*With the exception of programs from the ACCEL series, each of which qualifies for up to 4 Category 1 CME credits.
NEW Audio-Digest Ophthalmology
Volume 51, Issue 11
June 7, 2013
Refractive Cataract Surgery Lisa Brothers Arbisser, MD
Brunescent Cataracts Dr. Arbisser
Tube Versus Trabeculectomy (TVT) Study Steven J. Gedde, MD
Selective Laser Trabeculoplasty; Complications of Trabeculectomy Dr. Gedde
Complications of Trabeculectomy Dr. Gedde
From Through The Looking Glass: Adventures In Glaucoma, Neuro-ophthalmology, And Cataract, Presented By The New Orleans Academy Of Ophthalmology
The following is an abstracted summary, not a verbatim transcript, of the lectures/discussions on this audio program.
Ophthalmology Program Info Accreditation InfoCultural & Linguistic Competency Resources
From Through the Looking Glass: Adventures in Glaucoma, Neuro-Ophthalmology, and Cataract, presented by the New Orleans Academy of Ophthalmology
The goal of this program is to improve the outcomes of cataract and glaucoma surgeries. After hearing and assimilating this program, the clinician will be better able to:
1. Optimize the rates of success and rehabilitation after cataract surgery.
2. Effectively treat brunescent cataracts.
3. Choose between trabeculectomy and tube shunt surgery on the basis of evidence from the Tube Versus Trabeculectomy Study.
4. Choose between selective laser trabeculoplasty and argon laser trabeculoplasty for individual patients with glaucoma.
5. Prevent and treat complications associated with glaucoma surgery.
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 faculty and planning committee reported nothing to disclose. In her lecture, Dr. Arbisser presents information that is related to the off-label or investigational use of a therapy, product, or device.
Refractive Cataract Surgery
Lisa Brothers Arbisser, MD, Adjunct Associate Professor, University of Utah Moran Eye Center, Salt Lake City
Success rate: ≈60% of patients with previous radial keratotomy (RK) achieve desired visual acuity (VA) within 0.5 diopters (D); ≈70% to 80% of patients after laser in situ keratomileusis (LASIK); ≈80% to 90% of average patients
Femtosecond phacoemulsification (PE): one study showed no differences between manual capsulorrhexis and laser rhexis in centration and symmetry on optic at 1 mo; laser rhexis may produce less phimosis and may have lesser effect on zonules
Interval between eyes: individualize; 1 to 2 wk interval not appropriate for patient at higher risk for cystoid macular edema (CME); rate of complications falls steeply in first week, usually to final level; exceptions — diabetic retinopathy, CME; 1-wk interval in multifocal patients so as not to delay neuroadaptation
Immediate sequential bilateral surgery: speaker performs for patients who need anesthesia or have visually debilitating cataracts in both eyes; study showed no increased risk for bilateral endophthalmitis if correct procedure followed (Arshinoff, 2008; Arshinoff and Bastianelli, 2011); offers for children with dense cataracts in both eyes to avoid amblyopia between surgeries
Irregular astigmatism: perform topography; patients should discontinue use of soft contact lenses for 1 to 2 wk (4 to 12 wk for rigid lenses); treat basement membrane disease in advance
Missed refractive target: causes — wrong lens; wrong eye; measurements inaccurate; dry surface produced irregular keratometry (K) values; eye did not behave as predicted by formula; use third-generation Holladay II, Olsen, or Haigis formula; rectifying — exchange lens if grossly incorrect; for subtle changes involving both spherical error and toricity, consider corneal refractive surgery; piggyback lens has highest long-term risk but fits sulcus, and round tapered edge less likely to cause pigmentary dispersion syndrome
Lens choice: assess patient’s desire to avoid glasses; offer monofocal lens; encourage patients to treat astigmatism; speaker prefers Tecnis for near vision in dim light; ReSTOR has broader range of vision as +3 instead of +4; near point on back of lens and not as close with Tecnis as with refractive pattern on front in +4 ReSTOR; intermediate vision not as good
General principles: minimize changes in intraocular pressure (IOP) by supporting anterior chamber (AC) with balanced salt solution (BSS) through paracentesis when removing instrument from eye; go in on foot position 0, feathering or lowering pedal and raising bottle if needed; keep relationships of tissue plane stable; do not flip; critical to coat delicate tissue; dispersive viscoelastic very helpful; speaker uses Arshinoff soft-shell technique; minimize forces applied to globe; maintain visualization by staining capsule if necessary (brunescent reflex may obscure red reflex); maintain good focus
Technique: speaker prefers vertical chop for most cases; uses hydrodelineation for softest cases (vacuums and does not apply ultrasound); safer because energy applied at or below plane of iris; gentle for endothelium and zonules; important to mobilize nucleus within bag before removing; absence of sculpting avoids disinsertion of subincisional zonules; tight side-port incisions required; 22 mL/min of BSS exits through paracentesis if instrument does not occlude properly, creating turbulence; speaker uses second hand instrument that goes through 0.5-mm paracentesis; retracts sleeve to burrow in; uses burst mode (linear power ineffective and clogs); 70% to 90% PE power generally needed; establish flow before engaging PE to prevent burns; remove superficial cortex; bury tip into nucleus; speaker uses Rosen splitter; does not use sharp chopper; cross-action chopping keeps everything in better plane and does not require vacuum as with direct-action chop
Circumferential disassembly: not possible to hydrodelineate mature lens; debulk plane between endonucleus and nucleus or nucleofied epinucleus; thin down to epinuclear shell to protect bare capsule and keep zonules and bag unstretched; step down fluidics once capsule bared and disassembly of epinucleus begins
Tube Versus Trabeculectomy (TVT) Study
Steven J. Gedde, MD, Professor of Ophthalmology; Vice Chair of Education; Director of Resident Training, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL
Arms: multicenter randomized trial; IOP in 18 to 40 mm Hg range on maximal medical therapy and previous cataract surgery with intraocular lens (IOL) implantation and/or failed trabeculectomy; no secondary glaucoma; 107 patients in tube group received 350 Baerveldt implant superotemporally, with complete restriction of flow at implantation; 105 patients in trabeculectomy (TRAB) with mitomycin C (MMC) group underwent superior TRAB with 0.4 mg/mL MMC for 4 min
Reduction of IOP: both procedures produced sustained reduction of IOP to low teens over 5 yr; TRAB group had significantly greater early reduction; difference disappeared by 6 mo; results contradict those of Ophthalmic Technology Assessment (OTA), which reported IOPs produced by tube shunts (≈18 mm Hg) higher than those with TRAB; patients receiving tubes in TVT less refractory than in past
Use of medications: group with tube shunts required more medical glaucoma therapy early after surgery; use of medications equalized by 3 yr; both groups had significant reduction in use of adjunctive medications
Treatment failure: rate significantly higher in TRAB group (≈47% at 5 yr vs ≈30% in tube group); post hoc analyses with more stringent definition of failure found rate remained significantly higher in TRAB group; reasons — inadequate control of IOP (most patients), persistent hypotony (fewer patients), loss of light perception (1 patient per group); reoperation rate significantly higher in TRAB arm (29% vs 9% in tube group) at 5 yr); rate of vision loss similar in both arms
Complication rates: higher early after TRAB; rates of late complications and serious complications similar between arms; early wound leaks more common in TRAB group; total number of patients with ≥1 early postoperative complications higher in TRAB group; late complications related to bleb (eg, dysesthesia and bleb leak) more common in TRAB group; total number of patients with ≥1 late postoperative complications similar in both arms; serious complications (those requiring reoperation or resulting in loss of ≥2 Snellen lines) similar in 2 groups
Misinterpretations: rate of complications in TRAB arm excessively high — 50% rate of perioperative complications reported in Collaborative Initial Glaucoma Treatment Study vs 37% in TVT; 63% at 5 yr comparable to 54% in Advanced Glaucoma Intervention Study (AGIS); rates of specific complications similar across different studies; success rate in TRAB arm lower than expected — arm that received TRAB plus 5-fluorouracil (5-FU) in FFSS had identical rate of failure to that in TVT; failure rates in TVT and FFSS similar to rates reported in OTA (≈10%/yr) for TRAB; failure rate for tube arm in TVT lower than expected; TVT demonstrated superiority of tube shunt — TVT favored TRAB for early control of IOP and use of medications; cumulative cost of TRAB lower
Selective Laser Trabeculoplasty
Technique: selective laser trabeculoplasty (SLT) uses frequency-doubled yttrium-aluminum-garnet (YAG) laser; exposure time in SLT nanoseconds vs 0.1 sec in argon laser trabeculoplasty (ALT); ALT uses 50-µm spot focused precisely at junction between pigmented and nonpigmented trabecular meshwork (TM); energy titrated to produce small bubble or blanch in tissue; applications spaced 4 to 5 spot-widths apart (delivers 50 spots over 180˚, 100 over 360°); 400-µm spot with SLT spans entire TM; energy titrated as with ALT; at end point (formation of small bubbles) energy decreased slightly; spots applied contiguously (to deliver 50 over 180°, 100 over 360°)
Mechanisms of action: ALT improves outflow of aqueous humor through TM; affects division and migration of endothelial cells that clear debris out of TM and alters extracellular matrix; SLT uses photo lysis that selectively targets pigmented TM cells; short pulse generates confined heat; does not produce coagulative damage to TM tissue; stimulates trabecular endothelial cells to migrate and divide; 2001 study of 8 autopsy eyes showed crater-like defects in TM after ALT, with much coagulative necrosis; SLT preserved architecture of TM; produced small track-like defects
Outcomes: ALT — success rates range from 65% to 95%; ≈80% of patients have 20% to 30% reduction in IOP; effect lost at rate of ≈5% to 10% per year; SLT — case series showed ≈80% response rate, with 20% to 30% reduction of IOP; prospective comparisons found no significant differences in outcomes
Retreatment: ALT — some studies suggest response rate lower for repeat ALT; some paradoxical rise in IOP observed; single 360°-treatment with ALT generally considered maximum; patients who received 360° of SLT that worked for ≥6 mo had no change in response rate after retreatment (Hong et al, 2009); SLT after ALT — study showed previous ALT did not affect response to SLT; second study found significantly greater effect from subsequent SLT than from repeat ALT
Initial therapy: ALT shown more effective than timolol in 271 patients; SLT and latanoprost shown equally effective (McIlraith et al, 2006); similar reductions seen in IOP with SLT and medical treatment (Katz et al, 2012)
Complications of Trabeculectomy
Conjunctival buttonholes and wound leaks: cause shallowing of AC, low IOP, and low bleb; identified by Seidel test; treatment — observation for small leak associated with good bleb; external tamponade with contact lens or pressure patch required if bleb flat, IOP low, and AC shallow; suture if defect amenable; prevention — careful surgical dissection (especially in patients with previous ocular surgery); speaker often injects BSS subconjunctivally at beginning of TRAB to identify scarring; for limbus-based flap, close with Vicryl suture on blood vessel needle; close Tenon capsule and conjunctiva separately; always perform Seidel test
Choroidal effusions: shallow AC, low IOP, and low bleb; choroid elevated on fundus examination because of collection of fluid in potential space between sclera and choroid; hypotony and inflammation contribute; treatment — manage conservatively with cycloplegic agents (eg, atropine) to shift lens-iris diaphragm posteriorly and deepen chamber; give steroids to treat any underlying inflammation; drain if chamber flat with lens against cornea (rare); drain kissing choroidals (especially if persistent) to prevent retinal detachment; drain if corneal decompensation or failing bleb present; technique — speaker opens conjunctiva and makes cutdown incision (full-thickness) in sclera in inferior quadrants ≈3.5 mm behind limbus (may place sclerostomies anywhere posterior to scleral spur); uses Kelly Descemet punch to punch out small block of scleral tissue to allow continued draining for few weeks (until it heals over); closes conjunctiva; uses similar sclerostomy prophylactically in high-risk eyes (eg, nanophthalmos, elevated episcleral venous pressure); prevention — usually caused by hypotony; place sufficient sutures with adequate tension at TRAB site to provide resistance; speaker makes scleral flaps slightly tight and uses sequential laser suture lysis postoperatively
Overfiltration: produces shallowing of AC, low IOP, and large bleb; results from inadequate suturing of scleral flap; choroidal effusions may be associated; treatment — cycloplegia to optimize depth of AC; reduce steroids to allow healing response; may apply pressure over scleral flap with pressure patch or Simmons shell; resuturing of flap occasionally necessary; prevention — place adequate number of sutures at appropriate tension
Suprachoroidal hemorrhage (SCH): begins with acute onset of severe pain; AC shallow, IOP high, and bleb low; choroidal elevation seen on fundus examination, with darker brownish appearance; ultrasound helpful to differentiate from choroidal effusion and to follow resolution of SCH and lysis of clot; small SCH may resolve spontaneously; large SCH can cause total loss of vision; drainage — wait 1 to 2 wk if possible to allow lysis of clot; indications include intractable pain, uncontrolled IOP, kissing choroidals, associated retinal detachment, or if AC flat; risk factors — high preoperative IOP (SCH caused by dramatic drop in IOP); aphakia, high myopia, previous vitrectomy, anticoagulant therapy, advanced age, and vascular malformations; prevention — emphasize need to avoid lifting, bending, or straining early after surgery; suture flap tightly; leave IOP slightly high and slowly titrate down by sequential suture lysis
Aqueous misdirection: rare; aqueous misdirected posteriorly into or behind vitreous; causes increased volume in posterior segment and shift of iris-lens diaphragm forward; risk factors — chronic angle-closure and history of acute angle closure; typically develops during first few days after any incisional surgery; produces shallow AC, high IOP, and low bleb; diagnosis requires patent peripheral iridectomy in absence of suprachoroidal blood or effusion to exclude mimicking conditions (eg, pupillary block, SCH, ciliochoroidal effusion); treatment — use medical therapy initially (ie, cycloplegic-mydriatic to deepen AC, aqueous suppressants to minimize production, hyperosmotics to shrink vitreous, and steroids to minimize formation of synechiae); laser treatment and cyclophotocoagulation of ciliary processes used rarely; disruption of anterior hyaloids; make disruption peripheral to optic in pseudophakic eye (often through iridectomy) to establish communication between posterior segment and AC; surgery (eg, Chandler procedure, pars plana vitrectomy) required in some cases; prevention — minimize intraoperative shallowing of AC; aqueous misdirection in 1 eye indicates very high risk in fellow eye
Hypotony maculopathy: usually seen with low postoperative IOP (especially in young, highly myopic patients); characterized by folds in cornea and retina producing decreased vision; causes — overfiltration; bleb leaks, hyposecretion with inflammation, choroidal effusions, or cyclodialysis clefts; treat according to etiology; provide adequate flap resistance; consider cautiously using 5-FU
Bleb-related complications: can develop months or years after successful filtering surgery; typically produce redness, photophobia, pain, visual decline, purulence or small infiltrate in bleb, and associated AC reaction with possible frank hypopyon and vitritis; blebitis (infection localized) represents early stage or infection with less indolent organism; endophthalmitis implies vitreous involved; treatment — topical antibiotic for blebitis; intraocular antibiotics for endophthalmitis; risk factors — thin-walled cystic blebs; bleb leaks; inferior location of blebs; prevention — fornix-based flaps with diffuse application of MMC; place TRABs at 12 o’clock to maximize coverage by lower eyelid
Drs. Arbisser and Gedde spoke at Through the Looking Glass: Adventures in Glaucoma, Neuro-Ophthalmology, and Cataract, held January 25-27, 2013, in New Orleans, LA, and presented by the New Orleans Academy of Ophthalmology (to learn more about CME activities from the New Orleans Academy of Ophthalmology, please visit http://www.cme.ucsf.edu/cme/index.aspx). The Audio-Digest Foundation thanks the speakers and the New Orleans Academy of Ophthalmology for their cooperation in the production of this program.
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