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Inadvertent Corticosteroid Injection: Reply
VOL. 81, NO. 3
365
CORRESPONDENCE
Comparison of topical potency, however, could be complicated by differential penetra tion and local metabolism of the compound, as we pointed out in our article. Kupferman and Leibowitz1 claim that the bioavailability in the aqueous of prednisolone acetate ex ceeds that of prednisolone phosphate, while other studies2 show equal penetration of the compounds. Since difference derivatives were used topically we can only compare topical potency in terms of increased intra ocular pressure, not anterior segment bio availability. In this regard our conclusion of dissociation of topical and in vitro effects still stands. HERBERT L. CANTRILL,
M.D.
PAUL F. PALMBERG,
M.D.
HARRY A. Z I N K ,
M.D.
STEPHEN R. WALTMAN,
M.D.
BERNARD BECKER,
M.D.
St. Louis, Missouri STEVEN M. PODOS,
M.D.
New York, New York REFERENCES
1. Kupferman, A., and Leibowitz, H. M. : Topi cally applied steroids in corneal disease. 6. Kinetics of prednisolone sodium phosphate. Arch. Ophthal mol. 92:331, 1974. 2. Hull, D. S., Hine, J. E., Edelhauser, H. F., and Hyndiuk, R. A. : Permeability of the isolated rabbit cornea to corticosteroids. Invest. Ophthalmol. 13:457, 1974. INADVERTENT CORTICOSTEROID INJECTION
Editor : The interesting report, "Inadvertent in jection of corticosteroid into the choroidal vasculature" (Am. J. Ophthalmol. 80:835, 1975), by E. B. McClean has increased our awareness of the risks of periocular injec tions. The author postulated that his pa tient's "choroidal intravascular injection re sulted from inadvertent cannulation of an intrascleral or extrascleral vortex vein," and he then described anatomic considerations that might make such an event possible. This hypothesis does not explain the im
mediate appearance of "white fluocculent material in the anterior chamber," which 24 hours later was noted to have settled on the iris surface. It seems reasonable that this material was the corticosteroid, and Dr. Mc Lean documented a "similar material" in the choroidal vasculature. It is more plausi ble to postulate that the needle penetrated the sciera and that the injection was made into the choroid itself. The force of the in jection could easily cause a cyclodialysis with immediate appearance of corticosteroid in the anterior chamber and subsequent hypotony. M.
GILBERT GRAND,
RONALD M.
BÜRDE,
St. Louis,
M.D. M.D.
Missouri
REPLY
Editor: The hypothesis of Drs. Grand and Bürde with regard to the appearance of corti costeroid in the anterior chamber after an intended subtenon's corticosteroid injection provides additional explanation for an unusual occurrence. The case reported prompted similar hypotheses on my part and led to a limited laboratory investigation into a possible mechanism permitting ac cess of material into the anterior chamber. Briefly, extrascleral vortex veins of enucle ated human eyes were cannulated and in jected with methylprednisolone suspension under minimal pressures. Examination re vealed corticosteroid material within the choroidal vasculature in a pattern and distri bution similar to the clinical case described. The material was found in tributaries of the vortex injected, adjacent vortex sys tems via anastomoses, the anterior radially arranged choroidal veins coursing through the pars plana, venous loops within the ciliary processes, and veins of the iris. In jections directly into the choroid, as sug gested by Drs. Grand and Bürde, were not performed. From this limited investigation, it was apparent that material injected pos-
366
AMERICAN JOURNAL OF OPHTHALMOLOGY
teriorly could reach the anterior chamber entirely by intravascular channels. My in terpretation of this observation was that, in the clinical case reported, rupture of a superficial vessel at or near the root of the iris led to extravasation of material into the anterior chamber. As stated in my re port, the mechanism remains conjectural. EDWARD B . MCLEAN, M.D.
Seattle, Washington NYLON SUTURES IN KERATOPLASTY WOUND SEPARATIONS
Editor: In the paper, "Keratoplasty wound sepa rations" (Am. J . Ophthalmol. 80:161, 1975), by Perry S. Binder, Robert Abel, Jr., Frank M. Polack, and Herber Ε . Kauf man, the authors stated that they used "15-0 (13 μ.) monofilament nylon sutures." The U.S. Pharmacopeia X I X Hsts size 10-0 as the finest size with a diameter of 0.020 to 0.029 mm. For the first time the U.S. Pharmacopeia X I X now lists in addition to the U.S.P. size designations (10-0, 9.0, and the like) the corresponding metric sizes "to achieve a close conformity with the European Phar macopeia." Under these metric sizes there are two sizes finer than U.S.P. size 10-0, which are "0.1 with a diameter of 0.010 to 0.019 mm, and size 0.01 with a diameter of 0.001 to 0.009 mm. Diameter limits for individual sizes are the same for U.S.P. and metric sizes. The TABLE COMPARABLE
U.S.P.
AND M E T R I C S I Z E S O F
MONOFILAMENT NYLON S U T U R E S
U.S.P. Size
Metric Size No.
Limits on Diameter, mm
7-0 8-0 9-0 10-0
0.5 0.4 0.3 0.2 0.1 0.01
0.050-0.069 0.040-0.049 0.030-0.039 0.020-0.029 0.010-0.019 0.001-0.009
—
MARCH, 1976
U.S. Pharmacopeia X I X lists the four small est U.S.P. sizes, the corresponding metric sizes, plus the two even finer metric sizes which have no U.S.P. designation (Table). Applying the logic of U . S . Pharmacopeia X I X , metric size 0.1 would be U.S.P. size 11-0 and metric size 0.01 would be U.S.P. size 12-0, because the difference between diameters of 0.010 mm follows through to these finer sizes. Consequently a suture of 13 μ would be long under metric size 0.1 or U.S.P. size 11-0 if it were listed by the U . S . Phar macopeia X I X , but not 15-0 as stated in the article. I f we followed this logic and de ducted 0.010 mm for each smaller size, then a size smaller than U.S.P. size 12-0 would have a negative diameter. It would be interesting to learn how 13 μ has become 15-0, because it is clear that the smallest possible U.S.P. size would be 12-0. That is only theoretically possible because the technology to make such a fine fiber has not yet been achieved. This clarification certainly will establish order in claims as to suture sizes available, and as to suture sizes used as well. MR. L . E . DREPS
Washington, B.C. REPLY
Editor: Mr. Dreps is correct that there is no satis factory nomenclature for sutures smaller than the standard 23-μ 10-0 suture in com mon use. The U . S . Pharmacopeia has no way of differentiating the newer 13-μ and 16-μ sutures also in use. The classification of these as different from 10-0 by U . S . Pharmacopeia standards is therefore un satisfactory, and the common use of some of the finer classifications does not conform to the U.S. Pharmacopeia standards. The article specified that the suture we used was a 13-μ suture. This is extremely fine as com pared with the grosser 23-μ suture, and this is the major point. There was certainly no
365
CORRESPONDENCE
Comparison of topical potency, however, could be complicated by differential penetra tion and local metabolism of the compound, as we pointed out in our article. Kupferman and Leibowitz1 claim that the bioavailability in the aqueous of prednisolone acetate ex ceeds that of prednisolone phosphate, while other studies2 show equal penetration of the compounds. Since difference derivatives were used topically we can only compare topical potency in terms of increased intra ocular pressure, not anterior segment bio availability. In this regard our conclusion of dissociation of topical and in vitro effects still stands. HERBERT L. CANTRILL,
M.D.
PAUL F. PALMBERG,
M.D.
HARRY A. Z I N K ,
M.D.
STEPHEN R. WALTMAN,
M.D.
BERNARD BECKER,
M.D.
St. Louis, Missouri STEVEN M. PODOS,
M.D.
New York, New York REFERENCES
1. Kupferman, A., and Leibowitz, H. M. : Topi cally applied steroids in corneal disease. 6. Kinetics of prednisolone sodium phosphate. Arch. Ophthal mol. 92:331, 1974. 2. Hull, D. S., Hine, J. E., Edelhauser, H. F., and Hyndiuk, R. A. : Permeability of the isolated rabbit cornea to corticosteroids. Invest. Ophthalmol. 13:457, 1974. INADVERTENT CORTICOSTEROID INJECTION
Editor : The interesting report, "Inadvertent in jection of corticosteroid into the choroidal vasculature" (Am. J. Ophthalmol. 80:835, 1975), by E. B. McClean has increased our awareness of the risks of periocular injec tions. The author postulated that his pa tient's "choroidal intravascular injection re sulted from inadvertent cannulation of an intrascleral or extrascleral vortex vein," and he then described anatomic considerations that might make such an event possible. This hypothesis does not explain the im
mediate appearance of "white fluocculent material in the anterior chamber," which 24 hours later was noted to have settled on the iris surface. It seems reasonable that this material was the corticosteroid, and Dr. Mc Lean documented a "similar material" in the choroidal vasculature. It is more plausi ble to postulate that the needle penetrated the sciera and that the injection was made into the choroid itself. The force of the in jection could easily cause a cyclodialysis with immediate appearance of corticosteroid in the anterior chamber and subsequent hypotony. M.
GILBERT GRAND,
RONALD M.
BÜRDE,
St. Louis,
M.D. M.D.
Missouri
REPLY
Editor: The hypothesis of Drs. Grand and Bürde with regard to the appearance of corti costeroid in the anterior chamber after an intended subtenon's corticosteroid injection provides additional explanation for an unusual occurrence. The case reported prompted similar hypotheses on my part and led to a limited laboratory investigation into a possible mechanism permitting ac cess of material into the anterior chamber. Briefly, extrascleral vortex veins of enucle ated human eyes were cannulated and in jected with methylprednisolone suspension under minimal pressures. Examination re vealed corticosteroid material within the choroidal vasculature in a pattern and distri bution similar to the clinical case described. The material was found in tributaries of the vortex injected, adjacent vortex sys tems via anastomoses, the anterior radially arranged choroidal veins coursing through the pars plana, venous loops within the ciliary processes, and veins of the iris. In jections directly into the choroid, as sug gested by Drs. Grand and Bürde, were not performed. From this limited investigation, it was apparent that material injected pos-
366
AMERICAN JOURNAL OF OPHTHALMOLOGY
teriorly could reach the anterior chamber entirely by intravascular channels. My in terpretation of this observation was that, in the clinical case reported, rupture of a superficial vessel at or near the root of the iris led to extravasation of material into the anterior chamber. As stated in my re port, the mechanism remains conjectural. EDWARD B . MCLEAN, M.D.
Seattle, Washington NYLON SUTURES IN KERATOPLASTY WOUND SEPARATIONS
Editor: In the paper, "Keratoplasty wound sepa rations" (Am. J . Ophthalmol. 80:161, 1975), by Perry S. Binder, Robert Abel, Jr., Frank M. Polack, and Herber Ε . Kauf man, the authors stated that they used "15-0 (13 μ.) monofilament nylon sutures." The U.S. Pharmacopeia X I X Hsts size 10-0 as the finest size with a diameter of 0.020 to 0.029 mm. For the first time the U.S. Pharmacopeia X I X now lists in addition to the U.S.P. size designations (10-0, 9.0, and the like) the corresponding metric sizes "to achieve a close conformity with the European Phar macopeia." Under these metric sizes there are two sizes finer than U.S.P. size 10-0, which are "0.1 with a diameter of 0.010 to 0.019 mm, and size 0.01 with a diameter of 0.001 to 0.009 mm. Diameter limits for individual sizes are the same for U.S.P. and metric sizes. The TABLE COMPARABLE
U.S.P.
AND M E T R I C S I Z E S O F
MONOFILAMENT NYLON S U T U R E S
U.S.P. Size
Metric Size No.
Limits on Diameter, mm
7-0 8-0 9-0 10-0
0.5 0.4 0.3 0.2 0.1 0.01
0.050-0.069 0.040-0.049 0.030-0.039 0.020-0.029 0.010-0.019 0.001-0.009
—
MARCH, 1976
U.S. Pharmacopeia X I X lists the four small est U.S.P. sizes, the corresponding metric sizes, plus the two even finer metric sizes which have no U.S.P. designation (Table). Applying the logic of U . S . Pharmacopeia X I X , metric size 0.1 would be U.S.P. size 11-0 and metric size 0.01 would be U.S.P. size 12-0, because the difference between diameters of 0.010 mm follows through to these finer sizes. Consequently a suture of 13 μ would be long under metric size 0.1 or U.S.P. size 11-0 if it were listed by the U . S . Phar macopeia X I X , but not 15-0 as stated in the article. I f we followed this logic and de ducted 0.010 mm for each smaller size, then a size smaller than U.S.P. size 12-0 would have a negative diameter. It would be interesting to learn how 13 μ has become 15-0, because it is clear that the smallest possible U.S.P. size would be 12-0. That is only theoretically possible because the technology to make such a fine fiber has not yet been achieved. This clarification certainly will establish order in claims as to suture sizes available, and as to suture sizes used as well. MR. L . E . DREPS
Washington, B.C. REPLY
Editor: Mr. Dreps is correct that there is no satis factory nomenclature for sutures smaller than the standard 23-μ 10-0 suture in com mon use. The U . S . Pharmacopeia has no way of differentiating the newer 13-μ and 16-μ sutures also in use. The classification of these as different from 10-0 by U . S . Pharmacopeia standards is therefore un satisfactory, and the common use of some of the finer classifications does not conform to the U.S. Pharmacopeia standards. The article specified that the suture we used was a 13-μ suture. This is extremely fine as com pared with the grosser 23-μ suture, and this is the major point. There was certainly no