To receive a printed copy of "SCLERAL BUCKLING SURGERY - A Short History of Silicone Retinal Implants/Exoplants" edited by Michael Shea, M.B. F.R.C.S.(C), Toronto, Ontario please click here and request.

Scleral Buckling - The Beginning
Chronology of Key Advancements
Silicone Remains the Material of Choice
The Evolution of Silicone Implant Styles
Solid Silicone Implants
Silicone Sponge Implants
Conclusion
Footnote References
Bibliography

Scleral buckling, as a surgical technique to repair retinal detachments, was first used experimentally by ophthalmic surgeons in 1937. By the early 1960's, scleral buckling had become the surgical method of choice when the development of new materials, particularly silicone, offered surgeons exciting new opportunities for improving their outcomes. This evolution was facilitated by the development of binocular indirect ophthalmoscopy and slit lamp contact lens posterior segment biomicroscopy. These technical advances helped visualization and consequently the understanding of the process of vitreoretinal traction with retinal tear formation, and (at least in part) suggested methods for its correction. The availability of Silicone made this evolution of design much more practical than it had been prior to that time.

Since scleral buckling was first performed, many materials and procedural techniques have been used in an attempt to find the combination that will provide optimal results for the patient. The short review which follows highlights the history of scleral buckling surgery and chronicles the important advances that have been made, with a particular emphasis on the design and development of silicone implants for retinal detachment surgery. This history is not meant to serve as a text for learning new techniques. Rather, its purpose is to provide an historical perspective and a review of the evolution of retinal implant design.

Labtician Ophthalmics, Inc. is pleased to bring you this overview. Today most medical advances are meticulously chronicled and documented in medical literature publications. Such was not the case even four decades ago as Silicone Retinal Implants were being developed. As a result, some developments in the field of silicone retinal implant design are not well known. We have attempted to capture much of this background knowledge and bring it together here. We hope you enjoy this review and invite you to send us your insights. Please share your historical knowledge with us and add to our base of information. Please write to us with any comments or insights you might care to offer.

Labtician has been in the forefront of Silicone Retinal Implant development since the earliest days of its acceptance as a viable surgical technique. In 1959, Labtician was cited as being the first manufacturer of silicone retinal implants by Dr. Louis Girard (Houston, Texas) in a presentation to the Mid-Southern Section Meeting of the Association for Research in Ophthalmology. Today, 47 years later, Labtician continues to introduce advancements in the field. It should be noted that scleral buckling materials are sometimes referred to as implants, explants, or exoplants. For purposes of this text, most references use the word "implants".

SCLERAL BUCKLING – THE BEGINNING

In 1937, A. Jess (Germany) performed what may have been the first scleral buckling surgery using an explant when he reported that he had used a gauze pad to temporarily indent the eye wall to approximate the retina with the choroid.1

Many advances in scleral buckling materials and in surgical techniques have been made since that time and will, no doubt, continue to be made. The basic concept, however, remains the same ­ create a controlled injury to the retinal pigment epithelium and retina at the site of the detachment to produce an adhesion. A scleral buckling technique is then employed to approximate the retinal breaks to the underlying retinal pigment epithelium by countering the modest vitreous pull. If successful, a retinal reattachment results.

CHRONOLOGY OF KEY ADVANCEMENTS

1937 Jess reports use of gauze pad for scleral buckling.

1949 Custodis performs first scleral buckling operation using an episcleral explant.

1953 Custodis uses polyviol as an episcleral implant.

1957 Schepens, Okamura and Brockhurst develop procedures to use polyethylene tubing as an encircling element for scleral buckling.

1958 Supramid, Mersilene and nylon threads used in place of polyethylene tubing by Arruga.

1959 Girard reports the first use of Labtician silicone rubber rod for scleral buckling.

1960 Schepens, Okamura, Brockhurst and Regan begin to popularize the use of solid silicone implants and develop many of the basic styles still used today.

1965 Lincoff, Baras, and McLean are the first to report on the use of silicone sponge for treating large retinal tears.

1967 Hoepping reports the use of a balloon for scleral buckling of the macula, sutured in place (not temporary).

1972 Grignolo, Refojo, Calabria and Zingirian report buckling success using a hydrogel material.

1973 Banuelos, Refojo, Carbajo and Huamonte introduce expandable silicone implants.

1979 Lincoff and Kreissig develop a temporary balloon technique that does not require sutures.

SILICONE REMAINS THE MATERIAL OF CHOICE

Many other materials have been used for scleral buckling. The chart appended to this review chronicles their development, and in most cases, their demise. Surgeons have experimented with many materials and implant designs, seeking a combination that would be easy for the surgeon to use, maximize results for the patient, and minimize morbidity. All but silicone have subsequently been abandoned or fallen into disuse. Silicone has remained popular because of its inherent properties.

Silicone, a synthetic rubber compound of silicon, oxygen and carbon, is hydrophobic and stable within a very wide temperature range. Silicone retinal implants are economical, soft, biochemically inert, non-allergenic, and are well tolerated by the body. In vivo, they remain soft and retain their other physical properties for an extended period. They also retain these properties in extended storage.

The inherent smoothness of the silicone material and the implant's rounded contour leads to the development of a tough, collagenous capsule around the implant. At first vascularized, the capsule eventually becomes avascular and translucent. This capsule seals off the episcleral implant, helping to minimize the opportunity for later infection or migration. With intrascleral implants, the capsule also grows between the implant and sclera, protecting against erosion through the sclera. (If the implant has sharp corners, if an early infection occurs, or if the implant exerts excessive pressure on the eye wall, this capsule may be weak or absent.) Because silicone does not allow tissue ingrowth, the implant can be easily taken out in one piece without much trauma if removal does become necessary. The so-called silicone "sponge" implant is actually a closed cell foam which has the same chemical composition as the solid silicone implant. Silicone sponge was designed to be more elastic than solid implants. It produces a high buckle that usually increases postoperatively; an advantage when the procedure does not include the release of subretinal fluid. Sponges are usually used as episcleral exoplants but can be placed under scleral flaps if desired.

For the surgeon, implants made from silicone offer many advantages over other materials:

• The implant procedure does not require the disinsertion of the rectus muscles or the resection of the sclera.

• Silicone implants have been designed in a wide variety of shapes (see next section) to meet virtually every buckling requirement.

• The stretched silicone implant in vivo tends to contract, with its length determined by intraocular pressure. Over time, stress relaxation results in lengthening of the band. Its eventual length stabilizes between the original length and the length at the end of the operation, resulting in lower long-term stress on the eye.

• Solid silicone is nearly transparent, which, during re-operations, may allow the surgeon to see thin areas in the underlying sclera through the buckling material before it is removed.

• If the buckle is found to be improperly positioned, the implant can be moved anteriorly or posteriorly by moving the anchoring sutures so that the correct position is attained.

• If the buckling procedure is not successful, the eye remains sufficiently intact to permit other procedures to be performed.

• With solid silicone, the collagenous capsule which forms makes re-operation easier. It permits the implant to be easily identified and allows it to slide out of the capsule without adhering to surrounding tissue. • Solid and sponge silicone implants are cost effective.

THE EVOLUTION OF SILICONE IMPLANT STYLES

In the beginning, the design of scleral buckling materials was fairly simplistic. The surgeon needed an element that would encircle the eye, creating an indentation that would approximate the retina to the underlying choroid. Later, as surgeons sought ways to improve their outcomes, new element shapes were developed with specific applications in mind.

Today, more than 70 style options are available to the ophthalmic surgeon seeking an implant designed to achieve a particular width, height or shape of buckle. The evolution continues today as new techniques develop, and as surgeons identify new needs and suggest new styles to meet those needs.

The following section helps to explain the rationale for the various styles over the first 40 years of implant development.

SOLID SILICONE IMPLANTS

Silicone Rod

The first silicone implant employed by Dr. Louis Girard in 1959 was a simple rod or cylindrical shaped element.2 Its softness and elasticity made it less likely to erode through the sclera than its predecessor, polyethylene tubing. In 1961, Girard and Dr. Alice McPherson (Houston, Texas) reported more fully on the successful use of this silicone rubber rod.3

Drs. Regan, Schepens, Okamura and Brockhurst reported that the hardness and rigidity of polyethylene tubing exerted severe pressure on the globe. Its narrow bearing surface eventually caused erosion through the sclera and sometimes even the choroid.4

The softness of the silicone greatly reduced the opportunity for erosion, but the rod-like shape limited its usefulness. A new design was needed which would spread the indentation over a greater surface. Flat bands of various widths were developed and tried as encircling elements.

Circling Bands

Flat Circling Bands had largely replaced the round Silicone Rod as a buckling element by 1965. Circling Bands answered the need for greater lateral support and exhibited other advantages as well. The flattened configuration stretched better under the influence of ocular pressure and it resisted the ocular pressure more evenly over the entire bearing surface.

After much trial and error, two Circling Band widths emerged as the defacto standards, 2.0 mm and 2.5 mm. Today, these elements are still the most commonly used silicone implants with the 2.5 mm Circling Band being the most popular.

In 1993, more than 30 years after the development of the first Circling Bands, Dr. P. Gray (London, England) designed a modified Circling Band called the Silicone Lace.5 His design features a removable stainless steel aglet attached to one end of the band. The aglet provides a solid place to grasp the element firmly with less risk of damaging the silicone. The aglet also serves as a leader to facilitate the threading of the band around the globe through scleral tunnels or under mattress sutures and muscles. Perhaps most importantly, the aglet makes it faster and easier to pass the second (aglet) end of the implant through the Watzke Sleeve. The Silicone Lace is 10.0 mm longer than standard Circling Bands to allow room for the aglet, which is removed from the band at the end of the surgical procedure.

With earlier encircling elements made from polyethylene tubing, the surgeon could pass the securing suture through the lumen in the tube to tie the two ends of the element in place. When silicone Circling Bands began replacing the polyethylene tubing, a new method of securing the elements had to be found. Tantalum Clips were developed to meet this need.

Tantalum is quite ductile and malleable, so it can be bent a number of times without breaking. Tantalum Clips were found to be less bulky than sutures, allowing the surgeon to adjust the tension of the Circling Band. Tantalum Clips did not cause tissue reaction and did not harbor infection. Years later, another advantage was discovered - because tantalum is a non-ferrous metal (non-magnetic), Tantalum Clips are safe for MRI imaging. Tantalum Clips do still show up on X-rays, however. Originally, both single prong and double prong Clips were developed. Only double prong Clips are used today.

Boats were specifically designed to use under Tantalum Clips to prevent erosion of the underlying tissue. This application was first described by Schepens et al.6 Unfortunately, a Boat is not easy to maintain in place. The surgeon usually avoids its use by placing the Tantalum Clip in the groove of the main buckling element.

Another concept for holding the Circling Band in place was the Silicone Sleeve. Dr. Robert Watzke (Portland, Oregon) introduced the concept of a Silicone Sleeve in 1963.7 The Sleeve is derived from a small diameter silicone tube. The tube mouth is opened using specially designed forceps. The ends of the circling element are threaded through the Sleeve from opposite directions. They can then be pulled to adjust the tightness and length of the Circling Band. As Dr. Watzke reported at the time, "The connection is easily accomplished, inert and most importantly, easily re-adjustable. Since all such connections have more bulk than the encircling element itself, the Sleeve should be well buried under a Tenon's capsule and conjunctival closure and the intraocular pressure should be carefully adjusted to prevent scleral erosion."

Dr. Michael Shea (Toronto, Ontario) designed the newest concept for a Silicone Sleeve. Dr. Shea noted that when a Silicone Sleeve was used to hold one of the wider encircling elements (3.5 mm and larger) the encircling element was often "pinched" by the sleeve causing the Band to pucker instead of lying smoothly in place. Dr. Shea designed an Oval Sleeve that is more "anatomically correct" and which fits the encircling element more naturally thus avoiding the slight bulge created by Cylindrical Sleeves.

The concept of a flat Silicone Strip was derived from the basic Circling Band design. It was originally developed for use in trap door procedures. More recently, Silicone Strips have been used as encircling elements when the surgeon wants to achieve a wider buckle such as in cases of proliferative vitreoretinopathy. The 5.0 mm version has found an application as a prophylactic buckle following vitrectomy surgery.

Early implant designers soon recognized that they needed buckling elements which would yield something more than a simple band around the eye. They wanted to create buckles of varying heights and lengths. Out of this need grew the concept of the grooved implant. The posterior side of the implant would contain geometry to create a particular buckle profile. The anterior side was formed as a groove through which an encircling element could be passed to hold the underlying element in place. Eventually, Grooved Strips, Grooved Tires, Grooved Sponges and other accessory implants grew out of this design concept.

Grooved elements were designed for use in combination with the basic Circling Band as a means of creating different buckling configurations. By placing a grooved element under a Circling Band, it is possible to increase the width of the sclera that can be engaged using a Circling Band alone. Additionally, by changing the geometry of the grooved underlying element, different buckle configurations could be achieved. Grooved Strips were the earliest such elements to be developed, and were first described by Regan, Schepens, Okamura and Brockhurst.8

The Grooved Strips are manufactured in several appropriate sizes and shapes to reduce the need for trimming of the implant by the surgeon. The rectangular groove along the outer surface of the Grooved Strip permits a Circling Band to lie perfectly flat against the strip and, once secured in place, virtually eliminates the opportunity for the Band to slip off the implant. Grooved Strips are designed with either a 2.0 mm groove for use with a 2.0 mm Circling Band, or with a 2.5 mm groove which can be used with a 2.5 mm Circling Band. The Circling Band holds the Grooved Strip in position and contributes to the height of the buckle that is to be achieved. The choice of which Grooved Silicone Strip style to use depends upon the width, shape, and height of buckle required. Several profiles are available. Styles 20 and 219 provide average buckling. Style 220 provides a wide scleral bed, and Styles 31, 32 and 225 facilitate high buckles.

Silicone Tires

The concept of a Silicone Tire was first reported by Schepens et. al.9 Silicone Tires were developed to expand upon the concept of the Grooved Strip. The Tire encircles the globe on a "greater circle" under a Circling Band. Like Grooved Strips, Silicone Tires feature a groove in their outer surface for the placement of the Circling Band. Prior to use, the Tire is trimmed to a size appropriate for the case being treated. Often, only a small segment of the Tire is used.

Although the material is soft and supple, Silicone Tires are more rigid than Grooved Strips. This greater rigidity is achieved by molding the silicone rubber into a particular shape, while Grooved Strips are made using an extrusion process. The main advantage of a molded implant is that it can be formed with an inner arc that approximates the curvature of the eyeball. This makes tires easier to place and, although they remain soft and pliable, the molded geometry creates a buckle of a desired shape.

Silicone Tires are used most often for breaks near the ora serrata, for multiple breaks, for high scleral buckles, and to counteract vitreous traction.

Silicone Tires also create a wider bearing surface around the globe and spread the resulting force more evenly over a larger area. Consequently, less scleral indentation occurs. Tires are available in three basic configurations - Convex, Asymmetrical, and Concave. Each shape was designed with a different buckling effect in mind.

Asymmetrical Tires were designed primarily for use with anterior breaks. The asymmetrical design allows the surgeon to place the Circling Band near the equator of the eye while creating a buckle in the anterior portion. The designs of the various Asymmetrical Tires are similar, but various widths and thicknesses have been developed. This permits the surgeon to select the profile that best suits the requirements of the patient without the need to hand carve the silicone.

In 1987, Dr. Michael Gaynon (Palo Alto, California) redesigned the popular 280 Style Asymmetrical Tire to incorporate a 4.0 mm groove (Style 280LG). This allows the use of a 4.0 mm Silicone Strip as an encircling element to hold the tire in place. The pressure exerted on the sclera by the wider band is more broadly distributed than with narrow bands. Dr. Gaynon comments, "This results in more even scleral indentation and lower risk of scleral erosion. In addition, there are a number of retinal surgeons who use a 4.0 mm wide Encircling Band as their primary buckling material. For them, the 280LG is the first solid silicone implant available designed for supplementation of such a buckle. Finally, the ability to use the implant in conjunction with a 4.0 mm wide Encircling Band allows for broader coverage of peripheral retinal pathology in areas remote from the implant." 14

In 1990, Dr. Richard Munsen (Seattle, Washington) designed an asymmetrical style for use in smaller eyes with aphakic or pseudophakic breaks and retinal detachments (Style 275). He saw a smaller Asymmetrical Tire as being advantageous in nondrainage cases and when there is minimal subretinal fluid for drainage. He says "A reduced volume of explant minimizes the intraoperative complications of elevated intraocular pressure or the postoperative complication of choroidal detachments. I, therefore, designed the 275 Style Tire to be used when the extra width and volume of a 276 asymmetric was not needed. This 275 Tire produces a good buckle with an 8.0 mm suture bed."15

Concave Tires were designed for use in treating shallow breaks and for breaks with fluid pools that will be drained. Concave Tires all feature a similar inside curvature, but they are offered in several widths and thicknesses so that the right buckle can be achieved without the need to manually trim the implant to achieve a desired size. In 1997, Dr. Hugh Parsons (Vancouver, British Columbia) designed a new Concave Tire which mimicked the effect of a Meridional Implant. The Tire was designed to fit under a 4.0 mm (42 Style) Silicone Strip and provide additional support for retinal breaks that are posterior to the buckle.16

Regan, Schepens, Okamura and Brockhurst first described Meridional Implants in 1962.17 In the beginning, a Meridional Implant was hand crafted by the surgeon from a preformed silicone element called a "Cap". Today, three standardized styles are offered. Each style provides progressively greater buckling, from Style 103 (thin and narrow), Style 106 (high and mid size) to Style 112 (high and wide). The main purpose of the Meridional Implant is to minimize problems associated with puckering along the posterior edge of a large retinal tear. Puckering can occur when subretinal fluid is released. The fold extends in a meridional direction over the buckle toward the disk. When the possibility of such puckering exists, a wider and higher buckle is required. The posterior flange on the Meridional Implant holds the implant in position under a grooved implant on the posterior side. The flange is beveled to fit smoothly under the scleral flap.

Wedges are grooved implants. This allows them to be secured under a Circling Band. Dr. Ronald Pruett (Boston, Massachusetts) first discussed the Wedge in the medical literature in 1977 as a device designed to equalize the relative reduction in circumference during a scleral buckling procedure.18 This was felt to minimize the tendency of scleral buckling to cause radial retinal folding. To help to achieve this goal, the Wedge has both a radial axis and a contoured side-cut that follow the meridians of the eye. Its inner surface is concave from the equatorial zone, anteriorly. Posteriorly, it assumes a gradually increasing convex contour with the most sharply convex dimension located along its radial axis. At the equator, the implant is moderately thick and wide. The narrow, thinner anterior portion more nearly displaces the same relative volume at the ora serrata, as does the widest portion at the equator. With the same purpose in mind, the posterior extension narrows abruptly to end in a blunt, rounded tip that is the implant's thickest portion. This configuration permits a continuous variation in both the degree of indentation and the arc that is buckled along the meridian of the tear. Two sizes of the Wedge are available today.

The Silicone Pad was developed for use in closing a scleral rupture. It never became popular because scleral ruptures were rare, and other forms of implants did the job equally well.

The Button was designed to be used under a Grooved Strip to increase the thickness of the strip and thus produce a localized wider or higher buckle. It is fabricated with a depression in the external surface sized to fit under a Grooved Strip. Buttons were mentioned in the literature as early as 1965 but in practice, they are used infrequently.

SILICONE SPONGE IMPLANTS

In 1962, Dr. H. Lincoff (New York, New York) introduced a new surgical procedure to the United States. Dr. Ernst Custodis (Dusseldorf, Germany) originally developed the procedure that called for the use of polyviol (a red rubbery material) which could be compressed over the sclera to half its original thickness and which was held in place with a mattress suture. Over the next few hours as the intra-ocular pressure returned to normal, the explant expanded, creating a high buckle that closed the retinal break and attached the retina without drainage of sub-retinal fluid. The elasticity of polyviol was essential to the operation without drainage. However, polyviol, which is made of polyvinyl alcohol, gum arabic and congo red was irritating to the tissues. Subsequent reports associated it with an increased rate of scleral infection and extrusion. With these things in mind, Dr. Lincoff started to search for a replacement material.

Dr. Lincoff was seeking an elastic implant that, like polyviol, would create a buckle that increased in height postoperatively as the intra-ocular pressure returned to normal. At that time, Dow Corning was producing solid silicone which was being used for scleral buckling. Dow Corning supplied Dr. Lincoff with 5.0 mm diameter rods which seemed a promising material, but they lacked the elasticity of the polyviol. Dow suggested that a silicone sponge might provide the elasticity desired and made three samples. One was too soft, and one was too hard. The third seemed just about right. Animal trials were conducted that showed the sponge could be compressed to about half-thickness without scleral tearing. Observations over ten days showed no irritant effect and a good internal buckle effect.

"A clinical trial confirmed that the silicone sponge was a suitable replacement for the polyviol explant," Dr. Lincoff states. "The rate of infection was 3%, equal to the rate with solid silicone. There was a concern that the open-cell structure of the sponge might serve as a haven for bacteria and increase the long term risk. Animal studies into the cause of explant infections revealed that the foreign body, diathermy necrosis, and a pathogenic organism were all risk factors. To counter this, I replaced diathermy with cryopexy and Dow developed a closed cell sponge with a protective coating. These changes reduced the rate of explant infection to less than 0.5%. The new silicone sponge was elastic and safe.

"Further experience showed that radially oriented implants were more effective in closing retinal breaks than the traditional circumferentially oriented implants. A segment of the new sponge, a 5.0 mm cylinder radially oriented, was suitable for closing breaks with a circumferential diameter of 4.0 mm or less, which includes the vast majority of retinal breaks. Larger breaks could only be buckled with a circumferential sponge or treated with an internal gas tamponade. For circumferential buckling, grooved sponges were developed.

"To diminish the external hump that appeared with implants that were fixed anterior to the equator, half-thickness sponges were introduced. A half-thickness sponge sacrifices much of the elastic component of a full thickness sponge, but it proved adequate for anterior breaks which tend not to be as elevated. The 3.0 mm x 5.0 mm sponge is equally effective, provides a higher buckle and is my first choice for radial or circumferential buckling anterior to the equator."19

Today, Silicone Sponges are very popular materials for buckling. They have proven to be both effective and safe. According to Dr. Lincoff, "Most importantly, the elastic properties of the silicone sponge make external drainage of subretinal fluid unnecessary in most retinal detachment operations."

In 1965, Drs. Lincoff and McLean introduced the Round Silicone Sponge as a circling element.20 As was mentioned earlier, Lincoff also showed that short segments of the Round Sponge could be placed radially to close breaks with a circumferential diameter of 4.0 mm or less.21

Oval Sponges were introduced in 1967. As Dr. Lincoff observed, these sponges lie flatter on the globe than Round Sponges. For larger breaks, a 7.5 mm x 5.5 mm Oval Sponge was developed. It closed breaks as large as 6.0 mm, or one clock hour in diameter. The oval configuration also made it possible to overlap two sponges with a 14.0 mm mattress suture and close a break as large as 9.0 mm.

The smaller (4.0 mm x 2.5 mm) 501 Style Silicone Sponge was designed to create an element that would lie flatter on the globe than the original Oval Sponges. The small size proved very popular for peripheral breaks as well as small segmental buckles. In some cases, this style can be used as a Circling Band in combination with some of the Grooved Sponge styles that have been designed for that purpose.

Dr. A. Vaiser (Dallas, Texas) developed the Style 506 Oval Sponge (3.0 mm x 5.0 mm) in 1977 and reported on its use at the Paul Cibis Club in 1979.22 Its 3.0 mm x 5.0 mm profile is useful in situations such as a large dialysis with limited subretinal fluid, a large tear with a small satellite tear at a slightly different level, multiple tears at different levels, and large anterior horseshoe tears. Dr. Lincoff observes that the 3.0 mm x 5.0 mm Sponge is his first choice for radial or circumferential buckling anterior to the equator.23

Dr.'s M. Rubin and C. Fitzgerald first recommend the use of Partial Thickness Sponges in 1974.24 At that time, surgeons started cutting Full Thickness Sponges to the desired size. Trimming the sponge lessened their external bulk without substantially reducing their internal buckling effects.

Dr. R. Olk (St. Louis, Missouri) designed the first of the commercially prepared Partial Thickness Sponges (Styles 510 and 511) in 1987. These styles were half thickness versions of the popular 5.0 mm Round (Style 505) and 5.5 mm x 7.5 mm Oval (Style 507) Sponges. According to Dr. Olk, "The initial impetus for designing partial thickness scleral sponges was due to the fact that we were experiencing a small but significant incidence of extrusion as well as infection of full thickness sponges. It was thought that by decreasing the external thickness, we could reduce if not eliminate, the above complications. Our experience over the past decade has shown this to be the case. Initially, we manually cut down full thickness sponges to the desired thickness intraoperatively but then had these commercially developed. In addition, one other complication frequently encountered with full thickness sponges was that of significant motility problems in the postoperative period. This complication has virtually been eliminated using partial thickness sponges."25 Silicone Sponges that are prepared commercially offer the added benefit of having the surfaces sealed as a part of the extrusion process. When sponges are cut by hand, the sponge surface is much rougher.

In 1988, Drs. A. Brucker and F. Robinson (Philadelphia, Pennsylvania) developed two additional Partial Thickness Sponge Styles.26 They felt that their new designs (3.66 mm x 7.5 mm) Style 517 and (3.33 mm x 5.0 mm) Style 515 which are thicker than the first two Partial Thickness designs, gave a more regular and predictable width to the buckle.

Dr. C. Scholda (Vienna, Austria) developed the newest of the sponge designs. This novel style was developed following an extensive geometrical study of silicone sponge elements and their buckling effects. Dr. Scholda found that while the use of Partial Thickness Sponges greatly reduced their anterior bulk, their shallow profile made them less useful than full thickness elements. By altering their shape to include a small anterior curvature, Dr. Scholda was able to design an effective buckling element.27

Like other Solid Silicone Grooved Implants, Grooved Sponges were initially designed to be held in place with a Circling Band. Later it was found that they could often be used alone to achieve a desired buckling effect.

For instance the 509G Style Sponge was designed to create a sponge element that could be used for retinal tears requiring wide buckling. This element provided wide coverage and could be secured in place using a Circling Band.

Dr. R. Olk (St. Louis, Missouri) suggested the adaptation of his Partial Thickness Sponge designs in 1997. He saw a need to insert a partial circumferential segment under either a 40 or 240 Style Encircling Band. Dr. Olk reports that "Having a groove on the outer surface of the partial thickness sponge has made it much easier for the operating surgeon to insert a partial thickness circumferential segment intraoperatively."28

While a standard 2.5 mm Circling Band can be used with all of the Grooved Sponges, two of the elements (Style 516G & 519G) were designed by Dr. Lincoff to be used with a sponge circling element (Style 501). The grooves in these elements are designed with slanted rather than square shoulders to accommodate the bulkier sponge encircling element.

The Tunnel Sponge was designed to be used with a Circling Band threaded internally through the length of the sponge. This permits a high, localized buckle with little volume displacement of the globe. At the same time, buckle migration is minimized.

Oblong Sponges were designed for use in procedures where a wide buckle is indicated. For a time, surgeons accomplished such a buckle by attaching two pieces of sponge together in parallel. The introduction of an oblong shape eliminated this need.

Dr. Fuller designed the first of the wide Oblong Sponges (Style 508) for use when a wide, thick buckle was indicated. Later this design was modified by Dr. A. Frederick (Boston, Massachusetts), to provide a smaller, Oblong Sponge (Style 509) that reduces the overall bulk while still allowing wide coverage.

Dr. W. Snyder and associates (Dallas, Texas) developed the L-Shaped Sponge.21 The sponge was developed to assist in the repair of certain complicated retinal detachments such as tears that fall slightly behind the buckle or for tears that fishmouth. Radially placed, its purpose is the same as the Meridional Silicone Implant. The L-Shaped Sponge permits the surgeon to broaden the area of scleral indentation in the meridian of the retinal tear. The surgeon secures the sponge behind the encircling element with the extension inserted between the sclera and circling element. These sponges can also be used to help manage proliferative vitreoretinopathy.

CONCLUSION

With the exception of the development of sponge material, it is obvious that the changes in silicone retinal implant design have been evolutionary rather than revolutionary. Many surgeons have contributed their design inputs and have built on the success of their predecessors to achieve new design ideas. Each silicone element has been carefully thought out and developed by retinal surgeons to meet a specific need, to shorten surgery time or cost, and/or to produce an optimal outcome. Labtician is proud of the part we have played in this history, both as an early commercial developer and as a continuing innovator and catalyst. Of course, the search for improvements in scleral buckling technology is never-ending. As a result, this document attempts to cover all the highlights of the development of silicone implants, but it cannot be current for long. Therefore this historical review is designed as a living document. We plan to include new information and recent advancements with each update. During the production of this first edition, we were able to discuss the evolution of scleral buckling with many of the contributors mentioned. Unfortunately, we have undoubtedly left out some information that could be of interest to the reader. We invite you to help us in our effort to chronicle this history. Any personal input you might wish to offer will be appreciated. Please contact us with your comments, suggestions and historical insights.

Dr. M. Shea
c/o Labtician Ophthalmics, Inc.
Unit 6, 2140 Winston Park Drive
Oakville, ON L6H 5V5 Canada

E-mail: david@labtician.com
Telephone: 905-829-0055
Toll free: 1-800-265-8391
Facsimile: 905-829-0056

Footnote references

1 Jess A: Temporare skleraleindellung als hilfsmittel bei der operation der netzhautablosung Klin Monatsbl Augenheilkd 1937;99:318-319.
2 Girard LJ: Full thickness scleral buckling using silicon rubber rodding and the light coagulator. Presented at the Mid-Southern Section Meeting, Association for Research in Ophthalmology, Houston, Texas, Nov. 1959.
3 Girard LJ, McPherson AR: Scleral buckling: full thickness and circumferential, using silicon rubber rodding and photocoagulation. Arch Ophthalmol 1962;67:409-420.
4 Regan CDJ, Schepens CL: Erosion of the ocular wall by circling polyethylene tubing: a late cof scleral buckling. Trans Am Acad Ophthalmol Otolaryngol 1963;67:335-341.
5 Grey PJ: Tie up retinal surgery with the Silicone Lace. Retina 1993;13:269-270.
6 Schepens CL, Okamura ID, Brockhurst RJ, Regan CDJ: Scleral buckling procedures: V. synthetic sutures and silicone implants. Arch Ophthalmol 1960;64:868-881.
7 Watzke RC: An encircling element connection for scleral buckling procedures. Amer J Ophthalmol 1963;56
8 Regan CDJ, et al: The scleral buckling procedures: VI. further notes on silicone in primary operations. Arch Ophthalmol 1962;68:313-328
9 Schepens CL, Okamura ID, Brockhurst RJ, Regan CDJ: Scleral buckling procedures: V. synthetic sutures and silicone implants. Arch Ophthalmol 1960;64:868-881.
10 Rice T: Personal communications, 1998.
11 Wendell R: Personal communications, 1998.
12 Murray T: Personal communications, 1998.
13 Ross W: Personal communications, 1998.
14 Gaynon M: Personal communications, 1998.
15 Munsen R: Personal communications, 1998.
16 Parsons H: Personal communications, 1998.
17 Regan CDJ, et al: The scleral buckling procedures: VI. further notes on silicone in primary operations. Arch Ophthalmol 1962;68:313-328 18 Pruett RC: The fishmouth phenomenon, I:clinical characteristics and surgical options. Arch Ophthalmol 1977;95:1777-1781.
19 Lincoff H: Personal communications, 1998.
20 Lincoff H, McLean JM: Modifications to the Custodis procedure: II. a new silicone implant for large tears. Am J Ophthalmol 1967;64:877-879.
2 Lincoff H, Kreissig I: Advantages of radial buckling. Am J Ophthalmol 1975;79:955-957
22 Vaiser A: presentation to the Paul Cibis Club, 1979.
23 Lincoff H: Personal communication, 1998.
24 Rubin ML, Fitzgerald CR: The episcleral partial thickness sponge for scleral buckling. Mod Probl Ophthalmol 1974; 12:495
25 Olk R: Personal communication, 1998.
26 Robinson F, Brucker A.J.: Two-thirds thickness sponges for retinal reattachment surgery, Arch. Of Ophthalmology, 107:318, 1989
27 Scholda C: Personal Communication, 1999.
28 Olk R: Personal Communication, 1998.
29 Snyder WB, Jost BF, Hutton WL, Vaiser A, Fuller DG, Spencer R: L-shaped accessory sponge exoplant. Letter to the journal. Amer J Ophthalmol 1989;108:203-204.

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