Ординатура / Офтальмология / Английские материалы / Retinal and Vitreoretinal Diseases and Surgery_Boyd, Cortez, Sabates_2010

recommend it, after primary globe closure if there is a globe rupture. Ultrasound biomicroscopy can be used to identify occult IOFBs located in the ciliar body area.

Microbial Spectrum and Preoperative

Systemic Antibiotics

603

Surgical Management

If there is an IOFB associated with an acute globe rupture, the scleral, limbal, or corneal laceration should be initially repaired before the start of the vitrectomy.

The use of preoperative systemic antibiotics should be considered since posttraumatic endophthalmitis is serious complication and a poor visual prognosis factor, particularly in the setting of an IOFB.

Gram-positive organisms as coagulasenegative staphylococci (especially Staphylococcus epidermidis) and streptococci species are usually isolate in patients who develop posttraumatic endophthalmitis. But Gramnegative and fungal organisms may also be found. In some cases, polymicrobial infections have been described.

Some organisms that are considered specially virulent, as Bacillus, Pseudomonas, Enterococcus and Moraxella, are associated with poor visual acuity outcome.

The third-generation fluorquinolone levofloxacin, can be administered orally (400mg on the evening before surgery and 400mg 3 hours before surgery) and reaches aqueous and vitreous concentration enough to achieve the minimum inhibitory concentration to stop the growth of 90% of major ocular trauma pathogens.(3)

Operative considerations include timing of surgery (delayed versus immediate), primary cataract extraction versus lensectomy, route and instrument used for IOFB extraction, and the role of intraoperative antibiotics.

Timing of Surgery

Early vitrectomy is advocated when the risk of endophthalmitis is high. This risk increases from 3.5% to 13.4% if removal of IOFB is deferred for more than 24 hours.

Associated retinal detachment also expedites surgical intervention. Other advantages to immediate IOFB removal may include a decrease in the rate of proliferative vitreoretinopathy (PVR), and a single surgical procedure.

But delayed surgical intervention has some pros, as the resolution of anterior segment pathology (e.g. corneal edema), removing the posterior hyaloid in these young patients may be easier, and the inflammation and risk of intraoperative haemorrhage are lower.

When significant choroidal haemorrhage is present, surgery is generally delayed until

the haemorrhage is liquefied (14 days). Unless “kissing sign” (contact between retinal surfaces of choroidal detachment) is present. Then, prompt surgery would be required.

Cataract Extraction versus

Lensectomy

In several retrospective case series, cataract extraction and intraocular lens (IOL) implantation at the time of IOFB removal and vitrectomy, appeared to be a safe procedure. But the adequacy of capsular bag and zonular support for a posterior chamber or sulcus IOL should be considered prior to primary IOL implantation. Pars plana lensectomy may be requiered in traumatic cataract with lens capsule violation or poor zonular integrity.

Pars Plana Vitrectomy (PPV) and Removal of Intraocular Foreign Body (IOFB)

PPV should be performed at the time of IOFB removal of posterior located IOFBs.

Before vitrectomy era, external magnets were used to remove ferrous IOFBs. One study comparing PPV versus external magnet, found that anatomic and functional outcomes were significantly better in patients undergoing PPV.

Complications of external electromagnet were frequent, serious and were not observed

in the PPV group. Modern vitrectomy techniques and the use of intraocular forceps and intraocular magnets have improved the surgical management of the removal of ferromagnetic materials (Figure 4).

Standard 20-gauge vitrectomy offers reliability and versatility when treating the vitreoretinal complications of ocular trauma. The authors do not recommend small-gauge in most cases of ocular trauma. But if smallgauge vitrectomy is performed, two-steps trocar placement is preferable to avoid excessive globe manipulation and elevation of intraocular pressure (IOP).(4,5)

A 6-mm infusion may be helpful, especially if a choroidal haemorrhage is present. After removing cortical vitreous, posterior vitreous detachment (PVD) may be created if necessary. Then, the vitreous adhesions surrounding the IOFB may be cut circumferentially to ensure that the IOFB is not attached to any structure.

Vitreousremovalandposteriorhyaloidseparation are advocated to limit the fibrovascular proliferation within the tract of perforation and the adhesion of vitreous in the posterior exit wound in order to reduce the incidence of proliferative vitreoretinopathy (PVR) and to improve functional and anatomic outcomes. PVR is usually developed 3 months after the injury but it may occur at any point from 2 to 12 months of injury. Preretinal PVR and subretinal bands may appear. Cases with anterior loop PVR may develop hypotony.

If the cornea is clear enough to perform PPV with wide-angle viewing systems, the authors prefer not to associate keratoplasty since the corneal graft failure is higher at the time of IOFB removal.

The use of the high brightness xenon light source is helpful in IOFB visualization, especially in cases of corneal pathology. Its use with chandelier light source also allows for bimanual manipulation to remove the IOFB and to perform unassisted scleral depression.

Very small IOFBs may be removed with the intraocular magnet or with the conventional membranes forceps. Small and medium-sized IOFBs may be removed with IOFB forceps through the pars plana at the site of sclerotomy with enlargement of the wound if needed, or in aphakic eyes, through a limbical incision. If the IOFB is bigger than 4x4x4 mm, a scleral tunnel may be required (Figure 5).

After IOFB removal, 360o peripheral retina examination with scleral depression is critical to identify retinal tears, retinal detachment

and choroidal detachment. Also, other IOFBs that may be occult in some cases could be identified by scleral depression.

Retinal tears may be treated by endolaser and tamponade. Perfluorocarbons are used if retinal detachment is present. Few studies recommend prophylactic scleral buckle in posterior segment located IOFB cases. In large and anterior located IOFBs, it may decrease the risk of RD.

Series did not find differences in the visual outcome of patients undergoing silicone oil versus C3F8 after vitrectomy. But, usually silicone oil is used in severely injured eyes. Aretrospective 23-case series described the use of primary silicone oil tamponade following IOFB removal in eyes with severe concomitant posterior segment injuries, including lacerations of the sclera, choroid and retina. PVR occurred in 70% of eyes and mostly required surgical revision.(6,7)

Prognosis Factors

Reports in the literature differ in the examination factors associated with poor anatomic or functional outcomes.

Ocular trauma clinical features at the time of presentation that may be predictive of long-term VA include presenting VA, the presence or absence of endophthalmitis, globe rupture, perforating injury, retinal detachment and an afferent pupillary defect.

In the multivariate analysis of most of studies, when an IOFB is clinically observed, the factors associated with poor visual outcomes are corneoscleral entrance wound, uveal prolapse and retinal detachment.

The use of an external magnet is associated with poor visual outcome.

In most of studies, the best predictor of functional and anatomical outcome was the pattern of entrance and exit wounds. If those entering and exiting are anterior to the equator, visual and anatomic outcomes may be better than those with posterior exit wounds. This finding can be explained by the development of vitreoretinal traction at the posterior exit site and the degree of macular injury in posterior globe exit wounds. The amount of macula-involvedretinaldetachments,choroidal haemorrhage and conmotio retinae involving

607

the macula is significantly less with anterior exit wounds.(8,9)

Conclusions

Penetrating ocular injuries with IOFB associated, continues to be a major cause of visual impairment.

Initial evaluation includes a complete history, ophthalmic exam and imaging techniques to identify IOFB location and characteristics. Controversiesexistregardingimmediateversus delayed IOFB removal. Multiple factors should be considered prior to decide the surgical timing and plan. Above all, the presence of endophthalmitis and retinal detachment, require prompt surgery.

Recent studies have demonstrated that the administration of systemic and topical antibiotics pre and postoperatively may decrease the incidence of endophthalmitis.

Frequent postoperatively visits are required to detect and treat endophthalmitis, retinal detachment and PVR, which are associated with poor visual outcomes.

Patient education, occupational safety, and advancement in microsurgical techniques continue to help improve visual and anatomical outcomes.(10)

References

1.Ehlers JP et al. Metallic intraocular foreign bodies: characteristics, interventions, and prognostic factors for visual outcome and globe survival. Am J Ophthalmol.2008 Sept; 146 (3): 427-433

2.Szijártó Z et al. Prognosis of penetrating eye injuries with posterior segment intraocular foreign body. Graefes Arch Clin Exp Ophthalmol. 2008 Jan; 246 (1):161-5.

3.Yeh S et al. Current trends in the management of intraocular foreign bodies. Curr Opin Ophthalmol 19:225-233.

4.Kiss S, Vawas D. 25-gauge transconjuntival sutureless pars plana vitrectomy for the removal of retained lens fragments and intraocular foreign bodies. Retina. 2008 Oct; 28(9):1346-51.

5.Aldakaf A et al. Intraocular foreign bodies associated with traumatic cataract. Oftalmologia. 2006; 50(4):90-4.

6.Colyer MH et al. Perforating globe injuries during operation Iraqi Freedom. Ophthalmology. 2008 Nov; 115(11):2087-93.

7.Wickham L et al. Outcomes of surgery for posterior segment intraocular foreign bodies—a retrospective review of 17 years of clinical experience. Graefes Arch Clin Exp Ophthalmol. 2006 Dec; 244(12):1620-6.

8.Erakum T, Egrilmez S. Prognostic factors in vitrectomy for posterior segment intraocular foreign bodies. J Trauma. 2008 Apr; 64 (4):1034-7.

9.Woodcock MG et al. Mass and shape as factors in intraocular foreign body injuries. 2006 Dec; 113(12):2262-9.

10.Lala-Gitteau E et al. Intraocular foreign bodies: a descriptive and prognostic study of 52 cases. J Fr Ophthalmol. 2006 May; 29 (5):502-8

Endophthalmitis is a rare catastrophic complication, potentially the most devastating, of intraocular surgery or trauma. It involves inflammation of intraocular tissues, usually caused by an infection. Sterile non-infectious endophthalmitis may be a result of retained lens material and toxic agents. Panophthalmitis is an inflammation of all coats of the eye including intraocular structures. It is presented here because the management of endophthalmitis may require a vitrectomy and can be associated with many vitreo-retinal complications.

Exogenous endophthalmitis is more commonly seen following cataract surgery, penetrating injuries of the globe and infected glaucoma filtering blebs. Endogenous infection occurs in the setting of intravenous drug abuse and systemic immune suppression or incompetence.

Although the rate of postoperative infection is considerably lower in ophthalmic surgery than in other types of surgery, the severe consequencesofpostoperativeendophthalmitis make it essential for every ophthalmologist

to understand its diagnosis, management, and prophylaxis.

Prevention

Preoperative Evaluation and

Recognition of Risk Factors

Intraocular infection is preventable to a great degree. It is interesting that once the importance of sterility was recognized, the incidence of endophthalmitis actually fell in the West, long before the introduction of antibiotics. With the elimination of other risk factors, the rate has gradually dropped a little further in recent years. Antibiotics can be effective for the treatment of established infections. In preventing endophthalmitis, however, it is an understanding of the perioperative risk factors that is important. The most critical are pre-existing infectious processes around the eye, lids, adnexa, lacrimal system and in the upper respiratory tract that might contribute organisms to the surgical field. The lacrimal system should be patent and functional so that fluids do not stagnate.

Routine irrigation is not recommended unless there is evidence of obstruction such as tearing, discharge or reflux. Palpation of the lacrimal sac for reflux is appropriate.

There is very strong evidence that in the overwhelming percentage of endophthalmitis cases, the offending organism actually comes from the patient. While there have been epidemics of infection caused by contaminated irrigating solutions and lenses, most cases of surgical endophthalmitis are caused from organisms indigenous to and colonized in the adjacent face and eyelids such as Staphylococcus epidermidis, or Propionibacterium acnes. Preventing these organisms from contaminating the surgical field is the goal of prophylaxis.

The use of dilute antibiotics in the irrigating fluid during cataract surgery is contentious. Use of aminoglycocides such as gentamicin in the irrigating solution may be inappropriate, since gram-positive organisms which are seen most commonly as the cause of endophthalmitis are poorly treated by these antibiotics. Similarly, the use of vancomycin with any irrigating solution may not make theoretic sense due to the fact that although vancomycin is effective against gram-positive organisms, this medication needs several hours in contact with the bacteria to kill them and may not remain in the anterior chamber for more than one to two hours following surgery. There is also the theoretic risk of antibiotic resistance increasing by the widespread use of antibiotics within the irrigating solution.

Preparation for Surgery

Whether preoperative antibiotics should be administered to every patient is still

controversial. It is not our practice to use antibiotics prophylactically prior to surgery, and we have experienced extremely low incidences of postoperative endophthalmitis. Although one study suggests that antibiotic drops administered four times a day prior to surgery virtually sterilizes the conjunctiva, there is little evidence that this actually makes a difference in the infection rate provided that other preventive steps are taken.

Use of a specific method for preparing the skin and draping the eye can virtually eliminate all organisms from the surgical field and dramatically reduce the rate of endophthalmitis. Preoperative installation of 5% povidone-iodine solution has been shown to be highly effective in eliminating organisms in the conjunctival sac. This leaves the conjunctival sac sterile. It is important to use the solution of povidone-iodine rather than the detergent which is highly toxic to the cornea. Povidone-iodine is also painted on the surface of the eyelids, the brow, the face, and the adjacent part of the nose. Next, a cotton-tipped stick dipped in the solution is used to paint the lid margins. The solution is allowed to dry. The tissues are gently coated without excess pressure on the lids.

Pushing or squeezing the lids margins can express organisms from deep in the glands onto the conjunctiva and lid surface. Next in importance after preoperative preparation is prevention of contamination by organisms that can be expressed from the lids and glands. This can be achieved by proper draping. The principle is to cover the lid margins and skin in a way that prevents entry of organisms into the conjunctival sac. Steri-strips or brow tape can be used along the lid margin to access the lashes and stick them back against the eyelid. Trimming the eyelashes is controver-

sial-while lash trimming can reduce bacterial load in patients with significant blepharitis, it may stir up organisms at the roots of the lashes. As the patient is being draped, the nurse or the assistant can hold the lids apart with two cotton-tipped sticks so that the drape goes directly over the cornea. The surgeon then incises down the middle of the drape. A retractor or speculum can be used to tuck the plastic drape underneath the lid into the fornix. This procedure results in a sterile field. To reiterate, careful skin preparation is the most important step for preventing infection.

European Society of Cataract & Refractive Surgeons (ESCRS) multicenter study of the prophylaxis of endophthalmitis after cataract surgerysuggestedthatintracameralcefuroxime (1 mg in 0.1 mL normal saline) administered at the time of surgery significantly reduced the risk for developing endophthalmitis after cataract surgery. The incidence rate observed in those treatment groups not receiving cefuroxime prophylaxis was almost 5 times as high as that in the groups receiving this treatment. Intracameral vancomycin has been used intracameral quite routinely by a lot of surgeons. Recently moxifloxacin is being advocated for the same usage. The preparation of Vigamox for intracameral use is simple.

A new bottle of Vigamox is opened in the OR. A 10-mL syringe with a 20-gauge needle is used to draw 2 mL of Vigamox into the syringe. The same needle is then inserted into a new 25-mL bottle of BSS, and 8 mL BSS is drawn up into the syringe. This combination yields a 5:1 dilution of the original 500 μg/mL Vigamox to 100μg/mL. Rolling the syringe promotes mixing of the solution, which is already well combined by

Endophthalmitis

611

the turbulence of drawing the BSS up into the syringe after the Vigamox.

A 0.5-mL aliquot of the Vigamox mixture is injected from the same syringe, without changing the needle, into a small medicine cup on each case’s scrub table just before it is needed. Next, the scrub nurse draws the solution into a TB syringe. She then attaches a 27-gauge hockey stick cannula to expel any air and all but 0.2 mL of the Vigamox solution. She hands the syringe to me, and I inject 0.1 mL of the Vigamox into the eye through the side port incision, across the anterior chamber, and under the capsulorhexis’ edge. This process bathes the IOL in moxifloxacin, achieving antibacterial prophylaxis and pressurizing the anterior chamber simultaneously, and it is the final step of the procedure. A 0.2-mL Vigamox solution is given to the surgeon, rather than only 0.1 mL, because the extra amount allows the surgeon to expel any air from the cannula before inserting it into the eye.

Acute Postoperative

Endophthalmitis

Postoperative endophthalmitis can be classified by the interval in time after surgery when the infection manifests. Acute infection occurs within a few weeks of intraocular segment surgery, most typically between 2 and 7 days. The most common pathogens implicated in acute endophthalmitis today are Staphylococcus epidermidis and coagulasenegative staphylococci. In past years the predominant pathogens were more virulent organisms such as Staphylococcus aureus, streptococci, and Gram-negative bacteria, which fulminate in the first 24 - 48 hours after surgery.

Acute postoperative endophthalmitis usually manifests as a sudden loss of vision accompanied by pain. However, the ophthalmologist should not be lulled into complacency by the absence of pain. Similarly, the eye may appear relatively quiet externally. The presence of a hypopyon, diminution or absence of the red fundus reflex, or the formation of a pupillary membrane are other important indicators of postoperative infection.

Chronic Postoperative

Endophthalmitis

Thanks to the work of Meisler and others, we know that persistent, low-grade postoperative inflammation is usually infectious in origin and that low-virulence infections can persist in the eye for months or even years. Delayed or chronic postoperative endophthalmitis can present several months to more than one year after surgery.

Chronic postoperative endophthalmitis presents quite differently than acute endophthalmitis. It is usually not heralded by a significant initial decrease in vision, but remains indolent and is often detected only upon careful examination. Inflammation in the anterior chamber that responds to topical steroids and reappears when steroids are tapered off should alert the ophthalmologist to examine closely the intraocular lens, the haptics, and the capsular bag. Any white accumulations or plaques should be identified as infectious organisms. Other signs of chronic postoperative endophthalmitis include keraticprecipitates,vitreousreaction,orbeaded fibrin strands in the anterior chamber.

The organisms that produce chronic, lateonset endophthalmitis tend to be of low virulence. Propionibacterium acne is commonly implicated; however, infections by yeasts such as Candida albicans or Candida parapsilosis, and other pathogens of lower virulence have been reported.

Although these organisms grow slowly and are not very effective in overcoming the immunologic defenses of the eye, they can be sequestered within the capsular bag out of reach of host defenses and thus resistant to elimination. However, they do incite a persistent inflammatory reaction. The interval to presentation and the severity of symptoms usually correlate directly with the virulence of the organism.

Sterile Endophthalmitis

Severe marked intraocular inflammation following cataract surgery may closely mimic an infection. It presents mostly early on in the postoperative period, but can occur even after several months of the surgery. History of previous intraocular inflammation, pseudoexfoliation syndrome, inadequate mydriasis at the beginning of surgery, difficult intraoperative course, problems with IOL implantation, mechanical irritation of the iris with the intraocular lens, retention of lens fragments, residual monomers on PMMA lenses, topical anesthetic agents entering the eye, etc. are considered important risk factors for developing an enhanced postoperative inflammatory response.