The notion of omitting tube shunt plate fixation has been circulating for more than a decade.1 This study by Lee and colleagues is an important addition to the growing body of evidence that what they term the free plate AGV (FPAGV) technique has comparable safety and efficacy vs sutured plates. The authors' retrospective series thoroughly examines pressure outcomes and a variety of complications and the results of the FPAGV are at least equivalent to sutured plates. An intriguing aspect of the technique was the anterior anchoring suture passed through the silicone tube. This is in distinction to our group's comparative retrospective series on a similar technique where the suture was looped and cinched around the tube.2 Their penetrating suture may have acted as a venting wick3 as described in non-valved tube techniques and contributed to the relatively blunted hypertensive phase in the FPAGV group compared to the conventional group in Lee's series.
The study was performed in South Korea, and as the authors discussed, FPAGV has significantly facilitated tube placement in smaller inter-palpebral fissures where exposure and visualization are often challenging. This technique may also be of particular utility in allowing plates to be dropped behind high buckles and in avoiding suturing in areas of scleral thinning. Some cases may be potentially less well suited, such as shallow orbits or very large globes that might be more predisposed to anterior migration as the orbital rim and positioning behind the equator help maintain posterior plate position in our experience.
Although it is the preferred technique of many surgeons and there is mounting evidence for the safety of FPAGV, it has not been widely adopted among glaucoma surgeons. For those who implant tube shunts regularly, the risk of scleral perforation is low and the slight improvement in efficiency may not be thought to justify the perceived risks of forgoing plate sutures. However, FPAGV may be a helpful technique to turn to in scenarios where plate fixation is inherently challenging.
FPAGV may be a helpful technique to turn to in scenarios where plate fixation is inherently challenging