FILTRATION DEVICE FOR IOP REDUCTION

MI60 microincision IOL

A combination of micro-incision cataract surgery and implantation of an Ex-PRESS Glaucoma Filtration Device (Alcon Laboratories Inc.) under a scleral flap appears to provide a safe, simple and effective way to reduce IOP and the need for anti-glaucoma medication in eyes with open-angle glaucoma (OAG) and cataract, said Romeo Altafini MD, director of Glaucoma Surgery Dept, San Bassiano Hospital, Bassano del Grappa, Vicenza, Italy.

'The advantage of the implant over trabeculectomy is that you don't have to perform iridectomy, which results in a lower level of inflammatory reaction in the eyes with less scarring and major postoperative complications,' he told the 16th ESCRS Winter Meeting. Dr Altafini noted that in a study he and his associates carried out involving 48 eyes of 41 patients with primary open-angle glaucoma (POAG) and cataract that underwent the combined procedure, the mean IOP remained at less than half preoperative levels at two years' follow-up.

That is, the mean IOP decreased from 24.7 mmHg preoperatively to 10.5 mmHg at six months and to 11.3 mmHg after the second postoperative year. Furthermore, the average number of medications patients required to maintain the target IOP of 18 mmHg or less fell from 1.97 preoperatively, to 0.37 after a follow-up of up to two years.

Ex-PRESS Glaucoma Filtration Device under scleral flap

The MICS-Express technique
Prior to surgery, all eyes received topical anaesthesia with four per cent lidocaine applied to the conjunctiva with a sponge for 30 seconds. Dr Altafini then created a fornix-based conjunctival incision and used a crescent knife to create 4.0mm by 4.0mm scleral flap. He made his incisions starting from the limbus in the clear cornea and proceeding to the fornix in order to have a small scleral flap with good visualisation of the limbal transition zone.

All eyes in the study underwent clear-corneal MICS with a Stellaris phacoemulsification machine (Bausch + Lomb) and implantation of a MI60 microincision IOL (Bausch + Lomb) through a 2.2mm incision. In all cases he used a dual linear pedal phaco-chop technique during phacoemulsification, which allows the precise modulation of vacuum and ultrasound energy according to the requirements of each individual case.

'This technique is very fast and easy to use even in a hard nucleus. The MA 60 IOL has a good stability in the capsular bag thanks to its four haptic design. We obtained good quality of vision due to the asphericity of the optic,' he added. Before implanting the P 50 Ex-PRESS model Dr Altafini filled the anterior chamber with a cohesive viscoelastic device and used a 25-gauge needle coloured with methylene blue to create a scleral tunnel before implanting the device beneath the scleral flap.

The Ex-PRESS P 50 device is a stainless steel device consisting of a 27-gauge shaft with an outer diameter of 0.4mm and a 50 micron axial lumen. The shaft terminates in a faceplate, which fits into the scleral flap. The device was originally designed to direct drainage directly from the anterior chamber to the subconjunctival space. However, implanting the device under the conjunctiva resulted, most of the time, in extrusion of the Ex-PRESS. So Eli Dahan MD suggested implanting the device under scleral flap. 'The Ex-PRESS device allows the passage of aqueous humour from the anterior chamber to the subconjunctival space and by placing it beneath the scleral flap. Only if the sleral flap is too thin we had extrusion of the device,' Dr Altafini said. In order to prevent scarring of the sclera and conjunctiva to maintain the patency of the bleb for 15 days, Dr Altafini injected reticulate hyaluronic acid beneath the scleral flap after suturing it down, with a 10-0 nylon suture. He then injected more of the viscoelastic on top of the scleral flap before closing the conjunctival wound with a 7-0 re-absorbable suture.

Postoperative complications in the study included three cases of shallow of the anterior chamber, two of which were resolved with viscoelastic injection, while the remaining case required a re-suturing of the conjunctiva. In addition, one eye developed postoperative endophthalmitis 15 days after surgery, which was resolved by vitrectomy and silicon oil injection. There were also five cases of high IOP spikes immediately after surgery, the IOP spike was reduced, by argon laser lysis of the nylon suture.

Dr Altafini noted that previous studies by comparing trabeculectomy versus the implantation of the Ex-PRESS device beneath the scleral flap showed that there was no significant difference between the two techniques in terms of IOP reduction. However, they also showed that among eyes with the Ex-PRESS device there were lower rates of complications such as choroidal effusion and early postoperative hypotony.

'After two years of follow-up the Ex-PRESS device with the injection of reticulate hyaluronic acid below and on the top of the scleral flap and combined with 2.0mm MICS and IOL implantation was safe, simple and effective for reducing IOP and anti-glaucoma medication in eyes with open angle glaucoma and cataract,' he concluded.