Vitreoretinal traction created by conventional cutters during vitrectomy

Purpose: To quantify the vitreous traction created by pneumatic (20-, 23-, and 25-gauge) and electric cutters (20- and 25-gauge) during vitrectomy.

Design: Experimental study.

Participants: This is a preclinical study, and no patients were involved.

Methods: Five separate cutters for each drive mechanism and gauge (20-, 23-, and 25-gauge pneumatic and 20- and 25-gauge electric) were used for each cut speed at predetermined aspiration rates. The retinal layers of fresh porcine eyes were transfixed with a 0.15-mm steel wire and fixed to the load cell of a strain gauge. The cutter to be assessed was introduced into the eye by a micromanipulator at a 45-degree angle adjacent to the retina. The traction force was determined and evaluated at a distance of 3 and 5 mm from the retina with different vacuum and cut rates.

Main outcome measures: Vacuum, cut speed, force (dynes), distance (millimeters), vitreoretinal traction, and gauge.

Results: The 20-, 23-, and 25-gauge pneumatic cutters have a range of traction from 2.06 to 37.22 dynes, 3.85 to 15.38 dynes, 5.13 to 27.91 dynes, respectively. The 20- and 25-gauge electric cutters have a range of traction from 3.60 to 41.78 dynes and 5.28 to 27.91 dynes, respectively. All results are related to distance, cut, and aspiration rate. With an increase of 100 mmHg of vacuum/aspiration, the traction increased from 7.89 to 3.14 dynes (e.g., 4.96 for 20-gauge pneumatic). The traction decreased as the cut rate was increased, from 5.71 to 2.51 dynes (e.g., 3.41 for 20-gauge pneumatic).

Conclusions: The results indicate that retinal traction increased with increasing aspiration vacuum and proximity to the retina; conversely, retinal traction decreased with increasing cut rate. The present study demonstrates that the effects of aspiration, distance from the retina, and cut rate are crucial factors in the amount of retinal traction created by vitreous cutters.

Financial disclosure(s): Proprietary or commercial disclosure may be found after the references.