**4. Scientific evidence**

Some techniques perform a more aggressive treatment than others. It is logical to think that the less aggressive techniques will be used in eyes with glaucoma where the involvement of the TM is smaller, and that, on the contrary, the more aggressive techniques, such as the trabeculotomy with viscodilatation, will be used in cases where the involvement of the TM is much more intense.

If we review the literature in order to compare the different surgical techniques [12–21], we see that, except in some surgical techniques, in the most of the techniques, most of the studies present biases: they are not randomized, they are not prospective, they are simple series, they do not have washout, they use personal criteria, they do not record complications … therefore, we can affirm that the scientific evidence for MIGS surgery in comparison with other techniques is very limited, although it has been demonstrated a decrease in IOP, a decrease in the number of drugs and a decrease in complications.

If we focus on surgical success, understanding it such as a IOP reduction greater than 20%, most techniques reach a rate success of 60–80% (**Table 1**). Evidence A and B can only be found with the iStent, the Hydrus and the trabectome, while in OMNI and Kahook the grade of recommendation is C (**Table 1**).

If we focus on the IOP that these surgical techniques achieve, we see that in the most of the cases the IOP reached is between 15 and 17 mmHg (**Table 2**), a limitation that is given by the episcleral venous pressure.

#### *Current Cataract Surgical Techniques*


#### **Table 1.**

*Surgical success achieved with different MIGS techniques.*


#### **Table 2.**

*IOP achieved with different MIGS techniques.*
