GLAUCOMA UPDATE
From the 7th Annual Downeast Ophthalmology Symposium, presented by the Maine Society of Eye Physicians and
Surgeons
Educational Objectives
| The goal of this program is to improve the management of patients with glaucoma. After hearing and assimilating this
program, the clinician will be better able to:
|
 | 1. Compare advantages and disadvantages of various implantable drainage devices.
|
| 2. Describe indications for cyclodestructive procedures.
|
| 3. Choose appropriate therapy for specific types of refractory glaucoma.
|
| 4. Compare advantages and disadvantages of modified filtration surgery vs trabeculectomy as primary surgery for
glaucoma.
|
| 5. Evaluate the efficacy of newer forms of angle 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, Dr. Netland and planning committee reported nothing to disclose.
Acknowledgments
Dr. Netland was recorded at the 7th Annual Downeast Ophthalmology Symposium, presented September 19-21, 2008,
in Bar Harbor, ME, by the Maine Society of Eye Physicians and Surgeons. The Audio-Digest thanks Dr. Netland and
the Maine Society of Eye Physicians and Surgeons for their cooperation in the production of this program.
Peter A. Netland, MD, PhD
Professor of Ophthalmology, Siegal Professor and Director of Glaucoma, and Hamilton Eye Institute Vice Chair for Academic
Affairs, University of Tennessee College of Medicine, Memphis
What To Do if Primary Glaucoma Surgery Fails
| Trabeculectomy with mitomycin-C (MMC): conventional primary surgery; cautious use of MMC (ie, limit dose
and exposure) indicated to minimize risk for long-term complications; most clinicians use dose of 0.25 to 0.4 mg/
mL for 1 to 3 min
|
| Glaucoma drainage device implantation
|
| Indications: failure of conventional primary surgery; extensive limbal scarring (not enough mobile conjunctiva at
limbus for conventional surgery); conventional surgery likely to fail (due to, eg, neovascular glaucoma or severe
uveitis); trend toward use of glaucoma drainage implant as primary surgery to minimize or eliminate long-term
complications associated with trabeculectomy with MMC (eg, high risk for infection)
|
| Types of glaucoma drainage implants
|
| Open tube: Molteno implant; Baerveldt implant most popular in United States
|
| Flow-resistant valves: Eagle Vision implant (formerly Krupin implant)—first-generation; Ahmed Glaucoma Valve
(AGV)—second-generation (most popular worldwide)
|
| Efficacy (Siegner, 1995; Huang, 1999): open-tube and valved implants achieved mean intraocular pressure (IOP) at
level of midteens postoperatively; mean number of medications ≈1; success rate at 1 yr after implantation, 70%
to 90%
|
| Complications (Tsai, 2006): Baerveldt implant had higher rate of hypotony than AGV
|
| Choice of implant: varies with surgeon preference and experience (literature does not demonstrate real differences
between implants)
|
| Antifibrotic medications (eg, MMC): little or no effect on success or mean IOP after drainage implant placement
(unlike effect on trabeculectomy); AGV implantation and MMC (Costa, 2004)—intraoperative MMC does not significantly
alter postoperative IOP, number of postoperative medications, or surgical success rate
|
| Cyclodestructive procedures (indications): low potential for successful filtration; vision in affected eye poor or
worse than fellow eye; adjunctive use after other procedures (eg, glaucoma drainage device implantation)
|
Managing Refractory Glaucoma
| Elevated IOP after silicone oil injection (Al-Jazzaf, Netland, Charles, 2005): 450 eyes in 447 patients; ≈11%
developed elevated IOP (majority [78%] controlled with medical therapy alone); small percentage of patients
needed surgical treatment for glaucoma; trabeculectomy contraindicated because oil exits through sclerostomy (filter
likely to fail quickly); glaucoma drainage implant for refractory elevated IOP—place implant in inferior quadrant
(since oil floats, less likely to lose oil through drainage tube); keep patient supine intraoperatively (viscoelastic injected
into anterior chamber [AC] to keep oil back); patients need prolonged adjunctive treatment with steroids and
glaucoma medications for up to 1 yr (or longer) to avoid ocular inflammation and redness; summary—drainage implants
effective in refractory glaucoma associated with silicone oil injection; place implant in inferior quadrant (use
viscoelastic intraoperatively); patients require prolonged adjunctive treatment with steroids and glaucoma medications
|
| Elevated IOP after penetrating keratoplasty (PK)
|
| Study by Ayyala, 1998: multiple causes of glaucoma (some patients have closed angles, but majority have open angles;
patients may be treated equally effectively with trabeculectomy and MMC, drainage implants, or cyclophotocoagulation
(CPC)
|
| Glaucoma drainage tubes and corneal grafts: if IOP elevated after PK and not treated, graft failure rate almost
100%; similar failure rate seen with various procedures (no statistically significant difference); therefore, drainage
tubes not “bad” for grafts
|
| Paper in progress: no significant difference in graft failure rates or corneal complications, whether drainage tubes
implanted in pars plana or in AC; more data needed
|
| Elevated IOP in severe ocular surface disease (case): due to history of ocular cicatricial pemphigoid (OCP), patient
not candidate for trabeculectomy; no conjunctiva present (drainage implant indicated)
|
| Glaucoma after keratoprosthesis in patients with severe corneal disease (Netland, 1998): 55 eyes with
keratoprosthesis; majority developed glaucoma (most significant late complication); glaucoma drainage device implanted
at time of surgery or shortly afterward to improve control of IOP; glaucoma drainage implants shown to effectively
control IOP in majority of patients with severe ocular surface disease; some eyes progress despite
drainage implant (postoperative medications may be indicated); monitor patients for signs of progression
|
| Drainage implants in uveitic glaucoma (DaMata, 2000; Papadaki, 2007): if uveitis controlled, outcomes good
with glaucoma surgery (if uveitis chronic, poor outcome probable); use of immunomodulatory drugs key for steroid-sparing
effect and to control signs of chronic inflammation (eg, cells and flare in AC) and uveitis; success rate
94% at 4 yr (aggressive use of immunomodulatory medications to control uveitis associated with better outcomes)
|
| Neovascular glaucoma and bevacizumab (Avastin; Lupinacci, in press, 2008): neovascular glaucoma still associated
with poor prognosis; in series, visual outcomes better and need for glaucoma surgery decreased in treatment
group, compared to control group; caveat—if angle completely closed, glaucoma surgery indicated
regardless of whether Avastin used
|
| Treatment of aphakic or pseudophakic glaucoma in children (Ishida, Mandal, Netland, 2005): children
may be responsive to medical therapy; angle surgery not viable in most affected patients because they present at
later age; classic signs of congenital glaucoma (eg, buphthalmos) not present early on; trabeculectomy with MMC—
success rates 50% to 85%; drainage implant—success rates 56% to 95%; CPC—primarily used as adjunctive treatment
after placement of drainage implant
|
| Elevated IOP after drainage implant
|
| Evaluate etiology: treatment directed at specific cause; common causes—drainage tube obstruction; thickened capsule
(pseudocyst)
|
| Drainage tube blockage: diagnosis—IOP does not decrease with digital massage; blockage may be at tube tip or
valve, or inside tube lumen; treatment—for early fibrin obstruction, tissue plasminogen activator (tPA) 10 to 20
µg/0.1 mL; neodymium: yttrium-aluminum-garnet (Nd:YAG) laser; surgical intervention (inject viscoelastic into
AC if iris involved)
|
| Thickened capsule
|
| Diagnosis: elevated IOP 4 to 6 wk after surgery; often, IOP descreases slightly with digital massage; increased
IOP may be transient (“hypertensive phase” may last 2 mo); self-limited process tends toward improvement
|
| If persistent elevated IOP present: speaker starts with medical therapy and digital massage and checks for improvement
|
| If not improved, options include: surgical revision with adjunctive fluorouracil (5-FU; success rate 25%-42% [Tsai,
1999]); placement of additional implants (≈60% success rate; Shat, 2000; Godfrey, 2000); adjunctive CPC—
success rate ≤70% (including retreatments; Shields, 2002; Semchyshyn, 2002); can perform limited treatment using
diode laser (full treatment if necessary and if complications unlikely); few complications (phthisis and vision
loss after CPC usually associated with complete angle closure and lack of outflow)
|
| Conclusions: elevated IOP may not respond to medical therapy or initial surgical treatment; useful surgical options include
filtration surgery with antifibrotic medications, glaucoma drainage implants, and cyclodestructive procedures;
prognosis has improved for refractory cases of glaucoma
|
What’s New in Primary Surgery for Glaucoma?
| Introduction: medical therapy not always effective (patients frequently do not comply with medical treatment regimens);
patients and surgeons seek safe, effective, and predictable surgical procedures; new techniques include
modified filtration surgery, angle surgery, suprachoroidal aqueous drainage, and cyclodestruction
|
| Surgical therapy: trabeculectomy current gold standard for primary surgical treatment of glaucoma; adjunctive
techniques—use of antifibrotic medication (MMC or 5-FU) to help achieve lower mean IOPs and increase success
rates; laser suture lysis or releasable sutures; caveat—outcomes with modified trabeculectomy not as predictable or
gratifying as outcomes with cataract surgery
|
| Modified filtration surgery: Miami-InnFocus Drainage Implant (MIDI)—tube and drainage plate proposed (not
ready for implementation); Fugo blade—transciliary filtration; approved by Food and Drug Administration (FDA);
may reduce risk for flattened chambers; Ex-PRESS miniature glaucoma implant—nonvalved steel device; internal
diameter 50 to 200 µm; shunts aqueous from AC to subconjunctival space
|
| Ex-PRESS miniature glaucoma implant
|
| Overview: technique similar to trabeculectomy; advantages over standard trabeculectomy—reduced tissue trauma and
inflammation (no sclerectomy or peripheral iridectomy); results more predictable because no variation in sclerostomy
size (internal diameter of device 50 µm); less time required intra- and postoperatively; disadvantages—
increased cost; device-related complications
|
| Comparison of trabeculectomy to Ex-PRESS miniature glaucoma device implanted under scleral flap (Maris,
2007): ≈100 eyes; conclusions—Ex-PRESS shunt as effective as trabeculectomy for long-term IOP control; short
term, less early postoperative hypotony (may be due to resistance to aqueous flow, due to device [safety advantage]);
long-term results comparable
|
| Ex-PRESS implanted under scleral flap alone or combined with phacoemulsification (Kanner, in press): 231 eyes
treated with Ex-PRESS alone (114 received combined therapy); mean IOP slightly decreased in Ex-PRESS
group, compared to combined group; tube blockage most common device-related complication (treatable with
Nd:YAG laser)
|
| Nonpenetrating glaucoma surgery: viscocanalostomy or deep sclerectomy; advantages—little or no bleb; no peripheral
iridectomy; lower complication rate (however, learning curve steep); Netland, 2001—nonpenetrating
glaucoma surgery technically more difficult than trabeculectomy; slightly higher mean postoperative IOPs compared
to trabeculectomy; with experience, fewer complications compared to trabeculectomy
|
| iTrack ophthalmic microcatheter (iScience Interventional): canaloplasty technique—flexible catheter passed
around Schlemm’s canal, then suture tied to tip and pulled back; maintains opening of canal; complications
(Lewis, 2007; Shingleton, 2008)—microhyphema and hyphema most common; mean IOPs—midteens in early
postoperative period
|
| Trabectome (NeoMedix): developed by Baerveldt; electrosurgical tip passed across AC and visualized through goniolens;
trabecular meshwork engaged, then cut using tip; results—in large series, IOPs in midteens; good success
rate; most common complications include mild hyphema; number of adjunctive medications decreased
|
| iStent Trabecular Bypass Microstent (Glaukos): not yet FDA-approved; provides filtration out of Schlemm’s canal;
titanium (highly biocompatible); potential complications—hyphema; results—360° flow; good result may require
placement of >1 device; initial findings promising (mean IOPs decreased to midteens)
|
| Suprachoroidal aqueous drainage
|
| Cyclodialysis surgery: abandoned many years ago
|
| SOLX Gold Shunt: in phase 3 trials; shunts aqueous from AC into suprachoroidal space; advantages—alternative for
patients not candidates for other procedures; technique—make incision posterior to limbus; tunnel into AC with
blade (blade comes out near trabecular meshwork), then tunnel backwards into suprachoroidal space; create opening
in suprachoroidal space and insert device into pocket (tip into AC, tail into suprachoroidal space)
|
| Transscleral CPC: one option
|
| Endoscopic CPC: indications—treatment of elevated IOP in patients with atypical ciliary body anatomy, failure of
transscleral CPC, and need for other surgical procedures; efficacy as solo procedure for glaucoma controversial
|
Suggested Reading
Al-Jazzaf AM et al: Incidence and management of elevated intraocular pressure after silicone oil injection. J Glaucoma 14:40,
2005; Ayyala AM et al: Comparison of mitomycin C trabeculectomy, glaucoma drainage device implantation, and laser neodymium:YAG
cyclophotocoagulation in the management of intractable glaucoma after penetrating keratoplasty. Ophthalmology
105:1550, 1998; Costa VP et al: Efficacy and safety of adjunctive mitomycin C during Ahmed Glaucoma Valve implantation: a
prospective randomized clinical trial. Ophthalmology 111:1071, 2004; Da Mata A et al: Management of uveitic glaucoma with
Ahmed glaucoma valve implantation. Ophthalmology 106:2168, 1999; Godfrey DG et al: Implantation of second glaucoma
drainage devices after failure of primary devices. Ophthalmic Surg Lasers 33:37, 2002; Huang MC et al: Intermediate-term
clinical experience with the Ahmed Glaucoma Valve implant. Am J Ophthalmol 127:27, 1999; Ishida K et al: Glaucoma drainage
implants in pediatric patients. Ophthalmol Clin North Am 18:431, 2005; Lewis RA et al: Canaloplasty: circumferential viscodilation
and tensioning of Schlemm’s canal using a flexible microcatheter for the treatment of open-angle glaucoma in adults:
interim clinical study analysis. J Cataract Refract Surg 33:1217, 2007; Maris PJ Jr: Comparison of trabeculectomy with Ex-
PRESS miniature glaucoma device implanted under scleral flap. J Glaucoma 16:14, 2007; Netland PA et al: Glaucoma associated
with keratoprosthesis. Ophthalmology 105:751, 1998; Netland PA et al: Nonpenetrating glaucoma surgery. Ophthalmology
108:416, 2001; Papadaki TG et al: Long-term results of Ahmed glaucoma valve implantation for uveitic glaucoma. Am J
Ophthalmol 144:62, 2007; Semchyshyn TM et al: Supplemental transscleral diode laser cyclophotocoagulation after aqueous
shunt placement in refractory glaucoma. Ophthalmology 109:1078, 2002; Shah AA et al: Shunt revision versus additional tube
shunt implantation after failed tube shunt surgery in refractory glaucoma. Am J Ophthalmol 129:455, 2000; Shields SR, Chen
P: Sequential or simultaneous cyclophotocoagulation and glaucoma drainage implant for refractory glaucoma. J Glaucoma 11:203,
2002; Shingleton B et al: Circumferential viscodilation and tensioning of Schlemm canal (canaloplasty) with temporal clear corneal
phacoemulsification cataract surgery for open-angle glaucoma and visually significant cataract: one-year results. J Cataract
Refract Surg 34:433, 2008; Siegner SW et al: Clinical experience with the Baerveldt glaucoma drainage implant. Ophthalmology
102:1298, 1995; Tsai JC et al: Surgical revision of glaucoma shunt implants. Ophthalmic Surg Lasers 30:41, 1999; Tsai
JC et al: The Ahmed shunt versus the Baerveldt shunt for refractory glaucoma II: longer-term outcomes from a single surgeon.
Ophthalmology 113:913, 2006.
|
