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Biodegradability of the Krupin-Denver Valve
Vol. 105, No. 5
Letters to the Journal
Mawad, M.: Computed tomography and magnetic resonance imaging in the diagnosis of inflammatory disease of the optic nerve. Surv. Ophthalmol. 31:352, 1987.
559
dence of significant biodegradation of the seton. A 63-year-old man with neovascular glauco ma had undergone placement of a KrupinDenver valve in his left eye two years previous ly after a branch retinal vein occlusion. The valve, which had been placed according to the standard protocol, was guarded by a partialthickness scleral flap. The tube became occlud ed by granulation tissue and cryotherapy was Biodegradability of the necessary to control the intraocular pressure. Krupin-Denver Valve Visual acuity was reduced to 20/200. Both the scleral flap and the conjunctiva later became L. David Ormerod, M . D . , eroded. A narrow band of vessels derived from Michael Pickford, M . A . , the limbal vessels surrounded the basal part of and George Baerveldt, M . D . the intraocular nylon-6 tube. Department of Ophthalmology, Massachusetts Eye When perforation of the attenuated overlying and Ear Infirmary, Harvard Medical School, and the Eye Research Institute of Retina Foundation conjunctiva appeared imminent, removal of the (L.D.O.); and the Department Ophthalmology, Uni valve was attempted under retrobulbar anes versity of Southern California, and the Estelle thesia. The fibrous episcleral capsule was di Doheny Eye Foundation, (M.P., G.B.). vided and gentle retrograde traction applied to Inquiries to George Baerveldt, M.D., Estelle Doheny Eye the Silastic segment. The nylon-6 tube separat Foundation, 1355 San Pablo St., Los Angeles, CA 90033. ed at its midpoint, however, leaving the distal end tenuously adherent to the iris and in dan In neovascular glaucoma the anterior cham ger of displacement into the vitreous. Its imme ber angle is irreversibly occluded by proliferadiate intraocular removal was necessary. tive fibrovascular tissue. The prognosis for use Scanning electron microscopy showed the ful vision with conventional medical and midportion of the nylon-6 segment to be dif surgical management remains poor. Increased knowledge of the causes of bleb failure and fusely attenuated, fractured, and infolded (Fig. advances in polymer technology have led to a 1). The Silastic valve was normal. When com resurgence of interest in the development of pared to a sectioned, unused Krupin-Denver setons, aiming to control intraocular pressure valve (Fig. 2), which showed the nylon-6 tube permanently in this condition. One such suc cessful seton is the Krupin-Denver valve. 1 The valve consists of three major compo nents: an extraocular Silastic tube containing horizontal and vertical slits; an open nylon-6 (Supramid) intraocular tube with an internal diameter of 0.88 mm and uniform walls of 0.10 mm thickness; and two horizontal nylon-6 arms. The Silastic tube functions as a undirectional, pressure-sensitive valve and is designed to maintain intraocular pressure between 11 mm Hg and 14 mm Hg. The Silastic tube is molded at a 160-degree angle to the nylon-6 tube, and is trimmed during surgery to extend 1 to 4 mm into the anterior chamber. The two horizontal nylon-6 arms are attached to the undersurface of the junction between the two tubes, and are used for fixation. Complications from the use of the KrupinDenver valve include hyphema, ciliochoroidal detachment, external bleb failure, posterior Fig. 1 (Ormerod, Pickford, and Baerveldt). Scan valve migration, granulation tissue ingrowth ning electron micrograph showing diffuse attenua around the valve, and erosions of the scleral tion of the proximal fracture margin in the nylon-6 flap and conjunctiva. 2 To this list we add evi part of the Krupin-Denver valve (x 63.3).
560
AMERICAN JOURNAL OF OPHTHALMOLOGY
May, 1988
Chiasmal Compression Caused by a Catheter in the Suprasellar Cistern Michael L. Slavin, M.D., and Alan D. Rosenthal, M.D. Division of Neuro-ophthalmology, Department of Ophthalmology (M.L.S.), and the Division of Neurosurgery, Department of Surgery (A.D.R.), Long Is land Jewish Medical Center.
Fig. 2 (Ormerod, Pickford, and Baerveldt). Scan ning electron micrograph of a sectioned, unused (untrimmed) Krupin-Denver valve placed in embed ding medium (x 8.6). N, nylon-6 tube; S, Silastic tube and valve. to h a v e walls of e v e n t h i c k n e s s (0.1 m m ) , the nylon-6 t u b e in this case h a d u n d e r g o n e b o t h s e r i o u s b i o d e g r a d a t i o n a n d loss of tensile s t r e n g t h after two years in the a n t e r i o r c h a m ber. The o p h t h a l m i c b i o d e g r a d a b i l i t y of n y l o n 6, u s e d as s u t u r e s a n d intraocular lens l o o p s , has b e e n widely reported 3 - 4 a n d reviewed. 5 The u s e of nylon-6 in the K r u p i n - D e n v e r valve m a y lead to its late m e c h a n i c a l failure, a n d s u r g e o n s r e m o v i n g this t u b e s h o u l d be alert to the possi bility of fracture.
References 1. Krupin, T., Kaufman, P., Mandell, A., Ritch, R., Asseff, C , Podos, S. M., and Becker, B.: Filtering valve implant surgery for eyes with neovascular glaucoma. Am. J. Ophthalmol. 89:338, 1980. 2. Krupin, T., Kaufman, P., Mandell, A. I., Terry, S. A., Ritch, R., Podos, S. M., and Becker, B.: Longterm results of valve implants in filtering surgery for eyes with neovascular glaucoma. Am. J. Ophthal mol. 95:775, 1983. 3. Drews, R. C , Smith, M. E., and Okun, N.: Scanning electron microscopy of intraocular lenses. Ophthalmology 85:415, 1978. 4. KronenthaJ, R. L.: Nylon in the anterior cham ber. Ophthalmology 88:965, 1981. 5. Refojo, M. F.: Polymers in ophthalmology. In Rubin, L. R. (ed.): Biomaterials in Reconstructive Surgery. St Louis, C. V. Mosby, 1983, pp. 955-967.
Inquiries to Michael L. Slavin, M.D., Department of Ophthalmology, Long Island Jewish Medical Center, New Hyde Park, NY 11042. In 1977, C o p p e t o a n d G a h m 1 r e p o r t e d a case in w h i c h chiasmal c o m p r e s s i o n w a s c a u s e d by a v e n t r i c u l a r c a t h e t e r that h a d i n a d v e r t e n t l y l o d g e d in t h e third ventricle. We treated a p a t i e n t w i t h p r o g r e s s i v e visual loss a n d bitemporal visual field defects c a u s e d by a Silastic c a t h e t e r in t h e s u p r a s e l l a r cistern. A 73-year-old w o m a n d e v e l o p e d ataxia a n d " d i z z i n e s s . " C o m p u t e d t o m o g r a p h y disclosed a n extra-axial p o s t e r i o r fossa m a s s a n d ventric ular e n l a r g e m e n t . A c r a n i o t o m y w a s per formed a n d a large m e n i n g i o m a w a s resected. An i n t r a v e n t r i c u l a r c a t h e t e r w a s placed a n d a t t a c h e d to a n O m m a y a reservoir, for the possi bility of c o n v e r s i o n to a v e n t r i c u l o p e r i t o n e a l s h u n t , if n e c e s s a r y . T h e p a t i e n t did well in the following year, except for p r o g r e s s i v e left tem p o r a l v i s u a l field d i s t u r b a n c e . O n n e u r o - o p h t h a l m i c e x a m i n a t i o n , best cor rected visual acuity w a s R.E.: 20/30 a n d L.E.: 20/40. T h e r e w a s a distinct b i t e m p o r a l h e m i c h r o m a t o p s i a . Results of a visual field exam ination disclosed relative b i t e m p o r a l visual loss in the central i s o p t e r s . A left afferent p u pillary defect w a s n o t e d . The optic disks w e r e normal. Postoperative computed tomography showed t h a t t h e distal e n d of t h e s u p p o s e d i n t r a v e n tricular c a t h e t e r w a s located at t h e level of t h e s u p r a s e l l a r cistern (Figure). T h e c a t h e t e r w a s s u b s e q u e n t l y excised. O n follow-up e x a m i n a t i o n two m o n t h s later, best corrected visual acuity w a s R.E.: 20/20 a n d L.E.: 20/25. A q u e s t i o n a b l e left afferent p u p i l defect w a s n o t e d . Results of a visual field exam i n a t i o n w e r e nearly n o r m a l on the right, a n d s h o w e d a d i m i n i s h e d t e m p o r a l scotoma on the left. C h i a s m a l c o m p r e s s i o n m a y occur w h e n a c a t h e t e r i n t e n d e d for the lateral ventricle inad v e r t e n t l y l o d g e s in the third ventricle or in the s u p r a s e l l a r cistern. The p o s t e r i o r notch of the optic c h i a s m a n a t o m i c a l l y forms the a n t e r o inferior b o r d e r of the third ventricle. The nasal
Letters to the Journal
Mawad, M.: Computed tomography and magnetic resonance imaging in the diagnosis of inflammatory disease of the optic nerve. Surv. Ophthalmol. 31:352, 1987.
559
dence of significant biodegradation of the seton. A 63-year-old man with neovascular glauco ma had undergone placement of a KrupinDenver valve in his left eye two years previous ly after a branch retinal vein occlusion. The valve, which had been placed according to the standard protocol, was guarded by a partialthickness scleral flap. The tube became occlud ed by granulation tissue and cryotherapy was Biodegradability of the necessary to control the intraocular pressure. Krupin-Denver Valve Visual acuity was reduced to 20/200. Both the scleral flap and the conjunctiva later became L. David Ormerod, M . D . , eroded. A narrow band of vessels derived from Michael Pickford, M . A . , the limbal vessels surrounded the basal part of and George Baerveldt, M . D . the intraocular nylon-6 tube. Department of Ophthalmology, Massachusetts Eye When perforation of the attenuated overlying and Ear Infirmary, Harvard Medical School, and the Eye Research Institute of Retina Foundation conjunctiva appeared imminent, removal of the (L.D.O.); and the Department Ophthalmology, Uni valve was attempted under retrobulbar anes versity of Southern California, and the Estelle thesia. The fibrous episcleral capsule was di Doheny Eye Foundation, (M.P., G.B.). vided and gentle retrograde traction applied to Inquiries to George Baerveldt, M.D., Estelle Doheny Eye the Silastic segment. The nylon-6 tube separat Foundation, 1355 San Pablo St., Los Angeles, CA 90033. ed at its midpoint, however, leaving the distal end tenuously adherent to the iris and in dan In neovascular glaucoma the anterior cham ger of displacement into the vitreous. Its imme ber angle is irreversibly occluded by proliferadiate intraocular removal was necessary. tive fibrovascular tissue. The prognosis for use Scanning electron microscopy showed the ful vision with conventional medical and midportion of the nylon-6 segment to be dif surgical management remains poor. Increased knowledge of the causes of bleb failure and fusely attenuated, fractured, and infolded (Fig. advances in polymer technology have led to a 1). The Silastic valve was normal. When com resurgence of interest in the development of pared to a sectioned, unused Krupin-Denver setons, aiming to control intraocular pressure valve (Fig. 2), which showed the nylon-6 tube permanently in this condition. One such suc cessful seton is the Krupin-Denver valve. 1 The valve consists of three major compo nents: an extraocular Silastic tube containing horizontal and vertical slits; an open nylon-6 (Supramid) intraocular tube with an internal diameter of 0.88 mm and uniform walls of 0.10 mm thickness; and two horizontal nylon-6 arms. The Silastic tube functions as a undirectional, pressure-sensitive valve and is designed to maintain intraocular pressure between 11 mm Hg and 14 mm Hg. The Silastic tube is molded at a 160-degree angle to the nylon-6 tube, and is trimmed during surgery to extend 1 to 4 mm into the anterior chamber. The two horizontal nylon-6 arms are attached to the undersurface of the junction between the two tubes, and are used for fixation. Complications from the use of the KrupinDenver valve include hyphema, ciliochoroidal detachment, external bleb failure, posterior Fig. 1 (Ormerod, Pickford, and Baerveldt). Scan valve migration, granulation tissue ingrowth ning electron micrograph showing diffuse attenua around the valve, and erosions of the scleral tion of the proximal fracture margin in the nylon-6 flap and conjunctiva. 2 To this list we add evi part of the Krupin-Denver valve (x 63.3).
560
AMERICAN JOURNAL OF OPHTHALMOLOGY
May, 1988
Chiasmal Compression Caused by a Catheter in the Suprasellar Cistern Michael L. Slavin, M.D., and Alan D. Rosenthal, M.D. Division of Neuro-ophthalmology, Department of Ophthalmology (M.L.S.), and the Division of Neurosurgery, Department of Surgery (A.D.R.), Long Is land Jewish Medical Center.
Fig. 2 (Ormerod, Pickford, and Baerveldt). Scan ning electron micrograph of a sectioned, unused (untrimmed) Krupin-Denver valve placed in embed ding medium (x 8.6). N, nylon-6 tube; S, Silastic tube and valve. to h a v e walls of e v e n t h i c k n e s s (0.1 m m ) , the nylon-6 t u b e in this case h a d u n d e r g o n e b o t h s e r i o u s b i o d e g r a d a t i o n a n d loss of tensile s t r e n g t h after two years in the a n t e r i o r c h a m ber. The o p h t h a l m i c b i o d e g r a d a b i l i t y of n y l o n 6, u s e d as s u t u r e s a n d intraocular lens l o o p s , has b e e n widely reported 3 - 4 a n d reviewed. 5 The u s e of nylon-6 in the K r u p i n - D e n v e r valve m a y lead to its late m e c h a n i c a l failure, a n d s u r g e o n s r e m o v i n g this t u b e s h o u l d be alert to the possi bility of fracture.
References 1. Krupin, T., Kaufman, P., Mandell, A., Ritch, R., Asseff, C , Podos, S. M., and Becker, B.: Filtering valve implant surgery for eyes with neovascular glaucoma. Am. J. Ophthalmol. 89:338, 1980. 2. Krupin, T., Kaufman, P., Mandell, A. I., Terry, S. A., Ritch, R., Podos, S. M., and Becker, B.: Longterm results of valve implants in filtering surgery for eyes with neovascular glaucoma. Am. J. Ophthal mol. 95:775, 1983. 3. Drews, R. C , Smith, M. E., and Okun, N.: Scanning electron microscopy of intraocular lenses. Ophthalmology 85:415, 1978. 4. KronenthaJ, R. L.: Nylon in the anterior cham ber. Ophthalmology 88:965, 1981. 5. Refojo, M. F.: Polymers in ophthalmology. In Rubin, L. R. (ed.): Biomaterials in Reconstructive Surgery. St Louis, C. V. Mosby, 1983, pp. 955-967.
Inquiries to Michael L. Slavin, M.D., Department of Ophthalmology, Long Island Jewish Medical Center, New Hyde Park, NY 11042. In 1977, C o p p e t o a n d G a h m 1 r e p o r t e d a case in w h i c h chiasmal c o m p r e s s i o n w a s c a u s e d by a v e n t r i c u l a r c a t h e t e r that h a d i n a d v e r t e n t l y l o d g e d in t h e third ventricle. We treated a p a t i e n t w i t h p r o g r e s s i v e visual loss a n d bitemporal visual field defects c a u s e d by a Silastic c a t h e t e r in t h e s u p r a s e l l a r cistern. A 73-year-old w o m a n d e v e l o p e d ataxia a n d " d i z z i n e s s . " C o m p u t e d t o m o g r a p h y disclosed a n extra-axial p o s t e r i o r fossa m a s s a n d ventric ular e n l a r g e m e n t . A c r a n i o t o m y w a s per formed a n d a large m e n i n g i o m a w a s resected. An i n t r a v e n t r i c u l a r c a t h e t e r w a s placed a n d a t t a c h e d to a n O m m a y a reservoir, for the possi bility of c o n v e r s i o n to a v e n t r i c u l o p e r i t o n e a l s h u n t , if n e c e s s a r y . T h e p a t i e n t did well in the following year, except for p r o g r e s s i v e left tem p o r a l v i s u a l field d i s t u r b a n c e . O n n e u r o - o p h t h a l m i c e x a m i n a t i o n , best cor rected visual acuity w a s R.E.: 20/30 a n d L.E.: 20/40. T h e r e w a s a distinct b i t e m p o r a l h e m i c h r o m a t o p s i a . Results of a visual field exam ination disclosed relative b i t e m p o r a l visual loss in the central i s o p t e r s . A left afferent p u pillary defect w a s n o t e d . The optic disks w e r e normal. Postoperative computed tomography showed t h a t t h e distal e n d of t h e s u p p o s e d i n t r a v e n tricular c a t h e t e r w a s located at t h e level of t h e s u p r a s e l l a r cistern (Figure). T h e c a t h e t e r w a s s u b s e q u e n t l y excised. O n follow-up e x a m i n a t i o n two m o n t h s later, best corrected visual acuity w a s R.E.: 20/20 a n d L.E.: 20/25. A q u e s t i o n a b l e left afferent p u p i l defect w a s n o t e d . Results of a visual field exam i n a t i o n w e r e nearly n o r m a l on the right, a n d s h o w e d a d i m i n i s h e d t e m p o r a l scotoma on the left. C h i a s m a l c o m p r e s s i o n m a y occur w h e n a c a t h e t e r i n t e n d e d for the lateral ventricle inad v e r t e n t l y l o d g e s in the third ventricle or in the s u p r a s e l l a r cistern. The p o s t e r i o r notch of the optic c h i a s m a n a t o m i c a l l y forms the a n t e r o inferior b o r d e r of the third ventricle. The nasal