Is there an optimal therapy management for uncontrolled glaucoma?

Glaucoma surgeons focus on filtering surgery and MIGS. We now also have the surgical manipulation of the uveoscleral outflow pathway at our disposal.

A new potential treatment algorithm in glaucoma therapy 

A major problem in glaucoma surgery is the nature of the conjunctiva. Long-term therapy with anti-glaucomatous eye drops can lead to scarring. Therefore, it is all the more important to intervene in time. Surgical procedures that are less invasive than trabeculectomy can already be used for early glaucoma.

Good results with MIGS procedures so far, but long-term data are lacking

MIGS (Microinvasive Glaucoma Surgeries) are divided into trabecular and subconjunctival procedures. The iStent® inject is probably the best known of the trabecular procedures and is often performed in combination with cataract surgery. With this method, a pressure reduction of 15-25% can be achieved. A 20% reduction in pressure is also possible with the Hydrus® microstent. This surgical procedure is also combined with cataract surgery. The iStent® is made of ferromagnetic titanium coated with heparin. The Hydrus® microstent is based on a nitinol scaffold. XEN® is a collagen-based subconjunctival gel implant. XEN® is implanted ab interno.

This method can also be combined with cataract surgery. The antimetabolite MMC is also used here. The non-degradable XEN® implant allows 1.2 μl/min to flow out. In combination with cataract surgery, a pressure reduction of 30-45% can be achieved with XEN® implantation. With this method, "primary needling" may be necessary if the expected pressure reduction does not occur. Preserflo®/SIBS is also a subconjunctival MIGS procedure. This is a shunt made of a thermoplastic elastomer. With this shunt-guided trabeculectomy, a pressure reduction of up to 53% is possible.1

Long-term data will show whether MIGS procedures can maintain stable pressure reduction over decades and thus compete with the gold standard in the long run.

10-year data of the SOLX® Gold MicroShunt, rather disappointing

There are other approaches to improving aqueous humour outflow. This is where the uveoscleral outflow pathway of the eye comes into play. Prostaglandins already use this pathway to lower intraocular pressure. However, the uveal segment of the uveoscleral outflow pathway is the velocity-limiting part of this route due to the muscular part of the ciliary body. The situation is different in the suprachoroidal space. Once the fluid has passed through the uveal segment and reached this area, there is little resistance.

Due to the high complication rate, cyclodialysis is now rarely used. Exactly one year ago, the 10-year data of the SOLX® Gold MicroShunt in refractory glaucoma were presented. Unfortunately, none of the patients achieved complete success 5 years after using the SOLX® Gold MicroShunt.2,3

A new contender for the uveoscleral outflow pathway

A brand new approach comes from Ciliatech: Ciliatech's CID implant is a cilio-scleral intermediate positioning device made of hydrophilic hydrogel. It has a plate-like format, is foldable and thus fits through even small incisions. It adapts to the surrounding anatomy without exerting pressure. The acronym CID stands for "Cilio-Scleral Inter-positioning Device". It is the first implant of its kind to effectively lower intraocular pressure without penetrating the anterior chamber or creating subconjunctival filtration. This gives it an advantage over some other surgical techniques that can cause serious complications. The plate-like format allows separation of the sclera and ciliary muscle.4

Positive clinical results after CID implantation

In the SAFARI 1 study, a total of 20 patients received a CID implant. In the SAFARI 2 study, 22 patients received two CID implants. SAFARI stands for "SuprAciliary Filtration Alone Reduces IOP". After 12 months, both studies showed consistent results (n=30):

At the same time, the safety profile was very good. The 24-month follow-up phase followed the two studies SAFARI 1 (12-month follow-up) and 2 (6-month follow-up). Patients in SAFARI 1 showed stable IOP values of 15.6 mmHg even after 24 months. IOP was reduced by 33%. The CID implant was effective without the need for a filtering pad and antimetabolite, and without being associated with hypotony or endothelial cell loss. Currently, the SAFARI 4 study (NCT05625958) with a follow-up period of 36 months is already being planned.5,6

With the CID implant, a new innovative surgical method could now be added to the treatment algorithm for glaucoma, which is so far unique in its nature. It acts via the uveoscleral outflow pathway and leaves the anterior segment of the eye virtually untouched.4-6

References
  1. Hoffmann EM. et al. (2021). Aktuelle Glaukomchirurgie [English: Glaucoma Surgery Today]. Ophthalmologe. 2021 Mar;118(3):239-247. In German only.
  2. Kent C. (2010). Uveoscleral Outflow: A Better Way to Go? Review of Ophthalmology. https://www.reviewofophthalmology.com/article/uveoscleral-outflow-a-better-way-to-go. Zugriff im Mai 2023.
  3. Figus M, Loiudice P, Passani A, Perciballi L, Agnifili L, Nardi M, Posarelli C. Long-term outcome of supraciliary gold micro shunt in refractory glaucoma. Acta Ophthalmol. 2022 May;100(3):e753-e759.
  4. https://www.cilia.tech
  5. https://www.eyenews.uk.com/news/post/ciliatech-reports-positive-clinical-results-on-novel-glaucoma-implant-cid-in-24-month-post-operative-follow-up
  6. https://ichgcp.net/clinical-trials-registry/NCT05625958