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Comparative Ophthalmodynamometry Using Scleral Pressure, Suction, and Corneal Pressure Units
COMPARATIVE OPHTHALMODYNAMOMETRY USING SCLERAL PRESSURE, SUCTION, AND CORNEAL P R E S S U R E U N I T S A PILOT STUDY OF 56 NORMAL SUBJECTS HAMPSON A. SISLER,
M.D.
New York, New York
Ophthalmodynamometry, a method of de termining ophthalmic artery pressures by means of artificially raising the intraocular pressure to equal first diastolic and then sys tolic pressures, was introduced in 1917 by Bailliart and Magitot.1 The first instrument applied graduated direct mechanical pressure to the equator of the globe of the eye while an ophthalmoscope was used to see the endpoints (onset of full-amplitude arterial pul sation at the optic disk, for the diastole, and total cessation of arterial flow for systole). Scierai suction, as a means of producing graded elevation of the intraocular pressure to equal vascular levels, was introduced by Kukan, 2 in 1936. His instrument has since been refined, most recently by Gregus and Galin.3 The new optical corneal pressure ophthalmodynamometer uses the slit lamp micro scopic system and its own fundus-focusing lens, thereby eliminating the ophthalmoscope. Instead of the axes of pressure (or of suc tion) and of optic disk visualization being roughly perpendicular to each other, as in the earlier instruments, they now coincide and must both be exactly radial to the globe, pass ing through its optical center. The examiner's visual axis controls both concurrently, so that oblique (and therefore partially ineffec tive) vectors of force are theoretically elimi nated. In order to test the relative consistency, 56 normal subjects were examined by the differ ent instruments, and this paper presents a comparison of the results obtained. From the Department of Ophthalmology, New York Eye and Ear Infirmary, New York. Reprint requests to Hampson A. Sisler, M.D., Department of Ophthalmology, New York Eye and Ear Infirmary, 310 East 14th Street, New York, New York 10003.
MATERIAL AND METHODS
Since bilaterally unequal intraocular pres sures are known to affect dynamometric de terminations inversely, both eyes of all sub jects being considered for this study were examined by applanation tonometry (Amer ican Optical Co. unit) at the slit lamp as the first step. Those in whom readings for the two eyes differed by more than 2 mm H g were eliminated from the series. Brachial di astolic pressures were taken by sphygmomanometry both before and after dynamomet ric readings by the three techniques. This served as a means of eliminating patients whose nervousness caused vascular pressure fluctuations (thus, introducing artifactual differences between their two eyes), and it also permitted us to see how these readings correlated with the ophthalmic vascular pres sures. There were 56 normal subjects considered suitable for this investigation, and in these, diastolic pressures were taken once in each eye with each of the three instruments to be compared in this study. Systolic pressures, though possible with all three instruments, were avoided since we felt that it would be unsafe as well as uncomfortable for the ex aminee have his intraocular pressure raised to such high levels in both eyes by all three methods in a relatively brief period. All patients were seated quietly before the slit lamp for 10 minutes before the study was started, and throughout all of the proce dures they were not moved, except for rota tion on the same stool, in an effort to keep vascular pressures stable throughout. The three instruments used in this investi gation: Bailliart dial-spring pressure unit (Handaya, Tokyo, Japan), a Gregus-Galen suction unit (Smith, Miller, and Patch) with 964
VOL. 74, NO. 5
COMPARATIVE OPHTHALMODYNAMOMETRY
965
TABLE 1 DlASTOLIC OPHTHALMODYNAMOMETRIC DATA AND STATISTICAL ANALYSIS
Bailliart (grams)
Patient
J.K.
T.S. L.W.
J.G.
G.P. L.A. R.H. I.F. D.B. G.A. D.B. S.L. L.M. P.S. B.C.
E.J.
E.F. L.R. R.C. G.A. R.B. F.R. F.M. S.E. C.R. E.S. H.K. K.L. H.U. B.K. D.T. W.S. M.M. P.V. A.S. E.M. E.D. T.D. M.M. P.M. R.B. S.H. A.S. R.P. W.R. M.T. B.P. S.K. L.P.
J.F. J.D.
P.M.
v.s. P.B.
D.G. M.K.
Suction (mm Hg)
Corneal Pressure (grams)
RE
LE
RE
LE
RE
LE
48 52 60 40 43 53 63 47 46 48 50 74 53 55 30 40 57 60 62 45 65 57 35 52 45 50 57 42 67 55 48 42 46 43 33 46 50 40 44 65 47 30 49 52 51 42 49 32 50 65 45 46 63 41 47 42
50 62 70 40 38 43 55 42 44 52 45 85 54 65 40 46 60 45 53 47 75 53 43 47 38 60 63 46 54 66 46 38 53 56 47 57 52 53 49 76 43 38 52 44 54 50 55 40 58 55 40 54 55 35 42 43
56 58 73 65 55 62 67 50 53 69 65 83 65 69 65 67 62 65 85 65 75 61 55 62 61 62 81 56 73 85 52 65 44 65 59 53 44 47 59 65 49 50 64 53 50 49 54 49 53 73 52 59 61 56 47 65
69 73 77 50 52 58 81 56 62 65 59 87 56 85 56 55 77 53 83 62 79 75 61 56 56 69 87 53 62 83 62 56 56 62 62 56 41 47 62 69 52 38 61 49 55 52 46 47 65 62 49 69 73 46 52 53
48 58 68 60 49 64 82 44 44 60 55 112 58 76 43 40 57 53 72 56 75 62 55 70 47 52 56 52 63 56 33 40 57 60 61 48 54 62 40 92 43 44 56 52 62 52 74 37 80 63 50 46 70 42 42 44
47 57 64 64 46 65 78 48 48 60 53 111 54 69 39 39 62 49 71 52 69 64 52 78 50 58 61 58 56 55 40 4» 52 62 60 60 52 69 47 84 45 44 55 54 62 49 71 38 76 62 52 44 68 41 40 45
966
AMERICAN JOURNAL OF OPHTHALMOLOGY
NOVEMBER, 1972
TABLE 2 DlASTOLIC OPTHALMODYNAMOMETRIC DATA AND STATISTICAL ANALYSIS
Mean value (all patients) RE: LE: Correlation coefficient (fellow eyes with each other, in all patients) Standard deviation for mean values of all right vs all left eyes Mean applanation intraocular pressure (all eyes together) Mean brachial diastolic pressure
a hand-held May direct ophthalmoscope for disk observation, and an optical corneal pres sure unit prepared for me by American Op tical Company. This unit is affixed to the ap planation tonometer platform of the Ameri can Optical Company slit lamp. A minimum of five minutes elapsed be tween readings on individual eyes, and read ings were always alternated between the two eyes of each patient. With each of the instru ments, an attempt was made to apply the in strumental stress to the globe—pressure or suction—evenly and with a comparable de gree of speed bilaterally. RESULTS
Table 1 shows the individual instrument readings, while Table 2 shows statistical analyses of the results, including mean val ues for all right and all left eyes for each of the three methods. It also shows the correla tion coefficients and standard deviations be tween the two eyes as tested by the three dif ferent instruments. Average overall intraoc ular pressure and brachial diastolic pressure are included for comparison with dynamometric averages. DISCUSSION
Although this was a small pilot study, Ta ble 1 shows that the correlation coefficient approaches unity much more closely with the optical corneal pressure ophthalmodyna-
Baillart
Suction
Corneal Pressure
49.268 51.179 0.709 3.75 17.31 mmHg 81.53 mm Hg
60.839 61.412 0.716 4.39
56.982 56.946 0.957 2.55
mometer than with the other two instru ments. This indicates a high degree of con sistency in readings between the two eyes of these normal subjects in whom ophthalmic artery pressures might be expected to be equal bilaterally. The standard deviation be tween the readings for the two eyes is smaller for the new instrument than for the other two techniques, also indicating greater accuracy with it than with the other two. SUMMARY
Ophthalmodynamometric diastolic read ings were taken by three techniques: Bailliart scierai pressure, Gregus-Galen suction, and a new optical corneal pressure method, in 56 normal subjects in whom ophthalmic artery pressures were equal bilaterally. Cor relation coefficients and standard deviations between the two eyes of the same subject, tested in all three ways, showed greater con sistency—and therefore greater accuracy— with the new instrument than with the older techniques. REFERENCES
1. Bailliart, P. : La Pression arterielle dans les branches de l'artère centrale de la rétine; nouvelle techniques pour la déterminer. Am. Ocul. 154:648, 1917. 2. Kukan, F. : Ergebnisse der Blutdruckmessun gen mit einem neuen ophthalmodynamometer. Z. Augenheilk. 90:166, 1936. 3. Gregus, P., and Galin, M. A. : Suction ophthalmodynamometry via fluidic control. Tr. Am. Acad. Ophth. Otolaryng. 75:647, 1971.
M.D.
New York, New York
Ophthalmodynamometry, a method of de termining ophthalmic artery pressures by means of artificially raising the intraocular pressure to equal first diastolic and then sys tolic pressures, was introduced in 1917 by Bailliart and Magitot.1 The first instrument applied graduated direct mechanical pressure to the equator of the globe of the eye while an ophthalmoscope was used to see the endpoints (onset of full-amplitude arterial pul sation at the optic disk, for the diastole, and total cessation of arterial flow for systole). Scierai suction, as a means of producing graded elevation of the intraocular pressure to equal vascular levels, was introduced by Kukan, 2 in 1936. His instrument has since been refined, most recently by Gregus and Galin.3 The new optical corneal pressure ophthalmodynamometer uses the slit lamp micro scopic system and its own fundus-focusing lens, thereby eliminating the ophthalmoscope. Instead of the axes of pressure (or of suc tion) and of optic disk visualization being roughly perpendicular to each other, as in the earlier instruments, they now coincide and must both be exactly radial to the globe, pass ing through its optical center. The examiner's visual axis controls both concurrently, so that oblique (and therefore partially ineffec tive) vectors of force are theoretically elimi nated. In order to test the relative consistency, 56 normal subjects were examined by the differ ent instruments, and this paper presents a comparison of the results obtained. From the Department of Ophthalmology, New York Eye and Ear Infirmary, New York. Reprint requests to Hampson A. Sisler, M.D., Department of Ophthalmology, New York Eye and Ear Infirmary, 310 East 14th Street, New York, New York 10003.
MATERIAL AND METHODS
Since bilaterally unequal intraocular pres sures are known to affect dynamometric de terminations inversely, both eyes of all sub jects being considered for this study were examined by applanation tonometry (Amer ican Optical Co. unit) at the slit lamp as the first step. Those in whom readings for the two eyes differed by more than 2 mm H g were eliminated from the series. Brachial di astolic pressures were taken by sphygmomanometry both before and after dynamomet ric readings by the three techniques. This served as a means of eliminating patients whose nervousness caused vascular pressure fluctuations (thus, introducing artifactual differences between their two eyes), and it also permitted us to see how these readings correlated with the ophthalmic vascular pres sures. There were 56 normal subjects considered suitable for this investigation, and in these, diastolic pressures were taken once in each eye with each of the three instruments to be compared in this study. Systolic pressures, though possible with all three instruments, were avoided since we felt that it would be unsafe as well as uncomfortable for the ex aminee have his intraocular pressure raised to such high levels in both eyes by all three methods in a relatively brief period. All patients were seated quietly before the slit lamp for 10 minutes before the study was started, and throughout all of the proce dures they were not moved, except for rota tion on the same stool, in an effort to keep vascular pressures stable throughout. The three instruments used in this investi gation: Bailliart dial-spring pressure unit (Handaya, Tokyo, Japan), a Gregus-Galen suction unit (Smith, Miller, and Patch) with 964
VOL. 74, NO. 5
COMPARATIVE OPHTHALMODYNAMOMETRY
965
TABLE 1 DlASTOLIC OPHTHALMODYNAMOMETRIC DATA AND STATISTICAL ANALYSIS
Bailliart (grams)
Patient
J.K.
T.S. L.W.
J.G.
G.P. L.A. R.H. I.F. D.B. G.A. D.B. S.L. L.M. P.S. B.C.
E.J.
E.F. L.R. R.C. G.A. R.B. F.R. F.M. S.E. C.R. E.S. H.K. K.L. H.U. B.K. D.T. W.S. M.M. P.V. A.S. E.M. E.D. T.D. M.M. P.M. R.B. S.H. A.S. R.P. W.R. M.T. B.P. S.K. L.P.
J.F. J.D.
P.M.
v.s. P.B.
D.G. M.K.
Suction (mm Hg)
Corneal Pressure (grams)
RE
LE
RE
LE
RE
LE
48 52 60 40 43 53 63 47 46 48 50 74 53 55 30 40 57 60 62 45 65 57 35 52 45 50 57 42 67 55 48 42 46 43 33 46 50 40 44 65 47 30 49 52 51 42 49 32 50 65 45 46 63 41 47 42
50 62 70 40 38 43 55 42 44 52 45 85 54 65 40 46 60 45 53 47 75 53 43 47 38 60 63 46 54 66 46 38 53 56 47 57 52 53 49 76 43 38 52 44 54 50 55 40 58 55 40 54 55 35 42 43
56 58 73 65 55 62 67 50 53 69 65 83 65 69 65 67 62 65 85 65 75 61 55 62 61 62 81 56 73 85 52 65 44 65 59 53 44 47 59 65 49 50 64 53 50 49 54 49 53 73 52 59 61 56 47 65
69 73 77 50 52 58 81 56 62 65 59 87 56 85 56 55 77 53 83 62 79 75 61 56 56 69 87 53 62 83 62 56 56 62 62 56 41 47 62 69 52 38 61 49 55 52 46 47 65 62 49 69 73 46 52 53
48 58 68 60 49 64 82 44 44 60 55 112 58 76 43 40 57 53 72 56 75 62 55 70 47 52 56 52 63 56 33 40 57 60 61 48 54 62 40 92 43 44 56 52 62 52 74 37 80 63 50 46 70 42 42 44
47 57 64 64 46 65 78 48 48 60 53 111 54 69 39 39 62 49 71 52 69 64 52 78 50 58 61 58 56 55 40 4» 52 62 60 60 52 69 47 84 45 44 55 54 62 49 71 38 76 62 52 44 68 41 40 45
966
AMERICAN JOURNAL OF OPHTHALMOLOGY
NOVEMBER, 1972
TABLE 2 DlASTOLIC OPTHALMODYNAMOMETRIC DATA AND STATISTICAL ANALYSIS
Mean value (all patients) RE: LE: Correlation coefficient (fellow eyes with each other, in all patients) Standard deviation for mean values of all right vs all left eyes Mean applanation intraocular pressure (all eyes together) Mean brachial diastolic pressure
a hand-held May direct ophthalmoscope for disk observation, and an optical corneal pres sure unit prepared for me by American Op tical Company. This unit is affixed to the ap planation tonometer platform of the Ameri can Optical Company slit lamp. A minimum of five minutes elapsed be tween readings on individual eyes, and read ings were always alternated between the two eyes of each patient. With each of the instru ments, an attempt was made to apply the in strumental stress to the globe—pressure or suction—evenly and with a comparable de gree of speed bilaterally. RESULTS
Table 1 shows the individual instrument readings, while Table 2 shows statistical analyses of the results, including mean val ues for all right and all left eyes for each of the three methods. It also shows the correla tion coefficients and standard deviations be tween the two eyes as tested by the three dif ferent instruments. Average overall intraoc ular pressure and brachial diastolic pressure are included for comparison with dynamometric averages. DISCUSSION
Although this was a small pilot study, Ta ble 1 shows that the correlation coefficient approaches unity much more closely with the optical corneal pressure ophthalmodyna-
Baillart
Suction
Corneal Pressure
49.268 51.179 0.709 3.75 17.31 mmHg 81.53 mm Hg
60.839 61.412 0.716 4.39
56.982 56.946 0.957 2.55
mometer than with the other two instru ments. This indicates a high degree of con sistency in readings between the two eyes of these normal subjects in whom ophthalmic artery pressures might be expected to be equal bilaterally. The standard deviation be tween the readings for the two eyes is smaller for the new instrument than for the other two techniques, also indicating greater accuracy with it than with the other two. SUMMARY
Ophthalmodynamometric diastolic read ings were taken by three techniques: Bailliart scierai pressure, Gregus-Galen suction, and a new optical corneal pressure method, in 56 normal subjects in whom ophthalmic artery pressures were equal bilaterally. Cor relation coefficients and standard deviations between the two eyes of the same subject, tested in all three ways, showed greater con sistency—and therefore greater accuracy— with the new instrument than with the older techniques. REFERENCES
1. Bailliart, P. : La Pression arterielle dans les branches de l'artère centrale de la rétine; nouvelle techniques pour la déterminer. Am. Ocul. 154:648, 1917. 2. Kukan, F. : Ergebnisse der Blutdruckmessun gen mit einem neuen ophthalmodynamometer. Z. Augenheilk. 90:166, 1936. 3. Gregus, P., and Galin, M. A. : Suction ophthalmodynamometry via fluidic control. Tr. Am. Acad. Ophth. Otolaryng. 75:647, 1971.