Sclera and Retina Suturing Techniques 9 Kirk H

Chapter 9

Sclera and Retina Suturing Techniques 9 Kirk H. Packo and Sohail J. Hasan

Key Points 9. 1 Introduction Surgical Indications • Vitrectomy Discussion of ophthalmic microsurgical suturing tech- – Infusion line niques as they apply to retinal surgery warrants atten- – Sclerotomies tion to two main categories of operations: vitrectomy – Conjunctival closure and scleral buckling. Th is chapter reviews the surgical – Ancillary techniques indications, basic instrumentation, surgical tech- • Scleral buckles niques, and complications associated with suturing – Encircling bands techniques in vitrectomy and scleral buckle surgery. A – Meridional elements brief discussion of future advances in retinal surgery Instrumentation appears at the end of this chapter. • Vitrectomy – Instruments – Sutures 9.2 • Scleral buckles Surgical Indications – Instruments – Sutures Surgical Technique 9.2.1 • Vitrectomy Vitrectomy – Suturing the infusion line in place – Closing sclerotomies Typically, there are three indications for suturing dur- • Scleral buckles ing vitrectomy surgery: placement of the infusion can- – Rectus muscle fi xation sutures nula, closure of sclerotomy, and the conjunctival clo- – Suturing encircling elements to the sclera sure. A variety of ancillary suturing techniques may be – Suturing meridional elements to the sclera employed during vitrectomy, including the external – Closing sclerotomy drainage sites securing of a lens ring for contact lens visualization, • Closure of the conjunctiva placement of transconjunctival or scleral fi xation su- Complications tures to manipulate the eye, and transscleral suturing • General complications of dislocated intraocular lenses. Some suturing tech- – Break in sterile technique with suture nee- niques such as iris dilation sutures and transretinal su- dles tures in giant tear repairs have now been replaced with – Breaking sutures other non–suturing techniques, such as the use of per- – Inappropriate knot creation fl uorocarbon liquids. • Vitrectomy – Complications associated with sclerotomy closure 9.2.2 ■ Intraoperative Scleral Buckles ■ Postoperative • Scleral buckles Suturing during scleral buckle surgery involves place- – Complications associated with suturing to ment of rectus muscle fi xation sutures, securing encir- the sclera cling elements, securing meridional elements, tying – Complications associated with suturing the ends of encircling elements, closing sclerotomy conjunctiva drainage sites, and closing the conjunctiva. Future advances and alternatives to sutures • Vitrectomy • Scleral buckles 86 Kirk H. Packo and Sohail J. Hasan

9.3 with Vicryl, 9.3% close with a synthetic monofi lament, Instrumentation 0.5% close with plain gut, and 1.3% close with another suture type [17]. Conjunctival sutures are most commonly plain gut, and may have either spatula or taper- 9.3.1 tip styles. Some surgeons conserve resources by using Vitrectomy the same suture to close the sclerotomies as the conjunctiva. Th e scissors chosen to cut the stitches are ei- Instrumentation required for suturing during vitrec- ther the Westcott scissors typically used for the con- tomy includes caliper, forceps, needle holder, suture, junctival opening or a separate dedicated sharp-tip and scissors. Calipers can be in a wide variety of styles. stitch scissor. Cutting large sutures such as a 5-0 Mer- We have found a fi xed caliper of 4.0 and 3.5 mm at al- silene should be done with larger tips, and more deli- ternate ends to be the most useful for vitrectomy. Th e cate scissors such as Vannas style should be avoided. two tissues involved with suturing during vitrectomy are the conjunctiva and sclera. Th e fi xation forceps chosen to handle each tissue are by surgeon prefer- 9.3.2 ence. We prefer to use a non-toothed ring forceps Scleral Buckles (ASICO, Chicago, Ill.) to manipulate conjunctiva. Th e ring tip provides an excellent grasp of the conjunctiva Th e surgical instruments required for suturing during while minimizing bleeding. For scleral fi xation, either scleral buckle surgery include caliper, forceps, scissors, 0.12-, 0.3-, or 0.5-mm toothed forceps, or 0.1-mm muscle hooks, needle holders, sutures, and retractors. Maumenee-Colibri forceps can be used to grasp the Th e same fi xation forceps and needle holders described sclera. Th e larger toothed forceps are useful for general for vitreous surgery have utility in scleral buckling. scleral fi xation, whereas the smaller-toothed varieties Th e suture choice to fi x an episcleral implant varies, are useful for grasping the cut edge of sclera as in scle- again, by surgeon preference and training. A spatula rotomy closure. We fi nd that Maumenee-Colibri for- needle is universally chosen to ensure more depth con- ceps are particularly useful because of their angle and trol within scleral lamellae. Th e two most commonly small tooth size, which provides an excellent grasp of utilized suture materials are either a 5-0 nonabsorb- the cut scleral edges. Needle holders are chosen by sur- able nylon suture or a 5-0 nonabsorbable soft suture geon preference. Design choices include platform size, such as polyester Mersilene. Th e advantage of nylon is locking versus non-locking, and straight versus curved. that its stiff memory holds the knot between throws Because running and fi gure-of-eight sutures are com- and does not loosen as easily as does Mersilene. In ad- mon, we have found straight locking holders to be the dition, studies have shown less infl ammatory reaction most useful. to nylon than to synthetic braided sutures, following Suture choices also vary by surgeon preference. Th e chronic implantations in infected experimental spatula-tipped needle was fi rst introduced by Lincoff wounds [24]. A Schepens-style orbital forked retractor in the 1960s and was a great advance for scleral sutur- or the de Juan retractor works very well to help visual- ing. Th e side cutting design allows the needle to pass ize sclera for suturing [3]. A custom-designed illumi- within the scleral lamellae rather than across them, ma- nated orbital retractor is useful in visualizing the scler- king tissue depth more constant throughout the pass. al surface in deep or tight orbits. Th e ends of an Several options exist for the infusion line cannula re- encircling band can be secured with a clove hitch non- tention suture. A 5-0 Mersilene polyester fi ber suture absorbable suture [1], tantalum clip [7], or silicone with a spatula needle can be used to temporarily fi x the sleeve [25]. cannula, and is later removed completely at the end of the case. Alternatively, a 7-0 Vicryl suture can be placed in a fi gure-of-eight fashion (see Sect. 9.4 below) to se- 9.4 cure the infusion cannula. If temporarily tied, this Surgical Technique same suture can be loosened and used to close the sclerotomy site at the end of the case. Another option for Retinal surgeons should exercise basic surgical princi- sclerotomy site closure is to use a 9-0 or 10-0 synthetic ples that are universal to all ophthalmic suturing tech- monofi lament suture, such as nylon or Prolene. Mono- niques. Th ese include: fi lament nylon sutures are elastic, and close wounds 1. Always manipulate needles with instruments and that have opened as a result of undue pressure on the never with the gloved hand. Holding needles with globe [2]. For this reason, completely sutures (such as the fi nger tips is quick and oft en tempting, but runs silk) should not be used. In a survey of 398 retinal sur- the risk of accidental perforation of the glove tip. geons by the American Society of Retina Specialist in Th is perforation is oft en unrecognized and breaks 1999, 86% of surgeons prefer to close sclerotomies sterile technique. Chapter 9 Sclera and Retina Suturing Techniques 87

2. Never grasp a needle tip with the pick-up forceps. 9.4.1 Needles should be grasped and held only with nee- Vitrectomy: Suturing of the Infusion Line dle holders. When repositioning the needle on the holder, it should be done by holding the suture Using a caliper, a mark is placed in the inferotemporal rather than the needle with the pick-up forceps near quadrant 4 mm from the limbus in phakic eyes or where the suture is swedged into the needle. Th is 3.5 mm from the limbus in pseudophakic eyes below technique protects the fi ne teeth of the forceps. the horizontal, avoiding placement that would injure 3. Always match the needle holder platform size with the long ciliary artery and nerve at the direct horizon- the needle, and match the size of the scissors to the tal (Fig. 9.1a). Th e eye should be fi xated immediately size of the suture being cut. For example, cutting adjacent to where the suture will be passed using fi ne- 2-0 silk traction sutures with fi ne Vannas scissors toothed forceps. Fixating on the opposite side of the will damage the scissor tips. Holding a large needle globe allows “scissoring” of the eye as the needle is with too fi ne a needle holder allows less control passed and loss of control. and may also damage the holder. Th e suture passes should be parallel to the limbus at 4. Always unlock a locking needle holder prior to en- least one half to three quarters of scleral depth and tering the tissue with the needle pass. Th is allows a should straddle the caliper mark. For a right-handed simple open release at the completion of the pass, surgeon, the fi rst pass should be to the right of the and obviates the squeeze to release the lock while caliper mark regardless of the eye being operated on. the needle is embedded into the tissue, possibly Th e fi rst pass for a left -handed surgeon should be to contributing to tissue tearing or inadvertent pene- the left of the mark. Th is orientation is useful, allowing tration. the surgeon to simply part his or her hands on the de- 5. Always keep spatula needles fl at to the tissue sur- livery of the fi rst knot rather than crossing them. Th e face to avoid cheese-wiring of the suture, or im- fi rst pass is placed in a backhanded fashion, traveling proper depth of pass. away from the surgeon (Fig. 9.1b). Th e second pass of 6. Bury all conjunctival knots. the same needle is spaced to accommodate the base of

4.00 – 3.5 mm ab

c d

Fig. 9.1 Vitrectomy: suturing of the infusion line 88 Kirk H. Packo and Sohail J. Hasan

the infusion cannula and travels toward the surgeon. to remain. Th e sclerotomy site is created with the MVR Th is creates a horizontal mattress suture parallel to the blade, taking care not to inadvertently cut the pre- limbus (Fig. 9.1c). Th e suture slack is pulled, allowing placed suture (Fig. 9.2c). Th e cannula is twisted into a 0.5-cm diameter loop to remain on the inferior end position as above, the preplaced suture loops are pulled of the suture passes. Aft er penetrating the sclera with a over the cannula wings, and the suture is tied in a 3-1- micro-vitreoretinal blade, the cannula is twisted into 1 fashion, leaving a temporary loop on the fi nal throw position in an oscillatory fashion to ensure passage to allow subsequent loosening of the suture (Fig. 9.2d). through the ciliary epithelium. Th e suture is then tied Th e ends of the suture are then trimmed, leaving a fi rmly in a 3-1-1 fashion (Fig. 9.1d). Th e ends of the generous length of suture to allow subsequent closure suture should be trimmed close to the fl ange of the at the end of the case. At the end of the case, following cannula. Th e cannula tip is then confi rmed to be with- closure of the superior sclerotomy sites, the fi nal throw in the vitreous cavity by direct inspection to prevent is simply released. Th e suture is loosened with fi ne for- inadvertent suprachoroidal or subretinal infusion. ceps, and the cannula is removed and the suture is tied An alternative method of infusion line fi xation al- in a 3-1-1 fashion. lows for the same suture to be used for sclerotomy site closure at the end of the case. Th e caliper mark and eye is fi xation is as described above. Two suture passes us- 9.4.2 ing a 7-0 Vicryl suture are made perpendicular to the Vitrectomy: Sclerotomy Site Closure limbus, with both passes placed toward the limbus. Th e fi rst pass should be superior to the caliper mark Unless a special shelved construction of a 20-gauge (Fig. 9.2a). Th e second pass should again be spaced to sclerotomy is created, a sclerotomy of this size must be accommodate the base of the infusion cannula. Th e sutured at the completion of the surgery. Although 20- second pass is made in the same direction as the fi rst gauge instruments are approximately 1 mm in diame- pass (toward the limbus), creating a fi gure-of-eight X ter, the sclerotomy created by a 20-gauge MVR blade is across the sclerotomy (Fig. 9.2b). Th e middle pass of approximately 1.4 mm long. Th is incision can be the suture is pulled, allowing a 0.5-cm diameter loop closed with a variety of techniques. A survey of 380

a b

c d

Fig. 9.2 Alternative method of infusion line fi xation allows for the same suture to be used for sclerotomy site closure at the end of the case Chapter 9 Sclera and Retina Suturing Techniques 89 surgeons by the American Society of Retina Specialists 9.4.3 in 2003 showed that 72% of surgeons close with a sin- Vitrectomy: Ancillary Suturing Techniques gle fi gure-of-eight stitch, 14% use a fi gure-of-eight with one or more additional passes, and 11% use a Over the past decade, the use of a non-contact wide single interrupted pass [7]. fi eld imaging system has replaced the use of contact Th e closure is begun by stabilizing the eye with fi ne- lenses and fi xation rings. However, some surgeons use toothed forceps (we prefer 0.1-mm Maumenee-Colibri an irrigating contact lens held over the eye by the as- forceps). Th e cut edge of the sclerotomy itself is grasped sistant. Some lens rings are made of a soft silicone and for maximum control, and a 7-0 Vicryl suture is used will adhere to the eye surface without sutures. If a lens for closure. When closing with a single interrupted ring is secured, it is most commonly held in place by pass, the suture is passed perpendicularly through the two 7-0 Vicryl sutures placed through the conjunctiva center of the incision. Unlike monofi lament sutures, at the horizontal limbus. Th e sutures are only loosely braided Vicryl holds the tension of the knot relatively tightened over the ring fi xation tabs. A loose place- well with a single or double throw, and a triple throw is ment allows the ring to be temporarily removed if not required. Th us, the knot is best created with a 2-1-1 needed, while leaving the suture loops still in place for sequence rather than 3-1-1. Th is minimizes the bulk of later replacement of the ring. Some surgeons will se- the knot, decreasing postoperative infl ammation cure the ring with a larger diameter suture, such as a slightly. For optimal security against wound leaks, we 4-0 silk, and leave the ring fi xation suture long. Th e recommend more than just a single interrupted clo- silk lens ring fi xation suture can then be used for eye sure. A second pass in the same direction will create a manipulation. Other ancillary suture techniques such standard fi gure-of-eight X-type cl osure (Fig. 9.3a). In as transscleral suture fi xation of intraocular lenses and this case, the fi rst pass should be made through the McCannel suturing of iris defects are described else- very end of sclerotomy and the second through the op- where in this book. posite end. Some surgeons prefer to make one or two more additional passes creating either an X-plus-1 closure or a double-X fi gure-of-eight (Fig. 9.3b). A total of 9.4.4 four throws are required to create a closure with two Scleral Buckles: Muscle Traction Sutures independent Xs. Th e fi rst pass is made through the dis- tal edge of the incision, the second through the center, Th e fi rst suturing requirement during scleral buckle the third through the proximal edge, and the fi nal pass surgery is the placement of the muscle traction sutures. is made again through the center of the incision (Fig. Passing sutures beneath the rectus muscle insertions 9.3c). Th is incision is particularly useful in closing inci- can be accomplished with a needleless tie or a suture sions in ectatic sclera, in reoperations that have already with a curved needle (Fig. 9.4). When passing a needle- thinned sclera, or in sclerotomies that have enlarged less tie, the suture can be passed beneath the insertion beyond 1.4 mm. All sutures are tied in a 2-1-1 fashion. with forceps or a curved hemostat. We prefer to use a

a b c Fig. 9.3 Vitrectomy: sclerotomy site closure 90 Kirk H. Packo and Sohail J. Hasan

Black suture

White White suture suture

Fig. 9.4 Gass muscle hook. When passing a needleless tie, the suture can be passed beneath the insertion with forceps or a hemostat. Th e suture is preloaded within th hook and then passed beneath the muscle, allowing the muscle insertion to be isolated at the same time the suture is passed. Black Typically, a large suture such as a 2-0 or a 4-0 silk tie is cho- suture sen. Fig. 9.5 Utilizing suture colors diff erently on the horizontal and the vertical rectus muscles helps to maintain orientation during surgery.

9.4.5 Scleral Buckles: Encircling Elements

Following identifi cation and localization of retinal breaks, an appropriate exoplant is selected. In 2003, a survey of 384 surgeons by the American Society of Retina Specialists showed that 82% of surgeons usually place an encircling element for most buckles, whereas 18% place either a meridional or circumferential seg- Fig. 9.6 Passing the Gass hook from the nasal side of the superior rectus avoids hooking the superior oblique tendon mental elements alone [17]. Th e vast majority of buckles are currently placed as exoplants. Regardless of technique, proper placement of the element requires Gass muscle hook containing an eyelet at its tip. Th e accurate and eff ective suturing technique. Encircling suture is preloaded within the hook, and then passed expolant bands can be secured to the sclera with su- beneath the muscle, allowing the muscle insertion to tureless partial thickness scleral “belt-loop” tunnels or be isolated at the same time the suture is passed. Typi- with scleral sutures. Larger encircling elements (spong- cally, a large suture such as a 2-0 or 4-0 silk tie is cho- es and tires) as well as meridional and segmental ele- sen. We prefer to use 2-0 black silk beneath the hori- ments require sutures. zontal rectus muscles, and 2-0 white cotton beneath Th e buckle’s goal of creating scleral indentation, the vertical muscles (Fig. 9.5). Color coding the oppo- thereby decreasing internal vitreous traction, can be site muscles in this way helps greatly in maintaining accomplished in two ways: (1) tightening the encircl- proper orientation and facilitating communication being element, ultimately decreasing the total circumfer- tween the surgeon and assistant. It is better to pass the ence of the eye, or (2) placing fi xation sutures wider Gass hook from the nasal side of the superior rectus to than the element, thereby imbricating the element and avoid hooking the superior oblique tendon (Fig. 9.6). driving it internally. If the indentation eff ect is created primarily by tightening the encircling element, the eye is elongated and increased myopia results (Fig. 9.7a). Relying on the sutures to create the indentation more than tightening the element is preferred, as this minimizes the elongation and secondary myopia (Fig. 9.7b). Properly placed sutures on a 360° element can actually result in very little additional myopia. Sutures Chapter 9 Sclera and Retina Suturing Techniques 91 should be placed in the sclera a minimum of 2 mm location and meridian as the retinal tear. Ideally, each wider than the width of the encircling element. Th is tear is marked on the sclera externally with an ink dot technique can actually decrease axial length [9]. When prior to the suture placements. A caliper is used to cre- silicone bands are secured only with scleral belt loops, ate a scleral indentation mark on either side of the the indentation eff ect can only be created with tighten- retinal tear location spot. As noted above, the width of ing of the element and a signifi cant amount of postop- the planned suture pass should be 2 to 3 mm wider erative myopia can occur. than the element to be secured. When placing episcleral sutures, it is vital that the Th e assistant must follow several important princi- globe be fi rmly fi xated to avoid inadvertent penetra- ples in holding the eye steady. First, it is vital to always tion into the eye by the needle. Th e eye can be fi xated hold the traction sutures at least 90° or more apart to by the surgeon with toothed forceps, or the eye can be maximize the stability (Fig. 9.8a). Holding the sutures held steady by the assistant. Since the maximum scler- at less than a 90° angle may allow the eye to scissor, al indentation is achieved directly below an episcleral causing inadvertent eye motion during the suture pass suture, it is desirable to locate the suture in the same (Fig. 9.8b). Secondly, the eye should be rotated by the

Tighten band

Suture wider than buckle a b Fig. 9.7 Th e buckle’s goal of creating scleral indentation, is created primarily by tightening the encircling element, the thereby decreasing internal vitreous traction, is accom- eye is elongated and increased myopia results (a). Relying on plished by (1) tightening the encircling element, ultimately the sutures to create the indentation more than tightening decreasing the total circumference of the eye, or (2) placing the element is preferred, as this minimizes the elongation fi xation sutures wider than the element, thereby imbricating and secondary myopia (b)’ the element and driving it internally. If the indentation eff ect

90° Less than or more 90°

Eye stable Eye may "scissors" and move ab

Fig. 9.8 When placing episcleral sutures, the assistant must or more apart to maximize the stability (a). Holding the su- follow several important principles in holding the eye steady. tures at less than a 90° angle may allow the eye to scissor, First, it is vital to always hold the traction sutures at least 90° causing inadvertent eye motion during the suture pass (b) 92 Kirk H. Packo and Sohail J. Hasan

assistant to move the exposed quadrant toward the along the curve of the needle. If the needle holder is of canthus. Th is maximizes exposure for the surgeon. the locking type, it should always be unlocked prior to Th ird, the assistant should pull quite fi rmly on the su- passage of the needle. We prefer to pass the most poste- tures to rotate the equator up out of the orbit, further rior pass fi rst, saving the anterior pass for last. improving exposure. Finally, the assistant should never As the curve of the globe and the curve of the nee- move once the surgeon begins the suture pass. An as- dle are in opposite directions, it is important to engage sistant may have the urge to lean forward to watch the the sclera deep enough at the start of the pass in order surgeon, and if this is done during the suture pass, the to avoid too shallow a placement. Th e use of a spatula eye may move slightly creating potential problems. needle helps to keep the needle within the same scleral Th e surgeon’s use of magnifi cation loupes can also fa- lamella during the pass; however, the needle still needs cilitate safe suture placement. to be placed deep enough to avoid cheese-wiring. A single-armed spatula needle with a 5-0 nonabsorb- Th ere is a natural tendency, especially among inexpe- able suture (we prefer nylon) is passed through the rienced surgeons, to avoid too deep a passage by be- sclera at one-half to three-fourths depth over a distance ginning the suture pass with the needle held very tan- of 3 to 5 mm parallel to the long axis of the encircling gential to the eye at the start. Th e best needle depth is element. Care should be taken to pass the needle at an achieved by actually beginning the needle pass more even depth to decrease the likelihood of scleral perfora- perpendicular to the sclera, passing directly into the tion. Adequate depth and length are essential for maxi- sclera, and then quickly fl attening the needle tangen- mum suture strength [14]. For safest passage through tially once the sclera has been engaged (Fig. 9.9). Sur- sclera, the needle should be grasped half of the way geons should take care to modify this technique and to begin more tangentially in highly myopic eyes or when obvious scleral thinning or dehiscences are visible. Ad- ditionally, it is most important to begin the needle pass with the fl at of the spatula held perfectly fl at to the eye. If the needle is tilted such that one of the cutting edges is higher than the other, the suture is more likely to cheese-wire through the sclera aft er tying. Aft er the needle has been passed through the sclera and the tip brought out, care should be taken to com- plete the passage, following the curve of the needle. Th is will help to avoid unnecessary posterior pressure on the base of the needle, which lead to scleral perforation. ab A second suture pass with the same needle is then made on the opposite side of the encircling element. Fig. 9.9 Th e best needle depth is achieved by actually beginning the needle pass more perpendicular to the sclera, pass- Alternatively, a double-armed suture can be used, and ing directly into the sclera, and then quickly fl attening the the opposite needle is passed for the anterior bite. One needle tangentially once the sclera has been engaged popular technique is to make the anterior pass at the muscle insertion line, ensuring that the encircling element creates a buckle eff ect to the ora serrata internally. Th e anterior second pass is made in the opposite direction of the fi rst for a simple vertical mattress suture across the element. If the second pass is made in the same direction as the fi rst to form a cross X-mattress suture across the element (Fig. 9.10a). A simple vertical mattress suture allows more imbrication than a b a cross X-mattress suture. As each suture is placed, it is Fig. 9.10 Th e anterior second pass is made in the opposite grasped temporarily with a serrefi ne clamp to help direction of the fi rst for a simple vertical mattress suture keep the numerous suture ends from tangling (Fig. across the element. If the second pass is made in the same 9.10b). Aft er all sutures are placed, the buckle is then direction as the fi rst to form a cross X-mattress suture across the element (a). A simple vertical mattress suture allows passed beneath each mattress suture and muscle inser- more imbrication than a cross X-mattress suture. As each tion as necessary. suture is placed, it is grasped temporarily with a serrefi ne When making the suture permanent, it is tied in a clamp to help keep the numerous suture ends from tangling 3-1-1 fashion. Th e memory nature of monofi lament (b). Aft er all sutures are placed, the buckle is then passed beneath each mattress suture and muscle insertion as neces- sutures tends to hold the tension of the initial triple sary throw nicely. If a soft braided suture such as Dacron or Chapter 9 Sclera and Retina Suturing Techniques 93

Merseline is used, the assistant will oft en need to grasp tight to exert some tension on the bands. Th e surgeon the initial triple throw knot to prevent its loosening as then adjusts the tension on the band as necessary, and the surgeon creates the next throw. Th e proper tension when fi nalized, the clove hitch is tightened more. Th e of the fi rst triple throw is the most important to achieve creation of a small nick with scissors in the edge of the the appropriate degree of imbrication. Tightening the silicone band on either side of the suture will prevent suture is the easiest when the eye is soft prior to the the band from loosening, since the suture will catch the attempt. Th us, draining the subretinal fl uid prior to the nick as the band slides open, preventing further loosen- suture tightening is desirable. If the surgeon expects to ing (Fig. 9.12). tap the anterior chamber to soft en the eye in non- drainage techniques, it is desirable to perform the tap prior to tightening the buckle sutures. In non-drainage 9.4.6 techniques, the eye will be fi rm, and tightening and Scleral Buckles: Meridional Elements judging the indentation eff ect are more diffi cult. Judg- ing the indentation eff ect of the sutures is more diffi - Some surgeons prefer to use meridional sponge ele- cult in non-drainage cases, as the indentation eff ect ments, based on the confi guration of the detachment will increase postoperatively as the eye pressure later and tear location. Many of the techniques of suture drops to normal. Once the knot has been completed placement described for encircling elements above ap- and cut fl ush, it should be rotated to the posterior edge ply to the placement of meridional buckles. Again, su- of the buckle to prevent later erosion though the con- tures are generally placed 2 mm beyond the width of junctiva. Th is is easily accomplished by pulling anteri- the sponge to allow for appropriate imbrication. Usu- orly on one arm of the mattress with one tying instru- ally, at least two horizontal mattress sutures are placed. ment while pulling posteriorly at the same time on the Unlike the placement of mattress sutures with encircl- opposite arm with a second instrument. ing elements, the mattress suture for meridional ele- Some variations in suture placement may be re- ments are placed perpendicular to the limbus. Th ey quired based on the individual anatomy or pathology can be simple mattress or crossed X-type mattress su- involved. When the posterior suture location is marked, it is not uncommon to need to place the pass of the suture at or near the exit of a scleral vortex vein. To avoid injury to the vein, it may be necessary to straddle the vein by taking a short bite on either side of the vein as it exits the sclera (Fig. 9.11). Sometimes long suture passes are not possible through thin sclera. In this case, it may be necessary to take several short bites in areas of thicker sclera. Once the encircling silicone tire or sponge is sutured to the episclera, the surgeon then addresses how the ends of the encircling element are secured. When a silicone tire is placed either 360° or segmentally, an overlying encircling silicone band is usually used. Th e ends of the silicone band can be closed with a silicone sleeve (Watzke sleeve), tantalum clip, or suture. A silicone sleeve allows easy adjustment of band tension. When closing with a suture, the most common stitch is a clove hitch knot. Soft multifi lament sutures work better than Fig. 9.11 Th e vortex vein is straddled with a suture stiff er monofi lament sutures for this closure, but both are adequate. Th is knot consists of two half hitches lying in opposite directions around the band. Unlike a square knot, a clove hitch is liable to slip. It requires a load in each direction in order to be eff ective, and this is typically achieved since the band will want to loosen in both directions under the knot. To tie a clove hitch, a loop is fi rst placed around both bands, with the working end of the suture on top. Th e working end of the suture is passed around the bands once more until the place meeting where the sutures cross, and then the working Fig. 9.12 Clove hitch knot. Note the notch in the silicone end is passed under the cross. Th e hitch knot is pulled band to prevent loosening past suture 94 Kirk H. Packo and Sohail J. Hasan

tures; however, the crossed mattress does not provide monly, a small knuckle of choroidal tissue will prolapse as much imbrication as a simple mattress suture; it is into the center of the sclerotomy. Th is prolapsed cho- less eff ective. We have found that passing the suture roid is also commonly shrunk slightly with diathermy from anterior to posterior is easier and more controlled in an attempt to avoid penetration into the subretinal than the reverse. For this reason, we use a double- space at this stage. Th e suture is then carefully pre- armed suture (Fig. 9.13a). As with encircling buckles, placed into the edges of the sclerotomy. We prefer to the tying of the suture is much easier to accomplish in place this preplaced suture by wearing the ophthalmo- a soft eye, and so the eye should be tapped or subretinal scope and utilizing the light of the scope through a 20- fl uid drained prior to attempting the suture tightening. diopter lens acting as a magnifying loop. It is necessary Th e rotation of the fi nal knot to the side of the sponge to move the buckle and orbital tissues out of the way can be done but is usually not necessary (Fig. 9.13b). during the suture placement. Once the suture is preplaced, it is carefully looped out of the way. We prefer to use the same monofi lament nylon to close the drain- 9.4.7 age site as was used to secure the buckle. Since nylon Closure of Sclerotomy Drainage Sites easily melts, it is important to avoid injuring the preplaced stitch when diathermizing the prolapsed cho- In a 2005 survey by the American Society of Retina roid. Once the drainage of the subretinal fl uid is ac- Specialists, 88% of surgeons prefer to routinely drain complished the suture is closed with a standard 3-1-1 subretinal fl uid dauring scleral buckle surgery [18]. knot and cut fl ush. When an external scleral cutdown is created, it may be placed under the planned buckle location or outside the buckle. If the sclerotomy is placed beneath the 9.4.8 buckle, it may be left open allowing the overlying Closure of the Conjunctiva buckle to close the opening once the buckle is secured. Some surgeons prefer to routinely close the sclerotomy Closure of the conjunctiva should be done with care even when located beneath the buckle, and any scle- for both vitrectomy and scleral buckle surgery. Im- rotomy outside the buckle must be sutured closed. proper conjunctival closure from retinal surgery can It is desirable to preplace the suture into the edges contribute greatly to many postoperative complica- of the sclerotomy prior to penetrating the choroid into tions outlined below. Taking time and extra care dur- the subretinal space. In this way the suture need only ing the conjunctival closure can signifi cantly add to be pulled up and closed at the end of the drainage, pre- the patient’s short- and long-term comfort and should venting additional scleral manipulation or retinal in- not be rushed. carceration. A single interrupted, horizontal mattress Th e surgeon may wish to irrigate Tenon’s capsule or fi gure-of-eight preplaced suture can all be used, but and the globe with antibiotic and retrobulbar anesthet- the latter provides the best closure. Aft er the scleral in- ic solution prior to closure. Th is acts to clean the surgi- cision is made, typically the edges of the scleral are cal fi eld and reduce postoperative pain, following ei- shrunk slightly with hot cautery or diathermy. Com- ther general or local anesthesia [4]. Additionally, this

Fig. 9.13 Passing the suture from anterior to posterior is easier and more controlled than is the reverse. For this reason, a double-armed suture can be used (a). As with encircling buckles, the tying of the suture is much easier to accomplish in a soft eye, and so the eye should be tapped or subretinal fl uid drained prior to attempting the suture tightening. Th e rotation of the fi nal knot to the side of the sponge can be done but is usually not neces- a b sary (b) Chapter 9 Sclera and Retina Suturing Techniques 95 irrigation serves to whiten the appearance of the Ten- greatest utility for running closures. As always, the on’s fascia as compared with the more pearl-colored locking mechanism should be released prior to passing conjunctiva assisting in proper tissue closure. the needle into the tissue with each pass. We also fi nd Th e conjunctiva can be closed alone or a layered ap- it easier to direct each pass from the conjunctival fl ap proach can be used to fi rst close Tenon’s capsule prior anteriorly into the collar of conjunctiva at the limbus to closure of the conjunctiva. We prefer a layered clo- rather than vice versa. Coming up through the collar sure over radial sponge elements in order to minimize from the posterior cut edge in this way allows a more the possibility of element extrusion. A layered closure controlled depth and accuracy, minimizing cheese- also acts to remove tension on the conjunctiva; this wiring of the needle. For effi ciency, it is desirable to can be especially useful when the conjunctiva is thin fi nish each pass by re-grasping the needle ready to and easily torn. Tenon’s capsule is identifi ed in all four proceed with the next pass rather than adjusting the quadrants. Th is is an essential step regardless of the needle manually between passes. When the needle is type of closure. In order to identify Tenon’s capsule, passed up through the tissue, it is pulled forward until the anterior edge of conjunctiva is fi rst held with for- the back swedge of the needle is just barely embedded ceps. A second set of forceps is then used to reach deep into the tissue. Th e needle holder can then be used to into the conjunctival fornix and grasp Tenon’s capsule. grasp the visible forward part of the needle at its mid- Th e capsule can then be attached to the edge of each portion, allowing it to be ready for the next pass. Al- muscle insertion by using two sutures in the quadrant though most passes are run smoothly without locking, of the radial element or by using two sutures per quad- an occasional pass can be locked to lessen the degree of rant in all four quadrants. We prefer to use 6-0 plain slippage. Care must be taken to prevent bunching of gut suture, single-armed, with a spatula needle for this the conjunctiva (particularly at the horizontal meridi- purpose. Other suture options for Tenon’s capsule and an nasally). Care should also be taken nasally to dis- conjunctival closure include 7-0 Vicryl and 8-0 colla- place the caruncle, which creates a poor cosmetic re- gen. Th e main advantages of 6-0 plain gut include sult. Aft er reaching the starting point temporally, the minimal knot slippage while tying, minimal suture re- suture is run down the radial relaxing incision. Here, action, and rapid dissolution. the suture can be tied to the short end of the original Conjunctival closure varies with the type of open- buried knot in a 2-1-1 fashion. ing [12, 16]. We routinely use a 360° incision 2 mm For patient comfort, it is always desirable to bury posterior to the limbus for scleral buckle surgery. Mak- the knots during conjunctival closure. Th is is the easi- ing the incision 2 mm posterior to the limbus (rather est during interrupted suture placement of when plac- than right at the limbus) also allows less disruption of ing the fi rst knot of a running closure. Th e fi rst pass limbal stems cells and creates less perilimbal conjunc- begins in the wound, and the needle is passed upwards tival irregularity. Such irregularity may contribute to to the surface of the conjunctiva. Th e suture is then postoperative dellen formation, and make subsequent carried across the conjunctival opening, through the contact lens wear more diffi cult. surface of the conjunctiva, ending within the wound. When a 360° peritomy is created, we prefer a 360° Tying the ends thus places the knot beneath the con- running suture for closure of conjunctiva around a junctival surface. Burying the end of a running suture scleral buckle encircling element. Alternatively, two or is more diffi cult, but still possible. At the end of the more interrupted sutures can be used at the limbus to running suture, the surgeon makes the fi nal pass by tack the peritomy back in place. If a non-running clo- allowing the suture to be looped out of the conjuncti- sure is used, care should be taken to avoid “hooding” val opening. Th e last pass of the suture is placed as a the conjunctiva on to the cornea. Although overhang- mattress pass back into the wound on the same side as ing conjunctiva will usually later retract, it may not if the fi nal pass. In this way, both the loop and the end of the corneal epithelium was also removed during the the suture containing the needle exit through the procedure, leading to a poor cosmetic result. Th e re- wound and not through the conjunctival surface. Th e laxing incision(s) can also be closed using the same fi nal knot is then tied in a 2-1-1 fashion, but only the running suture. Care should be taken to evert the edg- loop is cut away, leaving the end with the needle still in es of the incision to decrease the possibility of con- place. One fi nal pass is then made into the wound ad- junctival cyst formation. jacent to the knot, bringing the needle out through the We prefer “ring” forceps for manipulation of the undersurface of the conjunctiva. Th e slack on the stitch conjunctiva during closure. A buried knot is fi rst is pulled tight, pulling the knot deep under the con- placed at the anterior edge of the temporal relaxing in- junctiva. Th e suture is then cut away fl ush to the con- cision, pulling the temporal portion of the conjunctiva junctiva, allowing the trailing suture end to retract back into position fi rst. Th e short end of the suture is back beneath the surface. cut, and the remaining long end is then used to run the Closure of the conjunctival openings from vitreous closure 360°. A straight locking needle holder has the surgery is accomplished using the same techniques 96 Kirk H. Packo and Sohail J. Hasan

outlined above, attempting to again always bury the ditional suture can be passed over the fi rst. Th is creates knots and to completely cover the sclerotomy sites. more bulk to the suture contributing to more postoper- During reoperations, the conjunctiva may be scarred ative infl ammation, and it is oft en desirable to cut away and diffi cult to pull back over the sclerotomies com- the fi rst stitch and place a new primary closure with pletely. Th is can be facilitated by dissecting the con- deeper or more numerous passes. If the wound is ex- junctiva free more deeply into the orbit, freeing the tremely ectatic, more complex solutions may be needed, conjunctival tension assisting in the closure. Occasion- including using a synthetic or donor scleral patch graft , ally, the conjunctiva is so scarred or disrupted that the using a fi brin sealant like Tisseel or Hemacure or by sclerotomies cannot be covered, and must be left bare. using cyanoacrylate glue. Astigmatism is the result of corneal distortion secondary to deformation of the adjacent sclera by the su- 9.5 tures. Although astigmatism is oft en minimal and tem- Complications porary because of the use of dissolvable sutures typically 3.5 to 4 mm behind the limbus, signifi cant astigmatism can occasionally result. Th is side eff ect can 9.5.1 be lessened by ensuring that the sclerotomy sites are General Suture-Related Complications made the correct distance from the limbus (3.5 mm in pseudophakic patients and 4.0 mm in phakic patients). 9.5.1.1 Sutures should be tied fi rmly but not overtightened. Of Vitrectomy: Complications Associated with Scleroto- course, scleral deformation can also be lessened by my Site Closure eliminating the need for scleral sutures through the use of a sutureless 25-gauge vitrectomy system (see below). Th e complications associated with sclerotomy site clo- Neovascular ingrowth (especially in diabetics) can sure can be divided into intraoperative and postopera- be lessened by ensuring that the wound is as free of vit- tive complications. Intraoperative complications in- reous as possible prior to closure (see above for tech- clude ciliary body laceration and vitreous base nique). If neovascularization should occur, treatment incarceration in the wound [23]. Ciliary body lacera- with photocoagulation or cryotherapy may induce res- tion can lead to vitreous hemorrhage, which, if suffi - olution. In diffi cult cases resulting in repeated postop- ciently small, is usually self-limited and spontaneously erative hemorrhages, reoperations may be necessary. resolving. Th is complication can be avoided, of course, Finally, external symptoms such as injection and ir- by taking only partial thickness bites through sclera ritation can be caused by polyester or polyglycolic acid and by staying in close proximity to the sclerotomy site suture. It is for this reason that we prefer to use 7-0 with the suture pass. Vitreous base incarceration can polyglactin (Vicryl) suture for sclerotomy site closure. be avoided by properly preparing the wound prior to Vicryl can still insight a postoperative scleritis in some closure. Th e vitrectomy probe can be used to clear the patients that can be quite painful. Symptoms of Vicryl wound until a steady stream of fl uid passes through an scleritis include marked injection, induration, and unobstructed sclerotomy site. Care should be taken to point tenderness over each sclerotomy closure. Th is avoid damaging the sclerotomy site with the vitreous can be minimized by attempting to minimize the bulk cutter. Alternatively, a cellulose sponge together with of the Vicryl suture with fewer passes and suture Vannas scissors can be used to trim vitreous from the throws per closure. Some surgeons choose to avoid sclerotomy site. Th e sponge should be introduced into this scleritis altogether by using a nonabsorbable the wound in an attempt to engage vitreous. Th e monofi lament suture rather than Vicryl. When signifi - sponge should then be gently lift ed a short distance cant scleritis occurs in select patients, we have found from the sclera while vitreous is trimmed at the scleral the use on parenteral nonsteroidal medications such as surface using scissors. Th is sequence should be repeat- ibuprofen or indomethacin to be the most helpful. ed until it is no longer possible to engage vitreous Topical steroids or nonsteroidal drops are less eff ective through the wound using the sponge. in relieving symptoms. Postoperative complications associated with sclerotomy site closure include wound leak, astigmatism, neo- 9.5.1.2 vascular ingrowth, and external symptoms from polyes- Scleral Buckles: Complications Associated with ter (Dacron) or polyglycolic acid (Dexon) suture [23]. Suturing to Sclera Risk factors for wound leaks include reoperations, high myopia with thin sclera, and systemic diseases leading Th e complications associated with suturing encircling to scleral thinning. A number of options for closure are and meridional elements to the sclera include scleral available should the sclerotomy site continue to leak. If perforation and its seqeulae, suture erosion, and suture the wound is leaking aft er the initial closure attempt, ad- failure. Signifi cant risk factors for scleral perforation Chapter 9 Sclera and Retina Suturing Techniques 97 during retinal detachment surgery include reoperation area of incarceration. If the incarceration occurs with- aft er failed retinal detachment surgery and preexisting in a drainage sclerotomy that was initially planned to scleral pathologic conditions such as senile scleral de- be left open beneath a buckle element, it is best to hiscence or scleral thinning in high myopia. Although quickly place a suture to close the sclerotomy even this complication may be compatible with a good vi- when it beneath the buckle. Small amounts of incar- sual outcome in some patients, a high incidence of ceration need not be treated. Large amounts of incar- persistent or recurrent retinal detachment with prolif- ceration, however, should be supported with the buck- erative vitreoretinopathy worsens the visual outcome le or by the addition of a radial element. Controversial for most patients with this complication [22]. is whether or not an incarceration site need also to be Scleral perforation can be detected during suture treated with cryotherapy. Most oft en we choose not to placement in a number of ways. Th e needle may sud- induce additional infl ammation by cryotherapy to the denly give way as scleral resistance is no longer felt. incarceration site, but treat the area only by support Pigment, subretinal fl uid, or a combination thereof with the buckle [26]. may present through the suture tract. Should a perfo- Other postoperative complications of scleral perforation occur, the needle should be withdrawn slowly, ration include subretinal choroidal neovascularization and the retina should be inspected immediately with [11] and endophthalmitis. Just as for sclerotomy site an indirect ophthalmoscope. In the absence of bleed- neovascularization, treatment with photocoagulation ing, retinal perforation, or continued subretinal fl uid or cryotherapy may induce resolution of the neovascu- drainage, nothing further need be done in the area of larization. Inadvertent entry into the eye with a suture the needle pass, and another suture should be placed needle also increases the risk of endophthalmitis. in a new area of sclera. If subretinal fl uid drainage con- Treatment should be initiated as it would be for any tinues, drainage is allowed to proceed while maintain- other case of postoperative endophthalmitis. ing constant intraocular pressure (to help avoid retinal incarceration) with the use of cotton swabs externally 9.5.1.3 applied to the eye. When drainage stops, the retina Complications Associated with Suturing Conjunctiva should be inspected using an indirect ophthalmoscope. Any remaining sutures can then be placed and Th e complications associated with conjunctival clo- the buckle positioned appropriately. If the perforation sure include dehiscence, exposure of Tenon’s capsule, creates a retinal break, it should be treated immedi- suture granuloma, conjunctival cyst, and dellen for- ately with cryopexy or laser retinopexy. Th e break mation. Long-term complications, particularly in should be supported by the encircling element or with poorly closed conjunctiva, include tear fi lm disruption the use of an additional radial element. If scleral perfo- with the resultant signs and symptoms of dry eye. Risk ration results in a subretinal hemorrhage, immediate factors for conjunctival dehiscence include a thin, fri- pressure should be applied to the eye over the perfora- able conjunctiva, with or without excessive tension on tion site. Th e eye should be positioned to help avoid the conjunctiva. Use of atraumatic ring forceps will al- accumulation of blood beneath the fovea. If a massive low gentler manipulation of the conjunctiva and lessen subretinal hemorrhage occurs, one should consider the possibility of conjunctival tearing and hole forma- immediate vitrectomy with internal drainage of sub- tion during closure. Th is will, in turn, decrease the retinal fl uid and blood [20]. Choroidal hemorrhage is likelihood of conjunctival dehiscence. In addition, perhaps the most disastrous complication of scleral prior closure of Tenon’s capsule can remove tension on perforation. It may present with dark-red bleeding at the conjunctival closure, thereby lessening the chance the site of perforation. Th e site of perforation should of dehiscence. Exposure of Tenon’s capsule can result be closed immediately with a suture or with the scleral from conjunctival dehiscence or from inadvertent su- buckle itself. Th e intraocular pressure should be ele- turing of conjunctiva to Tenon’s capsule during closure vated above the systolic perfusion pressure. Th e eye creating a poor cosmetic result. Running closure of the should be positioned so that the perforation site is as radial relaxing conjunctival incision(s) will also reduce inferior as possible to avoid subfoveal blood (as above). the risk of subsequent exposure of Tenon’s capsule and Aft er the perforation site is closed, the pressure elevat- symblepharon formation. Granulomas can form at the ed, and the eye positioned, the extent of hemorrhage site of suture knots. Larger knots are more prone to should be assessed using the indirect ophthalmo- granuloma formation, as are more reactive nonabsorb- scope. able sutures such as Dacron or Merseline. Tying 6-0 Retinal incarceration may also develop as a result of plain gut in a 2-1-1 square knot fashion will result in a scleral perforation, or within a planned drainage site. compact knot that is less likely to form a granuloma Retinal incarceration can be identifi ed when the retina than is a knot with too many throws. It is important to is inspected with the indirect ophthalmoscope. Th e evert the edges of the incision during conjunctival clo- retina has a characteristic dimpled appearance in the sure in order to diminish the chance of conjunctival 98 Kirk H. Packo and Sohail J. Hasan

inclusion cyst formation. Should a cyst occur, the cyst able to close the leaking sclerotomy to prevent postop- can be observed, drained, or excised. Apart from the erative hypotony and its secondary complications [10, cosmetic appearance, conjunctival inclusion cysts are 15]. We prefer to close these leaking sclerotomies with usually harmless unless close to the limbus where they a single transconjunctival Vicryl suture. Th is prevents can promote dellen formation. Many large cysts will the need to open the conjunctiva, rapidly dissolves and ultimately fl atten without therapy if left untreated. In falls away, and still maximizes patient comfort. many cases, the cyst may need to be excised. Unfortu- nately, simple drainage is usually only a temporary solution, with a high recurrence of cyst formation. If ex- 9.6.2 cised, the entire cyst and its lining should be removed Scleral Buckles to decrease the possibility of recurrence. Corneal dellen can form as a result of a large suture Alternatives to sutures do exist for scleral buckle sur- knot, conjunctival inclusion cyst, or otherwise-elevat- gery. For example, in eyes with very thin sclera, poly- ed conjunctiva at the limbus. Dellen formation is par- methylmethacrylate belt loops can be fi xed to the ticularly problematic in the diabetic patient because of sclera with cyanoacrylate adhesive to allow 360° scleral poor corneal basement membrane and the higher like- buckling without sutures [21]. However, this may not lihood of continued epithelial breakdown. Compact spell an end to sutures entirely. For example, the use of buried knots and care to evert the conjunctival inci- cyanoacrylate adhesive such as Histoacryl to support sion during closure can help to avoid granulomas, in- suture bites in thin sclera has also been described [6]. clusion cysts, and subsequent dellen formation. Use of Th e use of Histoacryl tissue adhesive has been de- a 360° running closure (as opposed to cardinal sutures) scribed in some types of retinal detachment surgery can help to ensure a more level conjunctival closure [19]. Preserved human scleral graft and Histoacryl- that is less likely to promote dellen formation. It is for blue tissue adhesive were used in four cases of retinal this reason that care should be taken to avoid bunch- detachment surgery to obtain scleral buckling eff ect ing of the conjunctiva (particularly at the horizontal and to protect staphylomatous or necrotic scleral ar- meridian nasally) during the closure. Should a dellen eas. Th e use of Histoacryl produced a strong and resis- form, the treatment consists of aggressive topical lu- tant adhesion between the host and the preserved brication and removal of the inciting cause. scleral patch. Th e postoperative infl ammatory reaction Finally, dry eye can result from disruption of the was mild and disappeared within 1 week. tear fi lm secondary to conjunctival goblet cell destruction. Limbal stem cells can also incur damage because of disruption of the conjunctiva at the time of surgery. 9.7 A 360° incision made 1 mm posterior to the limbus, Conclusion which is subsequently closed using a 360° running suture, can help minimize limbal stem cell and goblet cell Th e materials and techniques for retinal surgery have destruction. undergone continued refi nement over the past 40 years. Th is has resulted in a relatively high rate of retinal reattachment. Further understanding of the patho- 9.6 physiology of retinal detachment together with phar- Future Advances and Alternatives macologic and instrument advances should contribute to Sutures to even further success in the future, with even less patient morbidity. Recently, advances in sutureless primary vitrectomy have been introduced. Although 9.6.1 these techniques clearly have some advantages, they Vitrectomy are unlikely to completely eliminate the need for sutures and excellent suturing technique. Th e advent of 25-gauge [8] and 23-gauge [5] transconjunctival sutureless vitrectomy instrumentation has reduced the need for sutures during vitrectomy alto- References gether. Lakhanpal et al. [13] have recently reported that 1. Aaberg TM, Wiznia RA (1976) Th e use of solid soft sili- 25-gauge instrumentation may hasten postoperative cone rubber exoplants in retinal detachment surgery. recovery by decreasing overall surgical time and post- Ophthalmic Surg 7:98–105 operative infl ammation. Procedures requiring minimal 2. Charles S (2001) Principles and techniques of vitreous surgery. In: Ryan S, Wilkinson C P (eds) Retina. Mosby, intraocular manipulation may be better suited for this St. Louis, pp 2121–2141 surgical modality. If a leaking sclerotomy is identifi ed 3. de Juan E Jr, Hickingbotham D, Allf B (1987) A conjunc- at the end of a small gauge vitrectomy, it is still desir- tival retractor for retinal surgery. Arch Ophthalmol 105:614 Chapter 9 Sclera and Retina Suturing Techniques 99

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