We have studied in vivo IOP fluctuation during the vitrectomy with or without an active intraocular pressure control system. Both systems are still imperfect during the high intraocular pressure procedures. However, during hypotony procedures, constelletion was quite stable. In addition, using cuttling on mode, non-valved cannular and/or vent system, the IOP can be somewhat controlled.


To compare the in vivo intraocular pressure (IOP) fluctuation during routine microincision vitrectomy using two different systems (Alcon Accurus and Constellation Vision System) with valved trocars.


Prospective, comparative, interventional case series. Participants: Among 61 eyes of 61 consecutive patents who underwent 25-gauge vitrectomy, 32 eyes were randomly assigned to the Accurus system (group I) and 29 eyes were assigned to the Constellation system (group II).


IOP fluctuations were evaluated during routine vitrectomy procedures, including scleral compression using a depressor and injection of perfluorocarbon liquid (PFCL), 0.05 mL intravitreal anti-VEGF, 0.05 mL triamcinolone, C3F8 gas, 0.2 mL indocyanine green (ICG), and silicone oil, using an automated disposable blood pressure transducer and monitor. Main Outcome Measures: Average and/or peak IOP change during vitrectomy and intravitreal injection.


Baseline age, axial length, and IOP were not different between the two groups (p = 0.604, 0.720 and 0.679). The initial IOP before vitrectomy was 20.3 ± 2.4 mmHg in group I using conventional vented gas forced infusion system and 20.0 ± 0.0 mmHg in group II using active IOP control at 20 mmHg (p = 0.532). However, the average IOP during core vitrectomy was -8.6 ± 4.3 mmHg in group I and -0.8±1.1 in group II (p < 0.001). The maximum IOP decrease was significant in group I (-17.0 ± 2.6 mmHg) compared with that in group II (-4.1 ± 2.2 mmHg) (p<0.001), and choroidal detachment was observed during vitrectomy only in group I (78.1%). The peak IOP significantly increased during scleral compression and gas and fluid injection, but the peak IOP was not significantly different between the two groups (all p ≥ 0.147). The range of IOP fluctuation was 50–70 mmHg in both groups.


The IOP fluctuated significantly during real routine vitrectomy using both systems. Hypotony and choroidal detachment were more frequently observed during vitrectomy with the Accurus system than with the Constellation system. However, both systems were vulnerable to IOP surge during indentation and intravitreal injection. Thus, Individual IOP monitoring may be quite useful for checking the IOP fluctuation.

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