Luiz F. Hagemann, MD (Blumenau, Brazil),* Luiz Eduardo de A. Marques, MD (Irvine, CA), Baruch D. Kuppermann, MD, PhD (Irvine, CA)*

PURPOSE:

To compare wound leakage between tunnel and straight scleral incisions after 25 gauge vitrectomy under progressive intraocular pressure elevation testing.

METHODS:

Ten enucleated New Zealand White rabbit eyes were used. Vitrectomy was performed using the Accurus®/Alcon 25 gauge system. An infusion cannula was placed 3 mm from the limbus. A tunnel incision was created and the cannula placed at the 10 o’clock position. Core vitrectomy was performed until free flow of fluid through the cannula was noticed. The cannula was removed with VGFI / eye pressure at 0 mmHg. Balanced saline solution was stained with ICG to help observation of leakage. Intraocular pressure was then increased progressively until leakage was noticed, and the pressure recorded. The straight scleral incision was then created at the 2 o’clock position and the same procedure performed.

RESULTS:

Results: One eye was excluded due to damage to the eye from high pressure during surgery. Of the remaining nine eyes, the average intraocular pressure when leakage was observed was 110 mm Hg (range 30-120, SD? 30) in the tunnel incision group and 12,8 mmHg (range 5-20, SD? 5,89) in the straight incision group (p<0.001). Eight of the nine tunnel sclerotomy incisions withstood the maximum pressure of 120 mm Hg without any sign of leakage, whereas none of the straight sclerotomy incisions withstood pressures greater than 20 mm Hg before leakage was seen. The one tunnel incision sclerotomy which did not withstand the maximum pressure appeared to have only minimal tunneling during cannula placement.

CONCLUSION:

Scleral tunnel incisions showed significantly increased resistance to leakage when compared with straight incisions under progressive intraocular pressure increase testing using the 25 gauge vitrectomy system in rabbit eyes. Performing scleral tunnel incisions may prevent leakage and improve the outcomes of 25 gauge vitrectomy surgeries.
* Financial interest disclosed