Ординатура / Офтальмология / Учебные материалы / Vitreo-retinal Surgery Progress III Essentials

Summary for the Clinician

References

1.Chen JC (1996) Sutureless pars plana vitrectomy through self-sealing sclerotomies. Arch Ophthalmol 114(10):1273– 1275

2.Kwok AK, Tham CC, Lam DS, Li M, Chen JC (1999) Modified sutureless sclerotomies in pars plana vitrectomy. Am J Ophthalmol 127(6):731–733

3.Schmidt J, Nietgen GW, Brieden S (1999) [Self-sealing, sutureless sclerotomy in pars plana vitrectomy] [Article in German]. Klin Monatsbl Augenheilkd 215(4):247–251

4.Assi AC, Scott RA, Charteris DG (2000) Reversed selfsealing pars plana sclerotomies. Retina 20(6):689–692

5.Jackson T (2000) Modified sutureless sclerotomies in pars plana vitrectomy. Am J Ophthalmol 129(1):116–117

6.Rahman R, Rosen PH, Riddell C, Towler H (2000) Selfsealing sclerotomies for sutureless pars plana vitrectomy. Ophthalmic Surg Lasers 31(6):462–466

7.Yeshurun I, Rock T, Bartov E (2004) Modified sutureless sclerotomies for pars plana vitrectomy. Am J Ophthalmol 138(5):866–867

8.Milibak T, Suveges I (1998) Complications of sutureless pars plana vitrectomy through self-sealing sclerotomies. Arch Ophthalmol 116(1):119

9.de Juan E Jr, Hickingbotham D (1990) Refinements in microinstrumentation for vitreous surgery. Am J Ophthalmol 109(2):218–220

10.Fujii GY, de Juan E Jr, Humayun MS, Pieramici DJ, Chang TS, Awh C, Ng E, Barnes A, Wu SL, Sommerville DN (2002) A new 25-gauge instrument system for transconjunctival sutureless vitrectomy surgery. Ophthalmology 109(10):1807–1812; discussion 1813

11.Chang CJ, Chang YH, Chiang SY, Lin LT (2005) Comparison of clear corneal phacoemulsification combined with 25-gauge transconjunctival sutureless vitrectomy and standard 20-gauge vitrectomy for patients with cata-

ract and vitreoretinal diseases. J Cataract Refract Surg 31(6):1198–1207

12.RizzoS,Genovesi-EbertF,MurriS,BeltingC,VentoA,CrestiF, Manca ML (2006) 25-gauge, sutureless vitrectomy and standard 20-gauge pars plana vitrectomy in idiopathic epiretinal membrane surgery: a comparative pilot study. Graefes Arch Clin Exp Ophthalmol 19:1–8 [Epub ahead of print].

13.Fujii GY, de Juan E Jr, Humayun MS, Chang TS, Pieramici DJ, Barnes A, Kent D (2002) Initial experience using the transconjunctival sutureless vitrectomy system for vitreoretinal surgery. Ophthalmology 109(10):1814–1820

14.Chalam KV, Gupta SK, Vinjamaram S, Shah VA (2003) Small-gauge, sutureless pars plana vitrectomy to manage vitreous loss during phacoemulsification. J Cataract Refract Surg 29(8):1482–1486

15.Chalam KV, Shah VA (2004) Successful management of cataract surgery associated vitreous loss with sutureless small-gauge pars plana vitrectomy. Am J Ophthalmol 138(1):79–84

16.Cho YJ, Lee JM, Kim SS (2004) Vitreoretinal surgery using transconjunctival sutureless vitrectomy. Yonsei Med J 45(4):615–620

17.Lakhanpal RR, Humayun MS, de Juan Jr E, Lim JI, Chong LP, Chang TS, Javaheri M, Fujii GY, Barnes AC, Alexandrou TJ (2005) Outcomes of 140 consecutive cases of 25gauge transconjunctival surgery for posterior segment disease. Ophthalmology 112(5):817–824

18.Yanyali A, Celik E, Horozoglu F, Nohutcu AF (2005) Corneal topographic changes after transconjunctival (25-gauge) sutureless vitrectomy. Am J Ophthalmol 140(5):939–941

19.Ibarra MS, Hermel M, Prenner JL, Hassan TS (2005) Longer-term outcomes of transconjunctival sutureless 25gauge vitrectomy. Am J Ophthalmol 139(5):831–836

20.Shimada H, Nakashizuka H, Mori R, Mizutani Y (2005) Expanded indications for 25-gauge transconjunctival vitrectomy. Jpn J Ophthalmol 49(5):397–401

21.Lam DS, Fan DS, Mohamed S, Yu CB, Zhang SB, Chen WQ (2005) 25-gauge transconjunctival sutureless vitrectomy system in the surgical management of children with posterior capsular opacification. Clin Experiment Ophthalmol 33(5):495–498

22.Chalam KV, Gupta SK, Agarwal S, Shah VA (2005) Sutureless limited vitrectomy for positive vitreous pressure in cataract surgery. Ophthalmic Surg Lasers Imag 36(6):518–522

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24.Liu DT, Chan CK, Fan DS, Lam SW, Lam DS, Chan WM (2005) Choroidal folds after 25 gauge transconjunctival sutureless vitrectomy. Eye 19(7):825–827

25.Inoue M, Noda K, Ishida S, Nagai N, Imamura Y, Oguchi Y (2004). Intraoperative breakage of a 25-gauge vitreous cutter. Am J Ophthalmol 138(5):867–869

26.Lundstrom M, Montan P, Stenevi U, Thorburn W Postoperative endophthalmitis related to type of incision in cataract surgery. Presented at the April 2005 meeting of the American Society of Cataract & Refractive Surgery

27.Miller JJ, Scott IU, Flynn HW Jr, Smiddy WE, Newton J, Miller D (2005) Acute-onset endophthalmitis after cataract surgery (2000–2004): incidence, clinical settings, and visual acuity outcomes after treatment. Am J Ophthalmol 139(6):983–987

References 67

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29.Lundstrom M (2006) Endophthalmitis and incision construction. Curr Opin Ophthalmol 17(1):68–71

30.Cohen SM, Flynn HW Jr, Murray TG, Smiddy WE (1995) Endophthalmitis after pars plana vitrectomy. The Postvitrectomy Endophthalmitis Study Group. Ophthalmology 102(5):705–712; Review

31.Taylor SR, Aylward GW (2005) Endophthalmitis following 25-gauge vitrectomy. Eye 19(11):1228–1229

■25-gauge vitrectomy simplifies and shortens many of the cases performed by the typical vitreoretinal surgeon.

■The 25-gauge system has been demonstrated to improve patient outcomes, in the form of more rapid recovery of vision and decreased postoperative discomfort.

■The specific complications to watch for in the immediate postoperative period are those of infection and hypotony.

■Differences in instrument performance and surgical techniques make case selection particularly important for surgeons learning 25-gauge vitrectomy.

8.1Introduction

The “early” days of 25-gauge vitrectomy were not so long ago. The concept of sutureless, transconjunctival cannulas, developed by Eugene de Juan, Jr. and co-workers around the year 2000 [1], was rapidly adopted for commercial use by 2001 [2]. Bausch and Lomb produced the first commercially available 25-gauge vitrectomy system, combining de Juan’s microcannulas with a 25-gauge version of a high-speed electric vitreous cutter that proved outstanding for this application. Soon, other companies followed with pneumatic 25-gauge cutter systems. Continual improvements in cannula designs, illumination devices, and instrumentation now allow surgeons to effectively address a broader spectrum of vitreoretinal pathology [3, 4], and most would agree that 25-gauge vitrectomy has taken a permanent place in our surgical armamentarium.

This chapter is primarily directed toward surgeons with little to no experience with 25-gauge vitrectomy, although the more experienced surgeon may find some useful tidbits. I will assume that the reader is already an experienced vitreous surgeon, and will not elaborate on issues that are common to all types of vitrectomy. My suggestions are based on my personal experience in over one thousand 25-gauge vitrectomy cases. Like many surgeons, my techniques are a combination of the evolutionary and the archaic, and the reader should be quick to reject these suggestions as his or her experience dictates.

Perhaps the first issue to address for the prospective 25-gauge vitrectomy surgeon is this: “why?” Given our ability to effectively address virtually all vitreoretinal surgical problems with 20-gauge instruments, and the recent advent of 23-gauge vitrectomy [5] instrumentation, this is an important question. The answer, in my opinion, is this: 25-gauge vitrectomy simplifies and shortens many of the cases performed by the typical vitreoretinal surgeon, is a more proven technology than 23-gauge vitrectomy (at least at the time of this writing), and has been demonstrated to improve patient outcomes, in the form of more rapid recovery of vision [6] and decreased postoperative discomfort. The techniques necessary to perform safe and effective 25-gauge vitrectomy are easily mastered by the experienced surgeon, and the wounds caused by the transconjunctival microcannulas differ primarily in scale from the wounds caused by conventional sclerotomies, as opposed to the longer, oblique incisions necessary to create sutureless wounds with larger-gauge instruments. The issues of patient outcome and wound healing, so relevant to this discussion, are reviewed elsewhere in this book.

Keep in mind the goals of your initial 25-gauge cases. In addition to the obvious, i.e., addressing the patient’s eye problem, the beginning 25-gauge surgeon should concentrate upon the following issues:

■Preoperative Considerations

●Case selection

●Preoperative preparation

■Intraoperative Considerations

●Cannula insertion

●Instrument insertion, manipulation, and removal

●Visualization and illumination

8.2Case Selection

Differences in instrument performance and surgical techniques make case selection particularly important for surgeons learning 25-gauge vitrectomy.

A well-defined macular epiretinal membrane or a simple non-clearing vitreous hemorrhage in a pseudophakic patient is an ideal first case, although other types of pathology are also suitable. In general, select eyes with healthy sclera and conjunctiva, a clear anterior segment, and with intraocular pathology that will not require peripheral dissection or multiple instrument exchanges. Surprisingly, eyes that have undergone previous pars plana vitrectomy can be excellent surgical candidates if they meet these criteria.

8.3Preoperative Preparation

8.3.1Anesthesia

Although 25-gauge vitrectomy can be performed with peribulbar and even with topical anesthesia, retrobulbar anesthesia is preferable for several reasons. The mild proptosis of the globe improves surgical access, and the volume effect of the anesthetic bolus makes it easier to insert the cannulas by minimizing retropulsion of the globe. The akinesia achieved by retrobulbar anesthesia is also desirable, given the more flexible nature of 25-gauge instruments.

In cases where the block is incomplete, it is often possible to achieve adequate patient comfort with supplemental topical anesthetic drops. If an additional injection is necessary, use the smallest volume possible, in order to minimize conjunctival chemosis. I use a 30-gauge needle to inject a small amount of subconjuntival 2% lidocaine in one quadrant of the eye, then gently “roll” the anesthetic agent to other quadrants of the subconjunctival space with a cot- ton-tipped swab, taking care to avoid conjunctival tears.

8.3.2Patient Position

Because the more flexible nature of 25-gauge instruments can make manipulation of the globe more difficult, careful attention should be given to the patient’s head and body position prior to the start of surgery. The patient’s head

should be positioned such that the visual axes of the eye and of the operating microscope are coaxial. It is particularly important for the eye to be pointed straight upward in cases where a non-sutured contact lens or sutureless lens ring will be utilized — this will minimize the tendency for the lens to slide off-axis during surgery. The exception to this rule is in patients with protruding brows or particularly deep-set eyes. In these cases, it can be helpful to slightly retroflex the patient’s neck and head to improve access to the eye.

8.3.3Surgical Prep

There are theoretical reasons that eyes undergoing 25-gauge vitrectomy may be more susceptible to endophthalmitis. Pathogens on the surface of the conjunctiva may be introduced into the vitreous cavity by the trocar/ cannula during insertion. The decreased amount of infusion (compared to conventional 20-gauge vitrectomy) may reduce dilution or efflux of intraocular pathogens. Postoperatively, the sutureless sclerotomies may provide access for pathogens, particularly in hypotonus eyes.

Careful preparation of the ocular surface is essential to minimize the possibility of endophthalmitis. Active surface infections, such as conjunctivitis or blepharitis, should be treated preoperatively. Even in the absence of preoperative infection, some surgeons prescribe several days of preoperative topical antibiotics, although there are no data to support this. I typically instill a drop of topical 5% povidone-iodine immediately after administering the anesthestic injection, allowing this to bathe the ocular surface during the surgical prep of the eyelids and periorbital skin with povidone-iodine. The eye is then copiously irrigated with a dilute solution (around 1%) of povidoneiodine in saline. The surgical drape and eyelid speculum should then be placed in a manner that prevents the cannulas and instruments from contacting the eyelashes.

Summary for the Clinician

■A well-defined macular epiretinal membrane or a simple non-clearing vitreous hemorrhage in a pseudophakic patient is an ideal first case.

■Retrobulbar anesthesia is preferable.

■Because the more flexible nature of 25-gauge instruments can make manipulation of the globe more difficult, careful attention should be given to the patient’s head and body position prior to the start of surgery.

■Careful preparation of the ocular surface is essential to minimize the possibility of endophthalmitis.

8.4Intraoperative Considerations

8.4.1Cannula Insertion

The transconjunctival cannulas are pre-loaded on 25-gauge trocars (Fig. 8.1). The surgeon or assistant should ensure that the cannulas are firmly seated on the trocars prior to insertion, to reduce the possibility of the cannula collapsing or buckling as it is driven through the sclera.

I typically insert the cannulas 3.0 mm posterior to the corneoscleral limbus in aphakic or pseudophakic eyes, or 3.5 mm in phakic eyes. The entry point can be determined with calipers or a scleral marker. One trocar design incorporates a marker at its proximal end (Fig. 8.2). I use a cotton-tipped applicator to displace the conjunctiva prior to cannula insertion, so that the conjunctival wound will slide away from the scleral wound when the cannulas are removed at the conclusion of surgery. Avoid grasping the conjunctiva with toothed forceps, to minimize conjunctival laceration.

I insert the cannulas tangential to the globe, although some surgeons prefer to insert them at a more acute angle to create a longer intrascleral wound. The first action should be a firm push through the conjunctiva and into the sclera. As the trocar penetrates the sclera, slight resistance may be encountered as the larger diameter cannula contacts the scleral wall. At this stage, gentle back and forth twisting can ease insertion of the cannula.

Insert the infusion line into the first cannula to maintain normal intraocular pressure during insertion of subsequent cannulas. The infusion line should be affixed to the sterile drape to direct the infusion flow toward the center of the vitreous cavity. I use a spring-loaded drape clip, not tape, for this purpose (Fig. 8.3). The clip allows me to more easily move the infusion line from cannula to cannula if needed. I typically insert the superior can-

Fig. 8.1 B&L 25-gauge cannula loaded on trocar

Fig. 8.2 B&L trocar with integrated scleral marker

Fig. 8.3 Surgical drape clip for infusion line

nulas at about the ten o’clock and two o’clock meridians, because I rely on the cannula hubs to stabilize a sutureless silicone lens ring. If the cannulas are placed too close to the horizontal meridian, the lens ring will tend to drift during surgery. Sometimes the condition of the eye or the target pathology will dictate a major deviation from the typical sclerotomy sites. One example of this, not recommended as an initial case, is the use of 25-gauge cannulas for vitrectomy in eyes with functioning glaucoma filtering blebs.

8.4.2Instrument Insertion, Manipulation, and Removal

It is easier to insert instruments into the eye through cannulas than through conventional sclerotomies. This is particularly true of flexible instruments, such as soft-tipped

cannulasordiamond-dustedmembranescrapers.However, there is minimal clearance between the instrument shaft and the inner wall of the cannula, and the resulting friction can loosen the cannulas during surgery. This is particularly

8.4.4 Visualization

Although I have mentioned the value of panoramic viewing systems for 25-gauge vitrectomy, I use a flat contact lens

While extracting an instrument, make sure to align the axis of the instrument with the axis of the cannula to minimize friction. If the cannula appears loose, use a forceps to stabilize the cannula hub, a task that must sometimes be performed by the surgical assistant if the surgeon’s fellow hand is holding a second instrument in the eye.

If a cannula comes loose during surgery, the surgeon has several options. If the problem is recognized before the instrument (e.g., the vitreous cutter) has been fully removed from the eye, keep the instrument tip within the vitreous cavity and use the instrument shaft as a guide to slide the cannula back into place. If the instrument has already been removed from the eye and if the cannula remains on the instrument shaft, locate the conjunctival incision (which will be displaced from the scleral incision) and reinsert the instrument through the conjunctiva and sclera, using it as a cannula guide. If neither of these options exists, then reload the cannula on the trocar and insert it in a new location. Plug the fellow cannula during these efforts. If the cannula has come free near the conclusion of the case, it is sometimes easiest to insert the instrument directly through the sclerotomy without using a cannula, although this technique is more likely to result in a wound leak.

8.4.3Instrument Manipulation

The more flexible nature of 25-gauge surgical instruments requires other modifications in technique. Even though the newer generations of instruments are stiffer, they will flex during attempts to forcibly rotate the globe. Therefore, surgery of the peripheral and anterior retina is ideally accomplished with a panoramic viewing system. With such a system, the eye can be left in a relatively stable upright position, and an instrument can be manipulated with the cannula as its pivot point, similar to a rowboat oar in its oarlock.

The tendency of the instruments to flex is relevant to the location and angle of cannula insertion at the start of the case. If the surgery will require a significant amount of work in the anterior portion of the globe (e.g., vitreous incarceration and retained intracapsular lens cortex following complicated cataract surgery) the cannulas should be inserted in a direction toward the target pathology. The patient’s nose may limit access from the nasal quadrants. In such cases, it is sometimes necessary to place the infusion line nasally and to shift the surgeon’s position to the temporal side of the patient.

securing contact lenses is a sew-on lens ring. However, to avoid the need for sutures, I typically use a silicone lens ring that is stabilized by three-point contact with the cannula hubs (Fig. 8.4). This allows me to use a flat quartz or sapphire lens, which provides a stable high-resolution view. Other options include a low-mass reusable plastic lens with stabilizing feet (Fig. 8.5), or disposable silicone lenses.

8.4.5Illumination

Available higher-output light sources and their compatible fiberoptic devices have eliminated inadequate illumination (compared to 20-gauge vitrectomy) as a problem during the 25-gauge vitrectomy. A variety of diffusion light pipes, chandeliers (Fig. 8.6), and even illuminated infusion cannulas are available, allowing bimanual surgery and surgeon-performed scleral depression during vitrectomy. However, for the initial cases, I recommend a standard non-diffusion light pipe. The discrete beam is better for identifying clear vitreous, epiretinal membranes and internal limiting membrane. If you have wisely selected a pseudophakic or aphakic patient, the standard light pipe should provide excellent illumination of the vitreous in all areas of the posterior segment.

Chandelier illumination is invaluable for cases that benefit from a comprehensive view of the retina (e.g., giant retinal tear detachment repair), bimanual technique, or surgeon-performed scleral depression. Although these

Fig. 8.4 Silicone lens ring, stabilized by cannula hubs

Fig. 8.5 Volk Self-Stabilizing Vitrectomy “SSV” contact lens

Fig. 8.6 25-gauge chandelier

types of cases are not suggested for the beginning surgeon, I offer a few suggestions for future reference:

1.Insert the chandelier before inserting the 25-gauge cannulas. The two-step technique necessary to insert the currently available chandeliers is more easily performed without the infusion line in place. Active infusion can cause chemosis after the initial stab incision, and makes insertion of the chandelier more difficult.

2.Direct the chandelier more posteriorly than the typical entry angle for the cannulas. This reduces glare.

3.Clear vitreous is difficult to visualize with diffuse illumination. A small amount of triamcinolone acetonide injected into the vitreous cavity makes the vitreous

much easier to identify. However, the use of intraocular steroids may theoretically increase susceptibility of the eye to infection, and I do not use this technique routinely.

4.At the conclusion of surgery, I usually remove the chandelier before removing the cannulas. Wound leaks are rare, since there are no instrument exchanges and usually relatively little removal of peripheral vitreous in the region of the chandelier.

8.4.6Fluidic Considerations

The smaller lumen of the vitreous cutter and infusion line results in reduced flow compared to 20-gauge vitreous cutters. This can be partially overcome by increasing infusion pressure. A typical working infusion pressure with the high-speed electric cutter system is around 35–40 mm Hg (equivalent to 70 inches of water). The pneumatic cutter, due to its lower maximum flow, typically requires a higher infusion pressure of 50–60 mm Hg. Because the fluidics of the electric cutter allows maximum flow at its maximum cut rate, flow can be regulated simply by varying the vacuum level. Maximum flow with the current generation of pneumatic cutter requires a combination of high vacuum and low cut rate, which can result in increased vitreous traction and is not recommended. Lower cut rates should be used primarily to allow the cutter to engage thicker or stiffer material (e.g., organized hemorrhage, lens capsule). The ability of 25-gauge cutters to effectively remove vitreous at high cut rates with low flow, combined with the smaller tip geometry compared to larger-gauge cutters, are an advantage when dissecting vitreous or membranes close to the retinal surface. This reduces the need for intraocular scissors or blades, and thus reduces the number of associated instrument exchanges.

The smaller port and reduced flow of the vitreous cutter makes it essential that the cutter tip be brought to the target tissue. A thorough vitrectomy is much more easily performed if the cutter is systematically and continually moved to engage the vitreous at its cut boundary. Temporary elevation of the infusion pressure can allow the surgeon to more rapidly perform the “core” vitrectomy or to engage the posterior cortical vitreous to create a posterior vitreous detachment. However, significant elevation of the infusion pressure should only be performed during periods of active aspiration or for temporary hemostasis. The cannulas allow much less flow of fluid around instrument shafts than do conventional sclerotomies, and the intraocular pressure can remain dangerously elevated during prolonged intraocular manipulations with non-aspirating instruments (e.g., forceps, laser probes, scissors) if the infusion pressure is not appropriately monitored and adjusted.

8.4.7Membrane Peeling

The most significant adjustment for most surgeons learning 25-gauge vitrectomy is in the feel and perform-

8ance of intraocular forceps. Epiretinal membrane peeling is one of the most technically demanding requirements

of any surgical procedure, and the slightly more flexible instrument shaft is noticeable to most experienced surgeons. This has no material effect on my ability to work in the posterior pole, but can make peripheral dissections difficult.

During your first cases of peeling epiretinal or internal limiting membrane, you will discover that the tips of 25gaugeinstruments,althoughprecisebyvirtueoftheirsmaller size, are also more likely to tear the edge of an elevated membrane. After identifying and elevating the membrane edge, re-grasp the membrane with the entire opposing surfaces of the forceps jaws. Turn the forceps tip so that its broadest and most blunt surface is perpendicular to the direction of membrane peeling. This will reduce the tendency of the tip of the instrument to tear the membrane.

8.4.8Concluding the Case

8.4.8.1Peripheral Retina Inspection

As with larger-gauge vitrectomy, it is important to inspect the peripheral retina for iatrogenic retinal breaks near the conclusion of surgery. I inspect the retina prior to any planned fluid-air exchange; otherwise it is my final act prior to removing the cannulas. Some surgeons use a panoramic viewing system to inspect the retinal periphery, but I typically use the indirect ophthalmoscope, with a cotton-tipped applicator as a scleral depressor. Take care to depress gently in the region of the cannulas to avoid tearing the conjunctiva, which is anchored to the sclera at these locations.

8.4.8.2Cannula Removal

I remove the cannulas with a heavy blunt forceps. I plug the cannulas to allow the intraocular pressure to normalize, and I clamp the infusion line before I remove the superior two cannulas. This may reduce the tendency of infusion fluid to force itself through the vitreous skirt and the sclerotomy, and reduce the chance of wound leakage. After removing a cannula, I apply brief gentle pressure to the region of the sclerotomy with a cotton-tipped applicator. I do not vigorously “massage” the conjunctiva. I then open the infusion line to ensure that the eye maintains a normal pressure, and to check for sclerotomy site leaks. If a suture seems necessary, this should be placed prior to removing the final cannula and infusion line. When

satisfied with the appearance of the eye, I remove the final cannula and infusion line as a single unit.

8.4.8.3 Wound Leaks

Wound leaks occur in around one percent of sclerotomies [7], and are more common in fluid-filled eyes. The surface tension of an intraocular gas bubble will effectively tamponade a minimally-leaking sclerotomy. Because of this, some surgeons advocate a fluid–air exchange at the conclusion of every 25-gauge vitrectomy. Given the relative infrequency of wound leaks, I find this unnecessary. If a sclerotomy site is leaking, I typically recommend the following steps:

1.Apply gentle constant pressure over the sclerotomy with the infusion line open. After 10–15 s, many small leaks will seal.

2.Inject a bubble of filtered air into the vitreous cavity with a 30-gauge needle to restore normal intraocular pressure and tamponade the sclerotomy. This will control all but the largest wound leaks.

3.Finally, suture the sclerotomy. The wound is simply a slightly stretched 25-gauge needle puncture. A single absorbable suture is sufficient to close the wound. Because only a small incision in the conjunctiva is necessary to expose the sclerotomy, conjunctival sutures are usually unnecessary. The avoidance of conjunctival sutures helps to minimize postoperative patient discomfort.

When in doubt, suture! It is far better to leave the operating room confident in the wound integrity than with worries about postoperative hypotony. As your experience and confidence grow, you will find that sutures are rarely necessary.

Summary for the Clinician

■It is easier to insert instruments into the eye through cannulas than through conventional sclerotomies.

■The more flexible nature of 25-gauge surgical instruments requires other modifications in technique. Even though the newer generations of instruments are stiffer, they will flex during attempts to forcibly rotate the globe.

■The tendency of the instruments to flex is relevant to the location and angle of cannula insertion at the start of the case.

■The most stable system for securing contact lenses is a sew-on lens ring.

■Available higher-output light sources and their compatible fiberoptic devices have eliminated inadequate illumination as a problem during 25-gauge vitrectomy.

Summary for the Clinician

■The smaller port and reduced flow of the vitreous cutter makes it essential that the cutter tip be brought to the target tissue.

■It is easier to insert instruments into the eye through cannulas than through conventional sclerotomies.

■The more flexible nature of 25-gauge surgical instruments requires other modifications in technique. Even though the newer generations of instruments are stiffer, they will flex during attempts to forcibly rotate the globe.

■The tendency of the instruments to flex is relevant to the location and angle of cannula insertion at the start of the case.

■The most stable system for securing contact lenses is a sew-on lens ring.

■Available higher-output light sources and their compatible fiberoptic devices have eliminated inadequate illumination as a problem during 25-gauge vitrectomy.

■The smaller port and reduced flow of the vitreous cutter makes it essential that the cutter tip be brought to the target tissue.

■The finer tips of 25-gauge instruments are more likely to tear the edges of a membrane during stripping or peeling maneuvers, requiring modifications in surgical technique.

■It is important to inspect the peripheral retina for iatrogenic retinal breaks near the conclusion of surgery.

■Clamp the infusion line before removing the superior two cannulas.

■At the end of the surgery if a sclerotomy site is leaking:

●Apply gentle constant pressure over the sclerotomy with the infusion line open.

●Inject a bubble of filtered air into the vitreous cavity with a 30-gauge needle to restore normal intraocular pressure and tamponade the sclerotomy.

●If all else fails, suture the sclerotomy.

8.5Postoperative Management

8.5.1Postoperative Antibiotics and Dressing

I typically administer a small amount of subconjunctival antibiotic and steroid at the conclusion of surgery, although there are no supporting data for this. I do not use aminoglycoside antiobiotics because of the possibility of inadvertent retinal exposure and toxicity. I create a subconjunctival bleb of antibiotic over each sclerotomy.

This further separates the conjunctival incision from the sclerotomy, and also serves to retract any vitreous wicks from the conjunctival surface.

I typically instill a drop of long-acting cycloplegic and a combination antibiotic/anti-inflammatory ointment before applying a relatively firm patch over the closed eyelids. The patch is left in place until the postoperative examination the next morning.

8.5.2Postoperative Examination

It is at the first postoperative examination that the benefits of 25-gauge vitrectomy are often most apparent to the surgeon and patient. The eye is typically comfortable and normal in appearance, with significantly less conjunctival hemorrhage and chemosis than is typically present after conventional sutured vitrectomy.

The specific complications to watch in the immediate postoperative period are those of infection and hypotony.

Endophthalmitis is rare, and should be managed in the typical fashion [8].

If appropriate caution has been used in the operating room, damaging postoperative hypotony should be exceedingly rare. Even if the intraocular pressure is lower than normal, treatment is not indicated if the anterior chamber is formed and there are no large choroidal effusions. In most cases, the intraocular pressure will return to the normal range within 1 week. I have not found patching the eye helpful in cases of mild-to-moderate hypotony, and I prefer to leave the eye unpatched to allow the patient to recognize any worrisome changes in visual acuity.

In the rare case of a persistent unacceptably low intraocular pressure, consider injecting a small bubble of filtered air or expansile gas if the leak is in the superior half of the eye and an adequate tamponade is possible. If this is not possible, return to the operating room and suture all potential leaking sclerotomies.

Summary for the Clinician

■Administer a small amount of subconjunctival antibiotic and steroid at the conclusion of surgery. Do not use aminoglycoside antiobiotics because of the possibility of inadvertent retinal exposure and toxicity. Inject a blister of subconjunctival antibiotic over each sclerotomy.

■The postoperative eye is typically comfortable and relatively normal in appearance.

■The specific complications to watch for in the immediate postoperative period are those of infection and hypotony. Endophthalmitis is rare, and should be managed in the typical fashion.

8.6Conclusion

25-gauge vitrectomy is currently the smallest of the “small-incision” sutureless vitrectomy techniques. The

8wounds are therefore the least traumatic to the eye and the most rapidly healing. Ever-improving instruments and

techniques now allow surgeons to address the majority of intraocular surgical problems with 25-gauge techniques.

References

1.Fujii GY, de Juan E Jr, Humayun MS, Pieramici DJ, Chang TS, Awh C et al (2002) A new 25-gauge instrument system for transconjunctival sutureless vitrectomy surgery. Ophthalmology 109:1807–1812

2.Fujii GY, de Juan E Jr, Humayun MS, Chang TS, Pieramici DJ, Barnes A et al (2002) Initial experience using the transconjunctival sutureless vitrectomy system for vitreoretinal surgery. Ophthalmology 109:1814–1820

3.Lakhanpal RR, Humayun MS, de Juan E Jr, Lim JI, Chong LP, Chang TS et al (2005) Outcomes of 140 consecutive cases of 25-gauge transconjunctival surgery for posterior segment disease. Ophthalmology 112:817–824

4.Ibarra MS, Hermel M, Prenner JL, Hassan TS (2005) Longer-term outcomes of transconjunctival sutureless 25-gauge vitrectomy. Am J Ophthalmol 139:831–836

5.Eckardt C (2005) Transconjunctival sutureless 23-gauge vitrectomy. Retina 25:208–211

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