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Low Viscosity Liquid Fluorochemicals in Vitreous Surgery
Low Viscosity Liquid Fluorochemicals in Vitreous Surgery Stanley Chang, M.D.
Low viscosity liquid fluorocarbons have physical properties potentially useful as intraoperative adjuncts during vitreous surgery for complicated retinal detachments. These sub stances are optically clear, have specific gravi ty greater than that of water, and interfacila tension properties similar to those of silicone oil. In four patients who had complicated reti nal detachments I used perfluorotributylamine and perfluorodecalin during vitreous surgery. Two giant retinal tears were flattened intraoperatively without turning the patient into the prone position. In two patients with severe proliferative vitreoretinopathy, perfluoro tributylamine allowed adequate retinal tamponade and avoided a posterior retinotomy for internal drainage of subretinaj fluid. Endophotocoagulation was applied. IN THE MANAGEMENT of complicated retinal
detachments, a satisfactory vitreous replace ment that is denser than saline has yet to be found. Sodium hyaluronate has been used clin ically, but it lacks adequate interfacial tension and can cause severe postoperative glauco ma.1"4 Experimental results in animal models using liquid fluorochemicals, such as per fluorotributylamine and perfluorodecalin, as vitreous substitutes have shown that these substances are unsatisfactory for long-term re placement because of a marked foam cell re sponse in the vitreous and dispersion of the oil into smaller droplets. 5,6 However, perfluor otributylamine appears relatively well tolerated
when placed in the rabbit eye for periods of up to one week. 6 The low viscosity, high density, and desirable interfacial tension properties that characterize these liquids are ideal for use as an intraoperative tool during vitrectomy. The techniques for intraoperative use and observa tions in four patients are reported here.
Material and Methods Medical grade perfluorotributylamine and perfluorodecalin were used for temporary me chanical tamponade during vitrectomy in four patients. Prior to use the liquids were filtered through two 0.22-urn millipore filters. Liquid fluorochemicals were used in patients with retinal detachment associated with ad vanced proliferative vitreoretinopathy or with giant retinal tears requiring vitreous surgery. The decision to use liquid fluorochemicals was made intraoperatively to stabilize the retina mechanically for additional membrane delamination or peeling, and when a posterior retinot omy to aspirate subretinal fluid during fluidgas exchange was required. In patients with giant retinal tears liquid fluorochemicals were used to avoid turning the patient into the prone position during surgery. All patients except Patient 4 had had previous surgery for retinal detachment.
Case Reports Accepted for publication Sept. 26, 1986. From the Department of Ophthalmology, New York Hospital—Cornell University Medical College, New York, New York. This study was supported in part by the Henry Katz Foundation, National Institutes of Health Research Grant EY05982-01, and National Institutes of Health Biomedical Research Grant 2S07 RR05396-24, and the Maymar Corporation. Reprint requests to Stanley Chang, M.D., Department of Ophthalmology, New York Hospital-—Cornell Univer sity Medical College, 525 E. 68th St., New York, NY 10021.
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Case 1 A 10-year-old girl was referred with an evert ed 330-degree giant retinal tear in the right eye. She had undergone lensectomy, vitrec tomy, and scleral buckling with sulfur hexafluoride tamponade and cryotherapy two weeks before referral. After initial success, the retina redetached as the gas bubble resorbed. The tear extended from the 9 o'clock to the 8 o'clock meridians. Fixation of the inferior reti-
©AMERICAN JOURNAL OF OPHTHALMOLOGY 103:38-43, JANUARY, 1987
Vol. 103, No. 1
Liquid Fluorochemicals in Vitreous Surgery
na with retinal tacks and silicone oil tamponade were planned for the second procedure. During the operation, the retinal tacking device mal functioned and extensive bleeding developed from a peripheral retinal vessel. Hemostasis was achieved with endodiathermy. The tear was gently mobilized and sodium hyaluronate was used to try to prevent posterior slippage. Attempts to flatten the tear under gas were unsuccessful because of slippage. Before turn ing the patient into the prone position for fluid-air exchange, perfluorotributylamine was used. As the liquid was injected over the optic disk and up to the edges of the retinal tear, the retina completely unfolded and flattened. Endophotocoagulation was performed 360 de grees on the buckle through perfluorotributyla mine. Fluid-air exchange was performed, re moving the fluorochemical with the 20-gauge extrusion handpiece. Additional endophotoco agulation was applied anteriorly on the buckle through air. In the air-filled eye, silicone oil was injected for long-term tamponade. On the first postoperative day, the retina was com pletely attached. One month postoperatively, the retina redetached with extensive proliferative vitreoretinopathy. Case 2 A mentally retarded 42-year-old woman was referred for retinal detachment with proliferative vitreoretinopathy in both eyes. She had a history of self-abuse with gradual loss of ambu latory vision. A retinal detachment associated with a retinal dialysis from the 2 o'clock to the 4 o'clock meridians was found in the left eye. Cryotherapy, a scleral buckle with drainage of subretinal fluid, and air injection were per formed. There was initial successful retinal reattachment. However, eight weeks later the retina redetached because of proliferative vitre oretinopathy. Extensive posterior synechiae prevented pu pillary dilation and a lensectomy was neces sary. The retina was totally detached in a closed funnel configuration (Retina Society Classification D37). Periretinal membranes were peeled from the funnel, opening it and increas ing retinal mobility centrally. Sodium hyaluro nate was injected into the funnel in an attempt to spread open the detachment. However, as the membranes were peeled peripherally, the pulling forces tended to close the funnel. Per fluorotributylamine was injected with a blunt 20-gauge needle over the optic disk flattening the posterior retina until areas of residual trac
39
tion were visualized. Remaining posterior membranes were better visualized as the retina was held open by the perfluorotributylamine. As additional peripheral membranes were re moved liquid fluorocarbon was added, which further flattened the retina. Anterior loop trac tion was released working under the aqueous phase of the vitreous. The retinal tear extended from the 1 o'clock to the 4:30 o'clock meridians. As the retina flattened under fluorochemical, a small amount of subretinal hemorrhage initial ly located around the optic disk and macula was displaced peripherally. The scleral buckle was revised by adding a 289-silicone exoplant along the inferior 180 degrees of the globe. Endophotocoagulation was applied 360 de grees onto the scleral buckle. The retina ante rior to the fluorocarbon interface was still par tially elevated. Fluid-air exchange was used to flatten the anterior retina while removing the fluorocarbon completely. Under air additional endophotocoagulation was administered anter iorly on the buckle. Silicone oil was injected for long-term tamponade because of poor compli ance with head positioning. Two months post operatively the retina remains attached. Case 3 A 23-year-old woman was referred for retinal detachment with proliferative vitreoretinopa thy in the left eye. After blunt trauma the patient was treated for retinal detachment with scleral buckling. A retinal dialysis from the 11 o'clock to the 1 o'clock meridians was present. The retina did not flatten and drainage of sub retinal fluid with air injection was performed one week later. Four weeks later, a recurrent retinal detachment with proliferative vitreoret inopathy in a narrow funnel configuration (Retina Society Classification D27) developed (Fig. 1). During surgery dense pigmented periretinal membranes were peeled from the retina poster iorly. The retina became mobile as large sheets of membranes were removed to the periphery. No posterior retinal breaks were present. To avoid a posterior retinotomy for internal drain age of subretinal fluid, perfluorotributylamine was injected over the optic disk. The retinal funnel opened and flattened, expressing sub retinal fluid anteriorly through the retinal tear. The perfluorochemical was injected up to the level of the tear. Anterior membranes were removed when the retina was immobilized by the fluorochemical tamponade. Endophotoco agulation was delivered on the buckle posterior
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AMERICAN JOURNAL OF OPHTHALMOLOGY
Fig. 1 (Chang). Case 3. Preoperative photograph of retinal detachment with proliferative vitreoretinopathy (Stage D2, Retina Society classification7).
Fig. 2 (Chang). Case 3. Two months postoperatively the retina remains attached. Visual acuity is 20/200.
to the tear through the fluorochemical. Fluidair exchange flattened the anterior retina against the buckle and additional endophotocoagulation was applied 360 degrees anterior ly. At the conclusion of the procedure the air-filled eye was flushed with a 20% perfluoropropane-air mixture. The retina has remained attached for two months (Fig. 2).
lation was added on the anterior crest of the buckle after fluid-air exchange removed all of the liquid fluorocarbon. At the end of surgery the retina was completely flattened under air and the eye was flushed with a 20% perfluoropropane-air mixture.
Case 4 A 13-year-old boy was referred with a giant retinal tear in the right eye. He had undergone cataract aspiration six years earlier for congeni tal cataract. Subsequently he developed glau coma. A filtering procedure was performed without complication two weeks before the de velopment of retinal detachment. The superior giant tear extended from the 7:30 meridian to the 3 o'clock meridian. The tear was everted and immobile with the superior portion of the flap adherent to the inferior retina. Intraoperatively, the cortical vitreous was removed and the tear gently unfolded with bimanual instrumentation. Five milliliters of perfluorodecalin were infused over the optic disk. The retina immediately unfolded and flat tened as the liquid fluorocarbon was injected up to the level of the tear. A broad 3.2 x 6.4-mm grooved silicone explant was placed, encircling the globe. After placement of the scleral buckle endophotocoagulation was per formed through perfluorodecalin 360 degrees on the buckle as described above. Photocoagu-
Discussion The only vitreous replacement presently used in vitreous surgery that is denser than saline is sodium hyaluronate. It has been used frequently for retinal detachment surgery. 813 The ability to open a narrow funnel retinal detachment during open-sky vitrectomy was recognized by Pruett, Schepens, and Swann. 1 Fitzgerald 2 reported the value of a 1% concen tration of sodium hyaluronate in everting a rolled flap during vitrectomy for giant retinal tears. However, the 1% concentration has a specific gravity (1.036) similar to that of saline and the force of mechanical tamponade is weak. The solubility and lack of interfacial tension of sodium hyaluronate in saline are also undesirable physical characteristics. Its high viscosity (200,000 centistokes) makes it difficult to aspirate the material with small bore instruments, such as the tapered needle extru sion handpiece. Low viscosity liquid fluorochemicals have de sirable physical properties for use in vitreous
Vol. 103, No. 1
Liquid Fluorochemicals in Vitreous Surgery
TABLE FORCE OF TAMPONADE EXERTED BY VARIOUS VITREOUS SUBSTITUTES TAMPONADE FORCE' VITREOUS SUBSTITUTE
(0)
Silicone oil Fluorosilicone oil Perfluorotributylamine Gas/air
0.3 1.35 4.3 5.15
"TamDonade force = density difference (vitreous substitute and fluid vitreous) x volume of vitreous substitute (5.0 ml) (Parel, unpublished data).
surgery. Since the specific gravity is almost twice the density of water, they are excellent agents for retinal tamponade. The force exerted by 5 ml of perfluorotributylamine against the retina is 4.3 g (Table) using a formula suggested by Parel (unpublished data) to measure the force of tamponade exerted by a vitreous sub stitute. Compared with other vitreous substi tutes, this force is greater than that exerted by an equivalent volume of silicone oil or fluorosil icone oil but less than that of air or gases (Table). In these patients, perfluorotributylam ine provided an excellent tamponade by flat tening the retina and displacing subretinal fluid anteriorly allowing exit through peripher al retinal breaks. A posterior retinotomy for drainage of subretinal fluid was not required. Posterior retinal slippage of a giant retinal tear was avoided because of the higher density of the liquid fluorochemicals. The boiling point of perfluorotributylamine exceeds that of saline so that endophotocoagulation can be applied without intraocular vaporization. The refrac tive index of perfluorotributylamine is 1.29. This small difference with that of saline allows excellent intraoperative visualization. Visibility is also enhanced because fluorochemicals are immiscible with blood. The interfacial tension of liquid fluorochemicals in water is slightly higher than that of silicone oils (56 as compared to 51 dynes/cm at 20 C). This difference will probably not be of clinical significance. Low viscosity fluorochemicals are usually in the range of 2 to 3 centistokes at 25 C. This charac teristic favors removal through small gauge surgical instruments. Fluorochemicals are also immiscible with silicone oils, and the two substances form separate phases when mixed. Perfluorotributylamine and perfluorodecalin have similar physical properties. Miyamoto
41
and associates 5 have reported the experimental ocular tolerance of perfluoromethyldecalin. Perfluorodecalin may be advantageous over perfluorotributylamine because it consists sole ly of carbon-fluorine atoms and does not contain a heteroatom (nitrogen). The higher boiling point of perfluorotributylamine is advantageous since it is less likely to vaporize during endophotocoagulation. The compara tive efficacy and ocular tolerance of various other low viscosity fluorochemicals are current ly under investigation in our laboratory. In proliferative vitreoretinopathy the remov al of periretinal membranes is facilitated by the use of liquid fluorochemicals. The fluorochemical is used after all visible posterior membranes are removed in order to spread open the de tachment. This exposes any residual mem branes that can then be more easily visualized and removed. After flattening the posterior retina, peripheral membranes in the region of the vitreous base can be approached more easi ly working in the aqueous phase of the vitreous rather than through the fluorochemical (Fig. 3). The fluorochemical acts mechanically to stabi lize the retina and to provide counterpressure
Fig. 3 (Chang). The fluorochemical flattens the retina by displacing subretinal fluid through the retinal break. Residual posterior membranes are ex posed and removed through fluorochemical. Man agement of anterior loop traction is facilitated by the mechanical counterpressure assistance provided by liquid fluorochemical.
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January, 1987
Fig. 4 (Chang). Left, Fluorochemical is injected over the optic disk to unroll the flap of a giant retinal tear. Right, Injection is continued until fluorochemical reaches the edge of the tear. as the membranes in the periphery are pulled and peeled. A similar technique working through silicone oil has been previously de scribed by Scott14 and Zivojnovic, Mertens, and Peperkamp. 15 However, with a denser material it is less likely that the vitreous substitute would enter subretinally since most of the trac tion from membrane peeling is exerted in the aqueous phase. During extensive membrane dissection in the region of the vitreous base, and with the ocular manipulation introduced
during scleral buckle revision, dispersion of the perfluorotributylamine bubble or migration subretinally was not observed. In this group of patients, perfluorotributylamine was used for the longest period of time in Patient 2, approxi mately 90 minutes. Liquid fluorochemicals have sufficient densi ty to flatten the retina as it is introduced over the retina. In these patients it was unnecessary to perform a posterior retinotomy for internal drainage of subretinal fluid. The subretinal
Fig. 5 (Chang). Procedure for complete removal of fluorochemical. Left, During fluid-air exchange, the fluorochemical layer flattens making it difficult to aspirate the oil completely from the eye. Center, Residual fluorochemical can be removed by injecting a small amount of balanced salt solution, causing the oil to form round droplets. Right, These droplets can be removed using a flute needle.
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Liquid Fluorochemicals in Vitreous Surgery
fluid was displaced anteriorly and it exited through the retinal break. Intraoperative man agement of giant retinal tears is facilitated since the tear can be unfolded and maintained in position without posterior slippage (Fig. 4). The entire surgical procedure can be performed with the patient in the supine position. The fluorochemical was injected to the level of the retinal break with residual retinal detachment anterior to fluorochemical. After release of all peripheral traction the anterior retina is best flattened by fluid-air exchange. Fluorochemical can be removed using a blunt 20-gauge needle on a flute needle or extrusion handpiece. During fluid-air exchange the airfluorocarbon meniscus flattens, resulting in a thin flat layer of residual fluorocarbon oil. This oil is easily removed by injecting 0.5 to 0.8 ml of balanced salt solution into the air-filled eye. The residual fluorocarbon oil then forms small round beads in saline which can be easily re moved (Fig. 5). After fluid-air exchange, addi tional endophotocoagulation should be applied to the anterior retina. The vitreous substitute chosen for long-term tamponade is then inject ed into the air-filled eye. The intraoperative use of liquid fluorocarbons requires further evaluation in multicenter clinical trials. Further investigation with other compounds for ocular tolerance and the devel opment of new manufacturing and purification techniques of fluorochemicals for medical ap plication will be necessary to develop the ideal substances for the management of complicated retinal detachments.
References 1. Pruett, R. C , Schepens, C. L., and Swann, D. A.: Hyaluronic acid vitreous substitute. Arch. Ophthalmol. 97:2325, 1979.
43
2. Fitzgerald, C : The use of Healon in a case of rolled-over retina. Retina 1:227, 1981. 3. Gnad, H., Klemen, U. ML, and Radda, T. M.: Healon als innere Tamponade in der Netzhautchirurgie. Klin. Monatsbl. Augenheilkd. 183:184, 1983. 4. Folk, J. C , Packer, A. J., Weingeist, T. A., and Howcroft, M. J.: Sodium hyaluronate (Healon) in closed vitrectomy. Ophthalmic Surg. 17:299, 1986. 5. Miyamoto, K., Refojo, M. F., Tolentino, F. I., Fournier, G. A., and Albert, D. M.: Perfluoroether liquid as a long term vitreous substitute. An experi mental study. Retina 4:264, 1984. 6. Chang, S., Zimmerman, N. J., Iwamoto, T., Ortiz, R., and Faris, D.: Experimental vitreous re placement with perfluorotributylamine. Am. J. Oph thalmol. 102:29, 1986. 7. Retina Society Terminology Committee: The classification of retinal detachment with proliferative vitreoretinopathy. Ophthalmology 90:121, 1983. 8. Algvere, P.: Intravitreal implantation of a highmolecular hyaluronic acid in surgery for retinal de tachment. Acta Ophthalmol. 49:975, 1971. 9. Regnault, F.: Intravitreous hyaluronic acid and cryocoagulation in the treatment of severe types of retinal detachment. Bull. Soc. Ophthalmol. Fr. 84:106, 1971. 10. Kloti, R.: Hyaluronsaure als Glaskorpersubstituent. Ophthalmologica 165:351, 1972. 11. Edmund, J.: Vitreous substitute in the treat ment of retinal detachment. Mod. Probl. Ophthal mol. 12:370, 1974. 12. Kanski, J. }.: Intravitreal hyaluronic acid injec tion. A long-term clinical evaluation. Br. J. Ophthal mol. 59:255, 1975. 13. Stenkula, S., Ivert, L., and Giglason, I.: The use of sodium hyaluronate (Healon) in the treatment of retinal detachment. Ophthalmic Surg. 12:435, 1981. 14. Scott, J. D.: A rationale for the use of liquid silicone. Trans. Ophthalmol. Soc. U.K. 97:235, 1977. 15. Zivojnovic, R., Mertens, D. E., and Peperkamp, E.: Das flussige Silikon in Amotiochirugie (II) Bericht uber 280 Falle,weitere Entwicklung der Technik. Klin. Monatsbl. Augenheilkd. 181:444, 1982.
Low viscosity liquid fluorocarbons have physical properties potentially useful as intraoperative adjuncts during vitreous surgery for complicated retinal detachments. These sub stances are optically clear, have specific gravi ty greater than that of water, and interfacila tension properties similar to those of silicone oil. In four patients who had complicated reti nal detachments I used perfluorotributylamine and perfluorodecalin during vitreous surgery. Two giant retinal tears were flattened intraoperatively without turning the patient into the prone position. In two patients with severe proliferative vitreoretinopathy, perfluoro tributylamine allowed adequate retinal tamponade and avoided a posterior retinotomy for internal drainage of subretinaj fluid. Endophotocoagulation was applied. IN THE MANAGEMENT of complicated retinal
detachments, a satisfactory vitreous replace ment that is denser than saline has yet to be found. Sodium hyaluronate has been used clin ically, but it lacks adequate interfacial tension and can cause severe postoperative glauco ma.1"4 Experimental results in animal models using liquid fluorochemicals, such as per fluorotributylamine and perfluorodecalin, as vitreous substitutes have shown that these substances are unsatisfactory for long-term re placement because of a marked foam cell re sponse in the vitreous and dispersion of the oil into smaller droplets. 5,6 However, perfluor otributylamine appears relatively well tolerated
when placed in the rabbit eye for periods of up to one week. 6 The low viscosity, high density, and desirable interfacial tension properties that characterize these liquids are ideal for use as an intraoperative tool during vitrectomy. The techniques for intraoperative use and observa tions in four patients are reported here.
Material and Methods Medical grade perfluorotributylamine and perfluorodecalin were used for temporary me chanical tamponade during vitrectomy in four patients. Prior to use the liquids were filtered through two 0.22-urn millipore filters. Liquid fluorochemicals were used in patients with retinal detachment associated with ad vanced proliferative vitreoretinopathy or with giant retinal tears requiring vitreous surgery. The decision to use liquid fluorochemicals was made intraoperatively to stabilize the retina mechanically for additional membrane delamination or peeling, and when a posterior retinot omy to aspirate subretinal fluid during fluidgas exchange was required. In patients with giant retinal tears liquid fluorochemicals were used to avoid turning the patient into the prone position during surgery. All patients except Patient 4 had had previous surgery for retinal detachment.
Case Reports Accepted for publication Sept. 26, 1986. From the Department of Ophthalmology, New York Hospital—Cornell University Medical College, New York, New York. This study was supported in part by the Henry Katz Foundation, National Institutes of Health Research Grant EY05982-01, and National Institutes of Health Biomedical Research Grant 2S07 RR05396-24, and the Maymar Corporation. Reprint requests to Stanley Chang, M.D., Department of Ophthalmology, New York Hospital-—Cornell Univer sity Medical College, 525 E. 68th St., New York, NY 10021.
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Case 1 A 10-year-old girl was referred with an evert ed 330-degree giant retinal tear in the right eye. She had undergone lensectomy, vitrec tomy, and scleral buckling with sulfur hexafluoride tamponade and cryotherapy two weeks before referral. After initial success, the retina redetached as the gas bubble resorbed. The tear extended from the 9 o'clock to the 8 o'clock meridians. Fixation of the inferior reti-
©AMERICAN JOURNAL OF OPHTHALMOLOGY 103:38-43, JANUARY, 1987
Vol. 103, No. 1
Liquid Fluorochemicals in Vitreous Surgery
na with retinal tacks and silicone oil tamponade were planned for the second procedure. During the operation, the retinal tacking device mal functioned and extensive bleeding developed from a peripheral retinal vessel. Hemostasis was achieved with endodiathermy. The tear was gently mobilized and sodium hyaluronate was used to try to prevent posterior slippage. Attempts to flatten the tear under gas were unsuccessful because of slippage. Before turn ing the patient into the prone position for fluid-air exchange, perfluorotributylamine was used. As the liquid was injected over the optic disk and up to the edges of the retinal tear, the retina completely unfolded and flattened. Endophotocoagulation was performed 360 de grees on the buckle through perfluorotributyla mine. Fluid-air exchange was performed, re moving the fluorochemical with the 20-gauge extrusion handpiece. Additional endophotoco agulation was applied anteriorly on the buckle through air. In the air-filled eye, silicone oil was injected for long-term tamponade. On the first postoperative day, the retina was com pletely attached. One month postoperatively, the retina redetached with extensive proliferative vitreoretinopathy. Case 2 A mentally retarded 42-year-old woman was referred for retinal detachment with proliferative vitreoretinopathy in both eyes. She had a history of self-abuse with gradual loss of ambu latory vision. A retinal detachment associated with a retinal dialysis from the 2 o'clock to the 4 o'clock meridians was found in the left eye. Cryotherapy, a scleral buckle with drainage of subretinal fluid, and air injection were per formed. There was initial successful retinal reattachment. However, eight weeks later the retina redetached because of proliferative vitre oretinopathy. Extensive posterior synechiae prevented pu pillary dilation and a lensectomy was neces sary. The retina was totally detached in a closed funnel configuration (Retina Society Classification D37). Periretinal membranes were peeled from the funnel, opening it and increas ing retinal mobility centrally. Sodium hyaluro nate was injected into the funnel in an attempt to spread open the detachment. However, as the membranes were peeled peripherally, the pulling forces tended to close the funnel. Per fluorotributylamine was injected with a blunt 20-gauge needle over the optic disk flattening the posterior retina until areas of residual trac
39
tion were visualized. Remaining posterior membranes were better visualized as the retina was held open by the perfluorotributylamine. As additional peripheral membranes were re moved liquid fluorocarbon was added, which further flattened the retina. Anterior loop trac tion was released working under the aqueous phase of the vitreous. The retinal tear extended from the 1 o'clock to the 4:30 o'clock meridians. As the retina flattened under fluorochemical, a small amount of subretinal hemorrhage initial ly located around the optic disk and macula was displaced peripherally. The scleral buckle was revised by adding a 289-silicone exoplant along the inferior 180 degrees of the globe. Endophotocoagulation was applied 360 de grees onto the scleral buckle. The retina ante rior to the fluorocarbon interface was still par tially elevated. Fluid-air exchange was used to flatten the anterior retina while removing the fluorocarbon completely. Under air additional endophotocoagulation was administered anter iorly on the buckle. Silicone oil was injected for long-term tamponade because of poor compli ance with head positioning. Two months post operatively the retina remains attached. Case 3 A 23-year-old woman was referred for retinal detachment with proliferative vitreoretinopa thy in the left eye. After blunt trauma the patient was treated for retinal detachment with scleral buckling. A retinal dialysis from the 11 o'clock to the 1 o'clock meridians was present. The retina did not flatten and drainage of sub retinal fluid with air injection was performed one week later. Four weeks later, a recurrent retinal detachment with proliferative vitreoret inopathy in a narrow funnel configuration (Retina Society Classification D27) developed (Fig. 1). During surgery dense pigmented periretinal membranes were peeled from the retina poster iorly. The retina became mobile as large sheets of membranes were removed to the periphery. No posterior retinal breaks were present. To avoid a posterior retinotomy for internal drain age of subretinal fluid, perfluorotributylamine was injected over the optic disk. The retinal funnel opened and flattened, expressing sub retinal fluid anteriorly through the retinal tear. The perfluorochemical was injected up to the level of the tear. Anterior membranes were removed when the retina was immobilized by the fluorochemical tamponade. Endophotoco agulation was delivered on the buckle posterior
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AMERICAN JOURNAL OF OPHTHALMOLOGY
Fig. 1 (Chang). Case 3. Preoperative photograph of retinal detachment with proliferative vitreoretinopathy (Stage D2, Retina Society classification7).
Fig. 2 (Chang). Case 3. Two months postoperatively the retina remains attached. Visual acuity is 20/200.
to the tear through the fluorochemical. Fluidair exchange flattened the anterior retina against the buckle and additional endophotocoagulation was applied 360 degrees anterior ly. At the conclusion of the procedure the air-filled eye was flushed with a 20% perfluoropropane-air mixture. The retina has remained attached for two months (Fig. 2).
lation was added on the anterior crest of the buckle after fluid-air exchange removed all of the liquid fluorocarbon. At the end of surgery the retina was completely flattened under air and the eye was flushed with a 20% perfluoropropane-air mixture.
Case 4 A 13-year-old boy was referred with a giant retinal tear in the right eye. He had undergone cataract aspiration six years earlier for congeni tal cataract. Subsequently he developed glau coma. A filtering procedure was performed without complication two weeks before the de velopment of retinal detachment. The superior giant tear extended from the 7:30 meridian to the 3 o'clock meridian. The tear was everted and immobile with the superior portion of the flap adherent to the inferior retina. Intraoperatively, the cortical vitreous was removed and the tear gently unfolded with bimanual instrumentation. Five milliliters of perfluorodecalin were infused over the optic disk. The retina immediately unfolded and flat tened as the liquid fluorocarbon was injected up to the level of the tear. A broad 3.2 x 6.4-mm grooved silicone explant was placed, encircling the globe. After placement of the scleral buckle endophotocoagulation was per formed through perfluorodecalin 360 degrees on the buckle as described above. Photocoagu-
Discussion The only vitreous replacement presently used in vitreous surgery that is denser than saline is sodium hyaluronate. It has been used frequently for retinal detachment surgery. 813 The ability to open a narrow funnel retinal detachment during open-sky vitrectomy was recognized by Pruett, Schepens, and Swann. 1 Fitzgerald 2 reported the value of a 1% concen tration of sodium hyaluronate in everting a rolled flap during vitrectomy for giant retinal tears. However, the 1% concentration has a specific gravity (1.036) similar to that of saline and the force of mechanical tamponade is weak. The solubility and lack of interfacial tension of sodium hyaluronate in saline are also undesirable physical characteristics. Its high viscosity (200,000 centistokes) makes it difficult to aspirate the material with small bore instruments, such as the tapered needle extru sion handpiece. Low viscosity liquid fluorochemicals have de sirable physical properties for use in vitreous
Vol. 103, No. 1
Liquid Fluorochemicals in Vitreous Surgery
TABLE FORCE OF TAMPONADE EXERTED BY VARIOUS VITREOUS SUBSTITUTES TAMPONADE FORCE' VITREOUS SUBSTITUTE
(0)
Silicone oil Fluorosilicone oil Perfluorotributylamine Gas/air
0.3 1.35 4.3 5.15
"TamDonade force = density difference (vitreous substitute and fluid vitreous) x volume of vitreous substitute (5.0 ml) (Parel, unpublished data).
surgery. Since the specific gravity is almost twice the density of water, they are excellent agents for retinal tamponade. The force exerted by 5 ml of perfluorotributylamine against the retina is 4.3 g (Table) using a formula suggested by Parel (unpublished data) to measure the force of tamponade exerted by a vitreous sub stitute. Compared with other vitreous substi tutes, this force is greater than that exerted by an equivalent volume of silicone oil or fluorosil icone oil but less than that of air or gases (Table). In these patients, perfluorotributylam ine provided an excellent tamponade by flat tening the retina and displacing subretinal fluid anteriorly allowing exit through peripher al retinal breaks. A posterior retinotomy for drainage of subretinal fluid was not required. Posterior retinal slippage of a giant retinal tear was avoided because of the higher density of the liquid fluorochemicals. The boiling point of perfluorotributylamine exceeds that of saline so that endophotocoagulation can be applied without intraocular vaporization. The refrac tive index of perfluorotributylamine is 1.29. This small difference with that of saline allows excellent intraoperative visualization. Visibility is also enhanced because fluorochemicals are immiscible with blood. The interfacial tension of liquid fluorochemicals in water is slightly higher than that of silicone oils (56 as compared to 51 dynes/cm at 20 C). This difference will probably not be of clinical significance. Low viscosity fluorochemicals are usually in the range of 2 to 3 centistokes at 25 C. This charac teristic favors removal through small gauge surgical instruments. Fluorochemicals are also immiscible with silicone oils, and the two substances form separate phases when mixed. Perfluorotributylamine and perfluorodecalin have similar physical properties. Miyamoto
41
and associates 5 have reported the experimental ocular tolerance of perfluoromethyldecalin. Perfluorodecalin may be advantageous over perfluorotributylamine because it consists sole ly of carbon-fluorine atoms and does not contain a heteroatom (nitrogen). The higher boiling point of perfluorotributylamine is advantageous since it is less likely to vaporize during endophotocoagulation. The compara tive efficacy and ocular tolerance of various other low viscosity fluorochemicals are current ly under investigation in our laboratory. In proliferative vitreoretinopathy the remov al of periretinal membranes is facilitated by the use of liquid fluorochemicals. The fluorochemical is used after all visible posterior membranes are removed in order to spread open the de tachment. This exposes any residual mem branes that can then be more easily visualized and removed. After flattening the posterior retina, peripheral membranes in the region of the vitreous base can be approached more easi ly working in the aqueous phase of the vitreous rather than through the fluorochemical (Fig. 3). The fluorochemical acts mechanically to stabi lize the retina and to provide counterpressure
Fig. 3 (Chang). The fluorochemical flattens the retina by displacing subretinal fluid through the retinal break. Residual posterior membranes are ex posed and removed through fluorochemical. Man agement of anterior loop traction is facilitated by the mechanical counterpressure assistance provided by liquid fluorochemical.
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AMERICAN JOURNAL OF OPHTHALMOLOGY
January, 1987
Fig. 4 (Chang). Left, Fluorochemical is injected over the optic disk to unroll the flap of a giant retinal tear. Right, Injection is continued until fluorochemical reaches the edge of the tear. as the membranes in the periphery are pulled and peeled. A similar technique working through silicone oil has been previously de scribed by Scott14 and Zivojnovic, Mertens, and Peperkamp. 15 However, with a denser material it is less likely that the vitreous substitute would enter subretinally since most of the trac tion from membrane peeling is exerted in the aqueous phase. During extensive membrane dissection in the region of the vitreous base, and with the ocular manipulation introduced
during scleral buckle revision, dispersion of the perfluorotributylamine bubble or migration subretinally was not observed. In this group of patients, perfluorotributylamine was used for the longest period of time in Patient 2, approxi mately 90 minutes. Liquid fluorochemicals have sufficient densi ty to flatten the retina as it is introduced over the retina. In these patients it was unnecessary to perform a posterior retinotomy for internal drainage of subretinal fluid. The subretinal
Fig. 5 (Chang). Procedure for complete removal of fluorochemical. Left, During fluid-air exchange, the fluorochemical layer flattens making it difficult to aspirate the oil completely from the eye. Center, Residual fluorochemical can be removed by injecting a small amount of balanced salt solution, causing the oil to form round droplets. Right, These droplets can be removed using a flute needle.
Vol. 103, No. 1
Liquid Fluorochemicals in Vitreous Surgery
fluid was displaced anteriorly and it exited through the retinal break. Intraoperative man agement of giant retinal tears is facilitated since the tear can be unfolded and maintained in position without posterior slippage (Fig. 4). The entire surgical procedure can be performed with the patient in the supine position. The fluorochemical was injected to the level of the retinal break with residual retinal detachment anterior to fluorochemical. After release of all peripheral traction the anterior retina is best flattened by fluid-air exchange. Fluorochemical can be removed using a blunt 20-gauge needle on a flute needle or extrusion handpiece. During fluid-air exchange the airfluorocarbon meniscus flattens, resulting in a thin flat layer of residual fluorocarbon oil. This oil is easily removed by injecting 0.5 to 0.8 ml of balanced salt solution into the air-filled eye. The residual fluorocarbon oil then forms small round beads in saline which can be easily re moved (Fig. 5). After fluid-air exchange, addi tional endophotocoagulation should be applied to the anterior retina. The vitreous substitute chosen for long-term tamponade is then inject ed into the air-filled eye. The intraoperative use of liquid fluorocarbons requires further evaluation in multicenter clinical trials. Further investigation with other compounds for ocular tolerance and the devel opment of new manufacturing and purification techniques of fluorochemicals for medical ap plication will be necessary to develop the ideal substances for the management of complicated retinal detachments.
References 1. Pruett, R. C , Schepens, C. L., and Swann, D. A.: Hyaluronic acid vitreous substitute. Arch. Ophthalmol. 97:2325, 1979.
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2. Fitzgerald, C : The use of Healon in a case of rolled-over retina. Retina 1:227, 1981. 3. Gnad, H., Klemen, U. ML, and Radda, T. M.: Healon als innere Tamponade in der Netzhautchirurgie. Klin. Monatsbl. Augenheilkd. 183:184, 1983. 4. Folk, J. C , Packer, A. J., Weingeist, T. A., and Howcroft, M. J.: Sodium hyaluronate (Healon) in closed vitrectomy. Ophthalmic Surg. 17:299, 1986. 5. Miyamoto, K., Refojo, M. F., Tolentino, F. I., Fournier, G. A., and Albert, D. M.: Perfluoroether liquid as a long term vitreous substitute. An experi mental study. Retina 4:264, 1984. 6. Chang, S., Zimmerman, N. J., Iwamoto, T., Ortiz, R., and Faris, D.: Experimental vitreous re placement with perfluorotributylamine. Am. J. Oph thalmol. 102:29, 1986. 7. Retina Society Terminology Committee: The classification of retinal detachment with proliferative vitreoretinopathy. Ophthalmology 90:121, 1983. 8. Algvere, P.: Intravitreal implantation of a highmolecular hyaluronic acid in surgery for retinal de tachment. Acta Ophthalmol. 49:975, 1971. 9. Regnault, F.: Intravitreous hyaluronic acid and cryocoagulation in the treatment of severe types of retinal detachment. Bull. Soc. Ophthalmol. Fr. 84:106, 1971. 10. Kloti, R.: Hyaluronsaure als Glaskorpersubstituent. Ophthalmologica 165:351, 1972. 11. Edmund, J.: Vitreous substitute in the treat ment of retinal detachment. Mod. Probl. Ophthal mol. 12:370, 1974. 12. Kanski, J. }.: Intravitreal hyaluronic acid injec tion. A long-term clinical evaluation. Br. J. Ophthal mol. 59:255, 1975. 13. Stenkula, S., Ivert, L., and Giglason, I.: The use of sodium hyaluronate (Healon) in the treatment of retinal detachment. Ophthalmic Surg. 12:435, 1981. 14. Scott, J. D.: A rationale for the use of liquid silicone. Trans. Ophthalmol. Soc. U.K. 97:235, 1977. 15. Zivojnovic, R., Mertens, D. E., and Peperkamp, E.: Das flussige Silikon in Amotiochirugie (II) Bericht uber 280 Falle,weitere Entwicklung der Technik. Klin. Monatsbl. Augenheilkd. 181:444, 1982.