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The authors set out to determine whether an intraoperative episcleral vein fluid wave (EVFW) can act as a potential indicator of the outcome of trabectome surgery. An underlying premise was that the fluid wave was reflective of the patency of the distal outflow system.
The ESFW outcome measures were fluid wave intensity and clock hours of blanching using a masked observer approach. The study demonstrated a statistically significant correlation between wave extent in clock hours and postoperative IOP at one month and three months but not at six or 12 months. At 12 months, the mean IOP in the extensive EVFW group (4,5 or 6 clock hours) was 13.3 ± 2.7 mmHg on 1.4 ± 1.2 medications compared with an IOP of 18.4 ± 3.1 mmHg on 2.9 ± 0.9 medications in the poorly defined group (both P = 0.001).
The authors conclude that the EVFW can provide a gauge for the patency of the distal outflow pathway and that the technique may be able to predict surgery outcomes after trabectome surgery. The paper points out that a spectrum of findings was present; the technique was particularly valuable when there was either a definitive intense fluid wave and/or extent of blanching or when fluid wave findings were very minimal.
Predictive value was less for those in the middle of the spectrum of EVFW findings. Both fluid wave intensity and the extent of the fluid wave are subjective observer-dependent criteria, a limitation that is regularly shared by studies of this type and is mitigated by the author’s use of a masked approach.
The authors are to be congratulated on their development of a test to predict surgical outcomes that becomes predictive immediately following the operating room procedure. Their insights suggest that in-office imaging techniques might one day be used to identify inappropriate candidates for MIGS surgery even before they reach the operating room.