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Results of a Temporary Balloon Buckle in the Treatment of 500 Retinal Detachments and a Comparison with Pneumatic Retinopexy
612
November, 1989
AMERICAN JOURNAL OF OPHTHALMOLOGY
3. Dutton, J. J.: Surgical management of floppy eyelid syndrome. Am. J. Ophthalmol. 99:557, 1985. 4. Goldberg, R., Seiff, S., McFarland, J., Simmons, K., and Shorr, N.: Floppy eyelid syndrome and blepharochalasis. Am. J. Ophthalmol. 102:376, 1986.
Correspondence Correspondence concerning recent articles or other material published in THE JOURNAL should be submitted within six weeks of publication. Correspondence must be typed double-spaced, on 8Vi x 11-inch bond paper with lte-inch margins on all four sides and should be no more than two typewritten pages in length. Every effort will be made to resolve controversies between the correspondents and the authors of the article before publication.
Results of a Temporary Balloon Buckle in the Treatment of 500 Retinal Detachments and a Comparison With Pneumatic Retinopexy EDITOR: The most interesting article, "Results of a temporary balloon buckle in the treatment of 500 retinal detachments and a comparison with pneumatic retinopexy," by I. Kreissig, J. Failer, H. Lincoff, and F. Ferrari (Am. J. Ophthalmol. 107:381, April 1989), raises several concerns. The summary states that the primary attachment rate was 91% "with parabulbar balloon and cryopexy" in 454 of 500 eyes. Later in the article the authors state that 125 patients required a second operation with laser photocoagulation. It would be preferable to state that the initial operation achieved reattachment in 66% of eyes, and that with the second procedure it was achieved in 9 1 % . Drs. Lincoff and Kreissig, the co-inventors of the balloon, have previously reported in chronological order, single operation success rates of 82/100 (82%),' 278/320 (87%), 2 and now 9 1 % , suggesting a definite learning curve. It is commendable that they have attained this high level of skill, but other surgeons have reported lower rates, such as 14/19 (73%), 2 16/20 (80%), 2 11/15 (73%), 2 and 18/28 (64%). 3 In the Results section the authors describe five complications. One wonders why they did not describe the eyes that had postoperative vitreous hemorrhage, and new retinal
breaks. In the Discussion, the authors state that "except for choroidal effusion in one eye there were no intraocular complications." This statement overlooks their cases of postoperative proliferative vitreoretinopathy, vitreous hemorrhage, and new retinal breaks. The last is particularly important in light of two recent series that have reported five of 28 (18%)3 and nine of 52 (17%)4 new breaks after the balloon operation. They compared their results to a "similar" group treated with the gas bubble. This similar control group are the data from ten papers from the literature, a dissimilar group. They provided a list of the preoperative features in their balloon cases. Unfortunately, preoperative data are not available for all of the 500 cases in which gas was used, but it is available in the two largest series of pneumatic retinopexy procedures (their references 15 and 19). The balloon group included pseudophakia in one of 500 (0.2%) and macular detachment in 93 of 500 (18%). But in the two largest pneumatic retinopexy series, there was pseudophakia in 70 of 203 (34%), and detachment of the macula in 114 of 203 (56%). This indicates that the two groups are not similar and should not be used for comparison. This comparison contrasts the work of an experienced balloon surgeon with that of surgeons reporting their initial experience with a new technique. Kreissig and associates report the highest cure rate to date and compare it to pneumatic retinopexy papers with variable results. A more accurate comparison would have included the various other papers on the balloon method that give lower cure rates. The authors omitted four other papers on the results of pneumatic retinopexy. These four papers all reported results that were better than the average of the ten papers they chose for their comparison in Table 3 (reference 5 below and their references 29, 31, and 33). GEORGE F. HILTON, M.D. San Francisco, California PAUL E. TORNAMBE, M.D. San Diego, California W. SANDERSON GRIZZARD, M.D. Tampa, Florida
References 1. Lincoff, H. A., and Kreissig, I.: Results with a temporary balloon buckle for the repair of retinal detachment. Am. J. Ophthalmol. 92:245, 1981.
Correspondence
Vol. 108, No. 5
2. Lincoff, H. A., Kreissig, I., Richard, G., Okun, E., Oik, R., Friedman, W., Mester, U., Witassek, B., Kroll, P., Binder, S., and Bissogiannis, Z.: A multicentered trial of the balloon buckle. In Henkind, P. (ed.): Acta: XXV International Congress of Ophthalmology, vol. 1. Philadelphia, J. B. Lippincott, 1983, pp. 517-519. 3. McAllister, I. L., Meyers, S. M., Zegarra, H., Gutman, F. A., Zakow, N., and Beck, G. J.: Comparison of pneumatic retinopexy with alternative surgical techniques. Ophthalmology 95:877, 1988. 4. Binder, S.: Repair of retinal detachments with temporary balloon buckling. Retina 6:210, 1988. 5. McAllister, I. L., Zegarra, H., Meyers, S. M., and Gutman, F. A.: Treatment of retinal detachments with multiple breaks by pneumatic retinopexy. Arch. Ophthalmol. 105:913, 1987.
Reply EDITOR: Drs. Hilton, Tornambe, and Grizzard are concerned that in our summary we state that 91% of 500 detachments were attached with a balloon and cryopexy and that in the Material and Methods we state supplemental laser was applied to 125 eyes. They would prefer that the laser be recorded as a second operation. Supplemental laser was applied once each to 125 eyes, in which all or part of the break was too posterior to be reached by the cryoprobe. The summary would have been more accurate if it had been stated that in 91% of the eyes attachment was achieved with a parabulbar balloon and coagulation, either cryopexy or laser. Drs. Hilton, Tornambe, and Grizzard are concerned about our choice of the 500 retinal detachments treated with pneumatic retinopexy that we used for comparison. We picked the ten largest series in which the selection of patients conformed to the criteria for selecting patients for the balloon, namely, an uncomplicated detachment with one break or group of breaks smaller than one clock hour. All of the reports on gas are from retinal surgeons of some distinction. Half are from Hilton, Tornambe, Grizzard, and Dominguez. Although the lower incidence of macular detachment in the balloon population might bias the balloon for better visual result, we did not compare visual results. They complain that anatomic results were prejudiced by the presence of 70 pseudophakic patients in their series, as opposed to one in the balloon series. Pseudophakic patients have only recently been treated in Tubingen, hence the single patient; however, there were 61 aphakic patients in the balloon series, which Drs. Hil-
613
ton, Tornambe, and Grizzard have overlooked. They take issue with our statement in the Discussion that, "except for choroidal effusion in one eye there were no intraocular complications from the balloon insertion." They ask that we take note of our incidence of proliferative vitreoretinopathy, new breaks, and hemorrhages. At that point in the Discussion, we were intent upon contrasting the occurrence of the 11 intraocular complications listed; all of these occurred after the gas operation and none after the balloon. We discussed postoperative development of proliferative vitreoretinopathy and new breaks. Hemorrhage did not occur. The 70 intraocular hemorrhages were present preoperatively, and were recorded in the Material and Methods. The postoperative incidence of proliferative vitreoretinopathy and new retinal breaks was the primary issue of our paper. We maintain that an extraocular procedure, whether a balloon or a sponge buckle, does not increase the natural incidence of proliferative vitreoretinopathy or new breaks. As evidence we cited the low incidence of new breaks (seven of 500) and proliferative vitreoretinopathy (one of 500) in the detachments treated with the balloon. The incidence of new breaks after an intraocular injection of gas is ten times greater and proliferative vitreoretinopathy 18 times greater. The difference is significant (P = .0002) and supports our contention that intraocular gas provokes the vitreous. Drs. Hilton, Tornambe, and Grizzard make no effort to refute this conclusion. We have considered and rejected a randomized controlled study. We have used the expanding gas technique for more than a decade, 1 3 and we have experienced all the complications reported. In contrast, with the balloon operation and some experience with it4 optimal reattachment rates, such as 94 of 100 (94% )5 and 43 of 48 (90%), 6 were obtained by others as well. Therefore we think that to treat 500, or even 100, uncomplicated detachments with intraocular gas at this point, solely to meet the criteria for randomization, would be frivolous. I. KREISSIG, M.D. J. FAILER, M.D. Tubingen, West Germany H. LINCOFF, M.D. New York, New York F. FERRARI, M.D. Tubingen, West Germany
614
November, 1989
AMERICAN JOURNAL OF OPHTHALMOLOGY
References 1. Kreissig, I.: Bisherige Erfahrungen mit SF6-Gas in der Ablatio-Chirurgie. Ber. Dtsch. Ophthalmol. Ges. 76:553, 1979. 2. Lincoff, H., Kreissig, I., Brodie, S., and Wilcox, L.: Expanding gas bubbles for the repair of tears in the posterior pole. Graefes Arch. Clin. Exp. Ophthalmol. 219:193, 1982. 3. Kreissig, I., Stanowsky, A., Lincoff, H., and Richard, G.: The treatment of difficult retinal detachments with an expanding gas bubble without vitrectomy. Graefes Arch. Clin. Exp. Ophthalmol. 224:51, 1986. 4. Kreissig, I.: Zehn Jahre Erfahrungen mit der Ballon-Operation. Anfangliche Skepsis, Weiterentwicklung der Methode, praktische Hinweise fur den Ballon-Operateur. Klin. Monatsbl. Augenheilkd. 194:145, 1989. 5. Pichard, G.: Indikation, Technik und Ergebnisse der Ballonoperation. Klin. Monatsbl. Augenheilkd. 190:484, 1987. 6. Hausmann, N.: Die Lincoff/Kreissig-Ballonplombe. Indikationen und Stellenwert in unserem Stufenplan der minimalen Ablatiobehandlung. Spektrum Augenheilkd. 2:264, 1988.
Corneal Compression Sutures for the Reduction of Astigmatism After Penetrating Keratoplasty EDITOR: T h e article, " C o r n e a l c o m p r e s s i o n s u t u r e s for the r e d u c t i o n of a s t i g m a t i s m after p e n e t r a t i n g k e r a t o p l a s t y , " b y M. B. L i m b e r g , S. A. D i n g e l d e i n , M. T. G r e e n , S. D. Klyce, M. S. Insler, a n d H. E. K a u f m a n ( A m . J. O p h t h a l mol. 108:36, July 1989), r e p o r t e d t h a t n i n e to 12 m o n t h s after t h e u s e of c o m p r e s s i o n s u t u r e s , a s t i g m a t i s m after p e n e t r a t i n g k e r a t o plasty w a s r e d u c e d by 48% in ten e y e s . T h e ten e y e s in t h e s t u d y h a d a n a v e r a g e i n t e r v a l of 13 m o n t h s b e t w e e n p e n e t r a t i n g k e r a t o p l a s ty a n d p l a c e m e n t of t h e c o m p r e s s i o n s u t u r e s . In s e v e n of t h e t e n e y e s a c o n t i n u o u s 10-0 n y l o n s u t u r e h a d b e e n left a n d t h e c o m p r e s sion s u t u r e a d d e d . I h a v e t w o q u e s t i o n s : (1) W h y w a s n ' t t h e c o n t i n u o u s 11-0 s u t u r e r e m o v e d before a d d ing t h e c o m p r e s s i o n s u t u r e ? A c o n t i n u o u s s u t u r e left in place can p r o d u c e a s t i g m a t i s m ; I h a v e s e e n r e m o v a l of s u c h a s u t u r e result in a
1 2 - d i o p t e r c h a n g e . (2) 10-0 N y l o n is b i o d e g r a d a b l e . If t h e a u t h o r s e x p e c t e d to h a v e a c o n t i n u e d effect of t h e c o m p r e s s i o n s u t u r e beyond the 11-month follow-up, w h y didn't t h e y u s e a 10-0 p o l y p r o p y l e n e or 10-0 M e r s i l e n e , w h i c h are n o t b i o d e g r a d a b l e ? LOUIS J. GIRARD, M.D. Houston, Texas
Reply
-
EDITOR: We u n d e r t o o k this s t u d y to d e t e r m i n e if p l a c e m e n t of c o m p r e s s i o n s u t u r e s in t h e flat c o r n e a l axis after r e m o v a l of all i n t e r r u p t e d s u t u r e s c o u l d be u s e d for r a p i d v i s u a l r e h a b i l itation of p a t i e n t s after p e n e t r a t i n g k e r a t o p l a s t y . We k n e w t h a t selective s u t u r e r e m o v a l w o u l d allow r e d u c t i o n of c y l i n d e r , b u t t h i s a p p r o a c h involves m a n y patient visits, and s u b s e q u e n t l y r e q u i r e s r e m o v a l of a l a r g e n u m b e r of s u t u r e s , w i t h t h e p o t e n t i a l for increased astigmatism. The technique we used in t h e s t u d y w a s d e s i g n e d to allow r e m o v a l of t h e r u n n i n g or i n t e r r u p t e d 10-0 n y l o n s u t u r e s three m o n t h s postoperatively, without the w o u n d s e p a r a t i o n t h a t w o u l d be likely if t h e 11-0 s u t u r e w e r e r e m o v e d . T h e n , t w o i n t e r r u p t e d s u t u r e s c o u l d be r e p l a c e d o n l y if nece s s a r y , to r e d u c e excess c y l i n d e r . In a p r e l i m i n a r y s t u d y , w e u s e d 10-0 M e r s i l e n e ( p o l y e s t e r ) s u t u r e s in ten p a t i e n t s w i t h g o o d initial r e v e r s a l of c y l i n d e r . Two m o n t h s after s u t u r e p l a c e m e n t , h o w e v e r , 90% of t h e c o m p r e s s i v e effect w a s lost; t h e t h i n , inelastic s u t u r e h a d cut t h r o u g h t h e t i s s u e , b e c a u s e of t h e t e n s i o n o n t h e s u t u r e s r e q u i r e d to r e v e r s e large a m o u n t s of c y l i n d e r . To red u c e this p r o b l e m , w e c h o s e 9-0 n y l o n s u t u r e b e c a u s e of its elasticity a n d larger d i a m e t e r . T h e r u n n i n g 11-0 n y l o n s u t u r e , if p r e s e n t , w a s left in place to d e t e r m i n e if t h e effect of the compression suture would persist despite o t h e r w o u n d m o d e l i n g forces. This a l l o w e d u s to r e v e r s e p o s t k e r a t o p l a s t y a s t i g m a t i s m as early as t h r e e m o n t h s after t r a n s p l a n t a t i o n surgery. MICHAEL B. LIMBERG, M.D. STEVEN A. DINGELDEIN, M.D. MARYT. GREEN, M.D. STEPHEN D. KLYCE, Ph.D. MICHAEL S. INSLER, M.D. HERBERT E. KAUFMAN, M.D. New Orleans, Louisiana
November, 1989
AMERICAN JOURNAL OF OPHTHALMOLOGY
3. Dutton, J. J.: Surgical management of floppy eyelid syndrome. Am. J. Ophthalmol. 99:557, 1985. 4. Goldberg, R., Seiff, S., McFarland, J., Simmons, K., and Shorr, N.: Floppy eyelid syndrome and blepharochalasis. Am. J. Ophthalmol. 102:376, 1986.
Correspondence Correspondence concerning recent articles or other material published in THE JOURNAL should be submitted within six weeks of publication. Correspondence must be typed double-spaced, on 8Vi x 11-inch bond paper with lte-inch margins on all four sides and should be no more than two typewritten pages in length. Every effort will be made to resolve controversies between the correspondents and the authors of the article before publication.
Results of a Temporary Balloon Buckle in the Treatment of 500 Retinal Detachments and a Comparison With Pneumatic Retinopexy EDITOR: The most interesting article, "Results of a temporary balloon buckle in the treatment of 500 retinal detachments and a comparison with pneumatic retinopexy," by I. Kreissig, J. Failer, H. Lincoff, and F. Ferrari (Am. J. Ophthalmol. 107:381, April 1989), raises several concerns. The summary states that the primary attachment rate was 91% "with parabulbar balloon and cryopexy" in 454 of 500 eyes. Later in the article the authors state that 125 patients required a second operation with laser photocoagulation. It would be preferable to state that the initial operation achieved reattachment in 66% of eyes, and that with the second procedure it was achieved in 9 1 % . Drs. Lincoff and Kreissig, the co-inventors of the balloon, have previously reported in chronological order, single operation success rates of 82/100 (82%),' 278/320 (87%), 2 and now 9 1 % , suggesting a definite learning curve. It is commendable that they have attained this high level of skill, but other surgeons have reported lower rates, such as 14/19 (73%), 2 16/20 (80%), 2 11/15 (73%), 2 and 18/28 (64%). 3 In the Results section the authors describe five complications. One wonders why they did not describe the eyes that had postoperative vitreous hemorrhage, and new retinal
breaks. In the Discussion, the authors state that "except for choroidal effusion in one eye there were no intraocular complications." This statement overlooks their cases of postoperative proliferative vitreoretinopathy, vitreous hemorrhage, and new retinal breaks. The last is particularly important in light of two recent series that have reported five of 28 (18%)3 and nine of 52 (17%)4 new breaks after the balloon operation. They compared their results to a "similar" group treated with the gas bubble. This similar control group are the data from ten papers from the literature, a dissimilar group. They provided a list of the preoperative features in their balloon cases. Unfortunately, preoperative data are not available for all of the 500 cases in which gas was used, but it is available in the two largest series of pneumatic retinopexy procedures (their references 15 and 19). The balloon group included pseudophakia in one of 500 (0.2%) and macular detachment in 93 of 500 (18%). But in the two largest pneumatic retinopexy series, there was pseudophakia in 70 of 203 (34%), and detachment of the macula in 114 of 203 (56%). This indicates that the two groups are not similar and should not be used for comparison. This comparison contrasts the work of an experienced balloon surgeon with that of surgeons reporting their initial experience with a new technique. Kreissig and associates report the highest cure rate to date and compare it to pneumatic retinopexy papers with variable results. A more accurate comparison would have included the various other papers on the balloon method that give lower cure rates. The authors omitted four other papers on the results of pneumatic retinopexy. These four papers all reported results that were better than the average of the ten papers they chose for their comparison in Table 3 (reference 5 below and their references 29, 31, and 33). GEORGE F. HILTON, M.D. San Francisco, California PAUL E. TORNAMBE, M.D. San Diego, California W. SANDERSON GRIZZARD, M.D. Tampa, Florida
References 1. Lincoff, H. A., and Kreissig, I.: Results with a temporary balloon buckle for the repair of retinal detachment. Am. J. Ophthalmol. 92:245, 1981.
Correspondence
Vol. 108, No. 5
2. Lincoff, H. A., Kreissig, I., Richard, G., Okun, E., Oik, R., Friedman, W., Mester, U., Witassek, B., Kroll, P., Binder, S., and Bissogiannis, Z.: A multicentered trial of the balloon buckle. In Henkind, P. (ed.): Acta: XXV International Congress of Ophthalmology, vol. 1. Philadelphia, J. B. Lippincott, 1983, pp. 517-519. 3. McAllister, I. L., Meyers, S. M., Zegarra, H., Gutman, F. A., Zakow, N., and Beck, G. J.: Comparison of pneumatic retinopexy with alternative surgical techniques. Ophthalmology 95:877, 1988. 4. Binder, S.: Repair of retinal detachments with temporary balloon buckling. Retina 6:210, 1988. 5. McAllister, I. L., Zegarra, H., Meyers, S. M., and Gutman, F. A.: Treatment of retinal detachments with multiple breaks by pneumatic retinopexy. Arch. Ophthalmol. 105:913, 1987.
Reply EDITOR: Drs. Hilton, Tornambe, and Grizzard are concerned that in our summary we state that 91% of 500 detachments were attached with a balloon and cryopexy and that in the Material and Methods we state supplemental laser was applied to 125 eyes. They would prefer that the laser be recorded as a second operation. Supplemental laser was applied once each to 125 eyes, in which all or part of the break was too posterior to be reached by the cryoprobe. The summary would have been more accurate if it had been stated that in 91% of the eyes attachment was achieved with a parabulbar balloon and coagulation, either cryopexy or laser. Drs. Hilton, Tornambe, and Grizzard are concerned about our choice of the 500 retinal detachments treated with pneumatic retinopexy that we used for comparison. We picked the ten largest series in which the selection of patients conformed to the criteria for selecting patients for the balloon, namely, an uncomplicated detachment with one break or group of breaks smaller than one clock hour. All of the reports on gas are from retinal surgeons of some distinction. Half are from Hilton, Tornambe, Grizzard, and Dominguez. Although the lower incidence of macular detachment in the balloon population might bias the balloon for better visual result, we did not compare visual results. They complain that anatomic results were prejudiced by the presence of 70 pseudophakic patients in their series, as opposed to one in the balloon series. Pseudophakic patients have only recently been treated in Tubingen, hence the single patient; however, there were 61 aphakic patients in the balloon series, which Drs. Hil-
613
ton, Tornambe, and Grizzard have overlooked. They take issue with our statement in the Discussion that, "except for choroidal effusion in one eye there were no intraocular complications from the balloon insertion." They ask that we take note of our incidence of proliferative vitreoretinopathy, new breaks, and hemorrhages. At that point in the Discussion, we were intent upon contrasting the occurrence of the 11 intraocular complications listed; all of these occurred after the gas operation and none after the balloon. We discussed postoperative development of proliferative vitreoretinopathy and new breaks. Hemorrhage did not occur. The 70 intraocular hemorrhages were present preoperatively, and were recorded in the Material and Methods. The postoperative incidence of proliferative vitreoretinopathy and new retinal breaks was the primary issue of our paper. We maintain that an extraocular procedure, whether a balloon or a sponge buckle, does not increase the natural incidence of proliferative vitreoretinopathy or new breaks. As evidence we cited the low incidence of new breaks (seven of 500) and proliferative vitreoretinopathy (one of 500) in the detachments treated with the balloon. The incidence of new breaks after an intraocular injection of gas is ten times greater and proliferative vitreoretinopathy 18 times greater. The difference is significant (P = .0002) and supports our contention that intraocular gas provokes the vitreous. Drs. Hilton, Tornambe, and Grizzard make no effort to refute this conclusion. We have considered and rejected a randomized controlled study. We have used the expanding gas technique for more than a decade, 1 3 and we have experienced all the complications reported. In contrast, with the balloon operation and some experience with it4 optimal reattachment rates, such as 94 of 100 (94% )5 and 43 of 48 (90%), 6 were obtained by others as well. Therefore we think that to treat 500, or even 100, uncomplicated detachments with intraocular gas at this point, solely to meet the criteria for randomization, would be frivolous. I. KREISSIG, M.D. J. FAILER, M.D. Tubingen, West Germany H. LINCOFF, M.D. New York, New York F. FERRARI, M.D. Tubingen, West Germany
614
November, 1989
AMERICAN JOURNAL OF OPHTHALMOLOGY
References 1. Kreissig, I.: Bisherige Erfahrungen mit SF6-Gas in der Ablatio-Chirurgie. Ber. Dtsch. Ophthalmol. Ges. 76:553, 1979. 2. Lincoff, H., Kreissig, I., Brodie, S., and Wilcox, L.: Expanding gas bubbles for the repair of tears in the posterior pole. Graefes Arch. Clin. Exp. Ophthalmol. 219:193, 1982. 3. Kreissig, I., Stanowsky, A., Lincoff, H., and Richard, G.: The treatment of difficult retinal detachments with an expanding gas bubble without vitrectomy. Graefes Arch. Clin. Exp. Ophthalmol. 224:51, 1986. 4. Kreissig, I.: Zehn Jahre Erfahrungen mit der Ballon-Operation. Anfangliche Skepsis, Weiterentwicklung der Methode, praktische Hinweise fur den Ballon-Operateur. Klin. Monatsbl. Augenheilkd. 194:145, 1989. 5. Pichard, G.: Indikation, Technik und Ergebnisse der Ballonoperation. Klin. Monatsbl. Augenheilkd. 190:484, 1987. 6. Hausmann, N.: Die Lincoff/Kreissig-Ballonplombe. Indikationen und Stellenwert in unserem Stufenplan der minimalen Ablatiobehandlung. Spektrum Augenheilkd. 2:264, 1988.
Corneal Compression Sutures for the Reduction of Astigmatism After Penetrating Keratoplasty EDITOR: T h e article, " C o r n e a l c o m p r e s s i o n s u t u r e s for the r e d u c t i o n of a s t i g m a t i s m after p e n e t r a t i n g k e r a t o p l a s t y , " b y M. B. L i m b e r g , S. A. D i n g e l d e i n , M. T. G r e e n , S. D. Klyce, M. S. Insler, a n d H. E. K a u f m a n ( A m . J. O p h t h a l mol. 108:36, July 1989), r e p o r t e d t h a t n i n e to 12 m o n t h s after t h e u s e of c o m p r e s s i o n s u t u r e s , a s t i g m a t i s m after p e n e t r a t i n g k e r a t o plasty w a s r e d u c e d by 48% in ten e y e s . T h e ten e y e s in t h e s t u d y h a d a n a v e r a g e i n t e r v a l of 13 m o n t h s b e t w e e n p e n e t r a t i n g k e r a t o p l a s ty a n d p l a c e m e n t of t h e c o m p r e s s i o n s u t u r e s . In s e v e n of t h e t e n e y e s a c o n t i n u o u s 10-0 n y l o n s u t u r e h a d b e e n left a n d t h e c o m p r e s sion s u t u r e a d d e d . I h a v e t w o q u e s t i o n s : (1) W h y w a s n ' t t h e c o n t i n u o u s 11-0 s u t u r e r e m o v e d before a d d ing t h e c o m p r e s s i o n s u t u r e ? A c o n t i n u o u s s u t u r e left in place can p r o d u c e a s t i g m a t i s m ; I h a v e s e e n r e m o v a l of s u c h a s u t u r e result in a
1 2 - d i o p t e r c h a n g e . (2) 10-0 N y l o n is b i o d e g r a d a b l e . If t h e a u t h o r s e x p e c t e d to h a v e a c o n t i n u e d effect of t h e c o m p r e s s i o n s u t u r e beyond the 11-month follow-up, w h y didn't t h e y u s e a 10-0 p o l y p r o p y l e n e or 10-0 M e r s i l e n e , w h i c h are n o t b i o d e g r a d a b l e ? LOUIS J. GIRARD, M.D. Houston, Texas
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EDITOR: We u n d e r t o o k this s t u d y to d e t e r m i n e if p l a c e m e n t of c o m p r e s s i o n s u t u r e s in t h e flat c o r n e a l axis after r e m o v a l of all i n t e r r u p t e d s u t u r e s c o u l d be u s e d for r a p i d v i s u a l r e h a b i l itation of p a t i e n t s after p e n e t r a t i n g k e r a t o p l a s t y . We k n e w t h a t selective s u t u r e r e m o v a l w o u l d allow r e d u c t i o n of c y l i n d e r , b u t t h i s a p p r o a c h involves m a n y patient visits, and s u b s e q u e n t l y r e q u i r e s r e m o v a l of a l a r g e n u m b e r of s u t u r e s , w i t h t h e p o t e n t i a l for increased astigmatism. The technique we used in t h e s t u d y w a s d e s i g n e d to allow r e m o v a l of t h e r u n n i n g or i n t e r r u p t e d 10-0 n y l o n s u t u r e s three m o n t h s postoperatively, without the w o u n d s e p a r a t i o n t h a t w o u l d be likely if t h e 11-0 s u t u r e w e r e r e m o v e d . T h e n , t w o i n t e r r u p t e d s u t u r e s c o u l d be r e p l a c e d o n l y if nece s s a r y , to r e d u c e excess c y l i n d e r . In a p r e l i m i n a r y s t u d y , w e u s e d 10-0 M e r s i l e n e ( p o l y e s t e r ) s u t u r e s in ten p a t i e n t s w i t h g o o d initial r e v e r s a l of c y l i n d e r . Two m o n t h s after s u t u r e p l a c e m e n t , h o w e v e r , 90% of t h e c o m p r e s s i v e effect w a s lost; t h e t h i n , inelastic s u t u r e h a d cut t h r o u g h t h e t i s s u e , b e c a u s e of t h e t e n s i o n o n t h e s u t u r e s r e q u i r e d to r e v e r s e large a m o u n t s of c y l i n d e r . To red u c e this p r o b l e m , w e c h o s e 9-0 n y l o n s u t u r e b e c a u s e of its elasticity a n d larger d i a m e t e r . T h e r u n n i n g 11-0 n y l o n s u t u r e , if p r e s e n t , w a s left in place to d e t e r m i n e if t h e effect of the compression suture would persist despite o t h e r w o u n d m o d e l i n g forces. This a l l o w e d u s to r e v e r s e p o s t k e r a t o p l a s t y a s t i g m a t i s m as early as t h r e e m o n t h s after t r a n s p l a n t a t i o n surgery. MICHAEL B. LIMBERG, M.D. STEVEN A. DINGELDEIN, M.D. MARYT. GREEN, M.D. STEPHEN D. KLYCE, Ph.D. MICHAEL S. INSLER, M.D. HERBERT E. KAUFMAN, M.D. New Orleans, Louisiana