**2. Lymphatics**

Without a shadow of doubt, it has been proved that the conjunctival lymphatics do exist [1,12,17,22,23,24]. Every glaucoma surgeon should verify it with his own eyes. Under high magnification of a slit lamp microscope, the lymphatics are visible at the limbus, especially if there is some pigment. Pigment highlights the lymphatics. They stand out in cases of sub‐ conjunctival haemorhage as a result of trauma, accidental or surgical. The blood is drained through the lymphatics. The network of lymphatics can be charted by injecting tyrpan blue at the limbus. Injection of the dye in the sclera demonstrates scleral channels as well as their

© 2013 Singh; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2013 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

continuity with the sub-conjunctival lymphatics. Yeni et al [28] have demonstrated the pres‐ ence of lymphatics in the ciliary body. It becomes obvious that uveoscleral outflow is actual‐ ly a channel based aqueous pathway. No lymphatics can be demonstrated in the areas of subconjunctival scarring. All glaucoma surgeons need to be aware of the lymphatics.

**Figure 1.** Limbal lymphatics.They enter the cornea singly, but anastomose proximally and join the conjunctival lym‐ phatic network.The presence of pigment at the limbus makes the lymphatics prominent.

**Figure 2.** Microtrack filtration was done one day earlier to control glaucoma after blunt injury.Before removing dislo‐ cated lens, trypan blue was injected to chart lymphatics of conjunctva.

**Figure 3.** Entry of blood in the lymphatics after an unintended surgical trauma to the conjunctiva.Two hours later,

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most of the blood had migrated in to the conjunctival lymphatics.

continuity with the sub-conjunctival lymphatics. Yeni et al [28] have demonstrated the pres‐ ence of lymphatics in the ciliary body. It becomes obvious that uveoscleral outflow is actual‐ ly a channel based aqueous pathway. No lymphatics can be demonstrated in the areas of

**Figure 1.** Limbal lymphatics.They enter the cornea singly, but anastomose proximally and join the conjunctival lym‐

**Figure 2.** Microtrack filtration was done one day earlier to control glaucoma after blunt injury.Before removing dislo‐

phatic network.The presence of pigment at the limbus makes the lymphatics prominent.

cated lens, trypan blue was injected to chart lymphatics of conjunctva.

subconjunctival scarring. All glaucoma surgeons need to be aware of the lymphatics.

440 Glaucoma - Basic and Clinical Aspects

**Figure 3.** Entry of blood in the lymphatics after an unintended surgical trauma to the conjunctiva.Two hours later, most of the blood had migrated in to the conjunctival lymphatics.

Anatomy is the basis of physiology. The lymphatics drain the extracellular fluid, one that comes out of the arterial ends of the capillaries, the leakage from the aqueous veins and the uveoscleral outflow. The drainage occurs all around the limbus. When a filtration surgery is performed, there is a huge local outflow, which can be handled only by the flood drain like function of the lymphatics. Their sizes and capabilities match the changing needs after filtra‐

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The techniques of glaucoma surgery are limited by the tools that are employed to achieve them. For the last one century,the tools are basically the same - forceps, scissors, knife and cautery. Only they are now finer and sharper. Excellent magnification and coaxial light are recent helps for the surgeon. Tissues are cut and dissected in layers, which are sutured back, after making a large opening in to the anterior chamber. Tissue reaction and scarring is a serious concern to manage/prevent which anti-mitotics are used during and often post-sur‐

The arrival of a radically new surgical tool, Fugo blade, providing plasma energy on the tip of a filament has remained largely un-noticed or un-understood outside the United States

Fugo blade [3,4,8,9,13,14,15,16,17,26,27] produces "laser like plasma" on the operating blunt metal tip. It works on 4 rechargeable battery cells.Numerous glaucoma operations can be done after one charge. Cut power and intensity can be adjusted from the console. How does it function ? It focusses electromagnetic energy to the operating tip.The energy is pre-tuned to the tissues and is transferred by resonance. The moment the activated tip touches the tis‐ sues, the energy gets transferred to the tissue molecules, which go to higher energy levels, become unstable and explode, just as happens with excimer laser when it acts on the cor‐ nea.A plume with aromatic smell is produced.The molecules/tissues split in the path of inci‐ sion/ablation.The incisions are bloodless, since the small blood vessels are also removed from the path of incision.It is possible to ablate surfaces and create channels/tracks in simple

The width of the cutting plasma coating on the operating tip can be varied from "power" adjustment- 25, 50 or 75 microns.The intensity can be varied from 1 to 10 from the second

Fugo blade application in glaucoma surgery raises a dilemma. You cannot make the tradi‐ tional surgery any better with it. So why use it? That it opens newer ways to do glaucoma surgery is not yet attractive, because the new techniques have not yet been approved and advocated by the stalwarts in the field. That in stead of dissecting in layers, you can tap the aqueous chambers through direct track formation seems frightening, since it breaks the five decades old taboo by not making a "guarding scleral flap". The scleral flap in trabeculecto‐ my might help prevent over-filtration, but the prevention of infection always rests upon

tion surgery.

gery.

and even less actually used.

**2.1. What is Fugo blade ?**

and efficient manner.

healthy conjunctiva.

knob.

**Figure 4.** A failed case of trabeculectomy. Dye injection fails to show lymphatics in the totally scarred central area. The seen lymphatics are thin and have a disturbed pattern.

**Figure 5.** It demonstrates the intrascleral movement of injected trypan blue along the limbus where it ends in knobs. The proximal movement of the dye through the sclera enters the subconjunctival lymphatics, proving that conjunctival and scleral channels are one system.

Anatomy is the basis of physiology. The lymphatics drain the extracellular fluid, one that comes out of the arterial ends of the capillaries, the leakage from the aqueous veins and the uveoscleral outflow. The drainage occurs all around the limbus. When a filtration surgery is performed, there is a huge local outflow, which can be handled only by the flood drain like function of the lymphatics. Their sizes and capabilities match the changing needs after filtra‐ tion surgery.

The techniques of glaucoma surgery are limited by the tools that are employed to achieve them. For the last one century,the tools are basically the same - forceps, scissors, knife and cautery. Only they are now finer and sharper. Excellent magnification and coaxial light are recent helps for the surgeon. Tissues are cut and dissected in layers, which are sutured back, after making a large opening in to the anterior chamber. Tissue reaction and scarring is a serious concern to manage/prevent which anti-mitotics are used during and often post-sur‐ gery.

The arrival of a radically new surgical tool, Fugo blade, providing plasma energy on the tip of a filament has remained largely un-noticed or un-understood outside the United States and even less actually used.

#### **2.1. What is Fugo blade ?**

**Figure 4.** A failed case of trabeculectomy. Dye injection fails to show lymphatics in the totally scarred central area. The

**Figure 5.** It demonstrates the intrascleral movement of injected trypan blue along the limbus where it ends in knobs. The proximal movement of the dye through the sclera enters the subconjunctival lymphatics, proving that conjunctival

seen lymphatics are thin and have a disturbed pattern.

442 Glaucoma - Basic and Clinical Aspects

and scleral channels are one system.

Fugo blade [3,4,8,9,13,14,15,16,17,26,27] produces "laser like plasma" on the operating blunt metal tip. It works on 4 rechargeable battery cells.Numerous glaucoma operations can be done after one charge. Cut power and intensity can be adjusted from the console. How does it function ? It focusses electromagnetic energy to the operating tip.The energy is pre-tuned to the tissues and is transferred by resonance. The moment the activated tip touches the tis‐ sues, the energy gets transferred to the tissue molecules, which go to higher energy levels, become unstable and explode, just as happens with excimer laser when it acts on the cor‐ nea.A plume with aromatic smell is produced.The molecules/tissues split in the path of inci‐ sion/ablation.The incisions are bloodless, since the small blood vessels are also removed from the path of incision.It is possible to ablate surfaces and create channels/tracks in simple and efficient manner.

The width of the cutting plasma coating on the operating tip can be varied from "power" adjustment- 25, 50 or 75 microns.The intensity can be varied from 1 to 10 from the second knob.

Fugo blade application in glaucoma surgery raises a dilemma. You cannot make the tradi‐ tional surgery any better with it. So why use it? That it opens newer ways to do glaucoma surgery is not yet attractive, because the new techniques have not yet been approved and advocated by the stalwarts in the field. That in stead of dissecting in layers, you can tap the aqueous chambers through direct track formation seems frightening, since it breaks the five decades old taboo by not making a "guarding scleral flap". The scleral flap in trabeculecto‐ my might help prevent over-filtration, but the prevention of infection always rests upon healthy conjunctiva.

In short, lack of awareness about the lymphatic network that drains the aqueous normally and that works like flood drains after filtration surgery, and the failure to appreciate new possibilities of glaucoma surgery that are opened up with Fugo plasma blade, keeps the

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Trabeculectomy or its modification remains the operation of choice for most surgeons. Non perforating filtration under a scleral flap and glaucoma valve are other choices. Every opera‐ tion makes a fairly large foot print on the sclera and inevitably destroys the lymphatics in the surgical field. This happens because the surgery involves making flaps of the tissues. A "guarded flap" is a necessity for making a rather large trabeculectomy opening at the lim‐

Fugo blade allows the making of a filtration track (TCF) in to the posterior chamber.There is no other tool that has this capability. The filtration track goes through the sclera and the cili‐ ary body to reach the posterior chamber[2,5,6,7,10,17,19,21,23]. TCF may be done after mak‐ ing a fornix or limbus based conjunctival flap, which involves some/considerable trauma. Transconjunctival(TC) TCF minimizes surgical trauma. TCF prevents anterior chamber problems like a shallow or flat anterior chamber and hyphaema. No iridectomy is done in

**1.** The posterior edge of the surgical limbus is visible through the conjunctiva. It lies over the the anterior corneo-scleral trabeculae. A point is chosen 1.5 mm posterior to it.This

**2.** A 300 micron or 500 micron Fugo blade tip is chosen to be used at high power and intensity. The conjunctiva is pushed towards the limbus with a blunt sapphire knife till it reaches

**3.** The activated Fugo blade is passed through the conjunctiva, the sclera and the ciliary body to reach the posterior chamber. The track may be made in one step or a series of small steps progressively taking the track to the posterior chamber. The end point shows as

**4.** 0.1 ml to 0.2 ml of Mitomycin C (MMC) 0.01 % or 0.02 % is deposited under the conjunctiva.

An anteriorly misdirected track can open in to the anterior chamber and posterior misdirec‐

point is pressed with the blunt tip of a forceps to leave a mark on the sclera.

In all the operations described below, subconjunctival anaesthesia is given.

modern glaucoma surgery where it is - essentially a standstill.

**2.2. Minimally invasive glaucoma surgery**

**2.3. Transciliary Filtration (TCF)**

The steps of TCTCF are as follows:

the marked point on the sclera.

The conjunctival opening is sutured.

tion can lead to the vitreous show/prolapse.

aqueous drainage. Nothing further needs to be done.

bus.

this operation.

**Figure 6.** Fugo blade console, hand piece and the disposable operating tip.One connection goes to the hand-piece and the other to the foot-switch. The left knob is for cut power and the right for intensity. Manufacturer: Medisurg Ltd. c/o Richard J. Fugo. 100 West Fornance St. The Fugo Building. Norristown, Pa 19401.USA

**Figure 7.** High magnification photograph of activated Fugo blade tip showing yellow plasma coating (cutting) around the metal filament and the orange photonic cloud (non cutting).

In short, lack of awareness about the lymphatic network that drains the aqueous normally and that works like flood drains after filtration surgery, and the failure to appreciate new possibilities of glaucoma surgery that are opened up with Fugo plasma blade, keeps the modern glaucoma surgery where it is - essentially a standstill.

#### **2.2. Minimally invasive glaucoma surgery**

Trabeculectomy or its modification remains the operation of choice for most surgeons. Non perforating filtration under a scleral flap and glaucoma valve are other choices. Every opera‐ tion makes a fairly large foot print on the sclera and inevitably destroys the lymphatics in the surgical field. This happens because the surgery involves making flaps of the tissues. A "guarded flap" is a necessity for making a rather large trabeculectomy opening at the lim‐ bus.

#### **2.3. Transciliary Filtration (TCF)**

**Figure 6.** Fugo blade console, hand piece and the disposable operating tip.One connection goes to the hand-piece and the other to the foot-switch. The left knob is for cut power and the right for intensity. Manufacturer: Medisurg

**Figure 7.** High magnification photograph of activated Fugo blade tip showing yellow plasma coating (cutting) around

the metal filament and the orange photonic cloud (non cutting).

Ltd. c/o Richard J. Fugo. 100 West Fornance St. The Fugo Building. Norristown, Pa 19401.USA

444 Glaucoma - Basic and Clinical Aspects

Fugo blade allows the making of a filtration track (TCF) in to the posterior chamber.There is no other tool that has this capability. The filtration track goes through the sclera and the cili‐ ary body to reach the posterior chamber[2,5,6,7,10,17,19,21,23]. TCF may be done after mak‐ ing a fornix or limbus based conjunctival flap, which involves some/considerable trauma. Transconjunctival(TC) TCF minimizes surgical trauma. TCF prevents anterior chamber problems like a shallow or flat anterior chamber and hyphaema. No iridectomy is done in this operation.

In all the operations described below, subconjunctival anaesthesia is given.

The steps of TCTCF are as follows:


An anteriorly misdirected track can open in to the anterior chamber and posterior misdirec‐ tion can lead to the vitreous show/prolapse.

TCTCF is the least traumatic way to drain the posterior chamber. It is most useful in cases of acute congestive glaucoma, phakomorphic glaucoma and neovascular glaucoma. The last group of cases show vascularization of the iris and the angle, but there are no such changes over the ciliary body. TCTCF can be done in any case with a normal posterior chamber.

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TCTCF does pass through the tenon capsule, the thickness of the sclera and the highly vas‐

The following film depicts TCTCF in a difficult case of neovascular glaucoma. There was ex‐ tensive scarring around the limbus. TCTCF was done by approaching the posterior cham‐

TCTCF is handy to treat cases of phakomorphic glaucoma that has lasted for many days or weeks (a common happening in the third world).There is a vicious cycle of the swollen cata‐ ract raising IOP and the raised IOP pushing more fluid in to the swollen lens. The moment the posterior chamber drainage starts, there is an improvement in the depth of the anterior chamber. Over days one can see a diminution in the thickness of the intumescent cataract.

Now we turn our attention to anterior chamber filtration and look at the opportunities that

Microtrack Filtration (MTF) makes a track between the anterior chamber and the anterior most area of subconjunctival space[17,20,25]. If a filtering track between 100 micron to 250 micron could be sustained without internal block and outer scarring, and the aqueous kept seeping out and getting drained by the network of lymphatics, the problem of glaucoma is as good as solved. Easier said than done.Even a microtrack creates a few hurdles that need

Let us first describe the technique of Microtrack Filtration. The steps of surgery are as fol‐

**1.** Anaesthesia: Facial block and subconjunctival injection of lignocaine in adults. General

**2.** Eyeball fixation: An episcleral suture is passed close to the nasal limbus and the eye turned

**3.** Making an opening in the conjunctiva close to the 10 O' clock limbus with a Fugo blade

**4.** Through this hole, 0.1 to 0.2 ml of mitomycin C (MMC) 0.01 % or 0.02 %, is injected under

the conjunctiva with a 30 gauge cannula, to raise a bleb at the upper limbus.

cular ciliary body, which is a trauma, howsoever slight it may be.

The following film shows TCTCF in a case of phakomorphic glaucoma:

ber, from beyond the scarred area.

**2.4. Microtrack Filtration**

anesthesia in children.

to be crossed.

down.

100 micron tip.

lows:

http://www.youtube.com/watch?v=uO57F9gdTU4

http://www.youtube.com/watch?v=wSWrIr7Jesc

it offers for minimally traumatic filtration surgery.

**Figure 8.** in a case of phakomorphic glaucoma.The conjunctiva is pushed towards the limbus up to a pre-determined point.Fugo blade tip passes through the conjunctiva, the sclera and the ciliary body to drain the posterior chamber.

**Figure 9.** TCTCF with a 500 micron Fugo blade tip in a case of neovascular glaucoma, one day after surgery.

TCTCF is the least traumatic way to drain the posterior chamber. It is most useful in cases of acute congestive glaucoma, phakomorphic glaucoma and neovascular glaucoma. The last group of cases show vascularization of the iris and the angle, but there are no such changes over the ciliary body. TCTCF can be done in any case with a normal posterior chamber.

TCTCF does pass through the tenon capsule, the thickness of the sclera and the highly vas‐ cular ciliary body, which is a trauma, howsoever slight it may be.

The following film depicts TCTCF in a difficult case of neovascular glaucoma. There was ex‐ tensive scarring around the limbus. TCTCF was done by approaching the posterior cham‐ ber, from beyond the scarred area.

http://www.youtube.com/watch?v=uO57F9gdTU4

TCTCF is handy to treat cases of phakomorphic glaucoma that has lasted for many days or weeks (a common happening in the third world).There is a vicious cycle of the swollen cata‐ ract raising IOP and the raised IOP pushing more fluid in to the swollen lens. The moment the posterior chamber drainage starts, there is an improvement in the depth of the anterior chamber. Over days one can see a diminution in the thickness of the intumescent cataract.

The following film shows TCTCF in a case of phakomorphic glaucoma:

http://www.youtube.com/watch?v=wSWrIr7Jesc

Now we turn our attention to anterior chamber filtration and look at the opportunities that it offers for minimally traumatic filtration surgery.

#### **2.4. Microtrack Filtration**

**Figure 8.** in a case of phakomorphic glaucoma.The conjunctiva is pushed towards the limbus up to a pre-determined point.Fugo blade tip passes through the conjunctiva, the sclera and the ciliary body to drain the posterior chamber.

446 Glaucoma - Basic and Clinical Aspects

**Figure 9.** TCTCF with a 500 micron Fugo blade tip in a case of neovascular glaucoma, one day after surgery.

Microtrack Filtration (MTF) makes a track between the anterior chamber and the anterior most area of subconjunctival space[17,20,25]. If a filtering track between 100 micron to 250 micron could be sustained without internal block and outer scarring, and the aqueous kept seeping out and getting drained by the network of lymphatics, the problem of glaucoma is as good as solved. Easier said than done.Even a microtrack creates a few hurdles that need to be crossed.

Let us first describe the technique of Microtrack Filtration. The steps of surgery are as fol‐ lows:


**Figure 10.** Fugo blade tip is passed through the ballooned conjunctiva about 7 mm from the limbus.It is then pushed

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to the limbus in un-activated form. Activation of the tip instantly makes MTF track.

**Figure 11.** Microtrack filtration, one year after surgery. OCT shows MTF track.


Application of MTF:

Any patient with a healthy/virgin perilimbal conjunctiva and an intact anterior chamber is suitable for this operation. It can be used at any age. The surgical trauma is minimal, com‐ pared to all other available manual or laser procedures.

Here are some films on MTF:

http://www.youtube.com/watch?v=C5pHb2JfmaA

MTF in a case of buphthalmos is shown here:

http://www.youtube.com/watch?v=XKQ9-JnBx9I

MTF in a case of keratouveitis is shown here:

http://www.youtube.com/watch?v=C5pHb2JfmaA

**5.** A pocket incision is made in the anterior chamber with a 0.75 mm diamond knife close to the limbus. Depending upon the surgical plan of peripheral iridectomy, it may be made

**7.** Two or three iridotomies are made in the iris periphery, with the help of a 100 micron Fugo blade tip.The iris is touched with the tip and then activated with the highest energyan opening gets made instantly. Pigment from the posterior pigment epithelium raises a small cloud. The anterior chamber is irrigated with a 30 gauge cannula. It is also passed

**8.** A 1.5 mm 100 micron Fugo blade tip is passed through 12 O' clock conjunctiva about 7-8 mm from the limbus, with the lowest energy. It is then pushed under the ballooned/raised conjunctiva in un-activated form, to reach the limbus.When the tip reaches the limbus/

**9.** The tip is raised by about 30 degrees, while its point remains engaged at the limbus,close to, but slightly away from the attachment of conjunctiva.We wish to avoid conjunctival

**10.** The track making is the next step. The machine has been set at the desired power and intensity levels. The point of the tip is lightly pushing the limbal tissues, when it is acti‐ vated. In a fraction of a second,it passes through the limbus in to the anterior chamber.As the tip is withdrawn, the aqueous follows, raising an enlarging bleb. A track about 250

**12.** Sodium hyaluronate (NaHa) in the anterior chamber is optional.It also helps to keep the

Any patient with a healthy/virgin perilimbal conjunctiva and an intact anterior chamber is suitable for this operation. It can be used at any age. The surgical trauma is minimal, com‐

micron wide, gets formed anterior to the corneo-scleral trabeculae.

**6.** Pilocarpine or carbachol is injected in the anterior chamber to contract the pupil.

in line with 3 O' clock, 9 O' clock or 12 O' clock.

448 Glaucoma - Basic and Clinical Aspects

through the iridotomies to make sure they are patent.

desired point, its location is clearly visualized.

puncture at the time of microtrack formation.

**11.** Air is injected to deepen the anterior chamber.

pared to all other available manual or laser procedures.

http://www.youtube.com/watch?v=C5pHb2JfmaA

http://www.youtube.com/watch?v=XKQ9-JnBx9I

http://www.youtube.com/watch?v=C5pHb2JfmaA

MTF in a case of buphthalmos is shown here:

MTF in a case of keratouveitis is shown here:

anterior chamber deep.

Here are some films on MTF:

Application of MTF:

**Figure 10.** Fugo blade tip is passed through the ballooned conjunctiva about 7 mm from the limbus.It is then pushed to the limbus in un-activated form. Activation of the tip instantly makes MTF track.

**Figure 11.** Microtrack filtration, one year after surgery. OCT shows MTF track.

Postoperative course and management:

In the beginning the normal subconjunctival tissues offer little resistance to the outward flow of the aqueous. This little resistance is what keeps the anterior chamber formed, even though it is on the shallower side. We need to keep the iris away from the internal opening of the track. Therefore from day one the pupil is kept contracted by pilocarpine 2% three times a day.I firmly believe that lymphatics play a definite role in offering resistance to aqueous outflow. Initially they act as flood drains, but the outflow is so excessive that a big conjunctival bleb is formed. Later the initial rush of aqueous is over. Then sets in a balance between the out going aqueous and the tissue resistance,at least a part of which is resistance from the lymphatics.The anterior chamber begins to deepen. If it deepens too fast, and the bleb begins to dry up, it is a sign of a partial or complete closure of internal opening by the iris which needs early correction. If the block is complete, the pressure goes high and the patient experiences pain and reduction of vision. The tiny internal blockage with iris shuts down the system. The fluid filled subconjunctival tissues start shrinking and become capa‐ ble of greater resistance. The internal block is opened with a shot of Yag laser. Once the fil‐ tration restarts, the chances of its second time failure are much reduced. If the internal block is not opened for many days and weeks, the external opening also gets closed by healing process.Healing starts when fluid movement stops. One to two days of internal closure does not cause irreversible damage to the filtration track.In cases where cross-linked NaHa (Hea‐ laflow) has been used over the external opening track,the fluid movement has been restored after a week or even longer. During these crucial days the patient takes oral diamox and lo‐ cal pilocarpine drops.The moment the tiny piece of iris is detached with a shot of YAG laser, the filtration starts and conjunctival bleb forms.

Variations in Microtrack Filtration:

aged by the concentrations used.

to the anterior chamber.

**2.5. Choroidal detachment**

The steps of operation are as follows:

Film: drainage of suprachoroidal fluid.

of sutures are applied to the conjunctival incision.

http://www.youtube.com/watch?v=M35h7JShnqc

**Strategies to improve results with Microtrack Filtration**

Pre-tenon MTF:

fluid is drained.

ber collapse, which allows a second or even a third MTF.

track at the limbus. A film of this procedure can be see here:

http://www.youtube.com/watch?v=TXAw6tXPDfE&feature=endscreen

MMC may be deposited under the conjunctiva either at the beginning of surgery or at the end of it. We have ample photographic and OCT evidence that the lymphatics are not dam‐

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A side port incision serves many purposes - to make PI, to inject carbachol or NaHa. The last one is useful if more than one MTF tracks are planned. NaHa does not let the anterior cham‐

In some situations, especially repeat failures by any kind of technique, accompanied by sub‐ conjunctival scarring, it may be necessary to make a wider track up to 500 micron (300 mi‐ cron tip at highest energy setting). In a case of perilimbal scar formation, the track formation is started proximal to the scar and a longish track is made through the sclera and limbus in

The tenon capsule gets attached to the limbus, proximal to the attachment of the conjuncti‐ va. Thus there is a potential subconjunctival space distal to the tenon attachment. This pretenon subconjunctival space can be approached to produce a somewhat tangential filtration

Hypotony is the probable cause of choroidal detachment. There are greater chances of hy‐ potony In aphakes,vitrectomized eyes, trauma, buphthalmos and high myopia cases.It may start soon after surgery or during the first 2 postoperative days. In some cases there is severe pain at the start. Fundus examination and b-scan reveal choroidal detachment - from slight to kissing choroidals. The situation is watched for a week, after which the suprachoroidal

The conjunctiva is pushed towards the limbus from a distance of about 8 mm to a distance of 4-5 mm, with a blunt sapphire knife. A 100 micron Fugo blade tip is used to incise the conjunctiva, tenon capsule and the sclera, till supra-choroidal fluid starts draining. When sufficient fluid has drained, air is injected in the anterior chamber. No attempt is made to suture the scleral incision.The tenon capsule and the conjunctiva retract to normal. A couple

The strategies are based on the knowledge that the out coming aqueous is drained by the conjunctival lymphatics.Also on the observation that in the beginning the aqueous outflow

It is thus clear that the first 3-4 weeks after surgery need very careful watch both by the sur‐ geon and the patient. The vigilance is relaxed but not given up altogether after that. A regu‐ lar follow up on a monthly or two monthly basis is a must for every glaucoma operated case.

In one recent report (Roy et al 2012) on Deep Sclerectomy in which Healaflow (cross linked sodium hyaluronate)had been used as adjunct, a sizable percentage (38.2 %) of patients re‐ quired needling to treat bleb failure and encysted blebs. Nearly half (47.3 %) the patients re‐ quired Nd:YAG laser goniopuncture.

After MTF procedure, there is no scope/necessity for a needling procedure. A bleb leakage never occurs, since a conjunctival flap is not made. The only intervention required/possible is a shot of Nd:YAG laser to disengage the iris if it sticks to the internal opening. If filtration is tardy and the pressure does not come below 20 mm, a combination of timolol and pilocar‐ pine is started. The other medicine is the costlier latanoprost. If that too is ineffective or the patient feels the burden of cost, a re-operation is done. A re-operation is easy, since most of the conjunctiva along with lymphatics is intact.Failure is not an option, since a way can al‐ ways be found to create a new filtration track.

Film: drainage of suprachoroidal fluid.

http://www.youtube.com/watch?v=M35h7JShnqc

Variations in Microtrack Filtration:

MMC may be deposited under the conjunctiva either at the beginning of surgery or at the end of it. We have ample photographic and OCT evidence that the lymphatics are not dam‐ aged by the concentrations used.

A side port incision serves many purposes - to make PI, to inject carbachol or NaHa. The last one is useful if more than one MTF tracks are planned. NaHa does not let the anterior cham‐ ber collapse, which allows a second or even a third MTF.

In some situations, especially repeat failures by any kind of technique, accompanied by sub‐ conjunctival scarring, it may be necessary to make a wider track up to 500 micron (300 mi‐ cron tip at highest energy setting). In a case of perilimbal scar formation, the track formation is started proximal to the scar and a longish track is made through the sclera and limbus in to the anterior chamber.

Pre-tenon MTF:

Postoperative course and management:

450 Glaucoma - Basic and Clinical Aspects

the filtration starts and conjunctival bleb forms.

quired Nd:YAG laser goniopuncture.

ways be found to create a new filtration track.

http://www.youtube.com/watch?v=M35h7JShnqc

Film: drainage of suprachoroidal fluid.

case.

In the beginning the normal subconjunctival tissues offer little resistance to the outward flow of the aqueous. This little resistance is what keeps the anterior chamber formed, even though it is on the shallower side. We need to keep the iris away from the internal opening of the track. Therefore from day one the pupil is kept contracted by pilocarpine 2% three times a day.I firmly believe that lymphatics play a definite role in offering resistance to aqueous outflow. Initially they act as flood drains, but the outflow is so excessive that a big conjunctival bleb is formed. Later the initial rush of aqueous is over. Then sets in a balance between the out going aqueous and the tissue resistance,at least a part of which is resistance from the lymphatics.The anterior chamber begins to deepen. If it deepens too fast, and the bleb begins to dry up, it is a sign of a partial or complete closure of internal opening by the iris which needs early correction. If the block is complete, the pressure goes high and the patient experiences pain and reduction of vision. The tiny internal blockage with iris shuts down the system. The fluid filled subconjunctival tissues start shrinking and become capa‐ ble of greater resistance. The internal block is opened with a shot of Yag laser. Once the fil‐ tration restarts, the chances of its second time failure are much reduced. If the internal block is not opened for many days and weeks, the external opening also gets closed by healing process.Healing starts when fluid movement stops. One to two days of internal closure does not cause irreversible damage to the filtration track.In cases where cross-linked NaHa (Hea‐ laflow) has been used over the external opening track,the fluid movement has been restored after a week or even longer. During these crucial days the patient takes oral diamox and lo‐ cal pilocarpine drops.The moment the tiny piece of iris is detached with a shot of YAG laser,

It is thus clear that the first 3-4 weeks after surgery need very careful watch both by the sur‐ geon and the patient. The vigilance is relaxed but not given up altogether after that. A regu‐ lar follow up on a monthly or two monthly basis is a must for every glaucoma operated

In one recent report (Roy et al 2012) on Deep Sclerectomy in which Healaflow (cross linked sodium hyaluronate)had been used as adjunct, a sizable percentage (38.2 %) of patients re‐ quired needling to treat bleb failure and encysted blebs. Nearly half (47.3 %) the patients re‐

After MTF procedure, there is no scope/necessity for a needling procedure. A bleb leakage never occurs, since a conjunctival flap is not made. The only intervention required/possible is a shot of Nd:YAG laser to disengage the iris if it sticks to the internal opening. If filtration is tardy and the pressure does not come below 20 mm, a combination of timolol and pilocar‐ pine is started. The other medicine is the costlier latanoprost. If that too is ineffective or the patient feels the burden of cost, a re-operation is done. A re-operation is easy, since most of the conjunctiva along with lymphatics is intact.Failure is not an option, since a way can al‐

The tenon capsule gets attached to the limbus, proximal to the attachment of the conjuncti‐ va. Thus there is a potential subconjunctival space distal to the tenon attachment. This pretenon subconjunctival space can be approached to produce a somewhat tangential filtration track at the limbus. A film of this procedure can be see here:

http://www.youtube.com/watch?v=TXAw6tXPDfE&feature=endscreen

#### **2.5. Choroidal detachment**

Hypotony is the probable cause of choroidal detachment. There are greater chances of hy‐ potony In aphakes,vitrectomized eyes, trauma, buphthalmos and high myopia cases.It may start soon after surgery or during the first 2 postoperative days. In some cases there is severe pain at the start. Fundus examination and b-scan reveal choroidal detachment - from slight to kissing choroidals. The situation is watched for a week, after which the suprachoroidal fluid is drained.

The steps of operation are as follows:

The conjunctiva is pushed towards the limbus from a distance of about 8 mm to a distance of 4-5 mm, with a blunt sapphire knife. A 100 micron Fugo blade tip is used to incise the conjunctiva, tenon capsule and the sclera, till supra-choroidal fluid starts draining. When sufficient fluid has drained, air is injected in the anterior chamber. No attempt is made to suture the scleral incision.The tenon capsule and the conjunctiva retract to normal. A couple of sutures are applied to the conjunctival incision.

Film: drainage of suprachoroidal fluid.

http://www.youtube.com/watch?v=M35h7JShnqc

#### **Strategies to improve results with Microtrack Filtration**

The strategies are based on the knowledge that the out coming aqueous is drained by the conjunctival lymphatics.Also on the observation that in the beginning the aqueous outflow is excessive and can sometimes cause excessive shallowing of the anterior chamber, leading to internal closure by the iris.

**5.** Anterior chamber is irrigated with a 30 gauge cannula. It is also used to verify the patency

Minimally Invasive Glaucoma Surgery – Strategies for Success

http://dx.doi.org/10.5772/54421

453

**6.** Microtrack filtration is done as usual. The raised conjunctiva only makes the job easier.

**7.** Air or NaHa or both are injected in the anterior chamber, through the pocket incision.

The shape and the size of the filtration bleb is determined by the sutures.I call it a 'designer bleb'. The purpose is to restrict the outflow of aqueous, which reduces the tendency to shal‐

The resistance from the subconjunctival space between the sutures, can be further increased

Microtrack filtration, with two conjunctival sutures to restrain lymphatics is shown here:

**Figure 13.** Bleb resulting from two conjunctival sutures, 5 months after surgery.The IOP is 12 mm from the initial 40 mm.The bleb has a good conjunctival cover. The proximal end of the bleb shows pleating. OCT shows the effect of

two conjunctival sutures.There is a small kink. Lymphatics are also visible.

NaHa can also be placed under the conjunctiva, between the two sutures.

lowing of the anterior chamber, in the early postoperative period.

http://www.youtube.com/watch?v=YYwalTIXQ0s

by putting cross linked NaHa (Healaflow) or collagen matrix (Ologen).

The purpose of every exercise is to control the depth of the anterior chamber.

of iridotomies.

**Figure 12.** The ballooned conjunctiva is tied vertically on either side of 12 O' clock.Fugo blade is passed under the conjunctiva, taken to the limbus and MTF track made.A bleb gets formed.Air is injected in to the anterior chamber.

#### **2.6. Tying the lymphatics**

On either side of the proposed site of MTF, the conjunctiva is tied like a sheaf with a 10 zero suture. This ties the subconjunctival lymphatics too.

The steps of operation are as follows:


The shape and the size of the filtration bleb is determined by the sutures.I call it a 'designer bleb'. The purpose is to restrict the outflow of aqueous, which reduces the tendency to shal‐ lowing of the anterior chamber, in the early postoperative period.

The resistance from the subconjunctival space between the sutures, can be further increased by putting cross linked NaHa (Healaflow) or collagen matrix (Ologen).

The purpose of every exercise is to control the depth of the anterior chamber.

Microtrack filtration, with two conjunctival sutures to restrain lymphatics is shown here:

http://www.youtube.com/watch?v=YYwalTIXQ0s

is excessive and can sometimes cause excessive shallowing of the anterior chamber, leading

**Figure 12.** The ballooned conjunctiva is tied vertically on either side of 12 O' clock.Fugo blade is passed under the conjunctiva, taken to the limbus and MTF track made.A bleb gets formed.Air is injected in to the anterior chamber.

On either side of the proposed site of MTF, the conjunctiva is tied like a sheaf with a 10 zero

**2.** Injecting MMC 0.01%, 0.02 % through a 30 gauge cannula, to raise the conjunctiva widely,

**3.** A suture is tied at 1 O' clock, starting near the limbus and getting out of the conjunctiva, three or four mm proximally. The bite catches the subconjunctival lymphatics along with the conjunctiva. The suture may be 10 zero prolene or 30 micron steel.It may be tied loosely with the intention of removing it after a few days. Or it may be tied fast, the intention being to leave the suture permanently. The second suture is tied at 11 O' clock. The con‐

**4.** A 0.75 mm corneal pocket incision is made close to the limbus, through which two iri‐ dotomies are made with a 2 mm long 100 micron Fugo blade tip. Highest energy is given

to internal closure by the iris.

452 Glaucoma - Basic and Clinical Aspects

**2.6. Tying the lymphatics**

The steps of operation are as follows:

between 11 and 1 O' clock.

to the tip to do iridotomy.

suture. This ties the subconjunctival lymphatics too.

junctiva gets raised between the two sutures.

**1.** Making a hole in the conjunctiva close to the limbus of 10' O clock.

**Figure 13.** Bleb resulting from two conjunctival sutures, 5 months after surgery.The IOP is 12 mm from the initial 40 mm.The bleb has a good conjunctival cover. The proximal end of the bleb shows pleating. OCT shows the effect of two conjunctival sutures.There is a small kink. Lymphatics are also visible.
