Conjunctival Displacement to the Corneal Side for Oblique-Parallel Insertion in 25-Gauge Vitrectomy

Abstract

Purpose

To assess the usefulness of the method of oblique-parallel trocar insertion with conjunctival displacement to the corneal side in 25-gauge (G) transconjunctival vitrectomy.

Methods

25-G vitrectomy was performed in 77 consecutive eyes. Before making oblique-parallel trocar insertions, the conjunctiva was conventionally displaced superiorly in 35 eyes, but was displaced toward the corneal side in 42 eyes. After surgery, the distance between the scleral and conjunctival wounds was measured with calipers. The frequency of scleral wound exposure was assessed.

Results

After cannula removal at the end of surgery, inferior repositioning of the superiorly displaced conjunctiva was observed, while marked posterior repositioning of the corneal side caused displacement of the conjunctiva due to gravity. The superior displacement distances between the sclera and conjunctival wounds were 2.4±0.3 mm at the infusion port, 2.0±0.4 mm at the superior temporal port, and 1.9±0.4 mm at the superior nasal port, while the corresponding distances for corneal side displacement were 3.6±0.5, 3.5±0.5, and 2.5±0.5 mm, and were all significantly (p<0.0001) greater with corneal side displacement. The frequency of scleral wound exposure due to conjunctival damage around the cannula (infusion port) was significantly (p=0.0164) lower for corneal side displacement (0/42; 16.7%) than superior displacement (5/35; 14.3%). There was no postoperative endophthalmitis in all 77 patients studied.

Conclusions

In 25-G transconjunctival vitrectomy, using oblique-parallel trocar insertions with the conjunctiva displaced toward the corneal side results in marked posterior repositioning of the conjunctiva after cannula extraction. Corneal side conjunctival displacement is technically easy and completely covers the scleral wound. This method is expected to be effective in preventing endophthalmitis.