New filtering procedure still a consideration
Stefano A. Gandolfi, MD: The TVT study has not influenced my
indication for tube shunt surgery. In fact, the follow-up data are limited to a
1-year time frame.
Besides, the efficacy results are comparable in both treatment arms. The
reported incidence of sight-threatening adverse events deserves some attention:
A 57% complication rate (and 28% loss of more than two Snellen lines of visual
acuity) after a trabeculectomy does exceed immensely what is routinely
experienced by any glaucoma specialist, at least (a) in Europe and (b) upon
adoption of the safe trabeculectomy strategy developed by Peng Khaw
in Moorfields. On the contrary, a 1-year follow-up is by far too short for
evaluating the most common tubes-related serious adverse event, ie, corneal
Therefore, after a failed trabeculectomy, I still consider a new
filtering procedure as a primary option, shifting to a tube in case the limbal
conjunctiva appears in a very poor condition (ie, scarred, contracted,
shortened, etc.). Moreover, new procedures are being currently investigated in
refractory glaucomas (for example, the Gold Shunt, the trabecular-micro bypass,
etc). Their indication must be considered when offering the possible surgical
options to a high-risk patient bearing a failed trabeculectomy.
- Stefano Gandolfi, MD, can be reached at the University of Parma,
Department of Ophthalmology, Via Giuseppi Rossi 28, 43100 Parma, Italy;
+39-521-259-103; e-mail: firstname.lastname@example.org.
Longer follow-up needed
Ivan Goldberg, MBBS, FRANZCO, FRACS: While the TVT study results
are most interesting, to date they have not influenced my recommendations to
patients needing glaucoma surgery. To make the studys results more
meaningful clinically to the patients I care for, what is needed is longer
follow-up and a broader range of patients selected for randomization.
I have been inserting glaucoma drainage devices since 1984. For many
patients in whom trabeculectomy has proven most disappointing (such as poorly
controlled uveitis with secondary glaucoma, patients with the iridocorneal
endothelial syndrome or closed-angle glaucoma from neovascularization), these
devices have been most helpful.
Unfortunately, however, they are not without problems. Leaving aside the
short-term postoperative challenges through which most patients can be
navigated successfully, longer-term problems remain a serious challenge. In
particular, problems include corneal endothelial failure and decompensation and
thick encapsulation around the plate(s), leading to rising IOP and late tube
erosion through the conjunctiva.
Corneal decompensation can occur even with no physical tube/endothelial
contact. Late-rising IOP is unavoidable with current knowledge and
technologies. Tube erosion occurs even decades later despite scleral trapdoors
and overlying graft material. Even 3-year study results cannot capture some of
these problems with tubes, underlining the curse that is long-term
follow-up in glaucoma.
For each patient, the clinician needs to balance immediate needs for IOP
control against long-term complications with any suggested surgical route. No
one study, no matter how good, should influence unduly the considerations of
- Ivan Goldberg, MBBS, FRANZCO, FRACS, can be reached at 187 Macquarie
St., Park House, Floor 4, Suite 2, Sydney NSW 2000, Australia; +61-2-9247-9972;
fax: +61-2-9232-3086; e-mail: email@example.com.
Already using shunts more
Nathan G. Congdon, MD, MPH: The TVT studys two main
publications suggest that the Baerveldt tube shunt may be at least as safe and
effective as trabeculectomy surgery among patients with previous surgery (which
might only include phacoemulsification).
This is a group of patients for whom many glaucoma specialists might
have performed trabeculectomies in the past. I expect that these results will
likely accelerate a trend which had already seen trabeculectomies decline by
53% and tube shunts increase by 184% among Medicare beneficiaries in the decade
prior to the TVT. The fact is that prior to the TVT, I was already performing
more tube shunts than trabeculectomies, probably an indication of the
tertiary-care nature of my practice as much as anything else.
However, I think there are some issues worth considering in deciding to
perform tube shunt vs. trabeculectomy surgery in the post-TVT world.
In the first place, the basic message of TVT from my perspective was
one of equivalency between the procedures. In patients where either procedure
would do, I think that we ought to have a specific justification for using a
several hundred dollar device where similar results might be achieved without
one. While some of us may associate such thinking with bean
counters and resent its intrusion into clinical practice, in a world
where every trend (an aging population, the constant discovery of new
procedures and medications) mandates rising medical costs, it is increasingly
responsible and appropriate that we as physicians do what we can to hold costs
The TVT was conceived and directed by some of the most respected names
in academic glaucoma, participants were drawn from the top clinical centers,
and the results published in outstanding peer-reviewed journals. We take
nothing away from any of these individuals and institutions when we remind
ourselves that the TVT was funded in part by the manufacturer of the Baerveldt
A recent study of postoperative adverse outcome after glaucoma surgery
among Medicare beneficiaries has reported a significantly higher incidence of
endophthalmitis, retinal detachment and blindness among patients receiving tube
shunts as compared to filtration surgery, with the differences widening over 6
years of follow-up. As the authors themselves point out, these results may
reflect unmeasured differences in case severity between the two surgical
groups, but they certainly bear further investigation.
I continue to perform a large number of tube shunt surgeries in my
practice, but now, as before the TVT, I weigh my options carefully before
deciding to proceed with a drainage device.
- Ramulu P, Corcoran KJ, Corcoran SL, Robin A. Utilization of various
glaucoma surgeries and procedures in Medicare beneficiaries from 1995 to 2004.
- Stein JD, Ruiz D Jr., Belsky D, Lee PP, Sloan FA. Longitudinal rates
of postoperative adverse outcomes after glaucoma surgery among Medicare
beneficiaries 1994-2005. Ophthalmology.
- Nathan G. Congdon, MD, MPH, can be reached at the Department of
Ophthalmology and Visual Science, Chinese University of Hong Kong; e-mail: