Abstract
Purpose: :
To investigate intraocular pressure (IOP) fluctuations during conventional 20–gauge vitrectomy and 25–gauge transconjunctival sutureless vitrectomy.
Methods: :
After pars plana lensectomy was performed on pig eyes, 27–gauge needle, connected to a pressure transducer, was inserted into the anterior chamber to measure real–time IOP. Experimental vitrectomy was performed using 20– and 25– gauge infusion tube and vitreous cutter, in conjugation with the gravity infusion with the bottle height of 40 to 75 cm or vented gas forced infusion (VGFI) with the set infusion pressure of 30 to 60mmHg. Cut rate / vacuum pressure was 1500cpm/100–400mmHg and 1000cpm/100–600mmHg for 20– and 25–gauge system, respectively.
Results: :
Before aspiration, IOP was dependent on the bottle height and the set infusion pressure with gravity infusion and VGFI, respectively, and IOP was not different between the 20– and 25–gauge system. Aspiration induced maximal percentage IOP reduction of 83 and 66% with gravity infusion and VGFI, respectively, for 20–gauge system and 34 and 15% with gravity infusion and VGFI, respectively, for 25–gauge system. Scleral indentation induced IOP fluctuation up to 36 and 42 mmHg with gravity infusion and VGFI, respectively, for 20–gauge system, and 42 and 62 mmHg with gravity infusion and VGFI, respectively, for 25–gauge system.
Conclusions: :
During vitrectomy without scleral indentation, IOP fluctuation is smaller with 25–gauge system than that with 20–gauge system, and the use of VGFI caused less IOP fluctuation when compared to gravity infusion. In contrast, after scleral indentation, IOP fluctuation was larger with 25–gauge system than that with 20–gauge system, and the use of VGFI caused much IOP fluctuation when compared to gravity infusion.
Keywords: intraocular pressure • vitreoretinal surgery • clinical laboratory testing