**9. Glaucoma drainage implants**

Drainage implants drain the aqueous humour to the subconjunctival space. They are consid‐ ered if one or two trabeculectomies with MMC fail or if extensive conjunctival scarring ex‐ ists. [51] Some authors who have favorable outcomes with glaucoma drainage implant select it as the procedure of choice in uveitic glaucoma. [52], [53] Two types of drainage implants exist. The first type is with control of the flow (with a "valve" or flow resistance) and in‐ cludes Ahmed (New World Medical, Rancho Cucamonga, CA) and Krupin-Denver (Hood Laboratories, Pembroke, MA) drainage implants. The second type is without pressure con‐ trol (no valve) and includes Molteno single or double plate (IOP, Inc., Costa Mesa, CA, USA, and Molteno OpLimited, Dunedin, New Zealand), Baerveldt (Advanced Medical Optics, Santa Ana, California, USA), Shocket (self-assembled) and Eagle Vision (Eagle Vision, Inc. Memphis, TN, USA) implants. The later require blocking the aqueous flow for a few days externally by temporary suture or internally passing a suture through the lumen of the tube or injecting viscoelastic agent. The implantation may also be performed as a two-stage im‐ plantation, to decrease the risk for postoperative hypotony. Ahmed and Krupin implants should be preferred over the implants without a valve, because the risk for postoperative overflow and hypotony that may result in endothelial-iris and lens touch. This is more prev‐ alent in patients with uveitis than without it because the aqueous production is usually low. Ahmed valve has convenient plate of variable sizes including for pediatric population.

The success rate of Ahmed implant in uveitic glaucoma at one year is 77-94% and at 4 years 50%. [54]- [56] The success rate of Baeveldt implant at 1 year is 92%. [47] A decrease in cor‐ neal endothelial cell count has been observed with glaucoma drainage devices (Ahmed) in comparison with non-valved implanted eyes. The decrease in endothelium is related to the age of the patient, duration of the uveitis and presence of the implant and corneal-valve touch. [57]

#### **9.1. ExPress shunt**

gery for uveitic eyes as it does in congenital cataract surgery. [40] Glaucoma surgery may be combined with cataract extraction. The data on the newer procedures in uveitic glaucoma are limited. Detailed description of the newer devices can be found in chapter 19 in this book, chapter 20 in Rumelt S. Ed. Glaucoma – basic and clinical concepts. Rijeka, Croatia: Intech 2011 and chapter 17 in Rumelt S. Ed. Advances in ophthalmology. Rijeka, Croatia: In‐

As for all secondary glaucomas, uveitic glaucoma that does not respond to medical treat‐ ment should be treated with trabeculectomy and mitomycin C (MMC) or other shunting procedure. [41]-[46] Without MMC, trabeculectomy may fail. Trabeculectomy with MMC is indicated for open and closed angle glaucomas. MMC decreases the risk of scarring of the filtering bleb, which is higher in uveitic glaucoma than in primary glaucomas, because of the increased postoperative inflammation. MMC 0.04% may be applied for 3 min under the scleral flap (or the conjunctiva) avoiding the conjunctival margins. Copious BSS irrigation is

The cumulative probability for success of trabeculectomy with MMC or 5-fluorouracil at 1 and 2 years was 78 and 68% respectively. [4] Risk factors for failure include male gender and young age. [47] The use of spacers such as collagen matrix (Ologen®) or other biodegrada‐ ble material may prove to be beneficial as well as injection of subconjunctival bevacizumab

Non-penetrating glaucoma surgery (NPGS) is a filtration procedure in which the anterior chamber is not penetrated. [48]- [50] It is based on creation of a partial thickness scleral flap and a deep pocket in the area of the outer wall of the Schlemm's canal. It involves the Schlemm's canal without penetrating its inner wall. Three variations of the procedure exist: canaloplasty, viscocanalostomy and deep sclerostomy. In the first procedure, a 10-0 nylon is passed through the Schlemm's canal while in the second, viscoelastic agent such as hyalur‐ onic acid (Healon®) is injected into the canal. The aqueous flows through the trabeculo-De‐ scemet's membrane into scleral pocket and from there to surrounding blood and aqueous vessels. The NPGS with intraoperative MMC is promising showing good short-term (be‐

Drainage implants drain the aqueous humour to the subconjunctival space. They are consid‐ ered if one or two trabeculectomies with MMC fail or if extensive conjunctival scarring ex‐ ists. [51] Some authors who have favorable outcomes with glaucoma drainage implant select

tech 2012.

**7.3. Trabeculectomy**

370 Glaucoma - Basic and Clinical Aspects

performed to remove the free MMC.

**9. Glaucoma drainage implants**

2.5mg/0.1ml.These should be evaluated for uveitic glaucoma.

**8. Non-Penetrating Glaucoma Surgery (NPGS)**

tween one and three years) success, but a long follow-up is required.

It is expected that this device will have the advantages of trabeculectomy (guarded filtra‐ tion) and other glaucoma drainage device (uniform internal opening) as long as it will not be blocked by inflammatory products. We have found that it is beneficial in secondary glau‐ comas including uveitic glaucoma (in publication). The only exceptions are neovascular glaucoma and iridocorneal endothelial syndrome where it usually fails. No other data are available on the outcome of ExPress implantation in uveitic glaucoma.

#### **9.2. IStent**

IStent is a titanium device that is placed into the Schlemm's canal through the anterior chamber. This device may be effective in secondary glaucoma and may decrease the require‐ ment for postoperative hypotensive medications. It has not been proven yet to be effective in uveitic glaucoma.

#### **9.3. Trabectome**

Trabectome is a micro-electrical device that removes the trabecular meshwork and unroof the Schlemm's canal under gonioscopy to decrease the resistance to aqueous outflow. No re‐ sults of this device in uveitic glaucoma are available. It is expected that it will have only a temporary effect if the uveitis persists, since new inflammatory products may gradually ob‐ struct the surgical site.

**12. Summary**

**Author details**

Shimon Rumelt

**References**

2001:17-23.

Ophthalmol 1992;23:33-4.

uveitis. Ophthalmologica 1999;213:300-4.

dary glaucoma. Jpn J Ophthalmol 2002;46:556-62.

referral center. Ocul Immunol Inflamm 2009;17:243-8.

2004:111:491-500.

required to determine the best approach.

Uveitic glaucoma is a heterogeneous group of diseases in which glaucoma develops secon‐ dary to uveitis. The diagnosis is based on elevated IOP. Periodic evaluation of the optic disc should be made, and in patients with cup/disc ratio of 0.6 or more, visual field evaluations should be obtained. The management includes treating the uveitis, glaucoma and the under‐ lying disorder. Most of the uveitis types should be treated although uveitis in juvenile rheu‐ matoid arthritis requires minimal medical treatment to obtain remission and the uveitis in Fuchs' heterochromic iridocyclitis does not require any treatment. In contrary, glaucoma should always be treated aggressively. If medical treatment for glaucoma fails, surgical in‐ tervention should be promptly applied. Evaluation of the newer procedures and implants is

Uveitic Glaucoma

373

http://dx.doi.org/10.5772/55708

Department of Ophthalmology, Western Galilee, Nahariya Medical Center, Nahariya, Israel

[1] Foster CS, Vitale AT. Diagnosis and treatment of uveitis. Philadelphia: WB Sounders.

[2] Vadot E. Epidemiology of intermediate uveitis: a prospective study in Savoy. Dev

[3] Gritz C, Wong G. Incidence and prevalence of uveitis in Northern California. The Northern California Epidemiology of Uveitis Study. Ophthalmology

[4] Merayo-Lloves J, Power WJ, Rodriguez A et al. Secondary glaucoma in patients with

[5] Takahashi T, Ohtani S, Miyata K et al. Clinical evaluation of uveitis-associated secon‐

[6] Heinz C, Koch JM, Zurek-Imhoff B, Heiligenhaus A. Prevalence of uveitic secondary glaucoma and success of nonsurgical treatment in adults and children in a tertiary

[7] Netland PA, Denton NC. Uveitic glaucoma. Contemp Ophthalmol 2006;5:1-26.

#### **9.4. Solx Gold shunt and CyPass**

These devises are placed into the suprachoroidal space. Based on other devises with similar principle, it is expected that these devices will fail due to obstruction by uveal tissue espe‐ cially in eyes with uveitis.

#### **9.5. Cycloablation**

Cycloablation, preferably with 810nm infrared diode laser may be applied in uncontrolled glaucoma with no potential for improvement in visual acuity in which other anti-glaucoma procedures failed. [58], [59] The reason is that it is difficult to predict the outcome of the treatment (final IOP) and to control the post-treatment intraocular inflammation, which is usually, exacerbate. Such inflammation may result in CME with decrease in visual acuity and central scotoma, papillary and retropupillary membranes and phthisis bulbi. The initial settings for trans-scleral cyclophotocoagulation with this laser is 1,250mW, 2sec. Following topical anesthesia and additional peribulbar lidocaine 2% 2ml, the probe is placed 1.2mmbe‐ hind the limbus. The power is increased in 150mW increments but not over 2250mW until a "pop" sound is heard. Then it is decreased in 150mW until no "pop" is heard and treatment begins. Eighteen spots are delivered to 270° avoiding 3:00 and 9:00 positions where the long posterior ciliary nerves enter the eye. Prevention of CME may be possible by topical NSAID such as diclofenac sodium (Voltaren®) 0.1% qid for 6 months. Decrease in visual acuity mayoccur from CME if prophylactic treatment is refrained or in cases of advanced visual field loss (splitting of the fixation or high mean deviation) as in other surgical procedures.
