Background
A recent, alternative approach to treating glaucoma with filtration procedures, such as trabeculectomy, is the drainage of aqueous humor from the anterior chamber (AC) to the suprachoroidal space. This approach avoids the conjunctiva, which is known to be responsible for the failure of trabeculectomies. Another advantage to this shunt route is that the pressure in the suprachoroidal space serves as a natural counter pressure to prevent severe postoperative hypotony. Emi et al. found a drop in hydrostatic pressure from the anterior chamber to the suprachoroidal space up to -3.7 ± 0.4 mmHg that increased with experimentally raised intraocular pressure. This negative pressure in the suprachoroidal space provides the rational for a shunt from the AC to the suprachoroidal space to lower the intraocular pressure (IOP). Aqueous filtration across the sclera may be another possible outflow pathway.
We reported our encouraging experience with a silicone shunt which connected the anterior chamber to the suprachoroidal space. We then exploited the advantages of this novel shunt route, but replaced silicone with gold as the shunt material, seeking a more stable and safe IOP reduction. Therefore we evaluated this recent device for suprachoroidal drainage, the Gold Micro Shunt Plus (GMS+).