Intraocular pressure rise during 25-gauge vitrectomy trocar placement

Purpose Small-gauge vitrectomy has been used to treat various vitreous and macular pathologies. Trocar/cannula insertion may raise intraocular pressure (IOP) to the point it might become detrimental to the eye, especially in the setting of open-globe trauma and eyes with severe vascular compromise. We propose to determine the magnitude of this IOP rise and its possible implications. Methods Three different settings were designed to measure IOP rise during trocar placement for 25 ga vitrectomy (TSV); water-column manometry was performed during trocar placement in pig eyes. Electronic applanation tonometry was recorded in human eyes undergoing 25-ga vitrectomy for macular pathology during trocar placement, and wound behavior was recorded during trocar placement in harvested dog eyes with a previously sutured corneal wound. Results The pressure recorded during trocar placement was 57.5 mmHg in pig eyes and 63.7 mmHg in human eyes. Sutured corneal wounds in dog eyes showed wound leakage and tissue incarceration during trocar insertion. Conclusions The 25-ga vitrectomy system may have limited usefulness in the setting of open-eye trauma and compromised bloodflow, due to the elevated pressures reached during trocar placement.