Glaucoma is one of the leading causes of blindness worldwide. In the UK, the estimated prevalence of open angle glaucoma ranges from 0.3% in the 40s to 3.3% in the 70s. It is one of the leading causes for blind registration in the UK, second only to macular degeneration. Trabeculectomy remains the mainstay of surgical treatment. In this review, the authors look at the evidence and reasons for cataract formation after trabeculectomy surgery and examine the evidence surrounding bleb failure after cataract extraction. The review highlights that the reasons for cataract formation in those undergoing filtration surgery are poorly understood, and more research needs to be undertaken in this area.