In vivo comparison of 23- and 25-gauge sutureless vitrectomy incision architecture using spectral domain optical coherence tomography

Comparative analysis of 23-, 25-, and 27-gauge forceps stiffness and related displacement

PURPOSE

To test the stiffness and displacement of different vitreous forceps. Physical features and deformation after multiple procedures were also measured.

METHODS

Eleven different 23-, 25-, and 27-gauge vitreous forceps were studied. The measurements were repeated loading the probe at different distances from the tip: at the top of the tip and 10 and 20 mm from the tip, respectively. For each probe, 10 successive identical bending tests were performed. The total length and the internal and external diameters of each forceps were also measured.

RESULTS

A total of 330 successive identical bending tests were performed. No progression in deformation after the repeated measurements was recorded (p > 0.05). In each gauge group, displacement differences were detected according to the manufacturing metal properties, the total length, and the thickness of the shaft wall. A minimal adequate model to describes forceps displacements in terms of their significant predictors, such as gauge, model, and load distance from the tip, was created.

CONCLUSION

We provided a precise assessment of the stiffness and displacement of different vitreous forceps to enable surgeons to select the optimal instrument according to the benefits and limitations of each forceps.

Comparison of subconjunctival scarring after microincision vitrectomy surgery using 20-, 23-, 25- and 27-gauge systems in rabbits

PURPOSE

To compare subconjunctival scarring after vitrectomy in rabbit eyes using different gauge systems by analysing anterior segment optical coherence tomography (AS-OCT) images and histological sections.

METHODS

Vitrectomy using 20-, 23-, 25- and 27-gauge systems was performed for rabbits. Anterior segment optical coherence tomography (AS-OCT) images of the incision sites were obtained before and at day 1, 7 and 1 month after surgery. We measured the thickness of conjunctival epithelium, stroma, Tenon's capsule and total conjunctiva of these three layers, then determined the preservation rates of the borderlines between each layer. Surgical invasion was estimated by histological observation.

RESULTS

The thickness of total conjunctiva, or the thickness of both conjunctival stroma and Tenon's capsule in the 20-gauge group was significantly thicker than that in the 27-gauge group at day 1 and day 7 after surgery. Preservation rates of the conjunctival stroma/Tenon's capsule borderline were significantly lower in the 20-gauge group than in the 25- and 27-gauge groups at day 1, day 7 and 1 month. Preservation rates of the Tenon's capsule/sclera borderline were significantly lower in the 20-gauge group than in the 25- and 27-gauge groups at 1 month. In the 27-gauge group, the number of α-smooth muscle actin-positive fibroblasts was significantly smaller than in the 20-gauge group at day 7.

CONCLUSION

Based on the finding of AS-OCT and histology, micro incision vitreous surgery, especially using 27-gauge, contributed to less subconjunctival scarring postoperatively. Therefore, the 27-gauge pars plana vitrectomy (PPV) may be a more effective technique for preserving the structure of conjunctiva.

Spectral-domain optical coherence tomography evaluation of choroidal melanoma and nevus fine-needle aspiration biopsy incision sites

The authors present three cases in which spectral-domain optical coherence tomography was used to identify fine-needle aspiration biopsy incision sites. These biopsies were performed to obtain tissue for gene expression profiling of choroidal tumors. A transvitreal route into the apex of the tumors was utilized for the biopsies while the patients underwent pars plana vitrectomy, membrane peel, laser ablation, phacoemulsification with posterior chamber intraocular lens implantation, and intravitreal triamcinolone acetonide. To the best of the authors' knowledge, this is the first report documenting fine-needle aspiration biopsy incision wound architecture of the posterior segment with optical coherence tomography.

Intraoperative endoscopic observation of sclerotomy site after cannula removal for 23-gauge vitrectomy

BACKGROUND

The purpose of this study was to determine the incidence of vitreous incarceration in sclerotomy after cannula removal during 23-gauge vitrectomy.

METHODS

Thirty-seven eyes underwent 23-gauge sutureless vitrectomy. Oblique sclerotomies were made parallel to the limbus and tangentially to the sclera. Once past the trocar sleeve, the angle was changed to 90 degrees perpendicular to the surface and the trocar and cannula inserted. Vitreous gel was removed until the intraocular edge of the infusion cannula was free from the gel. The cannula was extracted with insertion of a light probe. The sclerotomy site was evaluated endoscopically through another cannula in 32 eyes; in five eyes, another infusion tube was inserted into the cannula to maintain intraocular pressure, the original infusion was removed, and the sclerotomy site observed.

RESULTS

No vitreous incarceration occurred in 30 (94%) eyes when one cannula was removed with insertion of a light probe, and minimal incarceration occurred in two (6%) eyes. No incarceration occurred in five eyes with observation of the infusion site.

CONCLUSION

The incidence of vitreous incarceration is low when a light probe or vitreous cutter is inserted. Inserting the light probe through the cannula during its removal and creating an oblique sclerotomy may reduce vitreous incarceration.