Scleral flap

Ex-PressTM

Intrascleral lake

Fig. 8.38 Ultrabiomicroscopy imaging of an Ex-PRESSª forming an intrascleral bleb. (Courtesy Dr Andre Mermoud)

8.2.4Postoperative Management and Medication

Postoperative treatment consists of a steroidÐantibiotic combination drops three to four times a day for a minimum of 2 weeks. On day one, the IOP can vary from 0 to mid-20smmHg. In case of severe hypotony and a very shallow A/C, a viscoelastic substance can be injected into the A/C via an existing paracentesis in order to reform the A/C and normalize the IOP. This procedure can be performed under topical anesthesia with the slit lamp or in the theatre according to the surgeonÕs convenience. When the IOP is above 22mmHg on day one, the A/C can be decompressed by releasing some viscoelastic material via the existing paracentesis.

At 2 weeks or later postoperatively, is expected a temporary rise of IOP. This temporary IOP rise is usually self-limited and subsides within 2 weeks. It is suggested the topical steroids are stopped and substituted with nonsteroidal anti-inßammatory drugs (NSAIDS). The treatment with topical NSAIDs four times a day should be continued for a period of 8 weeks in order to reduce the postoperative inßammatory response and to favor efÞcient Þltration. Some surgeons who are familiar with sutures release choose to cut some of the scleral ßap sutures when the IOP rises postoperatively.

8.2.5Outcomes and Comparison with Other Techniques

The outcomes of MPGS with the Ex-PRESSª as reported by the present users have been so far very encouraging [10Ð13, 18Ð27, 29Ð36] because they mimic two accepted techniques, namely trabeculectomies and NPGS. Depending on the personal technique of scleral ßap formation, MPGS with the Ex-PRESSª can yield good IOP control with or without conjunctival bleb formation (Figs. 8.34Ð8.36). In some cases, there is evidence of intrascleral bleb formation, especially when a deep sclerectomy has been added under the superÞcial scleral ßap (Figs. 8.37 and 8.38). Prospective randomized studies comparing trabeculectomy, MPGSL with Ex-PRESSª, and NPGS are underway. Surgeons who were familiar with trabeculectomies and/or NPGS have switched to MPGS because of its relative advantages in terms of safety and simplicity. MPGS with the Ex-PRESSª can be performed in aphakic eyes without the need of iridectomy which is an advantage over the classic trabeculectomy. Glaucoma surgeons who were performing trabeculectomies before using the Ex-PRESSª implant tend to use the same basic technique and report comparable results except for the lower incidence of early postoperative complications [13, 30]. They also report on a quieter A/C on day one compared to trabeculectomies. Sherwood et al. conÞrmed this clinical impression in an experimental study on rabbitsÕ eyes when he measured the TGFs β2 in the aqueous humor postoperatively in trabeculectomies and MPGS with the Ex-PRESSª [5].

The Ex-PRESSª implant has not been compared yet to Setons, namely Molteno, Baerveldt, and Ahmed valves, in clinical studies. The Setons direct the aqueous to a posteriorly formed bleb whereas the Ex-PRESSª shunts it to an anteriorly formed bleb as in trabeculectomy and NPGS.

8.2.6 Complications and Management

8.2.6.1 General

The usual complications encountered in Þltration surgery can also occur in MPGS with the Ex-PRESSª implant. Immediate postoperative hypotony, shallow

A/C, hyphema, and choroidal detachment do occur, although to a lesser extent because of the small drainage oriÞce. The usual directives on how to avoid these complications in other Þltrations procedures are also applicable to the MPGS with the Ex-PRESSª.

8.2.6.2 Specific to the Technique

Early postoperative high IOP: At the end of the operation it is recommended to Þll the A/C with viscoelastic material. OverÞlling of the A/C might result in high IOP on day one. It is recommended to Þll only onethird of the A/C with standard viscosity viscoelastic material when the P model is used. When the X50 and X200 models are used, it is recommended to Þll twothirds of the A/C with standard viscosity viscoelastic material. The larger lumen and/or square body of the X models allow more drainage, and hence there is a greater risk of early postoperative hypotony. The surgeon can vary these amounts at his discretion according to his personal technique.

A preexisting side port at the temporal limbus created during the original surgery can be of use when the IOP is ≥22mmHg on day one. The A/C can be decompressed under local anesthesia using a 25-gauge needle with the slit lamp. This simple maneuver lowers the IOP immediately and avoids the use of hypotonic agents.

Early postoperative hypotony, loss of A/C depth, and choroidal detachment: A large, securely sutured scleral ßap is the best way to prevent early postoperative overÞltration in MPGS with the Ex-PRESSª. A preexisting side port at the temporal limbus created during the original surgery can be of use when the A/C is dangerously shallow and implant iris touch occurs. The A/C can be reformed by injecting viscoelastic material into the A/C under local anesthesia. This maneuver can be performed with the slit lamp if the patient is cooperative and when the surgeon is familiar with the procedure. Mild cases of hypotony or shallow A/C can be treated in the same manner as in the classic Þltration procedures, i.e., pressure bandage or double padding.

Implant iris touch: A preincision that is not parallel to the iris can result in iris implant touch. When the implant indents the iris aggressively, especially in phakic cases, it is recommended that the Ex-PRESSª implant is repositioned in the theatre. This requires removing the implant and making a new preincision adjacent to the original one, and reinserting the

Ex-PRESSª. Removing the Ex-PRESSª implant is done by holding its plate, twisting it so its spur is positioned horizontally and then retrieving it by enlarging the wound with a 15¡ superblade to allow enough room for the passage of the spur.

Early subconjunctival Þbrosis: The manufacturers suggest using MMC in every case to prevent early conjunctival Þbrosis and failure of the drainage operation. This is particularly true for patients with failed previous glaucoma surgery and/or for patients who were treated with maximal medical therapy over long periods [9, 10, 13, 21, 23, 29, 31]. Further reports on the comparison between trabeculectomy and MPGS with Ex-PRESSª will shed light on the Þbrosis and Þltration failure.

Conjuctiva and scleral ßap erosion: True scleral ßap erosion over the device plate has not yet been reported in the literature but it cannot be ruled out as a serious potential complication. This complication can occur when the scleral ßap is too thin or when conjunctival and scleral tissue melting occurs as a late complication.

8.2.6.3Several Characteristics of the Ex-PRESS™ Are Unique

a.It is made of metallic material. At present most, if not all, of the widely used glaucoma shunts are made of acrylic material and silicone rubber. The introduction of metal as a biocompatible material in glaucoma surgery is quite new [4]. It initially caused resistance and rejection amongst many ophthalmologists who could not accept the idea of a metallic foreign body in the eye because of associations with accidental iron foreign bodies. Because it is made of medical-grade stainless steel (316L) that is identical to cardiac stents widely used worldwide, its biocompatibility and safety are practically beyond doubt. At present, the Ex-PRESSª has been used in humans for more than 9 years with number reaching 30,000. FDA approval for use in ophthalmology in humans was granted in 2002. Very few reports on severe complications were published in the literature [2, 5, 6, 9]. All these complications occurred during the early period of initial use when the Ex-PRESSª was implanted under the conjunctiva. Since the method of implantation was changed to under a scleral ßap there have not been reports of