Conventional glaucoma implants and the new MIGS devices: a comprehensive review of current options and future directions

Glaucoma is a progressive optic neuropathy that is the second leading cause of preventable blindness worldwide, after cataract formation. A rise in the intraocular pressure (IOP) is considered to be a major risk factor for glaucoma and is associated with an abnormal increase of resistance to aqueous humour outflow from the anterior chamber. Glaucoma drainage devices have been developed to provide an alternative pathway through which aqueous humour can effectively exit the anterior chamber, thereby reducing IOP. These devices include the traditional aqueous shunts with tube-plate design, as well as more recent implants, such as the trabeculectomy-modifying EX-PRESS(®) implant and the new minimally invasive glaucoma surgery (MIGS) devices. In this review, we will describe each implant in detail, focusing on their efficacy in reducing IOP and safety profile. Additionally, a critical and evidence-based comparison between these implants will be provided. Finally, we will propose potential developments that may help to improve the performance of current devices.