Vitreoretinal Issues

From the 2009 Vitreoretinal Course Update, presented by the Bascom Palmer Eye Institute

Educational Objectives

The goal of this program is to improve vitreoretinal surgery. After hearing and assimilating this program, the clinician will be better able to:

1.   Minimize the risk for endophthalmitis associated with intravitreal injections, vitrectomy, and cataract surgery.

2.   Choose the most effective methods for managing dislocated intraocular lenses.

3.   Identify the most important factors influencing the removal of retained lens material.

4.   Accurately assess the risk for retinal detachment associated with refractive surgery.

5.   Determine the appropriate timing of retinal detachment surgery.

Faculty Disclosure

In adherence to ACCME Standards for Commercial Support, Audio-Digest requires all faculty and members of the plan­ning committee to disclose relevant financial relationships within the past 12 months that might create any personal con­flicts of interest. Any identified conflicts were resolved to ensure that this educational activity promotes quality in health care and not a proprietary business or commercial interest. For this program, the following has been disclosed: Dr. Flynn is a consultant for Alcon, Allergan, Genentech, Optimedia, Pfizer, and Carl Zeiss, and . Drs. Smiddy and Albini and the plan­ning committee reported nothing to disclose.

Acknowledgements

This program was recorded at the 2009 Vitreoretinal Course Update, held May 1-2, 2009, in Miami, FL, and sponsored by the Bascom Palmer Eye Institute. The Audio-Digest Foundation thanks the speakers and the sponsor for their cooperation in the production of this program.

Endophthalmitis Update

Harry W. Flynn Jr, MD, Professor of Ophthalmology, University of Miami School of Medicine and Bascom Palmer Eye Institute, Miami, FL

Intravitreal injections and endophthalmitis: injection of anti-vascular endothelial growth factor (VEGF) agents be­fore vitrectomy prevents or reverses neovascularization and markedly lowers risk for endophthalmitis; facilitates surgery; prevents “bleeding issues”

Patient preparation: apply topical anesthetic; apply 5% povidone iodine to conjunctiva, 10% to lashes and lid mar­gins; place speculum beneath lower eyelid to expose pars plana; dry excess fluids from cul-de-sac, and direct needle toward mid-vitreous

Incidence of endophthalmitis at Bascom Palmer from January 2005 through December 2008: use of anti-VEGF in­jections increased from 4000/yr to 12,000/yr during that period; on retrospective chart review of 34,208 injec­tions, 9 patients identified with treatment for clinically diagnosed endophthalmitis (incidence 0.028); 5 cases culture-positive; of 9 patients, most had age-related macular degeneration (AMD); 5 received bevacizumab; 4 re­ceived ranibizumab; patients reported pain and decreased vision 1 to 2 days after injection; culture-negative pa­tients eventually regained baseline visual acuity; 4 culture-positive patients had streptococcal infection; of those, only 1 achieved favorable visual outcome

Incidence of endophthalmitis associated with anti-VEGF injections at other institutions: ranges from 3 in 10,000 injections to 6 in 26,000 injections; conclusion  —  infection occurs once in every 3000 to 4000 injections; ranibi­zumab not available in pre-prepared syringes; need to draw up in syringe contributes to contamination risk; Streptococcus frequently found, and resulting endophthalmitis “generally bad”

Endophthalmitis associated with vitrectomy: sutureless, transconjunctival pars plana procedure currently in wide use; in 2008 survey of members of American Society of Retina Specialists, »20% of members reported ³1 case of endophthalmitis associated with 23-gauge or 25-gauge surgery; »2% reported 3 to 5 cases

Risk factors: leaking sclerotomy; wound distortion from eye rubbing; vitreous wick in sclerotomy sites; bacterial inoculum in patients with relative immunocompromise; failure to use subjconjunctival antibiotics; increasing use of adjuvants during surgery

Technical aspects of transconjunctival surgery: speaker and colleagues use angled incisions, with displacement of conjunctiva and entry of trocar and cannula; nondisposable instruments; multicenter study demonstrated rates of endophthalmitis associated with 20-gauge surgery lower than those associated with 25-gauge surgery; other stud­ies show comparable rates; during 2007 and 2008, one group of surgeons reported 1 case in 4400 20-gauge vit­rectomies (rate 0.023); in recent study of 23-gauge vitrectomy, rate was 1 case in 3300 surgeries (25-gauge surgery decreasing); outcomes usually good

Endophthalmitis after cataract surgery: risk factors include wound leak; relative immunocompromise; application of xylocaine gel before conjunctiva properly prepared; vitreous loss during surgery; wounds located inferiorly; preoperative blepharitis; silicone intraocular lenses

Susceptibility of coagulase-negative staphylococci: has continued to drop in patients studied at Bascom Palmer from 2005 to 2008; now 44% to 46% susceptible, compared to much higher susceptibility in 1990s; in Ocular Tracking Resistance in the US Today (TRUST) study, methicillin-resistant Staphylococcus aureus (MRSA) par­ticularly resistant to fluoroquinolones (only 15% of isolates sensitive); important to learn organism’s sensitivity to different topical antibiotics; surgeons at Bascom Palmer do not use antibiotics intracamerally or in irrigating solution during cataract surgery; patients prepared for surgery with povidone iodine only; no preoperative topical antibiotics; choice of postoperative antibiotics left to surgeon

Serratia marcescens: gram-negative organism that causes virulent endophthalmitis

Retained Lens Fragments and Dislocated IOLs

William E. Smiddy, MD, Professor of Ophthalmology, University of Miami School of Medicine and Bascom Palmer Eye Institute

Management of dislocated intraocular lenses (IOLs): observe, remove, or reposition; repositioning speaker’s first choice; if anterior capsular support sufficient, try sulcus fixation with existing IOL; possible to place posterior chamber (PC) lens in anterior chamber (AC)

Scleral suture fixation without capsular support: create scleral flaps so sutures not exposed (to reduce risk for endoph-thalmitis); retrieve IOL with vitreous cutter in suction mode; grasp with forceps; speaker introduces suture loop with 27-gauge needle prethreaded with 9-0 prolene

Common principles: place sutures under scleral flap; ideal location »1 mm posterior to limbus; pay close atten­tion to vitreous removal at preliminary and final stages (vitreous may settle anteriorly); handle haptics care­fully; speaker prefers 9-0 prolene because it provides extra support; this approach may not work with IOLs with short or floppy haptics

Visual outcomes: usually good; in series of 284 cases (including 51 in-the-bag dislocations managed by speaker and colleagues), 72% of patients achieved vision of 20/40 or better

In-the-bag dislocation: incidence growing; most common cause pseudoexfoliation; many authors recommend ex­changing for AC IOL; speaker prefers repositioning with scleral sutures; often occurs years after surgery; in speaker’s series, lenses with silicone plate haptics usually required exchange

Dislocated foldable IOLs: prolapse lens into anterior chamber to allow access to each haptic; must remove IOLs with silicone plate haptics due to insufficient capsular support, and replace with plate-haptic IOL; do not allow sutures to become entangled; IOL centers well as long as sutures positioned properly

Outcomes: in previously mentioned study of 284 eyes, 20% had undergone previous vitreoretinal surgery; 17% had previous yttrium aluminum garnet laser capsulotomy (fewer than in earlier studies, probably because PC dis­rupted during cataract removal); pseudoexfoliation accounted for 14% of all dislocations and 53% of in-the-bag dislocations; trauma “seemed to be a minor player”; overall, »75% of IOLs repositioned, with »50% requiring sutures, due to insufficient capsular support

Complications: rate “reasonably acceptably low”; hard to distinguish from those associated with cataract surgery; »10% of patients experienced cystoid macular edema; »4% developed retinal detachment; recurrent dislocation occurred in 17 eyes (5.98%; “of some concern”); retinal detachment coincident with IOL dislocation in »1% of cases; several occurred 5 to 6 mo after vitrectomy; all successfully reattached; of eyes with recurrent dislocation, 15 previously repositioned (8 with sutures; 1 exchanged for AC IOL, which also dislocated)

Conclusion: good results obtained with surgical management of dislocated IOLs, regardless of technique; previously reported techniques work well, even with newer foldable IOLs or endocapsular dislocation

Retained lens material: risk for retinal detachment and timing of surgery most important issues

Retinal detachment: rate 5% to 8% in many studies; long-term surveillance necessary; educate patient on signs and symptoms; associated with poorer prognosis, compared to cases without detachment

Precautions: maximize vitreous removal; induce posterior vitreous detachment if necessary; removal using low phacoemulsification power and high aspiration rates often better than using high phacoemulsification power; examine fundus periphery intraoperatively and treat peripheral breaks as necessary

Timing of surgery: some data suggest same-day surgery can maximize visual results and minimize risk for compli­cations; not possible at most institutions; no strong evidence that waiting 7 to 10 days produces worse outcomes than waiting only 1 or 2 days; visual and anatomic results usually good

Retinal Detachment and Refractive Surgery

Thomas A. Albini, MD, Assistant Professor of Clinical Ophthalmology, University of Miami School of Medi­cine and Bascom Palmer Eye Institute

Consequences of pathologic myopia: premature vitreous liquefaction, posterior vitreous detachment, and increased prevalence of lattice degeneration; risk for retinal detachment (RD) increases with degree of myopia

Photorefractive keratectomy: 90% of corrections <-6.0 D successful; generate significant acoustic shock waves; large ablation zones required in some patients lead to posterior pressure focus and potential for posterior segment damage; stress waves may also damage anterior vitreous and anterior retina

Laser-assisted keratomileusis (LASIK): optimal flap creation requires raising intraocular pressure briefly to >65 mm Hg, then rapidly decreasing it; may exert rapid mechanical stretch on vitreous base that could lead to retinal break and RD; suction causes rapid increase, then rebound decrease in axial length; laser itself produces shock waves; however, recent studies show RD rates correlate with degree of myopia in patient population; conclusion  —  LASIK does not increase risk for RD

Prophylaxis: in study of 1931 eyes, retinal breaks identified and treated in 39 (these patients had greater degree of myopia); only one developed RD during 19-mo follow-up; rate too low to determine whether prophylaxis benefi­cial; speaker recommends treating eyes with retinal lesions in same manner as those not scheduled for LASIK; American Academy of Ophthalmology (AAO) consensus advises treatment of symptomatic horseshoe tears and traumatic retinal breaks; data on other types of tears lacking

Other macular complications: macular holes reported in the only large series performed; case reports cite Valsalva-like retinopathy, choroidal neovascular membrane, epiretinal membrane, bilateral central serous, reactivation of toxoplasmosis, cystoid macular edema, and retinal nerve fiber layer defects

AAO conclusion: no evidence of higher rate of RD associated with LASIK or photorefractive keratotomy; speaker recommends treating patients same as others with similar fundus findings, but counsel patient about possibility of RD and its implications for surgery; also warn patients they remain at risk for RD despite reduction in refrac­tive error

General recommendations: thoroughly document abnormalities; discuss in detail risk for adverse outcomes associ­ated with RD; before surgery, discuss risk factors for RD and benefits and drawbacks of prophylaxis; treat pre-ex­isting retinal breaks and detachments before performing refractive surgery; benefit of prophylaxis unclear; postoperative evaluation recommended, especially for high-risk patients

Timing of Repair of Retinal Detachments

Dr. Smiddy

Background: macular involvement  single most important prognostic factor affecting outcomes of RD, per multiple studies

Index series: 672 patients followed retrospectively by speaker and colleagues for >2 yr after scleral buckling; two-thirds of cases macula-off, one-third macula-on; »50% pseudophakic or aphakic RD; among 385 patients with macula-off detachment, mean vision did not decrease for several weeks; initial presenting visual acuity remained relatively constant for first 30 days; no significant change in vision after second month, regardless of length of time macula off; data consistently show that if macula off <1 wk, performing surgery few days sooner or later will not affect outcome; more recent data show possible to obtain good outcome after >2 mo; study by Ross et al suggested height of macular involvement more important than duration (prognosis worse with high bullous de­tachment, regardless of duration); however, one study of 165 eyes demonstrated worse prognosis among those with detachment duration >3 mo; take-home message  —  warn patient that visual acuity may be limited if RD longstanding; however, duration of RD should not affect surgical results; surgery can wait few days if necessary

RD with macular involvement: concern about delayed visual acuity; most likely related to development of pockets of subretinal fluid; in one study, pockets persisted 6 wk after surgery, but eventually resolved; explains why vi­sion may continue to improve for months or years after surgery; conclusion  —  macular detachment urgent but not emergent; no need to rush to surgery

Macula-sparing detachment: seen in 196 patients in speaker’s series; »40% had symptoms >1 wk; macular disease, associated cataracts, and associated vitreous hemorrhages accounted for poor vision in other patients; detach­ment within arcades in 33% of cases; in »60%, detachment extended between arcades and equator; anterior to equator in »7%; in 50%, one quadrant involved; 2 quadrants in one-third of cases; >2 quadrants involved in re­maining cases; direction closest to fovea  —  from superior in one-third; from temporal in »25%; from inferior in »25%; from nasal in remaining eyes; >50% of patients had >1 retinal break; timing of surgery  —  within 24 hr for most patients, within 3 days for 85%; outcomes similar to those reported in literature; 87% of patients followed for >2 mo; of those, most maintained postoperative visual acuity of 20/40 or better; presenting visual acuity strongest predictor of final visual acuity

Factors associated with more urgent surgery: shorter duration of symptoms, superior location, and more posterior extent of detachment; little difference in visual and anatomic outcomes

Suggested Reading

Flynn HW Jr, Scott IU: Legacy of the endophthalmitis vitrectomy study. Arch Ophthalmol 126:559, 2008; Hassan TS et al: The effect of duration of macular detachment on results after the scleral buckle repair of primary, macula-off retinal detachments. Oph­thalmology 109:146, 2002; Kim SS et al: Management of dislocated intraocular lenses. Ophthalmology 115:1699, 2008; Kohnen T: Post-cataract endophthalmitis: can we do better? J Cataract Refract Surg 35:609, 2009; Lin SC, Tseng SH: Prophylactic laser photocoagulation for retinal breaks before laser in situ keratomileusis. J Refract Surg 19:661, 2003; Moore JK et al: Retinal de­tachment in eyes undergoing pars plana vitrectomy for removal of retained lens fragments. Ophthalmology 110:709, 2003; Mosh­feghi AA et al: Management of macular holes that develop after retinal detachment repair. Am J Ophthalmol 136:895, 2003; Ross W et al: The correlation between height of macular detachment and visual outcome in macula-off retinal detachments of < or = 7 days’ duration. Ophthalmology 112:1213, 2005; Scott IU et al: Clinical features and outcomes of pars plana vitrectomy in pa­tients with retained lens fragments. Ophthalmology 110:1567, 2003; Scott IU et al: Endophthalmitis after 25-gauge and 20-gauge pars plana vitrectomy: incidence and outcomes. Retina 28:138, 2008; Smiddy WE: Management of dislocated foldable intraocu­lar lenses. Retina 25:576, 2005; Sodhi A et al: Recent trends in the management of rhegmatogenous retinal detachment. Surv Ophthalmol 53:50, 2008.