With a seemingly infinite number of variations on the theme of placing a glaucoma drainage device, the topic of how to implant the perfect tube never seems to get old. Ligations, stents, vents, fenestrations, slits, valves, and orphan trabeculectomies can be placed in a combinatorial fashion to help regulate flow for the early postoperative period and beyond. Past “Inside Eyetube.net” columns have looked at trabeculectomy, blebless glaucoma surgery, and other alternatives to trabeculectomy. Additionally, they have considered a few augmentations of standard glaucoma drainage devices' placement such as the use of triamcinolone to verify flow through a glaucoma drainage device and placement of a tube in the sulcus.
As a surgeon who has a strong affinity for the Ahmed Glaucoma Valve (New World Medical, Inc., Rancho Cucamonga, CA), Molteno Implants (Molteno Ophthalmic Limited, Dunedin, New Zealand), and Baerveldt Glaucoma Implants (Abbott Medical Optics Inc., Santa Ana, CA), I often discuss the many indications for and variations of each valve with my colleagues. Although the indications vary from doctor to doctor, the Molteno3 Glaucoma Drainage Device deserves consideration. This tube seems to seek neutral territory in the Baerveldt versus Ahmed battle. The Molteno3 maintains an intermediate profile and contour. (It is placed between the rectus muscles rather than underneath them.) It maintains an overall silhouette more similar to the Ahmed valve's than to that of the lower but wider Baerveldt model BG-101-350. The Molteno3 is not valved and is made out of a stiffer polypropylene rather than the medical-grade silicone used for the Baerveldt and Ahmed model FP-7, and it comes in two sizes, 175 mm and 230 mm. The 175-mm device was designed for superonasal placement (to avoid the optic nerve and superior oblique muscle) in eyes requiring a second valve after the superotemporal placement of a Baerveldt or Ahmed valve.
SURGICAL PEARLS FOR IMPLANTING
THE MOLTENO3
Recently on Eyetube.net, Anup K. Khatana, MD, provided
a comprehensive series of videos demonstrating his technique for implanting a Molteno3 230-mm glaucoma
drainage device. He places the plate 8 to 10 mm posterior
to the limbus, with the tube's entering 1.5 mm posterior
to the limbus under a pericardial patch graft. Complete
attention to detail is provided in his narration, including
the manufacturer and style of each suture. For example,
after the tube is secured to the sclera, Dr. Khatana recommends
using a 9–0 monofilament Vicryl suture (VAS 100;
Ethicon, Inc., Somerville, NJ) to finish the surgery (Figure 1)
(http://eyetube.net/v.asp?molupo).
The suture is the same one used by glaucoma surgical guru Garry P. Condon, MD, in the wildly popular “Closing the Fornix-Based Conjunctival Flap” video. Most readers have likely heard about Dr. Condon's conjunctival closure after trabeculectomy or placement of the Ex-Press mini glaucoma shunt (Alcon Laboratories, Inc., Fort Worth, TX). This is the video that demonstrates the technique (Figure 2) (http://eyetube.net/v.asp?gehotu).
Going back to Dr. Khatana's Molteno3 video, I highly recommend this Eyetube.net series to experienced surgeons who use Molteno implants, experienced surgeons who have yet to place a Molteno3, and ophthalmology residents or glaucoma fellows who are interested in showing up to the OR with a solid foundation of knowledge on this highly nuanced surgery. Those who have never placed a Molteno3, in addition to Dr. Khatana's video, may also wish to review the Molteno3 surgical guide (http://www.molteno.com/information/glaucomadrainage- devices/molteno3/M3-SurgicalGuide.pdf). It was written by Anthony C. B. Molteno, FRCS, FRACO, and contains many useful pearls applicable to shunt procedures.
ARTFULLY PLACING THE MOLTENO3
When looking for tips on how to finesse the placement
of a glaucoma drainage device, whom better to learn from
than Jeffrey Freedman, MD, PhD. He demonstrates his
technique for a supra-Tenon's placement of a Molteno
in the eye of a patient with a previously failed Ex-Press
device. Dr. Freedman initiates the surgery by dissecting
both the conjunctiva and Tenon's capsule from the limbus
using a Bard-Parker Protected Surgical Blade (BD,
Franklin Lakes, NJ). Next, using Westcott forceps, he performs
an elegant dissection to separate the conjunctiva
from Tenon's capsule. Dr. Freedman points out that the
surgeon can titrate the anticipated capsular thickness by
altering the depth of dissection between Tenon's and the
conjunctiva. After pulling Tenon's capsule forward using a
7–0 Vicryl suture, he places the Molteno3 into the dissected
supra-Tenon's pocket. His technique involves the use of
a 3–0 supramid intraluminal suture to provide an option
for short- and intermediate-term IOP reduction. After
scleral fixation of the plate, a tenonectomy is performed
for the capsule located between the limbus and the
plate. After inserting the tube's tip into the anterior
chamber but before placing the pericardial patch graft,
Dr. Freedman uses a microsharp blade to make a 1- to
3-mm Sherwood slit, which is titratable to the level of
desired short-term IOP reduction (Figure 3)
(http://www.eyetube.net/v.asp?jutovu).1
CONCLUSION
Many surgeons' tube shunt techniques are an art in
constant evolution. When reconsidering their current
technique for implanting glaucoma drainage devices, I
recommend that surgeons take a look at videos on
Eyetube.net that demonstrate how colleagues perform
the surgery. Viewers may post comments or questions. I
encourage readers who use a technique that they do not
see on Eyetube.net to share it!
Section Editor Nathan M. Radcliffe, MD, is an assistant professor of ophthalmology at Weill Cornell Medical College, New York-Presbyterian Hospital, New York. He acknowledged no financial interest in the products or companies mentioned herein. Dr. Radcliffe may be reached at (646) 962- 2020; drradcliffe@gmail.com.
