Fig. 8.25 ArtistÕs impression showing an Ex-PRESSª Model P inserted in the anterior chamber, under a scleral ßap at the limbus

(MPGS). Both the device and the required incision into the A/C are miniaturized. Reßecting upon the two approaches of glaucoma surgery Ð penetrating and nonpenetrating Ð the Ex-PRESSª device offers a valid compromise between these two opposites. Trabeculectomy (penetrating), considered as the golden standard, has severe shortcomings because of its high-risk immediate postoperative course [12]. Nonpenetrating glaucoma surgery (NPGS) is recognized as a very safe drainage procedure but it has a long learning curve and the notorious reputation of being difÞcult to master [13]. MPGS with the Ex-PRESSª, being similar to trabeculectomy, has a very short learning curve and at the same time mimics NPGS with its restricted ßow.

Until recently, glaucoma surgery was offered as a lastresort treatment when medical therapy or laser interventions failed to lower IOP to acceptable levels. The Ex-PRESSª miniature glaucoma device has demystiÞed glaucoma surgery to a point where it can be offered earlier during the course of the disease to provide a safe and efÞcient treatment for glaucoma. The cost of the device is easily counterbalanced by the savings in medicine costs, shortened operating time, and reduced postoperative complications. Its development will further advance to the beneÞts of glaucoma patients worldwide.

8.2.1.1Indications for MPGS with the Ex-PRESS™ Mini-Shunt Under a Scleral Flap

In general, the indications for MPGS with the Ex-PRESSª are wider and more inclusive than those for classical trabeculectomies for two reasons: (1) MPGS with the Ex-PRESSª is safer but not less

efÞcient than trabeculectomies [10Ð36]; and (2) MPGS with the Ex-PRESSª is indicated in certain types of glaucoma where trabeculectomies normally fail or are not feasible [21, 26, 29, 35].

Glaucoma surgery is generally regarded as the last resort in the treatment of glaucoma. When medical therapy and laser fail to lower IOP to an acceptable level, glaucomatologists explain to their patients that an operation is necessary to halt the progression of the disease. The Ex-PRESSª with its lower complication rate can be offered earlier in the course of the disease. In fact, MPGS with the Ex-PRESSª can be offered as a Þrst-line treatment in cases where it is obvious that medical treatment will not lower IOP to acceptable levels. This factor is particularly important in glaucoma patients under 40 years who have a longer lifespan. Furthermore, glaucoma surgery is more successful in glaucoma patients who were not exposed to medical treatment [14Ð17, 28]. The noxious effects of topical medications on the conjunctiva are well documented [14Ð17, 28]. The conjunctival tissues undergo scarring processes when exposed to certain topical medications. Scarred conjunctiva, as found in patients who have been medically treated for years, is less amenable to the formation of a healthy diffuse bleb than a ÒvirginÓ conjunctiva. It is therefore logical to propose glaucoma surgery earlier than later when the chances of favorable outcomes are greater. The previous teaching of ÒÞrst medical & laser treatment and then surgical treatmentÓ has to be reviewed with the advent of the with promising outcomes of MPGS the Ex-PRESSª.

Open-Angle Glaucoma

Open-angle glaucoma is the commonest type of glaucoma and MPGS with the Ex-PRESSª is the best indication for it. During MPGS the limbus is incised at the level of the trabecular meshwork (TM) and the Ex-PRESSª implant is inserted into the A/C to allow a controlled ßow of aqueous from the A/C to the intrascleral and subconjunctival spaces. Furthermore, the eye is less inßamed following MPGS because of the lower postoperative concentration of TGFs [36].

Pigmentary Glaucoma

MPGS with the Ex-PRESSª is indicated for pigmentary glaucoma because it occurs more frequently in

young myopic male adults, and it is better to offer a safe surgical solution without depending on complex combination medical treatment. The Ex-PRESSª bypasses the site of pathology, namely the pigment-loaded TM.

Pseudoexfoliation Glaucoma

Pseudoexfoliation glaucoma is a form of open-angle glaucoma where there is accumulation of exfoliation material along all the aqueous outßow pathways. Since the exfoliation material is found especially in the TM and SchlemmÕs canal, MPGS with the Ex-PRESSª is the treatment of choice for this condition because the blocked TM is bypassed during this procedure. MPGS can be done alone or in conjunction with cataract extraction according to patient age, cataract status, and refractive error.

Aphakic Glaucoma

Formerly, glaucomatologists relied heavily on medication to lower IOP to acceptable levels in aphakic glaucoma. Progressive loss of visual Þeld and eventual loss of vision were often the rule. Trabeculectomies were not regarded as a valid proposition because they necessitate peripheral iridectomies. In aphakic glaucoma, iridectomy is not desirable because the vitreous may move forward through the iridectomy and block the Þltration site. Extensive basal vitrectomy is needed to prevent blockage, but it is difÞcult to accomplish. The ever-present residual vitreous often Þnds its way to the Þltration site and blocks it. Traction retinal detachment is not an uncommon complication in these combined vitrectomy-trabeculectomies. MPGS with the Ex-PRESSª does not require iridectomy; therefore, it is particularly indicated in aphakic glaucoma.

Sturge–Weber Syndrome

SturgeÐWeber syndrome, a cutaneous haemangiomatous disorder, is often associated with congenital or developmental glaucoma. The greater numbers and tortuosity of the conjunctival blood vessels can be an indicator of glaucoma. Minor angle abnormalities, heterochromia, and choroidal haemangioma are often

present in SturgeÐWeber syndrome patients with glaucoma. Since choroidal effusions following trabeculectomy are notoriously known in these patients, MPGS with the Ex-PRESSª offers a safer alternative because of its lower rate of prolonged postoperative hypotony.

Glaucoma Secondary to Uveitis

Glaucoma surgery is indicated when elevated IOP persists after the uveitis has subsided. MPGS with the Ex-PRESSª can offer efÞcient IOP reduction in these cases because it bypasses the inßamed nonfunctional TM. Furthermore, since its postoperative course is quieter than in trabeculectomies MPGS has an advantage over the classic trabeculectomy. Nevertheless, in cases where multiple peripheral anterior synechiae are present, the surgeon has to take special care when positioning the Ex-PRESSª in order to avoid iris tissue touch.

8.2.1.2Relative Contraindications for MPGS with the Ex-PRESS™ Mini-Shunt Under a Scleral Flap

The relative contraindications for MPGS depend on the depth of the A/C and on the expected outcome for a particular pathology.

Congenital and Juvenile Glaucoma

Congenital and juvenile glaucoma patients cannot rely on medication because of their longer lifespan. Generally, their glaucoma is severe and results in rapid optic-nerve damage and loss of vision. Practically, surgery is the only treatment available for these patients. Goniotomy and trabeculotomy are the preferred procedures for congenital and juvenile glaucoma. NPGS is a safe alternative for these classic interventions but it requires skill and long experience and should not be tried by a novice. When these operations fail MPGS with the Ex-PRESSª can be considered, with caution because that it is still a new operation with less than 10 years follow-up in humans. The long-term complications are still unknown and children should not be exposed to operations with relatively new implants unless everything else has failed.