GLAUCOMA TOPICS
| EFFECTIVENESS OF ALTERNATIVE MEDICATIONS FOR GLAUCOMA —John Hetherington Jr, MD, Clinical Professor of Ophthalmology, University of California, San Francisco, School of Medicine |
| Definition: use of nonstandard, unconventional therapy; includes vitamins, herbs, acupuncture, meditation, and even holy water; use has increased 10% to 15% within past 10 yr; in United States, highest use in women, whites, and well-educated individuals; 72 million Americans spend an estimated $27 billion on alternative medications each year, including 50% of people with glaucoma; in China, 70% to 80% of patients use alternative therapies |
| Vitamins: vitamin A—antioxidant; studies show no effect on intraocular pressure (IOP) or visual field; vitamin B1 (thiamine)—no effect on IOP or visual field; low levels associated with alcoholism; vitamin B12 —shown to improve visual field in one study (but study criticized as inadequate and poorly controlled); vitamin C—high levels of ascorbic acid concentrate in anterior chamber; massive doses reduce IOP but also cause diarrhea and dehydration, making such doses inadvisable for this purpose; topical application produces only minor decrease in IOP (not worthwhile); free radicals may mediate death of retinal ganglion cells; vitamin C may protect trabecular meshwork and alter outflow (studies under way); vitamin E—another antioxidant; does not change IOP; one uncontrolled study reported vague “expansion of visual field”; inhibits cell proliferation; sometimes used to reduce scar formation in patients undergoing filtering surgery |
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Nurse and Health Profession Study: lengthy follow-up of 474 patients with chronic open-angle glaucoma (OAG); examined effects of antioxidant supplementation in patients with field defects and vision loss; authors concluded vitamins had no proven value in treating glaucoma |
| Marijuana: contains 400 chemicals; cannabinoids of most interest, but so far no effect on glaucoma seen with moderately long-term follow-up, despite 25% decrease in IOP; effect short-lived, so must be taken many times daily; side effects — loss of concentration and coordination; emphysema; lung cancer; topical application ineffective; certain derivatives show promise, including dexanabinol (HU2; animal studies suggest neuroprotective as well as IOP-lowering effect); WIN-55 (binds CB1 and CB2 receptors in ciliary body and trabecular meshwork; in animal studies, reduces IOP by 2-4 mm Hg) |
| Ginkgo biloba: antioxidant; produces modest improvement in cognitive ability; in poorly controlled study, seemed to improve visual field in some patients with chronic OAG; increases ocular blood flow; may have neuroprotective effect |
| Bilberry: Vaccinium Myrtillus; no evidence that it promotes optic nerve health |
| Water: in Collaborative Glaucoma Study, IOP increased after patients drank 1 L water |
| Alcohol: 30 to 60 min after ingesting 4 oz 40% alcohol, IOP 13 to 19 mm Hg; regardless of baseline pressure; effect short-lived, but might be good emergency remedy if medicolegal questions can be resolved |
| Meditation: over long term, produces insignificant reduction in IOP |
| Acupuncture: not associated with any change in IOP; only one report of minor change in visual field |
| Exercise: “the best deal going”; after brief rise, IOP falls by 14% within 1 hr; over time, moderate exercise associated with reduction in IOP lasting several months |
| Lutein: in recent analysis at National Institutes of Health, one commercial preparation contained <0.02 mg lutein (according to label, 20 mg/capsule); lutein might have been oxidized |
| Conclusions: patients may not be getting what they think they are getting; side effects possible; pharmaceutical companies reluctant to conduct more research (not required by Food and Drug Administration) |
| LASER AND SURGICAL THERAPY: WHAT’S NEW ?—Peter A. Netland, MD, PhD, Siegal Professor of Ophthalmology, Hamilton Eye Institute, University of Tennessee Health Science Center, Memphis |
| Peripheral iridotomy: most commonly performed procedure for angle-closure glaucoma in United States |
| Laser trabeculoplasty: most common procedure for treating OAG; number peaked in 1992, then started falling due to reduced reimbursement, introduction of new medications, and changes in health care delivery; recent resurgence in interest, and concomitant increase in number of procedures, due partly to use of prostaglandins and partly to use of selective laser trabeculoplasty (SLT) |
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Procedure: requires use of Q-switched, frequency-doubled yttrium aluminum garnet (YAG) laser; pulse rate 3 nanoseconds; delivers 0.4 to 1.0 mJ; typical treatment 25 laser spots on 90° of trabecular meshwork, or 50 laser spots on 180° of trabecular meshwork; key is selective treatment of pigmented cells in trabecular meshwork; associated with fewer structural changes than argon laser trabeculoplasty (ALT); efficacy identical to that of laser trabeculoplasty (LTP) for initial treatment and first retreatment of glaucoma; for most patients, complications similar to those of LTP; repeatability theoretically possible, but not confirmed; procedure expensive (special machine required), but many clinicians now substituting SLT for ALT |
| Surgery: modified trabeculectomy still gold standard; safety and efficacy improved by 2 adjunctive techniques (use of mitomycin C or 5-fluorouracil, and laser suture lysis or releasable sutures); however, results still less predictable and less immediately gratifying than cataract surgery |
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Ex-PRESS: miniature glaucoma implant under scleral flap; 50-µm or 200-µm opening on internal diameter; placed under scleral flap in technique identical to trabeculectomy; device tip goes into anterior chamber to permit aqueous drainage through device, under scleral flap, and through conjunctiva to form bleb; technique associated with reduced tissue trauma and inflammation (no peripheral iridectomy; less tissue dissection required due to omission of sclerostomy); results more predictable, with fewer complications than standard trabeculectomy; disadvantages—cost; issues of implant biocompatibility; in first 100 eyes treated with this procedure, compared to standard trabeculectomy, implant associated with slightly less postoperative hypotony; long-term success rates for IOP nearly identical, with less inflammation; result—more predictable procedure; all other steps identical to those involved in trabeculectomy, including use of mitomycin C and suture lysis |
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Nonpenetrating glaucoma surgery: deep sclerectomy with or without collagen implant, and viscocanalostomy—advantages include little to no bleb formation and no peripheral iridectomy; initially described 30 yr ago, but interest now rekindling, due to recent studies showing fewer complications (after learning curve), compared to trabeculectomy; however, IOP levels achieved with nonpenetrating surgery slightly higher than those associated with trabeculectomy; nonpenetrating procedures also more difficult technically; niche not yet found |
| New procedures: cyclophotocoagulation (CYC) performed endoscopically; goniocurettage; transciliary filtration; excimer laser trabeculostomy; Trabectome (NeoMedix, Inc); iTrack Microcatheter (iScience Interventional); EyePass Glaucoma Implant (GMP Vision Solutions); SOLX Gold Shunt (OccuLogix, Inc); iStent (Glaukos Corp); MiDi Shunt (InnFocus, Inc); pneumatic trabeculoplasty; companies hope procedures will replace medical therapy as well as trabeculectomy; in various stages of development and evaluation (none yet ready for market) |
| Secondary surgical procedures: drainage implants (useful in refractory glaucoma); CYC; some procedures under development for primary use; speaker prefers drainage implants whenever possible; choice between open- tube implants and flow-resistive valves; decision depends on surgeon’s preference and experience; speaker prefers Ahmed Glaucoma Valve (New World Medical, Inc) due to low rate of early postoperative hypotony and associated complications |
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Anti-fibrosis drugs: prospective randomized clinical trial conducted by speaker and colleagues showed little to no effect on success or mean IOP after placement of drainage implant |
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Implant plate size: double plate associated with lower mean IOP and greater reduction in need for medications than single plate; however, increasing plate size does not improve results |
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Implant materials: in Ahmed Glaucoma Valve, silicone associated with slightly higher success rate than polypropylene |
| ENDOSCOPIC CYCLOPHOTOCOAGULATION —Brian A. Francis, MD, Associate Professor of Ophthalmology, Doheny Eye Institute, The Keck School of Medicine of the University of Southern California, Los Angeles |
| Background: cyclodestructive procedures lower IOP by lowering production of aqueous; modes include transscleral (contact and noncontact using YAG and semiconductor diode lasers), transvitreal (performed during intravitreal surgery), or endoscopic cyclophotocoagulation (ECP) using diode laser |
| Equipment: 19.5-gauge probe; consists of fiberoptic light source, endoscopic camera, aiming beam, and treatment laser; attached to console with foot pedal, which is attached to monitor |
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ECP vs YAG: normal ciliary process consists of stroma, blood vessels, and pigmented and nonpigmented ciliary epithelium; unlike photocoagulation with YAG laser, ECP leaves stroma and vessels intact, and preserves architecture of ciliary process |
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Phaco-ECP vs phacoemulsification alone: unpublished study by Burke and colleagues; mean follow-up 3 yr; reduction in IOP greater with phaco-ECP than with phacoemulsification alone; medications also reduced accordingly; IOP reductions with phacoemulsification alone sustained ≤1 yr (final IOP higher than baseline); considerable savings in medication costs associated with ECP |
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ECP vs Ahmed Glaucoma Valve: alternating allocation design; 68 patients with uncontrolled IOP; similarly effective for lowering IOP and reducing need for medications |
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ECP vs trabeculectomy: randomized prospective trial of 58 patients with IOP >30 mm Hg or progressive cupping or visual field loss; IOP decreased by 8.5 mm Hg in both groups (≈30% reduction); need for medication lower among patients undergoing trabeculectomy, but overall success and failure rates similar in both groups |
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ECP for refractory glaucoma: retrospective case series of 68 patients for whom medical therapy and various surgical treatments failed; ECP reduced average IOP by 34%; effect persisted ≥1 yr; overall success rate at 1 yr, 94%, and at 2 yr, 82%; concomitant reduction in medications; complications included fibrin formation, hyphema, cystoid macular edema, and choroidal effusion (rare) |
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ECP for patients who failed tube-shunt surgery: study conducted by speaker and colleagues; on average, IOP reduced from beginning measure of 24 mm Hg to 16 mm Hg at 1 yr (overall average reduction 7.5 mm Hg from baseline [30% reduction]); medications per patient reduced from preoperative average of 3.2 medications to 1.5 medications at 1 yr; overall success rate ≈85%; conclusion—good intermediate-term success in this subset of patients; procedure highly versatile (effective in wide variety of patients); overall, greater reductions in postsurgical hypotony, pain, and inflammation than with transscleral CYC; also less risky than trabeculectomy or tube shunts; useful for those who are poor candidates for (or have already failed) filtering surgery, and for those who have sustained ocular burns |
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Risks: cataract formation; cystoid macular edema; pressure spikes; inflammation; possible iris or lens trauma; failure usually due to undertreatment (treatment should cover as close to 360° as possible) |
| GLAUCOMA: WHEN TO REFER —Robert J. Noecker, MD, Vice Chair of Ophthalmology, Director of Glaucoma Service, and Associate Professor of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA |
| Disease-specific: more aggressive the case, greater the need for referral; eg, neovascular or uveitic glaucoma, steroid response, pediatric glaucoma |
| Practice-specific: depends on local availability of specialists; availability of imaging devices, pachymeters, and other types of devices can vary from practice to practice (may “tip the balance” for or against referral); presence of adequate resources and support staff also factor; handicap access is consideration |
| Practitioner-specific: little experience, especially with difficult cases; relationship (“dialogue”) with patient (or lack thereof) possible reason to refer; other considerations include inability to move forward with treatment algorithm without more specialized care |
| Patient-specific: desire for second opinion; concern over medicolegal consequences; failure of initial intervention; rapid progression of disease |
| Environment-specific: availability of resources and expert help (mostly consideration in rural areas); community standard of care (local presence of specialists and tertiary care centers vs mostly primary care providers); medicolegal issues (clustering of lawsuits in particular areas); local demographics (may be unrealistic to ask patient on low or fixed income to drive long distances and take time from work to see specialist) |
| Indications for referral: practitioner doubts about diagnosis and/or treatment; patient doubts about prognosis or adequacy of treatment; clinician’s reluctance or inability to treat more aggressively (eg, treating with medication vs incisional surgery) |
Suggested Reading
Al-Aswad LA et al: Clinical experience with the double-plate Ahmed glaucoma valve. Am J Ophthalmol 141:390, 2006; Bloom PA, Dharmaraj S: Endoscopic and transscleral cyclophotocoagulation. Br J Ophthalmol 90:666, 2006; Damji KF et al: Selective laser trabeculoplasty verus argon laser trabeculoplasty: results from a 1-year randomised clinical trial. Br J Ophthalmol 90:1490, 2006; Gunasekera V et al: Systematic internet-based review of complementary and alternative medicine for glaucoma. Ophthalmology Sept 25, 2007 [Epub ahead of print]; Holz HA, Lim MC: Glaucoma lasers: a review of the newer techniques. Curr Opin Ophthalmol 16:89, 2005; Jones LD et al: General practitioner with special interest improves the efficiency of glaucoma referrals. Eye 20:942, 2005; Lin SC et al: Vascular effects on ciliary tissue from endoscopic versus trans-scleral cyclophotocoagulation. Br J Ophthalmol 90:496, 2006; Maris PJ Jr et al: Comparison of trabeculectomy with Ex-PRESS miniature glaucoma device implanted under scleral flap. J Glaucoma 16:14, 2007; McIlraith I et al: Selective laser trabeculoplasty as initial and adjunctive treatment for open-angle glaucoma. J Glaucoma 15:124, 2006; Papadaki TG et al: Long-term results of Ahmed glaucoma valve implantation for uveitic glaucoma. Am J Ophthalmol 144:62, 2007; Ritch R: Complementary therapy for the treatment of glaucoma: a perspective. Ophthalmol Clin North Am 18:597, 2007; Song J et al: High failure rate associated with 180 degrees selective laser trabeculoplasty. J Glaucoma 14:400, 2005; Werner M et al: Selective laser trabeculoplasty in phakic and pseudophakic eyes. Ophthalmic Surg Lasers Imaging 38:182, 2007.
Educational Objectives
| The goal of this program is improve management of glaucoma. After hearing and assimilating this program, the clinician will be better able to: |
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1. Name the single best form of alternative treatment for glaucoma. |
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2. Explain why laser trabeculoplasty is enjoying a resurgence in popularity after several years of decline. |
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3. Describe the adjunctive techniques that have helped make modified trabeculectomy the gold standard for glaucoma surgery. |
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4. Compare the clinical results achieved with endoscopic cyclophotocoagulation to results achieved with therapies such as phacoemulsification and trabeculectomy. |
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5. Determine circumstances in which referral to a glaucoma specialist might be appropriate. |
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. Netland has received research funding from Alcon, Allergan, and Merck; Dr. Noecker has received research funding from Allergan, Zeiss, and Lumenis, is a consultant for Allergan, and is on the Speakers’ Bureaus of Allergan, Alcon, Lumenis, and Endo-Optics.
Acknowledgements
Dr. Hetherington spoke at Glaucoma Update 2007, held February 10, 2007, in San Francisco, CA, and sponsored by the Glaucoma Research and Education Group; Dr. Netland was recorded at What’s New in Anterior Segment Disorders, held October 21, 2006, in Cambridge, MA, and sponsored by the Massachusetts Eye and Ear Research and Surgery Institute; Dr. Francis appeared at the 2007 Ophthalmology Symposium, held June 2, 2007, in Anaheim, CA, and sponsored by Kaiser Permanente; and Dr. Noecker was recorded at the 29th Annual Midwest Glaucoma Symposium, held September 15-16, 2006, in Pittsburgh, PA, and sponsored by the University of Pittsburgh Medical Center. The Audio-Digest Foundation thanks the speakers and the sponsors for their cooperation in the production of this program.
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