMENT WITH TRIAL LENS FINDINGS.
1. Having the patient, open the eyes unnaturally wide, because, pressure of the lids upon the eyeball increases astigmatism with the rule and decreases astigmatism against the rule. Drawing the skin of the forehead may add to or detract from this pressure.
2. Taking the reading with the instrument improperly focused, because the farther the telescope is from the eye the larger the images will be and the more they will overlap, and vice versa.
3. Failure to correctly apply the rule for reducing from or adding to the reading.
4. Latent astigmatism.
1. Arbitrarily assuming that the secondary position is ninety degrees from the primary instead of finding it independentlybecause one-third of the cases will show some irregularity.
2. Tilting the patient's head, to bring the eyes to the same level, because they are most always placed at different levels in the head.
482 FRANKLIN STREET.
A SANATORIUM for consumptives, intended as a memorial of King Humbert I., was opened at Leghorn on November 19, 1904, in the presence of the King of Italy.-Med. Age.
The Electro-magnet in Eye Work-Its Use in Two Cases.
BY ALBERT C. SNELL, M. D., Rochester, N. Y. C ASE I.-On August 5, 1904, Mr. C., 26 years of age, was
sent to me by Dr. Percy with the statement that the patient had been struck in his left eye by a piece of steel. Examination showed a clean-cut vertical wound of the cornea, 2 in.m. long, situated opposite the nasal edge of the dilated pupil ; a small nick in the iris; and an opaque and swollen lens. Vision was reduced to light perception only. With the ophthalmoscope, no part of the fundus of the eye could be seen. The foreign body had apparently passed through cornea, iris and lens and had lodged somewhere in the vitreous or deeper.
In order to better determine the presence of a foreign body, Dr. Greenleaf was requested to make an x-ray picture. The plate showed the presence of the steel and indicated that it was deeply situated.
Patient was sent to the City Hospital and under a general anesthetic, the cornea was incised, an iridectomy performed, and the tip of a small electro-magnet introduced in the wound. After making repeated attempts with the various tips to find the steel and failing to attach it, the operation was desisted in.
Two days later the eye developed all the symptoms of panophthalmitis and the patient then consented to have the eye enucleated. This was done and the eye immediately opened. A triangular sliver of steel, 3 m.m. long and 1 m.m. in its thickest part, was found lying to the nasal side of the optic disc. It was imbedded in the sclera and covered with lymph and pus. The reason for failure to extract the steel was evidently due to its attachment in the sclera. And even had it been successfully removed the eye-ball would have been lost from infection; as thie steel was from the edge of a dirty, greasy tool and at the time of the magnet operation evidences of infection were found.
Case II.—Peter X., age 35, was struck in the left eye, June 1, 1904, by a piece of iron while breaking up scrap iron with a sledge hammer. Two years previously he had had a similar accident to his right eye which resulted in complete blindness of that eye. Examination of the left showed an open clean-cut wound, # m.m. long extending obliquely across the center of the cornea ; the sphincter of the iris slightly cut down and in; and the lens cataractous. Vision was light perception.
The patient was sent to the wards of the City Hospital where Dr. Andrew made an r-ray picture, which showed the presence of the foreign body. Under a general anesthetic the electromagnet operation was performed. Forty-eight hours had elapsed since the accident and the wound was closed, therefore an incision
1. Read at the 37th annual meeting of the Medical Association of Central New York, held at Rochester, N. Y., October 18, 1904.
was made above through the cornea similar to the incision for cataract. An iridectomy was done and the greater part of the soft lens removed by pressure and curette. The iron was not found in the lens. The short, blunt tip of the magnet was then introduced to the depth of the posterior surface of the lens and on withdrawing it there was found attached to it three small pieces of metal, 12 m.m. or less in their largest dimension. These were demonstrated to be metal by again magnetising them after wiping them from the tip. A longer and curved tip was now introduced and slowly pushed back to about one half the depth of the vitreous when a decided click was heard and the tip on being withdrawn was seen to have a piece of metal attached to it. This was seized between the lips of the wound with a pair of forceps and removed. It is a thin egg-shaped piece ✓ m.m. long and 3 m.m. broad.
The wound healed promptly and the eye made a good recovery. With a + 10 sph. lens patient has to vision which enables him to follow a useful occupation and to earn his livelihood. He was last seen October 4 and his excellent vision was still maintained.
I report these two cases not because of novelty either in the cases themselves or in the use of the electro-magnet. They are examples of a failure and of a success and are illustrative of a large number of similar cases which have been reported at various times. The use of the electro-magnet for removal of metal from the eye was first employed by Hirschberg and by Dr. Bradford in 1881. The permanent magnet was used previous to this date but was found to be of little value on account of its weak pulling power. Since this date the electro-magnet has been made in various sizes from the original Hirschberg, which weighs about a pound and is easily handled, to the Haab giant magnet which is non-portable on account of its size and weight and has pulling strength enough to pick pockets of watches.
Successful recovery of an eye which has had metal removed from it depends largely on two factors, infection and location. The nearer the metal lodges to the anterior surface of the eye the less the danger of destructive infection and the less the danger of doing irreparable damage to vision in the removal. The deeper it lodges the greater these dangers. A large percentage of foreign bodies lodged in the iris or lens are removed successfully both as to saving the eye-ball and as to saving its vision, while useful vision following extraction of metal from the vitreous is the exception.
My second case presents a point of special interest: the fact that with a single wound of entrance there existed within the eye-ball several pieces of metal lying in different locations. This