GLAUCOMA PEARLS
| WHAT’S NEW IN THE MANAGEMENT OF NEOVASCULAR GLAUCOMA (NVG)—Scott D. Smith, MD, MPH,
Assistant Professor of Ophthalmology, Glaucoma Department, The Cleveland Clinic Foundation, Cole Eye Institute, Cleveland,
OH
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| Role of elevated intraocular pressure (IOP): due to fibrovascular proliferation of tissue that obstructs trabecular
meshwork; eventually leads to peripheral anterior synechiae and outflow obstruction of aqueous; fibrovascular proliferation
occurs in response to stimulus (retinal ischemia in NVG); inflammation can also induce neovascular response; ischemia
triggers release of growth factors (vascular endothelial growth factor [VEGF] believed primary mediator); VEGF
levels increased in aqueous of patients with neovascularization of iris (NVI); conditions that result in release of VEGF
and/or other angiogenic growth factors include diabetic retinopathy, central retinal vein occlusion (CRVO), other retinovascular
diseases, ocular ischemia, and uveitis; development of glaucoma—occurs when neovascular process involves
angle; in early stage, no development of anterior synechiae, but IOP elevated; if process allowed to continue, complete
and permanent synechial angle closure eventually develops; if treatment initiated before synechiae formed, IOP may normalize
without surgery; once angle closed, surgical intervention necessary to control IOP; attempt to determine cause of
elevated IOP at initial presentation; in absence of obvious cause, consider ocular ischemia due to carotid stenosis
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| Treatment: elimination of stimulus for neovascularization (by treating underlying ocular or systemic disease) critical; reduction
of IOP important
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| Retinal ablation: most important element in salvaging eye; unable to perform panretinal photocoagulation (PRP) if IOP
elevated and cornea cloudy or edematous; occasionally, peripheral retinal cryotherapy necessary to ablate retina
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| VEGF inhibitors: bevacizumab (Avastin) shown to reduce NVI through inhibition of VEGF; not approved for use in
ocular disease; ranibizumab (Lucentis) only approved VEGF inhibitor for treatment of neovascular macular degeneration;
bevacizumab (intravitreal or intracameral) leads to rapid regression of neovascularization of iris; response seen in 1
to 2 days; useful for short-term control; not substitute for retinal ablation for long-term elimination of VEGF production;
adjunct (rather than alternative) to therapies to control NVI
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| Control of IOP: suppression of aqueous mainstay of medical treatment for neovascular glaucoma; achieved via β-blockers,
α2 -agonists, and topical carbonic anhydrase inhibitors (CAIs); if IOP extremely elevated, all 3 agents started; if not
possible, oral CAIs used; steroids and cycloplegia used to control inflammation; from outset, prepare patient psychologically
for surgery; avoid use of glaucoma medications that increase inflammation (eg, miotics, prostaglandins)
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| Surgery: determinants—degree of IOP elevation; status of optic nerve; severity of inflammation; presence of active NVI;
whether temporizing measures maintain IOP at nonurgent level while awaiting response; if surgery necessary, and eye
acutely inflamed with active NVI, prepare for complications (eg, hyphema, choroidal effusion); choosing appropriate
procedure—if, eg, active NVI and inflammation present at time of surgery, high risk for failure with trabeculectomy and
mitomycin C (MMC; glaucoma implant speaker’s first choice); also consider previous conjunctival surgery; potential
pitfalls—rapid decompression; bleeding from iridectomy (minimized by keeping iridectomy small and preliminary cauterizing
of surface of iris)
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| Prevention: vigilantly monitor for NVI in patients with proliferative diabetic retinopathy (PDR) and for several months
after CRVO; serial gonioscopy important in avoiding problems
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| PEARLS IN THE MANAGEMENT OF UVEITIC GLAUCOMA —Dr. Smith
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| Inflammatory or uveitic glaucoma: common; inflammation can cause significant changes in aqueous dynamics that
influence IOP; low IOP often seen in eyes with acute anterior segment inflammation, due to reduced aqueous production
and/or increased uveoscleral outflow; inflammatory process, or its treatment, leads to transient or permanent changes in
trabecular function that may cause rise in IOP and lead to secondary glaucoma; studies show rate of glaucoma 12% in
acute iridocyclitis (27% in chronic)
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| Mechanism of IOP elevation: secondary open-angle glaucoma—may develop if inflammatory debris accumulates in
trabecular meshwork, or in presence of trabeculitis or steroid response (from treatment of uveitis); secondary angle-closure
glaucoma—may develop if synechial angle closure occurs or if posterior synechiae lead to secluded pupil and iris
bombé; slit lamp examination—critical in determining mechanism of IOP elevation (and in selecting appropriate therapy);
subtleties of examination important; look for pattern of ocular injection, presence of keratic precipitates, degree of
cell and flare, depth of anterior chamber, presence of posterior synechiae, and configuration of iris, with careful inspection
for NVI, and scrutiny of angle by gonioscopy
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| Diagnosis: once etiology of IOP elevation determined, important to determine chronicity; amount of damage to optic
nerve (if any) gives indication of how well eye tolerates current level of IOP and urgency of IOP reduction; determine
whether associated posterior segment pathology present; often difficult to determine whether IOP elevation due to steroid
response or to inflammation; steroid response uncommon if patient on steroids <2 wk; if no inflammation present, trial of
decreasing steroids possibly helpful; in patients with chronic iridocyclitis, refer patient to uveitis specialist and rheumatologist
to consider use of steroid-sparing immunosuppressive therapy
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| Medical management: drugs that suppress aqueous production—topical medications, if possible; in acute IOP elevation,
acetazolamide (eg, Diamox) or other oral CAIs; cycloplegia important to prevent progressive formation of posterior
synechiae and avoid associated complications; avoid medications that increase inflammation (eg, prostaglandins)
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| Laser therapy: when iris bombé present, laser iridotomy effective in restoring normal iris contour and opening angle, if
permanent synechiae not yet formed; higher rate of reocclusion than routine iridotomy for primary angle closure, and in
some cases, surgical iridectomy necessary; laser trabeculoplasty not advisable for secondary open-angle glaucoma due to
uveitis
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| Surgical therapy: in patient with acute inflammation, trabeculectomy not likely to succeed, and primary glaucoma implant
better choice; whatever surgical procedure, reduce inflammation as much as possible to avoid inflammatory complications;
avoid combined cataract surgery when active inflammation present (increases risk for failure of glaucoma
surgery and for inflammatory complications); if trabeculectomy necessary, antifibrotic agents (eg, 5-fluorouracil [5-FU],
MMC) mandatory for reasonable chance for success with uveitic glaucoma; success rates 50% to 80%; trabeculectomy
with MMC—effective in short- to medium-term in controlling IOP in patients with uveitic glaucoma; dose of MMC adjusted
according to degree of inflammation; close follow-up necessary to ensure postoperative inflammatory response adequately
controlled; aggressive use of topical and oral steroids; supplemental 5-FU injections given if bleb more injected
than desired during postoperative period; timely use of laser suture lysis important for maintaining flow through trabeculectomy;
glaucoma drainage devices—prepare for postoperative complications; use caution in positioning of tube (especially
in patients with chronic anterior uveitis), to avoid irritating iris and potentially increasing inflammation; although
intravitreal triamcinolone used in patients with uveitis to treat macular edema, not advisable in patient with filtering bleb
(increased risk for endophthalmitis); point—choice of surgery dictated by individual case
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| CYCLOPHOTOCOAGULATION —Dr. Smith
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| Cyclodestruction: used for decades to reduce rate of aqueous production and thereby reduce IOP; because of postoperative
complications (eg, pain and inflammation, decompensation of cornea, hypotony), other alternatives sought
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| Laser cyclophotocoagulation: supplanted cyclocryotherapy; initially described using continuous-wave yttrium aluminum
garnet (YAG) laser; subsequently, diode laser version of transscleral cyclophotocoagulation; longer wavelength
in YAG or diode laser allows scleral penetration and absorption of laser energy by ciliary body (instead of sclera); continuous-wave
YAG laser has longer wavelength than diode laser, resulting in better scleral penetration and less absorption
of energy in more superficial tissues; diode laser has special probe designed to enhance alignment of beam in location relative
to limbus and direction of beam path to be absorbed by ciliary body; applied ≈1.5 mm posterior to limbus, and several
applications placed circumferentially around limbus; uses long pulse duration, while diode laser uses 2-sec pulse
duration; painful (requires retrobulbar or peribulbar anesthesia or general anesthesia); delivers 3 to 5 joules/pulse; during
initial treatment, one quadrant generally left untreated, to avoid overtreatment or excessive pressure reduction and hypotony;
results similar, regardless of particular instrument used; anecdotal reports of more inflammation when noncontact
YAG transscleral cyclophotocoagulation used; treatment success rate (pressure of 3-25 mm Hg) at 10 mo, 60%; complications
less severe and less common than with cyclocryotherapy, but potential for significant complications such as inflammation
(eg, iridocyclitis) as pressure spikes, or development of cystoid macular edema; patients should expect
multiple treatment sessions; in 10-yr follow-up, rate of hypotony with YAG cyclophotocoagulation ≈5%, with 50% of
patients requiring second intervention, and loss of light perception in almost 10% of patients; perforation of sclera at site
of laser application rare complication (more likely if debris accumulates on tip of instrument)
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| Endoscopic cyclophotocoagulation (ECP): alternative to trans-scleral cyclophotocoagulation; performed during
vitreoretinal surgery or using endoscopic laser; advantage of direct visualization and treatment of ciliary body; less risk
for corneal graft failure in patients who had penetrating keratoplasty (less inflammation after surgery); reports of successful
treatment after failed transscleral cyclophotocoagulation; device expensive; unless patient aphakic or pseudophakic,
significant risk for cataract; intraocular surgical procedure; patient selection important; speaker prefers patients with limited
visual potential or those in whom alternative procedures failed; treatment irreversible
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| MANAGEMENT OF GLAUCOMA IN THE CATARACT PATIENT —Michael C. Stiles, MD, Director of Glaucoma Services,
Department of Ophthalmology, University of Kansas, and Stiles Eyecare Excellence and Glaucoma Institute, Kansas
City, KS
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| Small-incision clear cornea cataract surgery: biggest advance in glaucoma care; spares conjunctiva and superior
limbus in patients with glaucoma; less inflammation and bleeding; easier to avoid preexisting filtration bleb and tube and
to control astigmatism and improve postoperative outcome
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| Cataract surgery alone: “glaucoma cocktail” (includes intraoperative carbachol [eg, Miostat]) used to prevent IOP
spike; concentration of carbachol reduced by 50% to avoid severe postoperative headaches (also induces nausea in more
frail patients); combination of pre- and postoperative α-agonist and nonselective β-blockers and postoperative acetazolamide
helps reduce incidence of postoperative IOP spikes; avoid prostaglandins for first month postoperatively (substitute
with aqueous suppressants); watch for steroid responders; if possible, avoid filtration surgery for first 6 mo after cataract
surgery; mean IOP reduction 1 to 2 yr postoperatively in open-angle glaucoma, 2 to 4 mm Hg (more dramatic reduction
in angle-closure glaucoma); indicated in patients well controlled on one medication (possibly 2), with minimal visual
field loss; better than glaucoma surgery for controlling IOP in angle-closure glaucoma (in patients with high IOP and cataracts);
lens causative factor; rationale for lens extraction—sparing of conjunctiva for future filtration surgery; greater
and more sustained IOP drop; deepens peripheral angle; IOP reduction with phacoemulsification indirectly proportional
to anterior chamber depth; phacoemulsification with goniolynechialysis and ECP preferred for patients with more advanced
chronic angle-closure glaucoma; filtration surgery helpful, particularly in patients with uncontrolled glaucoma
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| 2-stage approach: traditionally recommended for patients with uncontrolled glaucoma, preoperatively high IOP, and
coexisting cataract, due to concerns about increased intraoperative choroidal hemorrhage; assumption that lower IOP
achieved (short- and long-term) with trabeculectomy alone than with combined procedure; support for combined
approach—large retrospective study at Cleveland Clinic found no serious complications in patients with preexisting elevated
IOP; in staged approach, trabeculectomy alone results in lower IOP initially, but requires 6-mo wait before cataract
surgery; therefore, subsequent failure in significant portion of patients, particularly those with preexisting IOP >10 mm
Hg or when procedures not separated by ≥6 mo; no randomized controlled trials comparing combined surgery to staged
approach; 2 case-matched series found no difference in IOP reduction; considerations—visual significance of cataract;
study found that in patients with other factors (eg, high preoperative IOP, diagnosis other than open-angle glaucoma, previous
surgery for any other reason), combined approach did not result in prolonged IOP reduction and avoidance of future
glaucoma surgery; combined surgery decreasing in popularity and typically reserved for eyes with more significant
visual field loss; most patients do well, and fewer postoperative visits required, with phacoemulsification alone; untouched
conjunctiva available for subsequent filtration surgery, if necessary
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| Alternatives to combined surgery: phacoemulsification with ECP—ablates 270° of ciliary body through one incision,
once implant in place; concern with cystoid macular edema (CME), prolonged cyclitis, and hypotony; avoids necrosis
that can occur with traditional cyclodestructive procedures performed from external approach; in 5-yr study by Berke
and colleagues, pre- and postoperative IOP and medications at 3 yr fairly flat (no significant difference) with phacoemulsification
alone; with phacoemulsification with ECP, drop in IOP seen, but not statistically significant; statistically significant
drop (from 1.5 to 0.7) in number of postoperative medications; no difference in incidence of vision-threatening
complications; advantages—no trabeculectomy-related complications (no bleb); less involved postoperative care;
disadvantages—IOP lowering less reliable; low IOP less likely; more inflammation initially (easily controlled with aggressive
use of postoperative steroids); indications—patients with relatively well controlled or marginally controlled glaucoma on multiple
medications; visual field loss fairly negligible or not advanced; poor transportation for postoperative visits; avoid in—
those at risk for CME; inflammatory glaucoma; pseudoexfoliation glaucoma
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Suggested Reading
Azuara-Blanco A: Iridociliary apposition in plateau iris syndrome persists after cataract extraction. Am J Ophthalmol
136:395; author reply 395, 2003; Carrillo MM et al: Effect of cataract extraction on the visual fields of patients with
glaucoma. Arch Ophthalmol 123:929, 2005; Chung AN et al: Surgical outcomes of combined phacoemulsification and
glaucoma drainage implant surgery for Asian patients with refractory glaucoma with cataract. Am J Ophthalmol 137:294,
2004; Distelhorst JS et al: Open-angle glaucoma. Am Fam Physician 67:1937, 2003; Francis BA et al: Selective laser
trabeculoplasty as a replacement for medical therapy in open-angle glaucoma. Am J Ophthalmol 140:524, 2005; Gujral
S et al: Outcomes of small-incision cataract surgery in eyes with preexisting Ahmed Glaucoma Valves. Am J Ophthalmol
140:911, 2005; Iliev ME et al: Intravitreal bevacizumab (Avastin) in the treatment of neovascular glaucoma. Am J Ophthalmol
142:1054, 2006; Jamil AL et al: Glaucoma tube or trabeculectomy? That is the question. Am J Ophthalmol
143:141, 2007; Liu CJ et al: Factors predicting intraocular pressure control after phacoemulsification in angle-closure
glaucoma. Arch Ophthalmol 124:1390, 2006; Musch DC et al: Cataract extraction in the collaborative initial glaucoma
treatment study: incidence, risk factors, and the effect of cataract progression and extraction on clinical and quality-of-life
outcomes. Arch Ophthalmol 124:1694, 2006; Park UC et al: Phacotrabeculectomy with mitomycin C in patients with
uveitis. Am J Ophthalmol 142:1005, 2006; Rosenfeld PJ: Intravitreal avastin: the low cost alternative to lucentis? Am J
Ophthalmol 142:141, 2006; Satav SS et al: Preventing steroid-induced glaucoma. Arch Ophthalmol 123:1018; author reply
1018, 2005; Schlötzer-Schrehardt U et al: Ocular and systemic pseudoexfoliation syndrome. Am J Ophthalmol
141:921, 2006; Weinreb RN et al: Risk assessment in the management of patients with ocular hypertension. Am J Ophthalmol
138:458, 2004.
Educational Objectives
| The goal of this program is to improve the management of glaucoma. After hearing and assimilating this
program, the clinician will be better able to:
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 | 1. Describe the mechanism of increased intraocular pressure in glaucoma.
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| 2. Determine when surgery is appropriate for treatment of neovascular glaucoma.
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| 3. Choose the appropriate surgical option for treatment of uveitic glaucoma.
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| 4. Explain the surgical options for cataracts in glaucomatous eyes.
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| 5. Discuss the advantages and disadvantages of the combined surgery alternatives for cataracts in glaucomatous
eyes.
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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 faculty and planning committee reported nothing to disclose.
Acknowledgements
Dr. Smith was recorded at Glaucoma Management in 2008: Pearls and Pitfalls, held January 12, 2008, in Cleveland, OH, and
sponsored by the Cole Eye Institute of the Cleveland Clinic Foundation. Dr. Stiles was recorded at the Annual Clinical Conference
, held January 11-12, 2008, in Overland Park, KS, and sponsored by the Kansas City Society of Ophthalmology and
Otolaryngology. The Audio-Digest Foundation thanks the speakers and the sponsors for their cooperation in the production
of this program.
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