Fighting ‘the silent thief of sight’

The collegiate atmosphere at this year’s meeting was noticeably different from most other gatherings of ophthalmologists I’ve been to, and was probably because of the focused nature of the event.Contributing to that atmosphere was the fact that glaucoma patients, especially complicated cases, often present a significant challenge to their ophthalmologist as there is still some debate over what treatment and/ or medication regimen is the most appropriate. That is complicated by differing expert opinions and conflicting supporting literature because, in reality, the glaucoma evidence base is still a work in progress, and our understanding of the condition incomplete.The roots of the Australian and New Zealand Glaucoma Society (ANZGS) can be traced back to 1988, when it was first conceived of as the Glaucoma Club, before evolving into the ANZ Glaucoma Interest Group (ANZGIG), and finally the ANZGS. Current ANZGS president, Associate Professor Anne Brooks (ophthalmologist, Melbourne) and Sydney ophthalmologist Dr Ridia Lim were central to the organisation of this year’s meeting, which welcomed delegates spanning the spectrum from medical practitioners with ambitions to become ophthalmologists, all the way through to acknowledged experts and acadics in the glaucoma field.New Zealand was well represented both in the audience and the faculty, while industry had a presence at the meeting in the form of major sponsors Alcon, Allergan, and Novartis. The Lim-led local organising committee included Drs Colin Clent, Mitchell Lawlor, David Manning, and Associate Professor Ivan Goldberg.Drainage tube placentDr Liane Papantoniou and colleagues from Westmead Hospital, Sydney, presented some clinical results from locating the ocular point of entry of a silicone drainage tube in the ciliary sulcus rather than the anterior chamber. The latter has an attendant risk of corneal decompensation.Technically, the ciliary sulcus is in the posterior chamber and is the anatomical feature bounded by the posterior iris anteriorly and the anterior ciliary body posteriorly. A 23-gauge needle was used to penetrate the sclera some 2 mm from the limbus, taking an approach from inside the eye (ab interno). This is docked with a 27-gauge needle via a handshake manoeuvre, and that needle is then docked with a Healon GV syringe similarly.The Healon syringe is then passed back out the original site of penetration and the silicone drainage tube fitted over the protruding end with enough overlap to secure the combination. The drainage tube is drawn into the eye via the ciliary sulcus portal just made. Importantly, the vitreous must never find its way to the tube’s inlet aperture.The technique is recent and was first used in March 2017. Average IOP went from 33.8 to 11.3 mm Hg by three months, while the number of medications was reduced from 4.2 to 2.0. However, a slight drop in VA was noted and ETDRS letters went from 51.1 to 49.3 post-operatively.Transient complications occurred in 36.4% of cases and further surgical intervention was required in 9.1% of cases. Most complications were attributed to the complexity of the cases involved rather than the approach through the ciliary sulcus per se. The authors concluded that the technique was easy to learn and was safe and effective.

KEYNOTE SPEAKERS
Liane Papantoniou	George Kong	David Manning	Paul Chew	Jed Lusthaus	Ridi Lim and Paul Healey

Presentation snapshotsDr George Kong (Melbourne-based co-inventor of the MRF iPad app) discussed how not all ocular probls are necessarily ocular in origin, but can be the result of changes further up the optic tract or higher still in the brain. He stated that in some cases of poor ocular perfusion, the services of a vascular surgeon may be required, especially in cases of intracranial stenosis, not all of which are detected by carotid ultrasound.Dr Lance Liu highlighted the use of Ahmed Glaucoma Valve implants in ‘young’ patients, and noted that encapsulation by the body’s natural defence mechanisms was a common occurrence. As such, he preferred the larger Baerveldt Glaucoma Implant in such cases, while he also noted in passing that silicone oil was almost impossible to rove from the eye completely.Dr David Manning spoke about SLT (selective laser trabeculoplasty). In his experience, some 15% of SLT cases do not get a decrease in IOP and some experience an increase in IOP, not all of which lower eventually. The effectiveness of the procedure is also not always sustained and his figures suggest the failure rate could be as high as 50% by five years. He estimated that for many, a 2–3-year period was the best that could be expected.A SLT can also cause corneal probls. Manning’s recommendation was that all SLT cases be re-examined within one week, and that only 180° of the trabecular meshwork should be lasered (not the full 360°). Cystoid macular oeda (CMO) is a possible sequelae, and the use of a laser has an inflammatory effect that might need detection and monitoring.He also cautioned that the use of a YAG laser for posterior capsular opacities (PCOs) can upset glaucoma therapy by inducing an inflammatory response and compromises to the trabecular meshwork. He recommended a further review at four weeks, and suggested the prophylactic use of IOP-lowering agents before lasering and before CMO develops.

Transscleral cyclophotocoagulationProfessor Paul Chew from the National University of Singapore (NUS) gave an update on the use of the Iridex MicroPulse P3 Transscleral Cyclophotocoagulator (the MP3) as an alternative glaucoma therapy. The MP3 targets the ciliary body to lower IOP using laser light applied through the sclera via a hand-held probe.That probe is equipped with a visible red light showing the exact location the therapy will be applied to. To avoid collateral damage, the device uses a therapeutic laser diode that is micro-pulsed (On:Off ratio can be as low as 1:19 but that is adjusted to control the duty cycle that can approach 33%).The pulsed delivery is designed to give a therapeutic dose without inducing significant damage (localised heating of adjacent structures), inflammation, and pain, with fewer risks. The instrument’s ‘voice’ guides and times the surgeon’s activities intraoperatively.Importantly, unlike most current MIGS implantations, the procedure can be carried out without the need to perform cataract surgery at the same time, i.e., it can be applied as a standalone procedure under current MBS controls. Unlike previous, established procedures involving the use of the more destructive continuous-wave transscleral cyclophotocoagulation (FDA approved), the MP3 can be used in mild (early) to moderate cases of uncontrolled glaucoma, as well as severe cases.The exact mechanism is still not understood fully, but the University of Washington’s Dr Murray Johnstone produced a 2017 video analysis in a primate that provides some insight into the process. Ciliary muscle shrinkage, particularly of the longitudinal muscle fibres of Brücke (those nearest the sclera and therefore the most irradiated) was observed, that in turn tugged on the trabecular meshwork and Schlm’s canal. That combination opens the aqueous drainage syst enhancing the eye’s outflow facility in a way the video’s creator likened to the action of pilocarpine.IOP reductions of 25% were claimed by Chew, who also noted that MP3 treatment has utility in angle-closure glaucoma as well as cases with closed or narrow angles (prophylactic treatment). However, he cautioned that it was still possible to misuse the device.MIGS sessionThis session involved both presentations and case reports. The first presenter was one-time Iranian refugee Dr Joobin Hooshmand from Tasmania, who reported on a study comparing the iStent and the iStent inject in POAG. The original iStent was approved by the TGA in 2014 and the iStent inject is a second-generation micro-bypass device for use in POAG.The study results focused on two main outcomes; patients achieving ≤18 mm IOP and with no medications, those with ≤18 mm IOP and a reduction in the number of their medications, or those with a 20% reduction in IOP with or without medications. Some 145 iStent and 100 iStent inject devices were implanted, and about 55% of iStent cases and 48% of iStent inject cases resulted in IOPs <18 mm and no medications required. Fifty-two per cent (iStent) and 54% (iStent inject) respectively achieved IOP lowering along with the use of fewer medications.Despite being an earlier device, the iStent proved to be slightly more effective (16.6 mm vs 16.9 mm but the difference was not statistically significant). Additionally, while fewer than 50% of the original iStent recipients rained medication-free at 18 months, some of the iStent inject recipients required medication after a median of 11 months to maintain their IOP.NSW ophthalmologist, Dr Jed Lusthaus also spoke about iStent inject. He gave the surgical indications as progressive glaucoma, uncontrolled IOP, and significant cataract combined with the need for IOP-lowering medications. His team’s retrospective study set out to determine if locating a point of episcleral aqueous outflow preoperatively was helpful in predicting efficacy of trabecular bypass stenting.As an aid to locating the iStent inject implantation point preoperatively, Lusthaus suggested locating a point of aqueous outflow in the nasal quadrant using a red-free filter on a slit-lamp, looking for obvious laminated blood-aqueous flow in episcleral vessels, vessel pulsatility, and/or jets of aqueous following palpation of the globe (forced increased outflow). Two iStent injects were injected into the trabecular meshwork adjacent to an area of identified aqueous outflow.In his study, most cases were off any medication by three months. Success was defined as at least a 20% decrease in IOP and no requirent for supplental medication. Qualified success was defined as at least a 20% IOP reduction with reduced supporting medication.Two of the 20 patients (one PACG, one POAG) developed peripheral anterior synechiae (PAS), making visualisation of the iStent inject impossible and requiring use of supplental medication after three months (one fewer that pre-insertion), suggesting iStent inject blockage. However, both those cases still achieved lower IOPs post-surgically. Largely because of the small patient numbers, no solid conclusion was reached.Melbourne ophthalmologist, Dr Nathan Kerr (CERA), reported his experiences with Alcon’s CyPass MicroStent (a polyamide, 300 micron ID stenting device), a supraciliary micro-stent for mild to moderate POAG cases who also needed cataract surgery. Although his experiences were limited to only 15 eyes, 14 eyes were medication-free after surgery.Kerr’s initial experiences suggest that the CyPass stent reduced IOP (most were at or below 14 mm), decreased the need for IOP-lowering medications, and allowed predictable refractive outcomes.Given the amount and utility of the information presented at the meeting, many will be looking forward in anticipation to the World Glaucoma Congress (WGC2019) being held in Melbourne in March 2019.

More reading: Gathering of minds at ANZGS 2018: Report Part 1