It’s an exciting and challenging time in glaucoma management.  Great progress has been made on the surgical management of glaucoma, some of which has been generated by advances with medical lasers, creating a very positive outlook for the future of glaucoma therapy.  However, there remains a healthy skepticism due to the failures of promising technologies to bare fruit in the past.  There is still a need for more evidence-based trials and clinical experience to solidify some of these new procedures in our armamentarium.  In addition, payers still have to recognize the benefits of these new procedures and agree to pay surgeons.  

Suffice it to say, most surgeons want less invasive techniques with quicker rehabilitation times, more efficiency in the operating room and the ability to combine glaucoma procedures with cataract surgery.    The mainstays in glaucoma treatment have been tube shunts and trabeculectomies, which are associated with severe infections, blood leaks, and the risk of hypotony.  Universally, surgeons are looking for higher success rates with lower risks, which has brought about the development of a number of new glaucoma treatments that aim to reduce risk while effectively lowering IOP.   While there is no formal classification, in general they can be categorized as ab externo or ab interno procedures. 

Already approved by the FDA are two ab externo procedures, meaning they involve a disruption of the conjunctiva.  An additional ab externo device is still under investigation.  These include:

·         The Ex-PRESS Glaucoma Filtration Device (Alcon) is a 0.4x3mm stainless minishunt, which really is an adaption to trabeculectomy.  Ex-PRESS shortens operating room time, eliminates the need for iridotomy, standardizes the outflow hole to 50microns and it has a faster visual recuperation. In one prospective study, 5 year results showed success with a trabeculectomy was 41%, and with Ex-PRESS was 53.9%.[i]  More importantly, there were less surgical interventions for complications with Ex-PRESS.

·         Canaloplasty’s (iScience International) goal is to create flow in Shlemm’s canal through a Descemet’s window.  It’s combined with laser dilation and stenting to open the canal and improve flow through aqueous collector channels.  There appears to be a relationship between canal dispersion and intraocular pressure lowering.  An on-going multi-centered study shows data for 134 patients divided into two groups, (1) canaloplasty alone and (2) canaloplasty with phacoemulsification.[ii]  Baseline IOP for all patients was 23.5mmHg + 4.5 with 1.9 + .8 medications.  At 36 months, IOP for the group who received canaloplasty alone was 15.5 mm Hg + 3.5, on .9 + .9 medications.  In the canaloplasty with phaco group, 36 month results went down to 13.6 + 3.6 on 0.3 + .5 medications.  Post operative complications included CME and high IOP. 

·         An additional ab externo device at the forefront of this type of research, which is not yet approved by the FDA, is the SOLX Gold Shunt.   This 99.95% pure gold implant is biocompatible and uses the eye’s natural pressure differential between the anterior chamber and the suprachoroidal space to reduce pressure.  While all of the data is still unpublished, as an investigator for this device I was able to see a decrease in baseline IOP in refractory and non-refractory glaucoma ranging from 30-40% at one year.

Among the innovative new treatment options for glaucoma is a segment which has been coined Minimally Invasive Glaucoma Surgeries (MIGS).   These are characterized as being micro-incision techniques that do not involve any destruction of tissue, no corneal flaps and no disruption of the conjunctiva.  These ab interno procedures are usually performed through clear corneal incisions and have an exceptional safety profile.  The flip side to their excellent safety profile is that, in general, they lower IOP less than more invasive procedures.  

·         The MIGS treatment that’s poised to reach the US market first is iStent (Glaukos).  As a clinical investigator with this device I’ve had the opportunity to have long-term follow-up with patients that have received the iStent in conjunction with cataract surgery and they have had excellent results.  The first Glaukos device to reach the market will be a 1mmx3mm titanium L-shaped trabecular micro bypass stent that is placed directly into Schlemm’s canal following cataract surgery, using the same clear corneal incision.   A multi-center study enrolled 240 patients with mild to moderate glaucoma and 72% of patients reach the primary goal of IOP of 21 mmHg or less without medications at 12 months.[iii]  In the control group of patients that received cataract surgery alone, only 50% reached this same goal.   The secondary efficacy endpoint was reduction of pressure greater than 20% at month 12.  66% in the iStent group and only 48% of the cataract-only group reached that goal.  But equally important, the post-op complications were the same in both treatment and control groups.   The iStent inject and iStent supra are in earlier stages of FDA trials, and together with the original iStent will offer the ability to titrate therapy to all stages of glaucoma.

·         The CyPass (Transcend Medical) is a 6mm-long polymide stent with 300micron lumens to be placed in the superciliary space with the assistance of a small guide wire.  It’s being evaluated in an FDA trial called the COMPASS trial and US results have not been released yet.

·         The Hydrus (Ivantis) device is implanted in Schlemm’s canal via an injector through a small step incision.  It advances in the Schlemm’s canal about 3 clock hours.  It’s made of nitinoyl, which is a compound used in vascular stents.  The Hydrous acts as a scaffolding to allow the aqueous to leave the implant and percolate in Schlemm’s canal.  There is no published control data available, but a multi-center US trial is in the planning stages.

·         ECP (Endo Optiks) – The first ab interno procedure to already be approved by the FDA, this is used for selective ablation of pigmented ciliary epithelium with a 810nanometer diode laser to reduce aqueous production. It can be used in conjunction with cataract surgery and it’s done under direct visualization with laser endoscope.  It can cause some inflammation, so there is a risk of CME and hypotony.  Stanley Burke’s study (presented at American Glaucoma Society in 2006), compared 626 eyes that had combined phaco and ECP to 81 eyes with cataract surgery alone.  Follow up was 5 ½ years, and in the phaco+ECP combined group pressure decreased by 3.4mm, while in the phaco alone group, it increased 0.7mm. 

·         Also already be approved by the FDA, Trabectome (NeoMedicx, Tustin, CA), is more invasive than the others.  It’s an ab interno trabeculectomy with ablation of the trabecular meshwork and the inner Schlemm’s canal via a micro electro-cautery device.  This creates a cleft that allows aqueous to go directly to the collector channels.  A study of 37 patients with an average pro-operative IOP of 28.2 + 4.4 mmHg showed a mean pressure of 16.3 on 2 medications at one year post procedure, representing a 40% drop in pressure.[iv]