MANAGING ELEVATED INTRAOCULAR PRESSURE
From the 26th Annual Current Concepts in Ophthalmology, presented by the San Diego Eye Bank
| CURRENT MEDICAL TREATMENT OF GLAUCOMA—Andrew G. Iwach, MD, Associate Clinical Professor, Department
of Ophthalmology, University of California, San Francisco, School of Medicine
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| Observation vs treatment: over time, most patients with elevated intraocular pressure (IOP) do not experience progression
of disease if untreated; consider patient’s age (significant risk factor) when deciding whether to observe or treat; observation
requires patient’s commitment to follow-up
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 | Patient compliance: problematic; factors influencing compliance include complacency and denial, complicated dosing,
side effects, and economic issues; large number of patients discontinue glaucoma therapy after several months; pharmaceutical
industry manufactures devices to increase medication compliance
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| Intravitreous triamcinolone acetonide (IVTA): indications increasing; places patient at risk for elevated IOP (can
occur early or late) and steroid-associated glaucoma; consider selective laser trabeculoplasty (SLT) in younger patient
with steroid-associated glaucoma to “buy some time” and avoid filtering microsurgery
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| Therapeutic agents for IOP: include prostaglandin analogues and β-blockers (more affordable than prostaglandin analogues);
preservative composition—consider preservative when deciding which agent to give patient; timolol ophthalmic
gel-forming solution (Timoptic-XE) contains different preservative; consider 0.15% brimonidine ophthalmic solution (Alphagan)
if patient allergic to benzalkonium chloride (BAK); combination agents— to improve compliance, drug combines
prostaglandin analogues and β-blocker (not yet approved in United States); study found dorzolamide and timolol (Cosopt) decreased
IOP average of 1.5 mm Hg; however, some patients had big decrease and some showed increases; brimonidine ophthalmic
solution—produces side effects; decreasing concentration in solution reduces side effects, but reduction in IOP
similar; contains different preservative; higher pH more comfortable for some patients; brimonidine and timolol
(Combigan)—available in Canada; α-agonists produce spikes in IOP; data suggest that not only best to decrease IOP, but
also to maintain that level (more typical of prostaglandin analogues and β-blockers); prostaglandin analogues—molecules
similar, though each with different chemical properties; latanoprost (Xalatan) associated with longest track record and approved
for first-line treatment; travoprost (Travatan) associated with decreased cost; bimatoprost (Lumigan) comes in larger-
size bottle and approved as first-line therapy for glaucoma; Xalatan, Lumigan, and Travatan (XLT) study found no statistically
significant difference in efficacy between 3 agents; University of California at San Francisco (UCSF) study found difference in
efficacy between latanoprost and bimatoprost; all agents associated with hyperemia, especially bimatoprost;
hyaluronidase—Vitrase thimerosal-free formulation; useful in patients who require peribulbar anesthesia injection; 5-fluorouracil
(5-FU)—Food and Drug Administration (FDA) safety recall because of potential for glass particles containing silica
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| Laser trabecular therapy: lasers of various wavelengths aimed at trabecular meshwork lower IOP temporarily;
SLT—not all patients respond; produces similar results as argon laser trabeculoplasty (ALT), but SLT produces larger
spot size, uses less energy, and has lower fluence; study showed patients had same IOP curves after ALT and SLT;
Doheny Eye Institute study showed response better in treatment-naïve patients and reduced medication use in patients on
medical therapy; poorest results found in patients taking maximum dose of medication; results not as good if laser procedure
used as last resort; study found similar results with latanoprost and SLT; consider SLT as alternative to medication
in some patients; study looking at adjunctive SLT found patients on prostaglandin analogues less responsive to treatment
with SLT; consider SLT and β-blockers in patients who do not have economic means for long-term prostaglandin analogue
treatment; study looked at effectiveness of SLT in glaucoma patients; most patients responded to laser procedure,
and medication use could be reduced in large number of patients
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| SURGICAL INTERVENTION IN GLAUCOMA—Dr. Iwach
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| Indications for filtration surgery: consider surgery in patient who has potential for vision loss within lifetime, in patient
with history of disease progression in fellow eye, and if medical option not appropriate for patient (eg, tolerability
issues, ineffective medications, compliance problems); consider combined procedure if cataract present
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| Nonglaucomatous field loss or optic nerve changes: avoid surgery in patients with nonglaucomatous field loss;
evaluate patient’s visual field, optic nerve; check for congenital problems, history of hypotensive episode; look at right
and left eyes side by side to check for respecting of vertical meridian (may find problem not coming from optic nerve, but
chiasma or posterior); look for normal variations of optic nerve and other causes of field defects; make sure to rule out all
other causes of field defects before filtering surgery for glaucoma
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| Surgical technique: most surgeons use corneal traction suture; options for conjunctival flaps include limbal-based or
fornix-based; do iridectomy during trabeculectomy in phakic eyes; remove specimen using punch; recommend use of antimetabolites
placed under conjunctiva on top of scleral flap; when creating fornix-based conjunctival flap, close at corners
with 8-0 vicryl stitch; conjunctiva should be under tension and up against ocular surface to create watertight seal;
shape of flap varies; distance between actual bite taken with punch and outer edge of flap important (determines resistance
and stitches needed); also laser suture lysis useful tool; retinal cautery unit useful for small bleeds; recommend
Healon-GV to tamponade bleeding; can use lens to cut suture postoperatively; speaker uses 50-µ spot size, but can use
larger; can use 400 mW laser; compress tissues to visualize and cut suture; avoid creating conjunctival hole
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| Complications of filtering surgery: many; to avoid postoperative complications, adjust medications, do laser suture
lysis or releasable suture, consider giving additional antimetabolities, eg, 5-FU, and have team available to provide good
continuity of care
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| 5-fluorouracil: apply 50 mg/mL intraoperatively for 5 min; 5-FU inhibits fibroblast growth, even with single application;
study found number of patients received postoperative 5-FU injections in addition to intraoperative injections; good success
rate after trabeculectomy if patients not on medications; consider 5-FU sponge if scarring occurs too quickly, or do laser
suture lysis and subconjunctival 5-FU injections; complications include epithelial defects, wound leaks, choroidal
hemorrhage, endophthalmitis, hypotony, and thin blebs; study concluded 5-FU relatively safe; consider use in low-risk patients
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| Mitomycin: “less forgiving” than 5-FU; complications include hypotony that tends to persist; extends postoperative window
for cutting sutures; risk for bleb leak; cut sutures cautiously; to manage hypotony, consider aqueous suppressants,
trichloroacetic acid, diathermy, heat, and, sometimes, reoperation
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| Failing filtering blebs: study found mitomycin placed on top of conjunctiva improved success rate during needling
procedure in animal model; aqueous suppressants or prostaglandin analogues accelerate scarring in failing filtering bleb;
consider putting patient with failing bleb on glaucoma medication and monitor bleb; if it has some” height” and scleral
flap visible underneath, consider revitalizing filtering bleb with needling procedure; larger procedure required if bleb flattens;
study looked at transconjunctival mitomycin use during needling revisions of failing filtering blebs; at 2 yr, complete
success rate ≈50% (defined as reduction in IOP by at least 30%; no glaucoma medications onboard) and qualified
success rate ≈60% (defined as IOP reduction of at least 30%; ocular hypotensive medications allowed); complications included
hyphema, blebitis, iritis, and macular hypotony; study concluded bleb needling of failing filtering blebs safe alternative
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| Trabeculectomy postoperative care: inform patients before surgery about postoperative care; early activity restrictions
include avoiding exercise, vigorous activity, stooping, Valsalva maneuver, and constipation; evaluate patient’s use of
anticoagulants, aspirin, and pulmonary medications; routine postoperative medications include atropine, antibiotics, corticosteroids,
and antimetabolities; for aggressive early healing methods, consider laser suture lysis, releasable sutures, 5-FU
injections, massage; delay restarting medications (may cause additional scarring); if late filter failure occurs, consider needling,
bleb revision, or new trabeculectomy
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| Long-term care: avoid direct bleb trauma, chemical irritation, and infections; instruct patient to inform physician if calling
after hours about previous surgery for glaucoma; have patients carry antibiotic to reduce risk for endophthalmitis or
blebitis
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| Cataract surgery and glaucoma: preoperative assessment and informed consent critical; advise patients that recovery
may be limited based on optic nerve; if optic nerve damaged, patient’s vision will not improve, despite positive potential
acuity meter (PAM) test; minimize inflammation and bleeding during surgery; exfoliative glaucoma common in
persons of Scandinavian or Eastern European descent; viscoelastics helpful in controlling iris and anterior chamber while
doing phacoemulsification; to stretch pupil, use hooks (use caution when placing; if too anterior, can catch edge of pupil)
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| GLAUCOMA TUBE SHUNTS: PHYSIOLOGY AND CHANGING CLINICAL INDICATIONS—Alfred M. Solish,
MD, Associate Clinical Professor, Department of Ophthalmology, David Geffen School of Medicine at the University of
California, Los Angeles
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| Filtration surgery: methods of scar prevention may be chemical (corticosteroids and antimetabolities [eg, mitomycin,
5-FU]) or mechanical (implants)
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| Glaucoma drainage devices: implant terminology—shunt moves fluid from one place to another; in tube, fluid
moves through lumen; valve restricts flow of fluid to single direction; seton drains fluid through capillary action along
edge; current devices for glaucoma drainage not setons; where fluid goes—most common devices send fluid to subconjunctival
space and usually to peribulbar implant, so fluid absorbed into periorbital tissue; no current devices send fluid to
suprachoroidal space, despite potential
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| Features of tube implants: common features—placed onto sclera and into anterior chamber; need explant, because human
body reacts to foreign object by expelling or encapsulating it; successful tube implants form encapsulated bleb; complications
do not occur because bleb becomes encapsulated; mechanism of action—body considers plate as foreign body and
encapsulated by fibrous tissue permeable to fluid; IOP—relationship between size of capsule, permeability of capsule, and
vascular outflow resistance; plate surface area—IOP related to surface area of device, eg, Molteno 135 mm2 per plate,
Krupin 184 mm2 , Baerveldt 250 and 350 mm2 , Ahmed 184 mm2 per plate, ExPress <10 mm2 ; tube implant capsules—
consist of multiple layers of collagen bundles; vascular network covers collagen; fluid exits via passive diffusion into surrounding
tissues; Advanced Glaucoma Intervention Study (AGIS)—analysis suggests that patients with IOP >17 mm Hg experience
worsening of visual field defect scores after 5 yr; patients with IOP 14 to 17 mm Hg have worsening of visual field defect
scores (but less than in patients with IOP >17 mm Hg); patients with IOP <14 mm Hg did not experience change in visual field
defect scores; literature review looking at different drainage devices; graph showing range of IOP in different studies; all glaucoma
drainage devices associated with IOPs ranging from 14 to low 20s mm Hg; analysis looking at success defined as <21
mm Hg showed good success rates
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| Success of tube implants: advantages—provide guaranteed flow of aqueous to subconjunctival space and/or orbit if
capsule permeable to fluid; can use when eye inflamed; disadvantages—when successful, IOP higher than surgery without
implant; usually requires additional medication to maintain IOP; may erode over time; complications—possible damage to
other structures; corneal decompensation, transplant failure, cataract formation, and chronic fibrosis; early postoperative hypotony
(lasts longer with larger plate; occurs with valved and nonvalved implants); higher incidence of suprachoroidal hemorrhage;
eye motility problems, especially with large implants (fibrous capsule can involve muscle and lead to restriction);
other disadvantages—associated with relatively high IOP (15-22 mm Hg), depending on size of explant; relatively high
failure rate because of dense capsules (success rate ≈70%)
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| When to use tube implants: consider if glaucoma filtration surgery (eg, trabeculectomy) success unlikely because of
chronic inflammation (eg, neovascular or uveitic glaucoma, glaucoma following corneal transplant), multiple failed filtration
surgeries, and in trauma with disordered anterior segment; advanced optic nerve damage—tube implants not first
choice because of high IOP and high complication and failure rates; tube implants useful when antimetabolites fail, in patients
with advanced glaucoma, and patients with no advanced optic nerve damage
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| Drainage devices: Molteno tube—oldest device; Molteno first to recognize need for implant attached to tube; consists of silicone
tube connected to polymethylmethacrylate (PMMA) plate; options include single- and double-plate design; pediatric size
available, and pressure ridge designed to prevent hypotony; Baerveldt tube—design features include larger surface area than
Molteno tube; single-quadrant implantation (implanted under rectus muscles); made of silicone; options include 250 mm2 , 350
mm2 , and pars plana implant; Ahmed glaucoma valve—leaflet “valve” (technically flow restrictor); fluid comes in between 2
plates, pushing them open; plates close again in order to prevent backflow; effective in maintaining anterior chamber; rigid design
made of PMMA and flexible style made of silicone; options include 96 mm2 for pediatric use; clip allows pars plana use; Krupin
valve—single plate/quadrant; increased surface area by raised wall height of plate; made of silicone; ExPress implant—
transitions from anterior chamber to subconjunctival space; stainless steel device; plate not for fluid distribution, but to keep device
from migrating into anterior chamber; “fish hook” keeps device from migrating
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Educational Objectives
The goal of this activity is to provide the listener with a greater understanding of the current medical and surgical
management of glaucoma and glaucoma tube shunts. After hearing and assimilating this program, the clinician will
be better able to:
| Review current medical alternatives to surgery in patients with glaucoma.
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| Describe the challenges to medication compliance in patients with glaucoma.
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| Discuss the role of surgical intervention in glaucoma.
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| Identify the mechanism of action of most tube shunts.
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| Recognize the common features of most commercial tube shunt devices.
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Discussed on This Program
Bimatoprost [Lumigan]
Brimonidine tartrate [Alphagan, Alphagan P]
Brimonidine tartrate and timolol maleate [Combigan]
Dorzolamide HCl and timolol maleate [Cosopt]
Fluorouracil (5-fluorouracil, 5-FU) [Adrucil, Carac, Efudex, Fluoroplex]
Latanoprost [Xalatan]
Mitomycin (mitomycin-C; MTC) [Mutamycin]
Timolol maleate [Betimol, Blocadren, Istalol, Timoptic, Timoptic-XE]
Travoprost [Travatan]
Triamcinolone acetonide (several trade names)
Suggested Reading
Agrawal S et al: Risk of sudden visual loss following filtration surgery in end-stage glaucoma. Am J Ophthalmol.
142(1):199, 2006; Brusini P: Categorizing the stage of glaucoma from prediagnosis to end-stage disease. Am J Ophthalmol
. 141(6):1169, 2006; Carrillo MM et al: Effect of cataract extraction on the visual fields of patients with
glaucoma. Arch Ophthalmol. 123(7):929, 2005; Fontana H et al:Trabeculectomy with mitomycin C in
pseudophakic patients with open-angle glaucoma: outcomes and risk factors for failure. Am J Ophthalmol.
141(4):652, 2006; Gedde SJ et al: Tube Versus Trabeculectomy Study Group. The tube versus trabeculectomy
study: design and baseline characteristics of study patients. Am J Ophthalmol. 140(2):275, 2005; Harwerth RS et
al: Visual field defects and retinal ganglion cell losses in patients with glaucoma. Arch Ophthalmol. 124(6):853,
2006; Higginbotham EJ: The case against glaucoma drainage implant surgery in patients with a poor prognosis for
standard filtering procedure. Arch Ophthalmol. 122(1):105, 2004; Higginbotham EJ: How much influence do socioeconomic
factors have on glaucoma prevalence and therapeutic outcomes? Arch Ophthalmol. 124(8):1185, 2006;
Higginbotham EJ: Why did my surgery fail, doc? Arch Ophthalmol. 124(6):903, 2006; Kymes SM et al: Ocular
Hypertension Treatment Study Group (OHTS). Management of ocular hypertension: a cost-effectiveness approach
from the Ocular Hypertension Treatment Study.Am J Ophthalmol. 141(6):997, 2006; Parrish RK 2nd: The case for
glaucoma drainage implant surgery in patients with a poor prognosis for standard filtering procedure. Arch Ophthalmol
. 122(1):104, 2004; Rolim de Moura C et al: Experience with the baerveldt glaucoma implant in the management
of pediatric glaucoma. Am J Ophthalmol. 139(5):847, 2005; Sherwood MB et al:Twice-Daily 0.2%
Brimonidine-0.5% Timolol Fixed-Combination Therapy vs Monotherapy With Timolol or Brimonidine in Patients
With Glaucoma or Ocular Hypertension: A 12-Month Randomized Trial. Spratt A et al: What's in a name? New
glaucoma drugs. Lancet. 368(9538):826, 2006; Arch Ophthalmol. 124(9):1230, 2006; Uva MG et al:The effect of
timolol-dorzolamide and timolol-pilocarpine combinations on ocular blood flow in patients with glaucoma. Am J
Ophthalmol. 141(6):1158, 2006; Wamsley S et al: Results of the use of the Ex-PRESS miniature glaucoma implant
in technically challenging, advanced glaucoma cases: a clinical pilot study. Am J Ophthalmol. 138(6):1049, 2004.
Faculty Disclosure
In adherence to ACCME guidelines, the Audio-Digest Foundation requests all lecturers to disclose any significant financial
relationship with the manufacturer or provider of any commercial product or service discussed. The following
has been disclosed: Dr. Iwach is on the Speakers’ Bureau for Alcon, Allergan, Merck, Pfizer, Zeiss, Lumenis, and
ISTA Pharmaceuticals. In addition, he is a consultant for iScience Surgical Corporation and Zeiss.
Drs. Iwach and Solish were recorded July 29, 2006, in San Diego, CA, at the 26th Annual Current Concepts in Ophthalmology
, sponsored by the San Diego Eye Bank. The Audio-Digest Foundation thanks the speakers and the sponsor
for their cooperation in the production of this program.
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