**6. Medical and surgical treatment of neovascular glaucoma**

The management of neovascular glaucoma is summarized in figure 5, and depends on whether the angle is open or closed, and whether media are clear or not in order to correctly visualize the retina. Management can be divided in:

Measures to decrease the amount of VEGF produced by the retina, or its effects: Pan-retinal photocoagulation, antiangiogenic drugs and/or pars-plana vitrectomy.

Measures to control intraocular pressure: Medications to reduce intraocular pressure and/or filtering procedures.

#### **6.1. Pan-retinal photocoagulation**

Neovascular glaucoma is best treated with prevention. Since retinal ischemia (and VEGF production) is the main predisposing factor for the development of rubeosis iridis, angle ne‐ ovascularization and NVG, laser photocoagulation to the areas of retinal ischemia continues to be one of the mainstays of treatment, and should be performed promptly in patients with NVG that have media clear enough for the treatment to be delivered.

**6.2. Antiangiogenic drugs**

anti-VEGF drugs have proven to be of great value.

ture describing the use of this drug.

its use despite a greater cost per dose.

ance of iris and/or angle neovascularization (Kahook MY, 2006).

As stated above, VEGF is the main molecule responsible for the development of neovascula‐ rization, and therefore neovascular glaucoma. Pan-retinal photocoagulation is very effective for long-term suppression of VEGF, but the decline of such levels tends to take place gradu‐ ally after treatment, which in theory could leave a time window for the disease to progress. Besides, the need of clear media for PRP treatment of most, if not all, the hypoxic retina may also increase the time before those VEGF levels begin to decrease. To address this problem,

Neovascular Glaucoma http://dx.doi.org/0.5772/53115 345

Since their appearance, both bevacizumab and later ranibizumab (Avastin and Lucentis, Genentech-Roche, South San Francisco, CA) have been used as adjuvants for the treatment of neovascular glaucoma. Injection of a single dose in most cases results in brisk disappear‐

The administration of bevacizumab has been shown to dramatically reduce VEGF levels in the aqueous humor after intracameral injection (Sasamoto Y, 2012) and to reduce edema, fi‐ brin deposition, inflammation and vascular congestion in trabecular meshwork specimens obtained during trabeculectomy performed after intravitreal injection.(Yoshida N, 2011) Several studies have found intravitreal bevacizumab to be of great value as an adjunct to the treatment of neovascular glaucoma of diverse etiologies, causing prompt regression of ante‐ rior segment neovascularization (ASNV), and better control of intraocular pressure.(Ehlers JP, 2008. Wakabayashi T, 2008. Yazdani S, 2009. Beutel J. 2010) Good results have also been obtained with ranibizumab (Caujolle JP, 2012), although there are fewer studies in the litera‐

These agents have also been used for reducing fibrosis in failed filtering blebs (Kahook MY, 2006b) and even for wound modulation in primary trabeculectomies (Horsley et al, 2010) and Ahmed valve implants (Rojo-Arnao, Albis-Donado et al, 2011). A similar trend has been observed with Ranibizumab, a drug designed for intraocular delivery, with an expanding range of on- and off-label indications (Kumar et al, 2012, Mota et al. 2012, Desai et al. 2012, Auila JS, 2012), especially since a potentially deleterious accumulation of Bevacizumab in retinal pigment epithelial cells (Deissler at al. 2012) and approval of Ranibizumab in Europe (and more recently by the FDA) for diabetic macular edema have recently further increased

As with any procedure, there are complications that have been reported with the use of anti-VEGF drugs. Most of the adverse effects are the ones expected with any intraocular injec‐ tion, such as subconjunctival hemorrhage, lens damage, or endophthalmitis (Gordon-Angelozzi M, 2009). Other complications, however, are not related to the procedure but to the effect of the drug itself, such as a decrease in the electroretinogram response (Wittström E, 2012), central retinal artery occlusion in eyes with ocular ischemic syndrome (Higashide T, 2012), abrupt angle closure (Canut MI, 2011), or induction of tractional retinal detachment in eyes with abundant retinal neovascular proliferations (Torres-Soriano M, 2009. Arevalo

JF, 2008), and should therefore be used with caution in patients at risk.

The rationale behind pan-retinal photocoagulation (PRP) is to preserve central vision, if pos‐ sible, by sacrificing peripheral vision. Retinal ablation is thought to reduce the metabolic needs of the hypoxic retina by reducing the total amount of functional retina, so remaining retinal circulation is sufficient to prevent further production of vessel growth factors by the non-ablated retinal tissue.

For the treatment to be applied correctly, a fluorescein angiogram is necessary, in order to determine the presence of areas of retinal non-perfusion and retinal neovascularization. Treatment is applied under pharmacologic mydriasis, using a wide-field contact lens (such as the Super-Quad or Mainster lenses). The parameters for retinal photocoagulation used in the ETDRS are preferred (ETDRS, 1987: A spot diameter of 500 µm, 100 msec duration and enough power to produce a gray-whitish burn on the retina, with a separation between spots of 250 µm), and the whole treatment is delivered in one session, if possible, in order to ablate the largest area of retina possible.

If there are concerns regarding possible complications of an excessive photocoagulation, such as serous retinal detachment or choroidal detachment, reduced fluence parameters may be used (spot diameter of 500 µm, 20 msec duration and power enough to produce a gray-whitish burn on the retina), which have proven to be effective, (Muqit MM, 2011) and to cause less discomfort to the patient (Alvarez-Verduzco O, Garcia-Aguirre G, 2010). These reduced fluence parameters may be used with the Pattern Scan Laser (PaScaL photocoagula‐ tor, OptiMedica) (Velez-Montoya R, Guerrero-Naranjo JL, 2010), or with a standard 532 nm laser (Alvarez-Verduzco O, Garcia-Aguirre G, 2010).

PRP has proven to be effective for the prevention of neovascular glaucoma secondary to dia‐ betic retinopathy (The Diabetic Retinopathy Study Research Group, 1976) and central retinal vein occlusion, (Central Vein Occlusion Study Group, 1996) which are the most frequent causal entities. Some concerns have been raised, however, regarding the efficacy of this treatment in central retinal vein occlusion (Hayreh SS, 2007).

The timing of PRP is critical, regarding final visual acuity and NVG prevention. It takes about 4 weeks for PRP to show regression of anterior segment neovascularization (ASNV), and this is thought to depend on the pre-existing levels of vitreous growth factors, mainly vascular endothelial growth factor (VEGF). Once PRP stops the hypoxic retina from produc‐ ing additional growth factors, existing VEGF and other factors remain in the vitreous for a period during which additional vessel growth may still occur under their influence.

To further complicate matters, a PRP treatment may need 2 or 3 sessions in order to be com‐ plete (2000 to 2500 shots), and these sessions are frequently done 2 to 4 weeks apart to avoid excessive inflammation. The period between sessions before a full-treatment has been given is also a period during which further VEGF production may be taking place, especially in the most hypoxic retinas.

#### **6.2. Antiangiogenic drugs**

to be one of the mainstays of treatment, and should be performed promptly in patients with

The rationale behind pan-retinal photocoagulation (PRP) is to preserve central vision, if pos‐ sible, by sacrificing peripheral vision. Retinal ablation is thought to reduce the metabolic needs of the hypoxic retina by reducing the total amount of functional retina, so remaining retinal circulation is sufficient to prevent further production of vessel growth factors by the

For the treatment to be applied correctly, a fluorescein angiogram is necessary, in order to determine the presence of areas of retinal non-perfusion and retinal neovascularization. Treatment is applied under pharmacologic mydriasis, using a wide-field contact lens (such as the Super-Quad or Mainster lenses). The parameters for retinal photocoagulation used in the ETDRS are preferred (ETDRS, 1987: A spot diameter of 500 µm, 100 msec duration and enough power to produce a gray-whitish burn on the retina, with a separation between spots of 250 µm), and the whole treatment is delivered in one session, if possible, in order to

If there are concerns regarding possible complications of an excessive photocoagulation, such as serous retinal detachment or choroidal detachment, reduced fluence parameters may be used (spot diameter of 500 µm, 20 msec duration and power enough to produce a gray-whitish burn on the retina), which have proven to be effective, (Muqit MM, 2011) and to cause less discomfort to the patient (Alvarez-Verduzco O, Garcia-Aguirre G, 2010). These reduced fluence parameters may be used with the Pattern Scan Laser (PaScaL photocoagula‐ tor, OptiMedica) (Velez-Montoya R, Guerrero-Naranjo JL, 2010), or with a standard 532 nm

PRP has proven to be effective for the prevention of neovascular glaucoma secondary to dia‐ betic retinopathy (The Diabetic Retinopathy Study Research Group, 1976) and central retinal vein occlusion, (Central Vein Occlusion Study Group, 1996) which are the most frequent causal entities. Some concerns have been raised, however, regarding the efficacy of this

The timing of PRP is critical, regarding final visual acuity and NVG prevention. It takes about 4 weeks for PRP to show regression of anterior segment neovascularization (ASNV), and this is thought to depend on the pre-existing levels of vitreous growth factors, mainly vascular endothelial growth factor (VEGF). Once PRP stops the hypoxic retina from produc‐ ing additional growth factors, existing VEGF and other factors remain in the vitreous for a

To further complicate matters, a PRP treatment may need 2 or 3 sessions in order to be com‐ plete (2000 to 2500 shots), and these sessions are frequently done 2 to 4 weeks apart to avoid excessive inflammation. The period between sessions before a full-treatment has been given is also a period during which further VEGF production may be taking place, especially in

period during which additional vessel growth may still occur under their influence.

NVG that have media clear enough for the treatment to be delivered.

non-ablated retinal tissue.

344 Glaucoma - Basic and Clinical Aspects

the most hypoxic retinas.

ablate the largest area of retina possible.

laser (Alvarez-Verduzco O, Garcia-Aguirre G, 2010).

treatment in central retinal vein occlusion (Hayreh SS, 2007).

As stated above, VEGF is the main molecule responsible for the development of neovascula‐ rization, and therefore neovascular glaucoma. Pan-retinal photocoagulation is very effective for long-term suppression of VEGF, but the decline of such levels tends to take place gradu‐ ally after treatment, which in theory could leave a time window for the disease to progress. Besides, the need of clear media for PRP treatment of most, if not all, the hypoxic retina may also increase the time before those VEGF levels begin to decrease. To address this problem, anti-VEGF drugs have proven to be of great value.

Since their appearance, both bevacizumab and later ranibizumab (Avastin and Lucentis, Genentech-Roche, South San Francisco, CA) have been used as adjuvants for the treatment of neovascular glaucoma. Injection of a single dose in most cases results in brisk disappear‐ ance of iris and/or angle neovascularization (Kahook MY, 2006).

The administration of bevacizumab has been shown to dramatically reduce VEGF levels in the aqueous humor after intracameral injection (Sasamoto Y, 2012) and to reduce edema, fi‐ brin deposition, inflammation and vascular congestion in trabecular meshwork specimens obtained during trabeculectomy performed after intravitreal injection.(Yoshida N, 2011) Several studies have found intravitreal bevacizumab to be of great value as an adjunct to the treatment of neovascular glaucoma of diverse etiologies, causing prompt regression of ante‐ rior segment neovascularization (ASNV), and better control of intraocular pressure.(Ehlers JP, 2008. Wakabayashi T, 2008. Yazdani S, 2009. Beutel J. 2010) Good results have also been obtained with ranibizumab (Caujolle JP, 2012), although there are fewer studies in the litera‐ ture describing the use of this drug.

These agents have also been used for reducing fibrosis in failed filtering blebs (Kahook MY, 2006b) and even for wound modulation in primary trabeculectomies (Horsley et al, 2010) and Ahmed valve implants (Rojo-Arnao, Albis-Donado et al, 2011). A similar trend has been observed with Ranibizumab, a drug designed for intraocular delivery, with an expanding range of on- and off-label indications (Kumar et al, 2012, Mota et al. 2012, Desai et al. 2012, Auila JS, 2012), especially since a potentially deleterious accumulation of Bevacizumab in retinal pigment epithelial cells (Deissler at al. 2012) and approval of Ranibizumab in Europe (and more recently by the FDA) for diabetic macular edema have recently further increased its use despite a greater cost per dose.

As with any procedure, there are complications that have been reported with the use of anti-VEGF drugs. Most of the adverse effects are the ones expected with any intraocular injec‐ tion, such as subconjunctival hemorrhage, lens damage, or endophthalmitis (Gordon-Angelozzi M, 2009). Other complications, however, are not related to the procedure but to the effect of the drug itself, such as a decrease in the electroretinogram response (Wittström E, 2012), central retinal artery occlusion in eyes with ocular ischemic syndrome (Higashide T, 2012), abrupt angle closure (Canut MI, 2011), or induction of tractional retinal detachment in eyes with abundant retinal neovascular proliferations (Torres-Soriano M, 2009. Arevalo JF, 2008), and should therefore be used with caution in patients at risk.

When anti-angiogenics are used before angle-closure has happened, ASNV regression will prevent IOP elevation, it may revert IOP elevation associated with angle neovessels or at least make it amenable to be medically controlled, and, subsequently, it can also prevent an‐ gle-closure and a more aggressive IOP elevation. During this period the media may clear enough for PRP to be completed or initiated.

ture or the second stage procedure, or it may happen on its own 3 to 6 weeks later for the

Neovascular Glaucoma http://dx.doi.org/0.5772/53115 347

Since many eyes might still have elevated IOP during this period, damage to the optic nerve may become so advanced as to make the eye legally or even fully blind. A metanalysis com‐ paring restrictive and non-restrictive implants has shown that the mean rate of decrease in visual acuity tends to be lower for the Ahmed valve (19 to 24%) as compared to the other devices (27 to 33%, Hong et al. 2005, Albis-Donado 2009). IOP control from day one and sub‐ sequent better visual results have made the Ahmed valve the implant of choice in our hospi‐

Our simpler surgical technique, without the use of a scleral graft patch, has been routinely used for the past 19 years and has been described elsewhere (Gil-Carrasco et al.1998, Albis-Donado, 2006, Albis-Donado et al. 2010). In brief, a fornix-based conjunctival flap is made in the designated quadrant, and then the valve is primed with BSS and fixated 8 to 10 mm be‐ hind the limbus with 7-0 silk. A scleral tunnel initiated 3-4 mm from the limbus is construct‐ ed using a 22 or 23 G needle, bent as a "Z" to avoid obstruction from the eyelids, brow or lid

The needle is passed bevel-up under the episclera, in a tangential direction; at the limbus the direction is abruptly changed to make the tunnel parallel to the iris, attempting to enter through the trabecular meshwork. The tube is then trimmed to create a 30-45º bevel and in‐ serted through the tunnel into the anterior chamber, leaving the tip at least 2 mm from the limbus. The conjunctiva is closed using the same 7-0 silk in cooperating adults. Post-opera‐ tive regimen includes steroid drops in a reducing dose for 3 months, antibiotic drops for 2

The most common complications after an Ahmed valve implant in NVG are hyphema (up to 45% without bevacizumab, and reduced to about 8% with an injection 1 day before the implant), and flat anterior chamber (around 32%, especially in phakic eyes, Albis-Donado

In the long term the most common complication is elevation of IOP during the so termed hypertensive phase, but that might become permanent, both are thought to occur due to fib‐ rosis around the plate. A tendency for lower rates of IOP elevation with the use of antiangio‐ genic drugs has been reported (Ehlers JP, 2008. Wakabayashi T, 2008. Yazdani S, 2009.

Removal of the fibrous tissue around the implant, adjuvant aqueous suppressants and mas‐

A significant proportion of eyes with neovascular glaucoma have significant media opacities that preclude adequate panretinal photocoagulation. In such cases, vitreoretinal surgery plays an important role in its management, since it allows to clear the media opacities, to repair the damaged posterior segment and/or to deliver laser treatment via endophotocoa‐

absorbable suture.

tal for NVG.

speculum.

et al, 2012).

*6.4.2. Pars plana vitrectomy*

weeks, and a cycloplegic for the first month.

Beutel J. 2010, Rojo-Arnao et al, 2011, Caujolle JP, 2012).

sage might also be of value for the long-term of IOP control.

#### **6.3. Medical management of glaucoma**

Once IOP is elevated in NVG cases medical therapy with aqueous production suppressors should be initiated. Topical beta-blockers, topical and oral carbonic anhydrase inhibitors and alpha-2-adrenergic agonists are used, whereas prostaglandin analogues, should not be used because they increase inflammation and may not even lower IOP, unless ASNV has re‐ gressed and has a low chance of reappearing, although the exact IOP lowering and safety profile in these patients is still in controversy.

Topical corticosteroids are used concurrently to treat associated inflammation, and may ac‐ tually help to prevent further angle closure during the initial phase. Atropine may also be used for its cycloplegic effect, but in addition to increasing uveoscleral outflow and maybe lower IOP, it may also help prevent miotic pupillary block, stabilize the blood-aqueous bar‐ rier and facilitate posterior segment visualization and treatment. Pilocarpine and other anti‐ cholinergic agents are contra-indicated, as they increase inflammation, cause miosis, worsen synechial angle closure and decrease uveoscleral outflow.

In most cases of NVG in closed angle-phases, medical therapy may not be enough to control IOP and prevent visual loss. (Kurt Spiteri Cornish. 2011). If angle-closure has already hap‐ pened an Ahmed valve-implant is recommended. It may also be needed for around 15% of open-angle phase NVG that remain with elevated IOP, despite anti-angiogenic therapy and adequate PRP. The immediate effect of previously administered intra-vitreous anti-angio‐ genics during surgery is a reduced tendency for bleeding at the time of tube insertion. On the long term a tendency for better IOP control has been reported (Desai et al. 2012).

#### **6.4. Surgical management of neovascular glaucoma**

#### *6.4.1. Tube-shunt surgery*

Glaucoma implants have made it possible to save many eyes with NVG from becoming blind, painful eyes. They have also made it possible to preserve useful vision, specially when IOP can be controlled from the day surgery is performed. Using non-valved implants (such as Barveldt or Molteno setons) requires the use of hypotony prevention strategies that have included a two-stage operation, tying off the tube with an absorbable suture or the use of a suture threaded inside the tube.

The idea is to let fibrous tissue grow around the implant, forming a semi-permeable barrier that will eventually absorb excess aqueous. Depending on the chosen strategy, the opening of the implant can be programmed for a couple of weeks in the future for the removable su‐ ture or the second stage procedure, or it may happen on its own 3 to 6 weeks later for the absorbable suture.

Since many eyes might still have elevated IOP during this period, damage to the optic nerve may become so advanced as to make the eye legally or even fully blind. A metanalysis com‐ paring restrictive and non-restrictive implants has shown that the mean rate of decrease in visual acuity tends to be lower for the Ahmed valve (19 to 24%) as compared to the other devices (27 to 33%, Hong et al. 2005, Albis-Donado 2009). IOP control from day one and sub‐ sequent better visual results have made the Ahmed valve the implant of choice in our hospi‐ tal for NVG.

Our simpler surgical technique, without the use of a scleral graft patch, has been routinely used for the past 19 years and has been described elsewhere (Gil-Carrasco et al.1998, Albis-Donado, 2006, Albis-Donado et al. 2010). In brief, a fornix-based conjunctival flap is made in the designated quadrant, and then the valve is primed with BSS and fixated 8 to 10 mm be‐ hind the limbus with 7-0 silk. A scleral tunnel initiated 3-4 mm from the limbus is construct‐ ed using a 22 or 23 G needle, bent as a "Z" to avoid obstruction from the eyelids, brow or lid speculum.

The needle is passed bevel-up under the episclera, in a tangential direction; at the limbus the direction is abruptly changed to make the tunnel parallel to the iris, attempting to enter through the trabecular meshwork. The tube is then trimmed to create a 30-45º bevel and in‐ serted through the tunnel into the anterior chamber, leaving the tip at least 2 mm from the limbus. The conjunctiva is closed using the same 7-0 silk in cooperating adults. Post-opera‐ tive regimen includes steroid drops in a reducing dose for 3 months, antibiotic drops for 2 weeks, and a cycloplegic for the first month.

The most common complications after an Ahmed valve implant in NVG are hyphema (up to 45% without bevacizumab, and reduced to about 8% with an injection 1 day before the implant), and flat anterior chamber (around 32%, especially in phakic eyes, Albis-Donado et al, 2012).

In the long term the most common complication is elevation of IOP during the so termed hypertensive phase, but that might become permanent, both are thought to occur due to fib‐ rosis around the plate. A tendency for lower rates of IOP elevation with the use of antiangio‐ genic drugs has been reported (Ehlers JP, 2008. Wakabayashi T, 2008. Yazdani S, 2009. Beutel J. 2010, Rojo-Arnao et al, 2011, Caujolle JP, 2012).

Removal of the fibrous tissue around the implant, adjuvant aqueous suppressants and mas‐ sage might also be of value for the long-term of IOP control.

#### *6.4.2. Pars plana vitrectomy*

When anti-angiogenics are used before angle-closure has happened, ASNV regression will prevent IOP elevation, it may revert IOP elevation associated with angle neovessels or at least make it amenable to be medically controlled, and, subsequently, it can also prevent an‐ gle-closure and a more aggressive IOP elevation. During this period the media may clear

Once IOP is elevated in NVG cases medical therapy with aqueous production suppressors should be initiated. Topical beta-blockers, topical and oral carbonic anhydrase inhibitors and alpha-2-adrenergic agonists are used, whereas prostaglandin analogues, should not be used because they increase inflammation and may not even lower IOP, unless ASNV has re‐ gressed and has a low chance of reappearing, although the exact IOP lowering and safety

Topical corticosteroids are used concurrently to treat associated inflammation, and may ac‐ tually help to prevent further angle closure during the initial phase. Atropine may also be used for its cycloplegic effect, but in addition to increasing uveoscleral outflow and maybe lower IOP, it may also help prevent miotic pupillary block, stabilize the blood-aqueous bar‐ rier and facilitate posterior segment visualization and treatment. Pilocarpine and other anti‐ cholinergic agents are contra-indicated, as they increase inflammation, cause miosis, worsen

In most cases of NVG in closed angle-phases, medical therapy may not be enough to control IOP and prevent visual loss. (Kurt Spiteri Cornish. 2011). If angle-closure has already hap‐ pened an Ahmed valve-implant is recommended. It may also be needed for around 15% of open-angle phase NVG that remain with elevated IOP, despite anti-angiogenic therapy and adequate PRP. The immediate effect of previously administered intra-vitreous anti-angio‐ genics during surgery is a reduced tendency for bleeding at the time of tube insertion. On

Glaucoma implants have made it possible to save many eyes with NVG from becoming blind, painful eyes. They have also made it possible to preserve useful vision, specially when IOP can be controlled from the day surgery is performed. Using non-valved implants (such as Barveldt or Molteno setons) requires the use of hypotony prevention strategies that have included a two-stage operation, tying off the tube with an absorbable suture or the use

The idea is to let fibrous tissue grow around the implant, forming a semi-permeable barrier that will eventually absorb excess aqueous. Depending on the chosen strategy, the opening of the implant can be programmed for a couple of weeks in the future for the removable su‐

the long term a tendency for better IOP control has been reported (Desai et al. 2012).

enough for PRP to be completed or initiated.

profile in these patients is still in controversy.

synechial angle closure and decrease uveoscleral outflow.

**6.4. Surgical management of neovascular glaucoma**

*6.4.1. Tube-shunt surgery*

of a suture threaded inside the tube.

**6.3. Medical management of glaucoma**

346 Glaucoma - Basic and Clinical Aspects

A significant proportion of eyes with neovascular glaucoma have significant media opacities that preclude adequate panretinal photocoagulation. In such cases, vitreoretinal surgery plays an important role in its management, since it allows to clear the media opacities, to repair the damaged posterior segment and/or to deliver laser treatment via endophotocoa‐ gulation probes. For this reason, several studies have been conducted to explore the useful‐ ness of posterior segment procedures for the treatment of neovascular glaucoma, most of the time performed in conjunction with filtering surgery.

One of the earliest studies was published in 1982 by Sinclair et al, who performed pars plana vitrectomy and lensectomy, and an sclerectomy in 14 eyes with neovascular glaucoma, with poor results. After six months, 64% of eyes had maintained or improved visual acuity, 7% had decreased visual acuity, and 28% lost light perception. This procedure had several com‐ plications, including fibrinous vitritis (71%), suprachoroidal hemorrhage (14%), endophthal‐ mitis (7%), retinal detachment (7%) and phthisis bulbi (14%).

Several years later, in 1991, Lloyd et al reported the results of a study in which pars plana vitrectomy and a pars plana Molteno implant were performed in 10 eyes, achieving control of intraocular pressure (21 mmHg or less) in 6 of them. However, three eyes developed vit‐ reous hemorrhage, three developed retinal detachment and two lost light perception.

In 1993, Gandham et al published a study of 20 eyes with glaucoma of difficult management (8 out of which had neovascular glaucoma), that underwent pars plana vitrectomy, and placement of a Molteno or Schocket implant. In six out of the eight eyes (75%), an intraocu‐ lar pressure of 22 mmHg or less was achieved.

In 1995, Luttrull and Avery reported 22 eyes in which pars plana vitrectomy and a pars pla‐ na Molteno implant placement were performed. As an additional procedure, either a liga‐ ture of the implant tube with absorbable suture or perfluropropane gas tamponade were performed, in order to avoid postoperative hypotony. With this procedure, an intraocular pressure of 21 mmHg or less was achieved in all eyes, and stabilization or improvement of visual acuity was achieved in 86% of eyes. Among the postoperative complications, retinal detachement was observed in two eyes, and loss of light perception in one eye.

**7. Conclusions**

to his/her own condition.

lenging course of treatment.

vented or treated the worst cases of NVG.

The physiopathology of NVG involves various biochemical and biological mechanisms that result in the presence of abnormal vessels that lead to the clinical forms of the disease. This natural history can be modified and steered into a more appropriate and less devastating be‐ havior, depending on the sagacity of the physician and the commitment that the patient has

**Figure 5.** Management of Neovascular Glaucoma. IOP: Intraocular pressure; PRP: Panretinal photocoagulation; IVB: Intravitreal bevacizumab; Topical IOP lowering drugs; FP: Filtering procedure (Ahmed valve); PRP 2wk: Panretinal pho‐

Neovascular Glaucoma http://dx.doi.org/0.5772/53115 349

tocoagulation 2 weeks after the procedure PPV+EPC: Pars plana vitrectomy and endophotocoagulation.

One fundamental aspect of NVG management is the treatment of the underlying condition that caused it. Uncontrolled diabetes, systemic hypertension, vascular diseases, and even primary open angle glaucoma are all modifiable factors that may reduce the incidence of NVG. Periodic ophthalmology visits for patients at risk should be part of their primary care,

What used to be a condition that was a synonym for irreversible, painful blindness is now expected to be controllable to a degree compatible with useful vision, but through a chal‐

Three strategies for preserving vision have increasingly improved the visual prognosis in NVG patients. First was the advent of Panretinal Photocoagulation, when done on time pre‐

especially since the prevalence of these systemic conditions seems to be on the rise.

More recently, Faghihi et al in 2007 published their experience in 18 eyes with neovascular glaucoma that underwent pars plana vitrectomy and pars plana Ahmed valve implant. An intraocular pressure of 21 or less was achieved in 13 eyes (72.2%). Light perception was lost in two eyes and two evolved to phthisis bulbi.

In these four studies, the justification to introduce the tube through the pars plana into the vitreous cavity instead of the anterior chamber was to avoid complications such as hyphema or blockage of the tube by a fibrovascular membrane.

#### *6.4.3. Cycloablation*

The main goal in the struggle with neovascular glaucoma in blind eyes is to control intraoc‐ ular pressure (IOP) and pain. (A Janićijević-Petrović M, 2012). In one prospective study the average value of IOP and eyeball pain intensity was significantly lower after cyclocryocoa‐ gulation. Cyclocryocoagulation could be a good method in the treatment of uncontrolled elevated IOP and pain of progressive NVG resistant to medical and surgical treatment, but does not have any effect on the improvement of sight in these patients. (Kovacić Z, Ivanisev‐ ić M, 2004)

**Figure 5.** Management of Neovascular Glaucoma. IOP: Intraocular pressure; PRP: Panretinal photocoagulation; IVB: Intravitreal bevacizumab; Topical IOP lowering drugs; FP: Filtering procedure (Ahmed valve); PRP 2wk: Panretinal pho‐ tocoagulation 2 weeks after the procedure PPV+EPC: Pars plana vitrectomy and endophotocoagulation.
