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The Prism Scotometer
50
NOTES. CASES AND
ing with a benign form of syphilis. How long ago the infection took place could not be determined, on account of the patient's mentality. Such a syph iloma has probably microscopically the appearance of granulation tissue. It seemed independent of the ciliary body, lying on the iris and in the an terior chamber. Its place at the limbus on the ciliary part of the iris was not specific. A similar condition was seen last year at the clinic, situated on the iris sphincter, between 8 and 10 o'clock. The iris showed a well developed "col larette" "Krause" so that the sphincter part showed as a sort of gutter be tween this collarette and the pupillary pigment border. T h e patient, a woman 45 years old, showed a very painful inflamed eye. Specific treat ment brought it to complete absorp tion, so that on discharge, after some weeks, nothing showed in the place of the large single syphiloma. Our case is interesting on account of the time of development of the pseudotumor. The eye had reacted beautifully to two operations; still it can hardly be doubted that these traumatisms had provocative actions. CONCLUSIONS. The slit lamp was of undoubted value in showing an inflam matory process of the interior part of the eye. In this particular instance the syphiloma appeared diametrically op posite the place which was twice traumatised, and which showed no ab normality in healing. T h e other eye: re mained permanently quiet. If, during the after treatment of cataract extraction, an iritis appears it is not necessary always to accuse in fection, or remaining cortex of capsule. Years ago, before the days of the W a s sermann reaction, in such a condition specific treatment produced the de sired eflfect. The literature does not contain many references to this com plication. I did not find any in the 1923 edition of Greafe-Saemisch, Augenartzliche Operationslehre, nor in Igersheimer's book on Syphilis and the Eye.
INSTRUMENTS
T H E PRISM SCOTOMETER. JOHN N . EVANS,
M.D.
BROOKLYN, N. Y .
When in the year 1668 the French priest Edmond Mariotte demonstrated the existence of the physiologic blind spot before the King of England, he had that monarch rotate his eye in various meridians until the original point of fixation disappeared and re appeared. Snellen and Landolt—in the first edition of Graefe-Saemisch— were still using his method. The method which has stood the test of time, however, has been that of main taining the eye in steady fixation and moving the object, thus permitting ac curate studies of form and relations. A third method of outlining Mariotte's blind spot presents itself. If on a tangent surface we place a small white object 163^^ degrees temporally from the point of fixation, we have lo cated the center of the normal scotoma. I f over the pupil of the fix ing eye we now insert a prism in such a way that its edge approaches close to the line of fixation, we produce the optical effect of moving the center of the blind spot away from the object. It is obvious then that if a prism of about S}i degrees be- used, we would make the object appear at the edge of the blind spot and by turning the prism base in the opposite direction, we would make it appear at the oppo site border. B y using a prism of three degrees -with its apex upward bisect ing the pupil, we can define the upper border and using one of four and onehalf degrees, apex down, we can locate the lower border. Altho this is probably only a curi osity as a means of outlining the blind spot, we can see how it is possible to devise a small instrument of this na ture to give readings accurately and rapidly. In a sense, it more nearly ap proaches objective studies than other methods, and one advantage lies in the fact that suggestion elements are re duced t o .1 minimum as no moN'ing ob ject appears in the v^isual field. ( A rotating variable prism held in front of the fixing eye could be m^de to measure exactly any deviation VCR quired to bring the point of fixation to the edge of the blind spot. E d . )
NOTES. CASES AND
ing with a benign form of syphilis. How long ago the infection took place could not be determined, on account of the patient's mentality. Such a syph iloma has probably microscopically the appearance of granulation tissue. It seemed independent of the ciliary body, lying on the iris and in the an terior chamber. Its place at the limbus on the ciliary part of the iris was not specific. A similar condition was seen last year at the clinic, situated on the iris sphincter, between 8 and 10 o'clock. The iris showed a well developed "col larette" "Krause" so that the sphincter part showed as a sort of gutter be tween this collarette and the pupillary pigment border. T h e patient, a woman 45 years old, showed a very painful inflamed eye. Specific treat ment brought it to complete absorp tion, so that on discharge, after some weeks, nothing showed in the place of the large single syphiloma. Our case is interesting on account of the time of development of the pseudotumor. The eye had reacted beautifully to two operations; still it can hardly be doubted that these traumatisms had provocative actions. CONCLUSIONS. The slit lamp was of undoubted value in showing an inflam matory process of the interior part of the eye. In this particular instance the syphiloma appeared diametrically op posite the place which was twice traumatised, and which showed no ab normality in healing. T h e other eye: re mained permanently quiet. If, during the after treatment of cataract extraction, an iritis appears it is not necessary always to accuse in fection, or remaining cortex of capsule. Years ago, before the days of the W a s sermann reaction, in such a condition specific treatment produced the de sired eflfect. The literature does not contain many references to this com plication. I did not find any in the 1923 edition of Greafe-Saemisch, Augenartzliche Operationslehre, nor in Igersheimer's book on Syphilis and the Eye.
INSTRUMENTS
T H E PRISM SCOTOMETER. JOHN N . EVANS,
M.D.
BROOKLYN, N. Y .
When in the year 1668 the French priest Edmond Mariotte demonstrated the existence of the physiologic blind spot before the King of England, he had that monarch rotate his eye in various meridians until the original point of fixation disappeared and re appeared. Snellen and Landolt—in the first edition of Graefe-Saemisch— were still using his method. The method which has stood the test of time, however, has been that of main taining the eye in steady fixation and moving the object, thus permitting ac curate studies of form and relations. A third method of outlining Mariotte's blind spot presents itself. If on a tangent surface we place a small white object 163^^ degrees temporally from the point of fixation, we have lo cated the center of the normal scotoma. I f over the pupil of the fix ing eye we now insert a prism in such a way that its edge approaches close to the line of fixation, we produce the optical effect of moving the center of the blind spot away from the object. It is obvious then that if a prism of about S}i degrees be- used, we would make the object appear at the edge of the blind spot and by turning the prism base in the opposite direction, we would make it appear at the oppo site border. B y using a prism of three degrees -with its apex upward bisect ing the pupil, we can define the upper border and using one of four and onehalf degrees, apex down, we can locate the lower border. Altho this is probably only a curi osity as a means of outlining the blind spot, we can see how it is possible to devise a small instrument of this na ture to give readings accurately and rapidly. In a sense, it more nearly ap proaches objective studies than other methods, and one advantage lies in the fact that suggestion elements are re duced t o .1 minimum as no moN'ing ob ject appears in the v^isual field. ( A rotating variable prism held in front of the fixing eye could be m^de to measure exactly any deviation VCR quired to bring the point of fixation to the edge of the blind spot. E d . )