To determine the effect on intraocular pressure (IOP) of bypassing the trabecular meshwork in cultured human anterior segments.

Prospective laboratory investigation using normal human eyes obtained at autopsy.

Anterior segments from 21 eyes were placed in perfusion culture, and trabecular bypass stents were inserted through the trabecular meshwork, with the lumen of the tube opening into Schlemm's canal. Eyes received from one to four stents, placed equidistant apart. In eyes receiving one or two stents, additional stents were later added to a maximum of four per eye.

Intraocular pressure was lowered after placement of a single stent, from 21.4 ± 3.8 mm Hg to 12.4 ± 4.2 (P < .001). This corresponded to an 84% increase in facility of outflow. Eyes receiving more than one stent had final IOP of 11.9 ± 3.7 mm Hg. Nine eyes had sequential addition of stents, and seven of these had a further decrease of IOP (13.6 ± 4.1 to 10.0 ± 4.3; P = .02). Excision of the entire meshwork, between stents, dropped IOP to 6.3 ± 3.2 mm Hg, indicating some residual meshwork or canal resistance remained even after placement of three stents.

Bypass of the trabecular meshwork lowers IOP in cultured human anterior segments. One stent produced the greatest change in pressure. The sequential addition of more stents further lowered pressure in seven of nine eyes. This technique holds promise as a new clinical surgery for glaucoma.