Pressure Reduction After Cataract Surgery With Trabecular Micro-Bypass Device
To evaluate the intraocular pressure (IOP) reduction achieved by cataract surgery with implantation of a trabecular micro-bypass device in patients with glaucoma.
Fifty-four eyes (37 patients) with glaucoma underwent cataract surgery with implantation of a trabecular bypass device (iStent, Glaukos Corp.) by three surgeons in a community-based practice. All eyes had at least 3 months of follow-up. Data recorded included preoperative and postoperative IOP and the glaucoma medication requirement. The preoperative pressure was used to stratify the patients into four groups: IOP ≤ 15 mmHg, IOP > 15mmHg and ≤ 18mmHg, IOP >18mmHg and ≤ 21mmHg and IOP > 21mmHg.
The average IOP reduction in all patients was 2.68±3.84 mmHg (p < 0.001). There was a significant correlation between the magnitude of pressure reduction and preoperative pressure (r = 0.7002, p<0.001)). In patients with IOP 19 to 21 mmHg, the IOP reduction was 3.2±1.47 mmHg (p < 0.001). In patients with IOP greater than 21 mmHg, the IOP reduction was 5.9±5.07 mmHg (p < 0.001). In patients with IOP above 18mmHg, 96% had a decrease in pressure. While there was no specific protocol for reducing medications, glaucoma eye drops on average were reduced from 1.89±1.16 to 1.67±1.26 (p < 0.01).
Cataract surgery with implantation of a trabecular micro-bypass device reduced the IOP in patients with glaucoma. The pressure-lowering effect was greater in eyes with higher pre-operative IOP.