GLAUCOMA PEARLS
| CRACKING THE DRAINAGE DEVICE CODE —Paul A. Sidoti, MD, Associate Professor of Ophthalmology, New York
Medical College, Valhalla, New York; Director, Comprehensive Eye Service, New York Eye and Ear Infirmary, New York
City
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| Classic indications for tube implants: eyes at high risk for failure of trabeculectomy with antifibrosis therapy; trabeculectomy
technically difficult to perform due to, eg, advanced scarring; situations where antifibrosis therapy contraindicated; patients
with poor hygiene or poor follow-up; previous failure of trabeculectomy with mitomycin-C; standard
trabeculectomy unlikely to work with—neovascular glaucomas; multiple previous or concurrent surgical procedures;
congenital or developmental glaucomas; penetrating keratoplasty; ocular trauma
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| Reasons for increased use of aqueous shunts: demonstrated efficacy (>30-yr experience); acceptable long- and short-
term complication profiles; increased familiarity of surgeons with devices; indications—previous cataract surgery or
failed trabeculectomy; primary surgery in standard open- and closed-angle glaucomas
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| Advantages over trabeculectomy: aqueous shunt less prone to failure due to subconjunctival and episcleral scarring; better
if concomitant or subsequent intraocular surgery anticipated; lower maintenance (less follow-up); reduces or eliminates
long- and short-term complications of trabeculectomy (bleb leaks; bleb-related infections)
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| Disadvantages compared to trabeculectomy: motility dysfunction—incidence 5% to 10%; difficult to correct surgically;
corneal endothelial damage—no good data looking at endothelial cell counts after tube implantation; probably
no significant effect over time with proper tube positioning; historically, eyes treated with tube implants more damaged
than eyes receiving trabeculectomy (may be higher incidence of corneal failure, but many patients had low endothelial
cell counts before procedure)
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| How to achieve low intraocular pressure (IOP)
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 | Device-related variables: large-surface-area devices associated with lower postoperative IOP and need for fewer postoperative
medications; however, follow-up comparison of Baerveldt devices suggests that difference not borne out over
longer follow-up; in general, larger-surface-area device gives more surface area for drainage and outflow and lower
long-term IOP
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| Scleral explant factors: material—studies by Ayala suggest that silicone may be associated with less inflammation than
polypropylene; positioning—posterior placement of explant 10 to 12 mm behind limbus on temporal side of eye important;
limited data; anteriorly positioned plates uncomfortable and cosmetically objectionable (in many cases, result
in worse IOP control)
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| Aggressive anti-inflammatory treatment: frequent topical corticosteroid use (8 times/day); in some patients, topical nonsteroidal
anti-inflammatory agent (NSAID); if compliance questionable, consider posterior sub-Tenon’s or intravitreal triamcinolone
(Kenalog) to reduce inflammatory stimulus to fibrosis
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| Antifibrosis therapy: aqueous shunts work by passive filtration; amount of fluid filtered depends on surface area thickness
and permeability of capsule; limited studies looking at effect of antifibrotic agents (eg, mitomycin-C) and formation of
bleb capsule; higher incidence of early postoperative complications, wound complications, and choroidal effusions using
mitomycin-C; feedback model of fibrosis (Wilcox)—increased surface tension on blood vessel stimulates fibroblasts to
produce collagen and extracellular matrix; reduction in transmural pressure—reduces stimulus to capsular fibrosis;
limits capsular thickness, increases hydraulic conductivity, and improves function of aqueous shunt
|
| Early aggressive aqueous suppression: restart topical aqueous suppressant medication when IOP >12 mm Hg in patients
with advanced disc damage; avoid use of topical prostaglandin analogues (not as helpful as aqueous suppressants after
tube implantation)
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| Adjunctive surgery options: in some cases, IOP still higher than adequate for health of optic nerve; second aqueous
shunt—effective; increases surface area for fluid outflow; good way to achieve low IOP in many patients; transscleral
cyclophotocoagulation—between 5 or 6 and 10 to 12 applications using diode laser with G-probe; consider posterior
sub-Tenon’s injection of Kenalog (can maintain low level of intraocular inflammation with low incidence of cystoid
macular edema)
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| Hypertensive phase: double-plated Molteno implants (study by Heuer)—plate size has effect on pressure during hypertensive
phase; maximum pressure in hypertensive phase considerably lower than with single-plate implant; onset, magnitude,
and duration of transient elevation in IOP varies from patient to patient and with different devices
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| Hypotony: uncommon in patients who produce normal amount of aqueous humor, particularly compared with trabeculectomy
with antifibrosis therapy; patients at risk—those producing subnormal amount of aqueous (ocular ischemics); causes—
neovascular glaucoma; chronic uveitis; previous cycloablative procedures; patients at risk for prolonged low IOP after shunts;
prevention—use small-surface-area device (eg, Baerveldt); flow-restricted tube (eg, Ahmed implant) does not protect
against profound hypotony; once opened, valve leaflet does not necessarily close as IOP drops; surgical reversal—removal
of tube usually effective (removal of plate often not necessary); when tube removed completely, IOP likely to increase; with
permanent ligation of tube, consider—restarting medications (IOP may not increase to previous level because eye has
been through previous procedure and now makes less aqueous); cyclophotocoagulation; implanting new smaller-surface-area
device simultaneously or in subsequent operation reasonable options to consider
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| Summary: IOP 8 to 15 mm Hg achievable with consistency after aqueous shunt surgery; speaker uses large-surface-area, non-
flow-restricted silicone device; posterior placement of scleral explant important; need complete closure of tube with delayed
tube ligature release and aggressive anti-inflammatory treatment in early postoperative period; early and aggressive use of
aqueous suppressant after release of tube ligature; second aqueous shunt or low-dose transscleral cyclophotocoagulation
considered when target IOP not achieved
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| GLAUCOMA: LEGAL PITFALLS —Robert L. Stamper, MD, Professor of Clinical Ophthalmology, and Director of the
Glaucoma Service, University of California, San Francisco, School of Medicine
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| Failure to diagnose: single most common reason why ophthalmologists sued relating to glaucoma (often relates to inadequate
examination); American Academy of Ophthalmology (AAO)—every patient deserves periodic dilated examination
and careful evaluation of optic nerve; patient presents with eye pain—if no explanation, perform gonioscopy; sometimes,
slit lamp screening misses angle closure; patients usually right; if patient has symptoms and physician does not find anything,
determine differential diagnosis (be aggressive); visual acuity—only one measure of visual function; if visual acuity
20/20 and patient says “I cannot see” or “I’m not functioning,” perform visual field assessment to rule out glaucoma; examine
optic nerve
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| Document in chart: that physician did inform patient that he or she has condition with potential for vision loss; visual field
that progresses more rapidly than usual with glaucoma and more pallor than cupping in optic nerve suggests problem
more posterior; watch out for bitemporal defect (look at both visual fields at same time)
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| Failure to follow up: need system that reminds people at least once that they should come back for follow-up; glaucoma
has no symptoms; many patients feel “it can’t happen to me”; some patients so frightened by prospect of going blind that
they choose not to deal with it; pressures of family, work, other health issues, or money
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| Failure to recognize progression: IOP only one parameter (look at optic nerve and visual fields); if cannot get photos,
need at least decent drawing or other means to document initial condition to give some basis for detecting progression;
make sure that patient understands that condition progressing and that options need to be discussed
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| Failure to recognize serious side effects of treatment: speaker avoids systemic carbonic anhydrase inhibitors; patients
need to be aware when β-blockers not indicated; failure to adequately follow patients on steroids for, eg, uveitis another
common source of lawsuits
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| Complications of surgery: document that informed consent obtained; frequent problem failure to communicate reasonable
expectations of glaucoma surgery; failure to warn about symptoms of blebitis or endophthalmitis leaves patients susceptible
to infection; some patients sue because they feel that physician has abandoned them; if you run into trouble, consider
getting expert advice (follow it or have good reason documented in chart why you did not)
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| What physician can do: dilate new patients and examine optic nerve carefully (asymptomatic patients should have full examination
every 2 to 4 yr); for glaucoma patients and suspects, dilate once yearly; get visual field once yearly; document
optic nerve status to provide basis for comparison; perform gonioscopy on all glaucoma and suspect patients initially,
then periodically thereafter; if complication occurs—discuss problem candidly with patient; assure patient that you will
handle it as effectively as possible or will refer to specialist; be sympathetic and empathic; let patient know that you feel
badly that outcome not as expected (patients more willing to forgive physician who says, “I’m sorry”); if sued—try not
to panic or take it personally; review care and relationship with patient; be honest in assessing where you might have
done better; never change records; weigh cost of settlement against cost of sleepless nights and disruption of practice
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| NEW TECHNOLOGIES IN GLAUCOMA —Gregory L. Skuta, MD, James P. Luton Professor of Ophthalmology, Dean
A. McGee Eye Institute, University of Oklahoma, College of Medicine, Oklahoma City
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Automated Perimetry
| Humphrey Swedish Interactive Thresholding Algorithm (SITA): requires 50% less time than standard threshold perimetry;
reduces test time substantially; SITA Standard vs SITA Fast (paper by Budenz)—SITA Standard reduced testing
time by ≈50% (SITA Fast further reduced test time); for moderate-to-severe defects, both algorithms fine; for milder
glaucomatous defects, sensitivity slightly higher for SITA Standard than SITA Fast
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| Short-wavelength automated perimetry (SWAP): large signal (violet stimulus against bright yellow background); presumably
reduces overlap and redundancy between receptors; more sensitive than white-on-white perimetry in detecting
early glaucomatous damage (2-5 yr before standard methods); results affected by age and cataract; SITA-SWAP—
current SITA program 12- to 13-min test; with SITA-SWAP, testing time 4-6 min; available soon
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| Glaucoma Progression Analysis (GPA): software assists practitioner in detecting glaucomatous progression by highlighting
changes from baseline that show larger-than-expected clinical variability in pattern deviation; corrects for ocular media
defects (eg, cataract)
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| Frequency doubling technology (FDT): patients respond to flickering black and white bars perceived in various locations of
visual field; stimulates subset of retinal ganglion cells in magnocellular pathway; fast; portable; detects glaucomatous damage
earlier than standard automated perimetry; Humphrey Matrix Perimeter—utilizes FDT technology; designed for long-term
glaucoma follow-up and management; published information limited
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Optic Nerve and Retinal Nerve Fiber Layer (RNFL) Analyzers
| New technologies (overview): 3 major instruments—1) optical coherence tomography (OCT); 2) GDx Nerve Fiber
Layer Analyzer; 3) Heidelberg Retinal Tomography (HRT) for scanning laser ophthalmoscopy; value based on premise
that structural changes precede and/or correspond to functional visual field changes; used to detect preperimetric glaucoma
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| Confocal scanning laser ophthalmoscopy (CSLO): performed with HRT; typically quantifies topographic characteristics
of optic nerve head and retina; some dependence on user for reproducibility; may have predictive value in patients progressing
from ocular hypertension to glaucoma
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| Ocular Hypertension Treatment Study (OHTS): baseline topographic characteristics associated with development of
primary open-angle glaucoma (POAG); indices included HRT classification and Moorfields regression analysis (MRA);
overall classification and MRA temporal superior classification have predictive value for progression from ocular hypertension
to glaucomatous damage; longer follow-up required to evaluate predictive accuracy of CSLO
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| GDx Nerve Fiber Analyzer: nerve fiber index reflects risk profile (higher score suggests higher probability of glaucoma);
significant corneal and lens birefringence can affect measurements (variable corneal compensator [VCC] allows physician
to make corrections); some inability to bring forward old information (less issue with HRT)
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| Optical coherence tomography (OCT III): parameters include RNFL, optic nerve head, and photographs of eg, diabetic
issues; useful in retinal disease
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| Optic nerve imaging (important principles): disc photographs still useful and still standard; AAO changing preferred
practice pattern to include imaging studies as way of following patients besides drawings or optic nerve photographs;
longitudinal information key (strength of HRT)
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Selective Laser Trabeculoplasty (SLT)
| Overview: not necessarily better than ALT; very large spot size; thermal effects on trabecular meshwork big issue
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| SLT in POAG with or without previous ALT (study by Wise): 85 eyes with no previous ALT vs 87 eyes that had previous
ALT; IOP lowering effect similar in 2 groups; speaker more comfortable doing SLT in patients in whom he probably
would not consider repeat ALT; less risk for sustained IOP increases afterwards
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Educational Objectives
| The goal of this program is to educate the listener about glaucoma management. After hearing and assimilating this program,
the clinician will be better able to:
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| 1. Identify advantages and disadvantages of aqueous tube-shunt implantation as compared to trabeculectomy.
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| 2. Describe effective techniques for optimizing outcomes in aqueous tube-shunt implantation.
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| 3. Recognize common sources of malpractice litigation arising from glaucoma management.
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| 4. Describe effective techniques for preventing and managing litigation related to glaucoma care.
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| 5. Evaluate the efficacy of new technologies for detecting glaucomatous progression.
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Discussed on This Program
Mitomycin (mitomycin-C; MTC) [Mutamycin]
Timolol maleate [Betimol, Blocadren, Isatol, Timoptic, Timoptic-XE]
Triamcinolone acetonide (several formulations and trade names)
Suggested Reading
Budenz DL et al: Comparison if glaucomatous visual field defect.using standard full threshold and Swedish interactive
threshold algorithms. Arch Ophthalmol 120:1136, 2002; Delgado MF et al: Automated perimetry: a report by the American
Academy of Ophthalmology. Ophthalmology 109:2362, 2002; Demirel S, Johnson CA: Incidence and prevalence of
short wavelength automated perimetry deficits in ocular hypertensive patients. Am J Ophthalmol 131:709, 2001; Fechter
HP, Parrish RK 2nd : Preventing and treating complications of Baerveldt Glaucoma Drainage Device surgery. In Ophthalmol
Clin 44:107, 2004; Harbick KH et al: Outcomes of infernasal Baerveldt glaucoma drainage implant surgery. J Glaucoma
15:7, 2006; Higgenbotham EJ: The case against glaucoma drainage implant surgery in patients with a poor
prognosis for standard filtering procedure. Arch Ophthalmol 122:105, 2004; Juzych MS et al: Comparison of long-term
outcomes of selective laser trabeculoplasty versus argon laser trabeculoplasty in open-angle glaucoma. Ophthalmology
111:1853, 2004; Martinez-de-la-Casa JM et al: Selective vs argon laser trabeculoplasty: hypotensive efficacy, anterior
chamber inflammation, and postoperative pain. Eye 18:498, 2004; Mavroforou A, Michalodimitrakis E: Physicians’ liability
in ophthalmology practice. Acta Ophthalmol Scand 81:321, 2003; Parrish RK 2nd : The case for glaucoma drainage
implant surgery in patients with a poor prognosis for standard filtering procedure. Arch Ophthalmol 122:104, 2004; Reus
NJ et al: The prevalence of glaucomatous defects with short-wavelength automated perimetry in patients with elevated intraocular
pressures. J Glaucoma 14:26, 2005; Sidoti PA: Inferonasal placement of aqueous shunts. J Glaucoma 13:520,
2004; Sit AJ et al: Short-wavelength automated perimetry can predict glaucomatous standard visual field loss by ten years.
Semin Ophthalmol 19:122, 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. Dr. Skuta has received travel
support, honoraria, or research support from Alcon, Allergan, Merck, and Pfizer; he has served as a consultant to Alcon,
Merck, Pfizer, and Vistacon.
Dr. Sidoti was recorded at Glaucoma Mid-Winter Symposium, presented February 10-11, 2006, in Key Biscayne,
Florida, by Bascom Palmer Eye Institute, Miami; Dr. Stamper was recorded at the 10th Annual Glaucoma Symposium
, presented February 11, 2006, in San Francisco, by the Glaucoma Research & Education Group, San Francisco;
Dr. Skuta was recorded at the Ninth Annual Clinical Update for the Comprehensive Ophthalmologist, presented December
3, 2005, in Memphis, by the University of Tennessee Health Science Center, Department of Ophthalmology.
The Audio-Digest Foundation thanks Drs. Sidoti, Stamper, and Skuta, and the sponsors for their cooperation in the
production of this program.
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