Twenty-three gauge cannula system with microvitreoretinal blade trocar

Scleral wound healing with cross-link technique using riboflavin and ultraviolet A on rabbit eyes

Purpose

The aim of study was to evaluate the cross-link using riboflavin and ultraviolet A (UVA) for improving scleral wound healing.

Materials and methods

This was an experimental study involving four New Zealand rabbits (eight eyes). Therapy procedure was chosen for the right eye and control procedure for the left one. UVA irradiation of 365 nm with a surface irradiance of 3 mW/cm² and a photosensitizer of riboflavin drops were applied for 30 minutes on the right eye at 2 mm from the limbus. Sclerotomy incision was performed at 2 mm from the limbus in both right (on the cross-link-treated area) and left eye. Then, 30 days after surgery, a morphological analysis and histological staining with hematoxylin–eosin and picrosirius red were performed, and the sclerotomy cicatrization of right and left eyes was compared. The variables investigated were as follows: sclerotomy incision pictures and measurements were made using the ImageJ Software. Scleral thickness was measured (employing the anterior optical coherence tomography and the digital caliper). Collagen fiber density stained with picrosirius red staining was measured using the Image Pro Plus software.

Results

The morphological analysis showed that in all samples, the right eye presented sclerotomy closure, and in two eyes, among them, there were no visible edges of the sclerotomies incision. The left eye presented sclerotomy closure and incision edges. The Image Pro demonstrated a higher density of collagen fibers in the right eye when compared to the one. The statistical analysis was significant when compared to the collagen fiber density in the treated eyes with the control eyes.

Conclusion

The cross-link procedure resulted in a better sclerotomy wound healing.

Subconjunctival Injection of Viscoelastic Material for Leaking Sclerotomy in Transconjunctival Sutureless Vitrectomy

Aim. To evaluate the effectiveness of subconjunctivally injected viscoelastic material (VEM) for the self-sealing of leaking sclerotomy in transconjunctival sutureless vitrectomy (TSV). Methods. This was a prospective interventional series. Subconjunctival injection of VEM was performed in eyes showing leaking sclerotomy at the end of TSV in selected cases. This procedure was performed in 24 consecutive eyes from 24 patients scheduled for 23- or 25-gauge TSV with phacoemulsification for various vitreoretinal diseases combined with cataracts. Results. Among the 24 eyes, 13 cases were scheduled for 23-gauge TSV, while 11 cases were scheduled for 25-gauge TSV. The average number of injection sites per eye was 1.7 ± 0.9 in the 23-gauge cases and 1.5 ± 0.7 in the 25-gauge cases. Leakage was most commonly observed at the vitrector site of the sclerotomy, while little leakage was observed at the illuminator site. There were no cases of postoperative hypotony. Conclusion. Subconjunctival injection of VEM was simple and effective for the self-sealing of leaking sclerotomy after TSV in selected cases.

Comparison of the effects of 23-gauge and 25-gauge microincision vitrectomy blade designs on incision architecture

Purpose

To compare the effects of different 23- and 25-gauge microincision vitrectomy trocar cannula entry systems on incision architecture.

Methods

We tested one ridged microvitreoretinal (MVR), one non-ridged MVR, one pointed beveled, and one round-tipped beveled blade (n=10 per blade design per incision type). Each blade’s straight and oblique incision architecture was assessed in a silicone disc simulating the sclera. Wound leakage under pressure and endoscopic observations were conducted on sclerotomy sites of isolated porcine eyes (n=4 per blade design) after simulated vitrectomy.

Results

Differences in blade design created distinct incision architecture. Incisions were linear with the ridged MVR blade, flattened “M-shaped” with the non-ridged MVR blade, asymmetrical chevron-shaped with the pointed beveled blade, and curved with the round-tipped beveled blade. With the exception of oblique entry incision thickness, both MVR blade designs created thinner incisions than the beveled blades at entry and exit sites. Only the ridged MVR blade created incisions with no leakage. Vitreous incarceration was observed with all trocar cannula systems.

Conclusion

Wound closure in porcine eyes was similar with all blades despite differences in incision architecture. Wound leakage occurred at low to moderate infusion pressures with most blades; no wound leakage was observed with ridged MVR blades.

Diathermy of leaking sclerotomies after 23-gauge transconjunctival pars plana vitrectomy: a prospective study

PURPOSE

To evaluate the efficacy of bipolar diathermy in ensuring closure of leaking sclerotomies after complete 23-gauge transconjunctival sutureless vitrectomy.

METHODS

In this prospective, interventional case series, in 136 eyes of 136 patients with at least one leaking sclerotomy at the end of a complete 23-gauge transconjunctival sutureless vitrectomy, external bipolar wet-field diathermy was applied to leaking sclerotomies, including the conjunctiva and sclera. Intraoperative wound closure, and postoperatively, at 6 hours, 1 day and 3 days, sclerotomies leakage, intraocular pressure, hypotony, and hypotony-related complications were evaluated.

RESULTS

Intraoperative closure was achieved in 231 of 238 leaking sclerotomies (97%) that received diathermy. One of these with postoperative leakage needed suture. Compared with baseline (14.4 ± 2.8 mmHg), mean intraocular pressure was lower at 6 hours (13.2 ± 3.8 mmHg, Tukey-Kramer P < 0.001) and not different at 24 hours or 72 hours. Hypotony (intraocular pressure <5 mmHg) was observed in 6 eyes (4.5%) at 6 hours, in 2 (1.5%) at 24 hours, and in none at 3 days. Logistic regression analysis showed that, 6 hours postoperatively, hypotony was related to younger age (≤50 years) at surgery (P = 0.031). No hypotony-related complications were recorded.

CONCLUSION

Bipolar wet-field diathermy of sutureless sclerotomies is an effective method for ensuring a leaking sclerotomies closure.

Advantages and limitations of small gauge vitrectomy

Small gauge vitrectomy utilizing 23- and 25-gauge instrumentation has definite advantages, but also limitations, due to the physics of smaller instruments and sutureless surgery. Higher infusion and aspiration pressures are needed to remove the vitreous using 23- and 25-gauge probes. The advantages include decreased surgical times, less tissue manipulation, reduced inflammation and pain postoperatively with more rapid visual recovery. A disadvantage is greater instrument flexion than 20-gauge probes, making small gauge vitrectomy more appropriate for indications such as vitreous opacities, epiretinal membranes, macular holes, and simple retinal detachments. There are also some increased complications related to small gauge vitrectomy, including dislocation of cannulas intraoperatively, early postoperative hypotony, choroidal detachment, and possibly an increased risk of infectious endophthalmitis.

Hypotony after 25-gauge vitrectomy

PURPOSE

To describe the incidence of hypotony after 25-gauge vitrectomy and to identify preoperative and intraoperative factors that influence the occurrence of hypotony.

DESIGN

Retrospective, nonrandomized, interventional case series.

METHODS

We reviewed 122 consecutive cases of 25-gauge vitrectomy for all surgical indications. The primary outcome measure was intraocular pressure (IOP) at postoperative day 1, measured with Goldmann tonometry. Secondary outcome measures were clinical signs of hypotony and other complications.

RESULTS

Hypotony, defined as an IOP of 5 mm Hg or less, was found in 13.1% of cases on postoperative day 1. Clinical signs of hypotony were encountered in 7 eyes (5.7%). The risk of hypotony was significantly lower in cases with air or gas tamponade (3.3%) than in cases without tamponade (22.4%). Hypotony was encountered more often in reoperations (29.9%) than in primary operations (9.2%; statistically significant difference). In cases in which intravitreal triamcinolone was used, the risk of hypotony was significantly higher (35.3%) than in cases without triamcinolone (10.3%). Phakic eyes had significantly less chance of hypotony (6.7%) than pseudophakic eyes (15.6%) and eyes undergoing combined phacoemulsification and vitrectomy (25.0%). At postoperative day 7, all cases of hypotony recovered spontaneously. None of our cases developed endophthalmitis.

CONCLUSION

Our results show that a transient hypotony occurs commonly after 25-gauge vitrectomy. Hypotony was significantly influenced by tamponade, reoperation, intraoperative lens status, and use of intravitreal triamcinolone. Although all cases of hypotony recovered spontaneously without permanent damage, the high frequency of hypotony does impose potential risks. Increased vigilance with focus on perioperative antisepsis and low tolerance of sclerotomy leakage are important for the prevention of endophthalmitis. Strategies aimed at lowering the risk of hypotony are needed to improve the safety of this promising technique.