USES O F RTVSILICONE
IN ORBITAL
RECONSTRUCTION
LARS M . VISTNES, M . D . , AND G E O R G E L . PARIS, M . D . Palo Alto,
T h e typical appearance of many patients after enucleation o f a globe is marked enophthalmos and deep superior sulcus depression. T h e problem is primarily caused by a volume deficit. When the normal globe containing 6 ml is removed and replaced with an implant and a prosthesis, there is an average deficit o f 2.5 ml in volume, given a spherical implant o f 14 mm (1.5 ml) and a prosthesis of 2 ml. T h i s volume deficit is corrected by adding various space-occupying materials to the orbit, thereby pushing the remaining orbital contents and the implant upward and outward to correct the deficit. Autogenous material as well as homologous tissues of bone, cartilage, and dermis have been u s e d . Foreign material such as polytef (Teflon), silicone in various shapes and forms, and glass beads have been used to occupy the potential space. *
California
Removal is tedious, as each bead forms it own capsule. Bony erosion is another complication, with resulting loss of volume. 8
1
2 - 5
6
7
Silicone and glass beads have been popular because they are easily placed through a small incision into a suitably sized subperiosteal pocket, where they conform easily to the compound curvature o f the orbit. Just as balls remain in the bottom of a bucket (the orbit) when the bucket is upright, there is a tendency for the balls to spill out when the bucket is placed on its side. T h u s , the glass beads are often found at the orbital margin, either laterally, superiorly, or inferiorly.
M A T E R I A L AND METHODS
Room temperature vulcanizing (RTV) silicone (Silastic) is a liquid medical grade silicone elastomer base that—with the addition of a catalyst (stannous octoate)— vulcanizes to a soft silicone rubber which is indistinguishable from medical grade silicone rubber. T h e vulcanization process occurs without the development o f any heat. Vulcanization will also occur in vivo when the catalyst has been added, without any apparent injury to the surrounding tissue, and the time can be varied depending on the amount o f catalyst that is added, according to the manufacturer. S i n c e this material theoretically provides an implant that accurately conforms to the compound curvature of the orbit, does not migrate, and is easily inserted through a small incision, we used animals to demonstrate tissue tolerance of this material under conditions of vulcanization in vivo. 9
A thin sheet of the finished product was made by vulcanizing in vitro on an x-ray film; round disks, 1 cm in diameter, were cut from this sheet o f prevulcanized R T V silicone. Experimental—Contralateral^ paired pockets in 3 0 200-g female Sprague Dawley rats were made under the paniculus carnosus on the back o f the animals. T h e From the Divisions of Plastic and Reconstructive prevulcanized disk was inserted into one Surgery (Dr. Vistnes) and Ophthalmology (Dr. Paris), Stanford University Medical Center and the pocket, and into the opposite pocket an Surgical Service, Veterans Administration Hospital, equal volume of nonvulcanized material Palo Alto, California. (base and catalyst) was injected through Presented at the annual meeting of the American Society of Ophthalmic Plastic and Reconstructive the hub of a small syringe, pulling the Surgery, Las Vegas, Oct. 6, 1976. suture tight on removal of the syringe, Reprint requests to Lars M. Vistnes, M.D., Divithereby allowing vulcanization to take sion of Plastic and Reconstructive Surgery, Stanford University Medical Center, Stanford, CA 94305. place in vivo. 577
578
AMERICAN JOURNAL O F OPHTHALMOLOGY
Both implants were removed in a block with overlying skin and capsule at ten and 4 2 days, fixed in formalin, prepared as slides, and stained with hematoxylin and eosin and elastic-van Gieson's stains. The slides were evaluated qualitatively and the capsular thickness was measured with an ocular micrometer at five uniform points on the superficial and deep edges. R E S U L T S — T h e usual capsule that develops around any silicone implant was found. T h e capsule was slightly more cellular at ten days, but matured with less cellularity at 4 2 days. There was no essential histological difference between the two sides (Fig. 1) and statistical analysis of capsular thickness showed no significant differences. This was in keeping with findings of other investigators. Clinical—The use of R T V silicone to 10
APRIL,1977
overcome the volume deficit in the enophthalmic orbit was reported by Hill and R a d f o r d in 1 9 6 5 . Shannon and C o y l e were also aware of its potential, and Freeman, Biggs, and B e a l l wrote an encouraging report on its use. Our method, originally used in seven cases in 1 9 7 3 , differs from the method of Hill and R a d f o r d (who reported 2 5 cases) in that their method consisted o f a direct percutaneous injection of 1 ml o f R T V silicone into undisturbed tissue, whereas in our method the material is accurately placed into a surgically dissected pocket in a quantity never less than 2.5 ml. W e used this method in 4 2 cases. Some of the patients were observed for almost five years. M E T H O D — W h i l e the patient is under general anesthesia, a 1-cm incision is 11
12
13
1 4
11
Fig. 1 (Vistnes and Paris). Top left, Capsule around prevulcanized RTV silicone at ten days (elastic-van Gieson's, x50). Top right, Capsule around in vivo vulcanized RTV silicone at ten days (elastic-van Gieson's, x50). Bottom left, Capsule around prevulcanized RTV silicone at ten days (elastic-van Gieson's, x280). Bottom right, Capsule around in vivo vulcanized RTV silicone at 42 days (elastic-van Gieson's, x280). Note the similar cellular density between the prevulcanized and in vivo vulcanized RTV capsules at ten days. The cellularity decreases by a similar amount in each at 42 days when the fibrous orientation is apparent. Note slightly rougher capsular implant margin of in vivo vulcanized RTV silicone.
VOL. 83, NO. 4
ORBITAL
RECONSTRUCTION
579
made over the lateral orbital margin just above the external (lateral) canthal ligament. T h e periosteum is incised and separated from the b o n y orbit with a curved septal elevator creating a pocket laterally and along the orbital floor, all the way back to the apex, but not along the roof, so as not to disturb the levator m u s c l e mechanism. A packing o f ribbon gauze placed in this cavity for five minutes controls bleeding. On removal, a piece o f intravenous connector tubing is placed to the back o f the orbit and the periosteum is closed around it. R T V silicone and catalyst are mixed in the correct proportion (five to six drops o f catalyst to 10 ml o f autoclaved base, giving an arrangement time o f five minutes), placed in a 5-ml syringe, and pushed into the dissected cavity through the positioned tubing. T h e prosthesis is removed at the start o f the procedure and sterilized by soaking in povidone-iodine (Betadine) solution, allowing preparation of the socket. T h e prosthesis is replaced just before placement o f the R T V silicone, allowing the operator to place the correct amount by comparing it with the normal side. B e tween 2 . 5 and 3.0 ml is needed for the average eye with a normal uninjured bony orbit. T h e tube is removed after vulcanization to prevent leakage or tissue infiltration. T h e n the incision is closed. An eye pad is the only dressing with the prosthesis in place. Prophylactic antibiotics are used for 7 2 hours. T h e first dose is given the night before surgery, or intravenously at the start o f the operation. R E S U L T S — T h e results of surgery were good. All patients had a normal bony orbit. T y p i c a l results of the correction are shown in F i g u r e 2 . Material was not placed in the deep upper sulcus area because correction o f that defect was obtained by placing material along the floor
Fig. 2 (Vistnes and Paris). Top, Typical appearance with enophthalmos and deep superior sulcus after enucleation. Bottom, Six months after correction by using RTV silicone for augmentation of orbital volume.
and posteriorly, thereby pushing existing soft tissue upward and forward to obtain the correction. O n e patient had a superficial wound infection and seven patients had unexplained excessive swelling that subsided in three to four days. T w o patients developed minimal upper eyelid blepharoptosis caused by the surgery. At that time, o n e of us (L.M.V.) routinely dissected extensively along the roof o f the orbit to push some o f the material forward to fill out the upper sulcus depression. T h e blepharoptosis was caused by a mechanical interference with the levator muscle m e c h a n i s m . S i n c e this maneuver was stopped there has been no problem. T h e r e have b e e n no instances of migration o f the material, and no implants have required removal. In several cases, we viewed the lateral aspect o f the implant at the time o f placement o f a fascia lata sling for the correction o f droopy lower eyelids in these p a t i e n t s , and no evidence o f bony erosion was seen. 15
Another clinical usage—RTV silicone was also useful in reconstructing the con-
580
AMERICAN JOURNAL O F OPHTHALMOLOGY
tracted socket, where its use as a stent over the graft provides accurate immobilization. M E T H O D — A f t e r the surgical correction of an inadequate socket, the defect is lined with grafts of skin or, preferably, mucosa, depending on the circumstances. A Kirschner wire is drilled through the lateral orbital rim with a hand drill. T h e pin is cut off so that its free end is approximately at the midpoint o f the orbit and the other end protrudes through the skin. B y using a shell conformer with a single hole fitted on the hub o f a 5-ml syringe, such as ocularists use to take impressions o f an orbit for the fitting o f a prosthesis, the syringe is filled with R T V silicone and injected into the orbit with the eyelids closed over the shell. T h e material pushes the graft up against all recipient tissue and, by surrounding the Kirschner wire, provides an i m m o b i l e stent.
APRIL, 1977
16
A temporary tarsorrhaphy may b e performed if the graft covers the underside o f the eyelids. Antibiotic drops may be instilled during the postoperative period. R E S U L T S — S i x weeks to two months later, the Kirschner wire was wiggled out by grasping the free end that protruded laterally with a heavy needle holder. T h e stent was removed in toto, or was easily broken into pieces ( F i g . 3 ) . T h e reconstructed socket was cleansed and a prosthesis was fitted immediately. I f this was impossible, a conformer made by injecting another batch o f R T V silicone was provided until the custom-made prosthesis was finished. T h i s method o f reconstruction o f the socket uses acceptable and used techniques. T h i s modification was easy, simple, and successful in 11 cases. It is offered as an alternative to previously suggested methods of immobilization o f the stent, which may be technically both difficult and cumbersome.
Fig. 3 (Vistnes and Paris). Top, Contracted socket after enucleation of the left eye because of trauma. Bottom, Patient with prosthesis after reconstruction and mucosal graft. RTV silicone was used as a stent.
SUMMARY
In a five-year follow-up of 4 2 patients with unsatisfactory cosmetic results after enucleation, room-temperature vulcanizing ( R T V ) silicone was used in the surgical correction' of enophthalmos and superior sulcus depression. R T V silicone with a catalyst was placed in a dissected pocket subperiosteally along the floor and lateral wall of the orbit to correct the volume deficit. When vulcanizing in situ into soft silicone rubber, the implant conformed to the orbital wall and did not migrate. W e determined tissue tolerance to in situ vulcanizing silicone histologically in 3 0 rats by inserting prevulcanized and in situ vulcanized material in paired subcutaneous pockets. No statistical difference was noted between the two methods. In 11 cases, the same material was used as a convenient stent to maintain the pressure over a graft and to maintain socket size after the reconstruction of a contracted socket, by filling the socket with R T V silicone which surrounded a Kirschner wire drilled through the lateral orbital rim.
VOL. 83, NO. 4
ORBITAL RECONSTRUCTION
REFERENCES
1. Spaeth, E . B.: Principles and Practise of Ophthalmic Surgery, 4th ed. Philadelphia, Lea and Febiger, 1948, p. 141. 2. Cutler, N. I.: Fascia-lata transplant for retrotarsal atrophy of upper lid following enucleation. Am. J. Ophthalmol. 29:176, 1946. 3. DeVoe, A. C : Experiences with surgery of the anophthalmie orbit. Am. J . Ophthalmol. 28:1346, 1945. 4. Fry, H. J. H.: The enucleated eye socket. Br. J. Plast. Surg. 21:290, 1968. 5. Spaeth, P. G.: Superior sulcus deformity and ptosis. Int. Ophthalmol. Clin. 10(4):791, 1970. 6. Hneleski, I. S., and Shannon, G. M.: Orbital floor implant. Am. J . Ophthalmol. 76:540, 1973. 7. Smith, B., Obear, M., and Leone, C. R.: The correction of enophthalmos associated with anophthalmos by glass bead implantation. Am. J. Ophthalmol. 64.1088, 1967. 8. Jobe, R., Iverson, R., and Vistnes, L.: Bone deformation beneath alloplastic implants. Plast. Reconstr. Surg. 51:169, 1973.
581
9. Braley, S.: The chemistry and properties of the medical grade silicones. J. Macromol. Sci-Chem. A4: 529, 1970. 10. Rigdoa, R. H., and Dricks, A.: Reaction associated with silicone rubber gel. An experimental study. J . Biomed. Mater. Res. 9:645, 1975. 11. Hill, J . C , and Radford, C. J.: Treatment of advancing enophthalmos. Am. J . Ophthalmol. 60: 487, 1965. 12. Shannon, G. M., and Coyle, J . J . : Rubber silicone injections. Arch. Ophthalmol. 74:811,1965. 13. Freeman, B. S., Biggs, T. M., and Beall, A. E.: Injectable Silastic in deformities of the facial skeleton. Arch. Surg. 90:166, 1965. 14. Iverson, R. E . , Vistnes, L. M., and Siegel, R. J.: Correction of enophthalmos in the anophthalmie orbit. Plast. Reconstr. Surg. 51:545, 1973. 15. Vistnes, L. M., Iverson, R. E . , and Laub, D. R.: The anophthalmie orbit; surgical correction of lower lid ptosis. Plast. Reconstr. Surg. 52:346, 1973. 16. Vistnes, L. M., and Iverson, R. E . : Surgical treatment of the contracted socket. Plast. Reconstr. Surg. 53:563, 1974.
IN ORBITAL
RECONSTRUCTION
LARS M . VISTNES, M . D . , AND G E O R G E L . PARIS, M . D . Palo Alto,
T h e typical appearance of many patients after enucleation o f a globe is marked enophthalmos and deep superior sulcus depression. T h e problem is primarily caused by a volume deficit. When the normal globe containing 6 ml is removed and replaced with an implant and a prosthesis, there is an average deficit o f 2.5 ml in volume, given a spherical implant o f 14 mm (1.5 ml) and a prosthesis of 2 ml. T h i s volume deficit is corrected by adding various space-occupying materials to the orbit, thereby pushing the remaining orbital contents and the implant upward and outward to correct the deficit. Autogenous material as well as homologous tissues of bone, cartilage, and dermis have been u s e d . Foreign material such as polytef (Teflon), silicone in various shapes and forms, and glass beads have been used to occupy the potential space. *
California
Removal is tedious, as each bead forms it own capsule. Bony erosion is another complication, with resulting loss of volume. 8
1
2 - 5
6
7
Silicone and glass beads have been popular because they are easily placed through a small incision into a suitably sized subperiosteal pocket, where they conform easily to the compound curvature o f the orbit. Just as balls remain in the bottom of a bucket (the orbit) when the bucket is upright, there is a tendency for the balls to spill out when the bucket is placed on its side. T h u s , the glass beads are often found at the orbital margin, either laterally, superiorly, or inferiorly.
M A T E R I A L AND METHODS
Room temperature vulcanizing (RTV) silicone (Silastic) is a liquid medical grade silicone elastomer base that—with the addition of a catalyst (stannous octoate)— vulcanizes to a soft silicone rubber which is indistinguishable from medical grade silicone rubber. T h e vulcanization process occurs without the development o f any heat. Vulcanization will also occur in vivo when the catalyst has been added, without any apparent injury to the surrounding tissue, and the time can be varied depending on the amount o f catalyst that is added, according to the manufacturer. S i n c e this material theoretically provides an implant that accurately conforms to the compound curvature of the orbit, does not migrate, and is easily inserted through a small incision, we used animals to demonstrate tissue tolerance of this material under conditions of vulcanization in vivo. 9
A thin sheet of the finished product was made by vulcanizing in vitro on an x-ray film; round disks, 1 cm in diameter, were cut from this sheet o f prevulcanized R T V silicone. Experimental—Contralateral^ paired pockets in 3 0 200-g female Sprague Dawley rats were made under the paniculus carnosus on the back o f the animals. T h e From the Divisions of Plastic and Reconstructive prevulcanized disk was inserted into one Surgery (Dr. Vistnes) and Ophthalmology (Dr. Paris), Stanford University Medical Center and the pocket, and into the opposite pocket an Surgical Service, Veterans Administration Hospital, equal volume of nonvulcanized material Palo Alto, California. (base and catalyst) was injected through Presented at the annual meeting of the American Society of Ophthalmic Plastic and Reconstructive the hub of a small syringe, pulling the Surgery, Las Vegas, Oct. 6, 1976. suture tight on removal of the syringe, Reprint requests to Lars M. Vistnes, M.D., Divithereby allowing vulcanization to take sion of Plastic and Reconstructive Surgery, Stanford University Medical Center, Stanford, CA 94305. place in vivo. 577
578
AMERICAN JOURNAL O F OPHTHALMOLOGY
Both implants were removed in a block with overlying skin and capsule at ten and 4 2 days, fixed in formalin, prepared as slides, and stained with hematoxylin and eosin and elastic-van Gieson's stains. The slides were evaluated qualitatively and the capsular thickness was measured with an ocular micrometer at five uniform points on the superficial and deep edges. R E S U L T S — T h e usual capsule that develops around any silicone implant was found. T h e capsule was slightly more cellular at ten days, but matured with less cellularity at 4 2 days. There was no essential histological difference between the two sides (Fig. 1) and statistical analysis of capsular thickness showed no significant differences. This was in keeping with findings of other investigators. Clinical—The use of R T V silicone to 10
APRIL,1977
overcome the volume deficit in the enophthalmic orbit was reported by Hill and R a d f o r d in 1 9 6 5 . Shannon and C o y l e were also aware of its potential, and Freeman, Biggs, and B e a l l wrote an encouraging report on its use. Our method, originally used in seven cases in 1 9 7 3 , differs from the method of Hill and R a d f o r d (who reported 2 5 cases) in that their method consisted o f a direct percutaneous injection of 1 ml o f R T V silicone into undisturbed tissue, whereas in our method the material is accurately placed into a surgically dissected pocket in a quantity never less than 2.5 ml. W e used this method in 4 2 cases. Some of the patients were observed for almost five years. M E T H O D — W h i l e the patient is under general anesthesia, a 1-cm incision is 11
12
13
1 4
11
Fig. 1 (Vistnes and Paris). Top left, Capsule around prevulcanized RTV silicone at ten days (elastic-van Gieson's, x50). Top right, Capsule around in vivo vulcanized RTV silicone at ten days (elastic-van Gieson's, x50). Bottom left, Capsule around prevulcanized RTV silicone at ten days (elastic-van Gieson's, x280). Bottom right, Capsule around in vivo vulcanized RTV silicone at 42 days (elastic-van Gieson's, x280). Note the similar cellular density between the prevulcanized and in vivo vulcanized RTV capsules at ten days. The cellularity decreases by a similar amount in each at 42 days when the fibrous orientation is apparent. Note slightly rougher capsular implant margin of in vivo vulcanized RTV silicone.
VOL. 83, NO. 4
ORBITAL
RECONSTRUCTION
579
made over the lateral orbital margin just above the external (lateral) canthal ligament. T h e periosteum is incised and separated from the b o n y orbit with a curved septal elevator creating a pocket laterally and along the orbital floor, all the way back to the apex, but not along the roof, so as not to disturb the levator m u s c l e mechanism. A packing o f ribbon gauze placed in this cavity for five minutes controls bleeding. On removal, a piece o f intravenous connector tubing is placed to the back o f the orbit and the periosteum is closed around it. R T V silicone and catalyst are mixed in the correct proportion (five to six drops o f catalyst to 10 ml o f autoclaved base, giving an arrangement time o f five minutes), placed in a 5-ml syringe, and pushed into the dissected cavity through the positioned tubing. T h e prosthesis is removed at the start o f the procedure and sterilized by soaking in povidone-iodine (Betadine) solution, allowing preparation of the socket. T h e prosthesis is replaced just before placement o f the R T V silicone, allowing the operator to place the correct amount by comparing it with the normal side. B e tween 2 . 5 and 3.0 ml is needed for the average eye with a normal uninjured bony orbit. T h e tube is removed after vulcanization to prevent leakage or tissue infiltration. T h e n the incision is closed. An eye pad is the only dressing with the prosthesis in place. Prophylactic antibiotics are used for 7 2 hours. T h e first dose is given the night before surgery, or intravenously at the start o f the operation. R E S U L T S — T h e results of surgery were good. All patients had a normal bony orbit. T y p i c a l results of the correction are shown in F i g u r e 2 . Material was not placed in the deep upper sulcus area because correction o f that defect was obtained by placing material along the floor
Fig. 2 (Vistnes and Paris). Top, Typical appearance with enophthalmos and deep superior sulcus after enucleation. Bottom, Six months after correction by using RTV silicone for augmentation of orbital volume.
and posteriorly, thereby pushing existing soft tissue upward and forward to obtain the correction. O n e patient had a superficial wound infection and seven patients had unexplained excessive swelling that subsided in three to four days. T w o patients developed minimal upper eyelid blepharoptosis caused by the surgery. At that time, o n e of us (L.M.V.) routinely dissected extensively along the roof o f the orbit to push some o f the material forward to fill out the upper sulcus depression. T h e blepharoptosis was caused by a mechanical interference with the levator muscle m e c h a n i s m . S i n c e this maneuver was stopped there has been no problem. T h e r e have b e e n no instances of migration o f the material, and no implants have required removal. In several cases, we viewed the lateral aspect o f the implant at the time o f placement o f a fascia lata sling for the correction o f droopy lower eyelids in these p a t i e n t s , and no evidence o f bony erosion was seen. 15
Another clinical usage—RTV silicone was also useful in reconstructing the con-
580
AMERICAN JOURNAL O F OPHTHALMOLOGY
tracted socket, where its use as a stent over the graft provides accurate immobilization. M E T H O D — A f t e r the surgical correction of an inadequate socket, the defect is lined with grafts of skin or, preferably, mucosa, depending on the circumstances. A Kirschner wire is drilled through the lateral orbital rim with a hand drill. T h e pin is cut off so that its free end is approximately at the midpoint o f the orbit and the other end protrudes through the skin. B y using a shell conformer with a single hole fitted on the hub o f a 5-ml syringe, such as ocularists use to take impressions o f an orbit for the fitting o f a prosthesis, the syringe is filled with R T V silicone and injected into the orbit with the eyelids closed over the shell. T h e material pushes the graft up against all recipient tissue and, by surrounding the Kirschner wire, provides an i m m o b i l e stent.
APRIL, 1977
16
A temporary tarsorrhaphy may b e performed if the graft covers the underside o f the eyelids. Antibiotic drops may be instilled during the postoperative period. R E S U L T S — S i x weeks to two months later, the Kirschner wire was wiggled out by grasping the free end that protruded laterally with a heavy needle holder. T h e stent was removed in toto, or was easily broken into pieces ( F i g . 3 ) . T h e reconstructed socket was cleansed and a prosthesis was fitted immediately. I f this was impossible, a conformer made by injecting another batch o f R T V silicone was provided until the custom-made prosthesis was finished. T h i s method o f reconstruction o f the socket uses acceptable and used techniques. T h i s modification was easy, simple, and successful in 11 cases. It is offered as an alternative to previously suggested methods of immobilization o f the stent, which may be technically both difficult and cumbersome.
Fig. 3 (Vistnes and Paris). Top, Contracted socket after enucleation of the left eye because of trauma. Bottom, Patient with prosthesis after reconstruction and mucosal graft. RTV silicone was used as a stent.
SUMMARY
In a five-year follow-up of 4 2 patients with unsatisfactory cosmetic results after enucleation, room-temperature vulcanizing ( R T V ) silicone was used in the surgical correction' of enophthalmos and superior sulcus depression. R T V silicone with a catalyst was placed in a dissected pocket subperiosteally along the floor and lateral wall of the orbit to correct the volume deficit. When vulcanizing in situ into soft silicone rubber, the implant conformed to the orbital wall and did not migrate. W e determined tissue tolerance to in situ vulcanizing silicone histologically in 3 0 rats by inserting prevulcanized and in situ vulcanized material in paired subcutaneous pockets. No statistical difference was noted between the two methods. In 11 cases, the same material was used as a convenient stent to maintain the pressure over a graft and to maintain socket size after the reconstruction of a contracted socket, by filling the socket with R T V silicone which surrounded a Kirschner wire drilled through the lateral orbital rim.
VOL. 83, NO. 4
ORBITAL RECONSTRUCTION
REFERENCES
1. Spaeth, E . B.: Principles and Practise of Ophthalmic Surgery, 4th ed. Philadelphia, Lea and Febiger, 1948, p. 141. 2. Cutler, N. I.: Fascia-lata transplant for retrotarsal atrophy of upper lid following enucleation. Am. J. Ophthalmol. 29:176, 1946. 3. DeVoe, A. C : Experiences with surgery of the anophthalmie orbit. Am. J . Ophthalmol. 28:1346, 1945. 4. Fry, H. J. H.: The enucleated eye socket. Br. J. Plast. Surg. 21:290, 1968. 5. Spaeth, P. G.: Superior sulcus deformity and ptosis. Int. Ophthalmol. Clin. 10(4):791, 1970. 6. Hneleski, I. S., and Shannon, G. M.: Orbital floor implant. Am. J . Ophthalmol. 76:540, 1973. 7. Smith, B., Obear, M., and Leone, C. R.: The correction of enophthalmos associated with anophthalmos by glass bead implantation. Am. J. Ophthalmol. 64.1088, 1967. 8. Jobe, R., Iverson, R., and Vistnes, L.: Bone deformation beneath alloplastic implants. Plast. Reconstr. Surg. 51:169, 1973.
581
9. Braley, S.: The chemistry and properties of the medical grade silicones. J. Macromol. Sci-Chem. A4: 529, 1970. 10. Rigdoa, R. H., and Dricks, A.: Reaction associated with silicone rubber gel. An experimental study. J . Biomed. Mater. Res. 9:645, 1975. 11. Hill, J . C , and Radford, C. J.: Treatment of advancing enophthalmos. Am. J . Ophthalmol. 60: 487, 1965. 12. Shannon, G. M., and Coyle, J . J . : Rubber silicone injections. Arch. Ophthalmol. 74:811,1965. 13. Freeman, B. S., Biggs, T. M., and Beall, A. E.: Injectable Silastic in deformities of the facial skeleton. Arch. Surg. 90:166, 1965. 14. Iverson, R. E . , Vistnes, L. M., and Siegel, R. J.: Correction of enophthalmos in the anophthalmie orbit. Plast. Reconstr. Surg. 51:545, 1973. 15. Vistnes, L. M., Iverson, R. E . , and Laub, D. R.: The anophthalmie orbit; surgical correction of lower lid ptosis. Plast. Reconstr. Surg. 52:346, 1973. 16. Vistnes, L. M., and Iverson, R. E . : Surgical treatment of the contracted socket. Plast. Reconstr. Surg. 53:563, 1974.
