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Pearls and insights from the experts at Moorfields International Glaucoma Symposium, part 2
Two sessions focused on MIGS and glaucoma with comorbidity, and an update on the United Kingdom Glaucoma Treatment Study was presented.
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Two particularly interesting and informative sessions at the Moorfields International Glaucoma Symposium were regarding minimally invasive glaucoma surgery and the management of glaucoma in patients with comorbidities. I will also share some lessons learned from the United Kingdom Glaucoma Treatment Study, the highest level of evidence for the management of glaucoma in the current literature.
MIGS
The MIGS session featured a debate between Gus Gazzard and John Salmon regarding the future of MIGS in glaucoma management. Gazzard argued that a procedure of modest benefit may be worth the cost of minimal additional risk. Salmon countered that MIGS procedures were only suitable for patients who are unlikely to lose vision from glaucoma anyway.
Keith Barton presented his experience with the Xen implant (AqueSys/Allergan). His tips included pre-insertion injection of 0.1 mL of 0.2 mg/mL mitomycin C superiorly and massaged superonasally; using an iris repositor passing in and out of the eye through two paracenteses to stabilize the eye; protecting the lens and guiding the injector toward the angle; hydrating the end of the Xen before implantation to encourage it to stay in position after injecting and not recoiling; leaving a small amount of viscoelastic in the eye to avoid early hypotony; and careful needling postoperatively to avoid pushing the Xen into the anterior chamber inadvertently.
Ingeborg Stalmans presented results from a phase 4 study of the Xen implant; in 200 participants, an average 34% IOP reduction was achieved at 1 year, with a reduction in number of medications from 2.6 to 0.6 (55% were medication free). Similar results were reported for solo procedures and combined procedures with cataract surgery, possibly suggesting that it is the Xen implantation that is causing the reduced pressure. The most common adverse event was hyphema, which occurred in 4%. While numerical hypotony occurred, there were no events of shallow anterior chamber or choroidals.
Laura Crawley shared her knowledge regarding whether glaucoma intraocular implants are safe for MRIs. The Alcon Ex-Press (titanium), Glaukos iStent (titanium), Ivantis Hydrus (nitinol) and Transcend Medical CyPass (polyamide) are all safe to 3 tesla. The Xen implant is gelatin and MRI safe.
Glaucoma with comorbidity
A session was dedicated to the management of glaucoma associated with systemic comorbidity. Alastair Denniston reminded us that around a quarter of uveitis patients will develop glaucoma in a 10-year period and that 5% of vision loss in uveitis is secondary to glaucoma. Importantly, vision loss due to glaucoma is irreversible unlike other causes of vision loss in uveitis such as cystoid macular edema and cataract. One of the challenges in managing chronic uveitis patients is the objective assessment of active inflammation, and Denniston shared with us potential new technologies for this, including OCT to quantitatively assess anterior chamber cells and vitreous haze. A strong message was that we need to control inflammation in uveitis patients without compromise in order to achieve long-term success, and this may well require glaucoma surgery.
Leon Au shared his experience of managing patients with corneal disease and glaucoma. He described the resurgence of trabeculectomy for some graft patients; while penetrating keratoplasty patients often require contact lenses postoperatively, precluding a drainage bleb, the advent of posterior lamellar keratoplasty has brought trabeculectomy back in fashion. Au advised we control glaucoma in our corneal patients before graft surgery. As a rough rule, he suggested we consider glaucoma surgery in patients with an IOP of greater than 18 mm Hg on two or more drops, and he advised we avoid temporizing measures such as selective laser trabeculoplasty or transscleral cyclophotocoagulation. Au gave specific advice regarding iridocorneal endothelial syndrome; given that grafts in ICE patients do not last long, we need to think twice before tube surgery in these patients, which may bring on corneal decompensation.
Patrick Yu Wai Man talked about the often poorly recognized overlap of clinical signs in glaucoma and other forms of optic neuropathy. He described non-glaucomatous cupping seen in mitochondrial neuropathies such as dominant optic atrophy and Leber’s hereditary optic neuropathy and how these conditions can be easily misclassified as glaucoma even by experts when just assessing the disc. However, Man also described some evidence that IOP may be a risk factor for progression even in mitochondrial neuropathies, suggesting etiological overlap for these complex conditions. Man described non-glaucomatous cupping in anterior ischemic optic neuropathy, which is usual in the arteritic form (seen in 90%) but unusual in the non-arteritic form (seen in 10%). Compressive optic neuropathy was also described as a cause for cupping, and Man stressed that MRI scans must be carried out with contrast when investigating such patients to avoid missing meningiomas.
Lessons from the UKGTS
Ted Garway-Heath gave us an update on the UKGTS. A striking finding is that the IOPcc measure derived from the Ocular Response Analyzer non-contact tonometer (Reichert) was the best single parameter to predict progression in the study. Garway-Heath discussed how better measurement of progression, using the ANSWERS algorithm, can allow much shorter study periods for glaucoma trials than previously thought. Hopefully this will be the advent of more clinical trials for new and existing glaucoma treatments.
- For more information:
- Anthony P. Khawaja, MB BS, MA(Cantab), MPhil, FRCOphth, OSN Europe Edition Board Member, can be reached at Moorfields Eye Hospital, 162 City Road, London EC1V 2PD, UK; email: anthony.khawaja@gmail.com.
Disclosure: Khawaja reports no relevant financial disclosures.