Indentation and internal visualization: A novel technique for posterior cannula placement in eyes with high myopia

High myopia, which is characterized by a refractive error of −6. 00 diopters or more or an axial length (AXL) greater than 26. 5 mm, is linked to an axial elongation. 1 This elongation makes individuals more prone to retinal pathologies, some of which may require surgical management. 2 Vitreoretinal surgery in highly myopic eyes presents unique difficulties, primarily due to the increased AXL and posterior staphylomas, as standard vitrectomy instruments may be too short to reach the target area effectively. 2 Removal of trocars during the procedure, allowing conventional instruments to reach the posterior pole. 2, 3 Innovative surgical techniques, such as posterior scleral indentation with Helvoston retractor, can assist in surgical maneuvers among eyes with AXL more than 34 mm. 4 Specially designed instruments, such as an extra-long cannula, a high myopic Eckardt end-gripping forceps with a longer shaft (7 mm), were more useful in highly myopic eyes. While these forceps are effective, their tips can still exhibit a degree of instability due to their extended length and delicate structure. 5, 6 However, these advanced tools may be inadequate for prominent posterior staphylomas. 2, 3 Due to the substantial distance between the posterior pole and the cannula, standard forceps may be unable to access the macula in highly myopic eyes. To overcome this, we propose a simple technique for posterior cannula placement with internal visualization. Methods A 39-year-old male presented with a recurrence of rhegmatogenous retinal detachment in the right eye 20 days after silicone oil removal elsewhere and was referred to us. He noticed a decrease in vision in his right eye after six days. Visual acuity in the right eye was the perception of light. The patient was pseudophakic in both eyes. The intraocular pressure (IOP) was 10 mmHg, and the AXL was 36. 13 mm. The right eye showed subtotal retinal detachment with retinal folds noted superiorly passing through the macula with a belt indent present Fig. 1a. The vision of the left eye was 20/20 with the retina attached and a 360-degree barrage laser scar. Before the procedure, peribulbar anesthesia was administered. A 25-gauge sclerotomy port was made, and a cannula (Alcon, Fort Worth, TX, USA) was placed at a seven o’clock position, 4 mm behind the limbus. The infusion cannula was connected to the inferotemporal port, and the infusion cannula was turned on. Superonasal trocar was positioned superiorly 4 mm away from the limbus Fig. 2a. The temporal sclera was indented using forceps, and the ora was visualized under endo-illumination using a light pipe under a microscope Fig. 2b. A 128D lens was used for the wide viewing system (Resight; Zeiss, Germany) under a Zeiss OPMI Lumera 700 surgical microscope. After localization, the temporal port was placed 9. 5 mm away from the limbus after confirming its position from the endo illuminator Fig. 2c-f, Video 1. During surgery, no obvious breaks were observed in the indentation. Nasal drainage retinotomy was performed Fig. 2g; brilliant blue dye was injected into the drainage retinotomy to localize the break, which was seen inferiorly at the six o’clock position at the edge of the previous cryo-scar, by noting the egress of the dye. The break location was marked using diathermy. Laser barrage was performed around the break, and drainage retinotomy Fig. 2h and circumferential barrage endolaser were performed along the entire margin after fluid-air exchange. A silicone oil endotamponade (5000 centistokes) was used to reattach the retina (approximately 10 mL). At the 1-week postoperative follow-up, visual acuity improved to 20/200, with an attached retina under oil Fig. 1b. The retina remained attached during the follow-up at 1 month, and Best corrected visual acuity (BCVA) improved to 20/200 with an IOP of 15 mmHg. Figure 1: (a) Preoperative fundus photograph of the right eye with recurrent retinal detachment with the presence of a buckle indent. (b) On postoperative day one, the fundus shows an attached retina under silicone oil with laser spotsFigure 2: Intraoperative findings from surgical videos. (a) A 25-gauge sclerotomy port was made, and a cannula was placed at a seven o’clock position 4 mm behind the limbus. Another trocar was placed superiorly, 4 mm from the limbus. The infusion cannula was connected to the infero-temporal port and turned on. (b) The temporal sclera was indented using forceps, and the ora was visualized with endo-illumination using a light pipe under the microscope. (c and d) Distance from limbus to temporal sclerotomy site was confirmed with a caliper to be 9. 5 mm. (e) After localization, the temporal port was placed after confirming the position. (f) Location of the cannula anterior to the ora is confirmed. (g) Nasal drainage retinotomy is being performed without much effort. (h) Laser retinopexy of the drainage retinotomy site is being performed "href": "Single Video Player", "role": "media-player-id", "content-type": "play-in-place", "position": "float", "orientation": "portrait", "label": "Video 1", "caption": "", "object-id": {"pub-id-type": "doi", "id": "", "pub-id-type": "other", "content-type": "media-stream-id", "id": "1ⱼm0lhbio", "pub-id-type": "other", "content-type": "media-source", "id": "Kaltura"} Discussion Anterior segment: Optical coherence tomography and ultrasound biomicroscopy-guided trocar insertion have been attempted in high myopic eyes. 7, 8 In eyes with increased AXL, the pars plana is wider. For AXL exceeding 27. 0 mm, the pars plana extends beyond 6 mm. Therefore, increasing the limbus-to-cannula distance to 6 mm is effective and safe in cases of extreme myopia. 3, 7, 8 In small-gauge pars plana vitrectomy, standard instruments may not reach the posterior pole in eyes with AXL exceeding 31. 0 mm, making surgery challenging. The direct visualization technique allows for posterior trocar placement, providing better access to the macula and eliminating the need for advanced equipment or intricate surgical maneuvers. Posterior placement of the cannula can cause problems, such as instruments contacting the speculum or bony structures around the eye. To tackle this problem, the instruments can be held farther away from the instrument tip to pivot them, avoiding any fulcrum effect. Procedures such as internal limiting membrane removal can be performed effectively and safely using conventional forceps introduced through a posteriorly placed cannula. Direct visualization with wide-angle viewing systems has a lower risk of iatrogenic injury, such as port-site retinal tears or dialysis. Further studies involving larger patient cohorts are warranted to validate for broader clinical applicability. Conclusion This report highlights the importance of posterior cannula placement with direct visualization, which offers a practical and effective solution for vitreoretinal surgery in highly myopic eyes. This technique enhances surgical access to the posterior pole without requiring specialized instruments. Our case demonstrates the feasibility and utility of this approach. Author contribution statement Dr. Vivek Pravin Dave: Concept, design, analysis, interpretation of data, and final approval. Dr. Manoj P Shettigar: Design, drafting of the paper and critical revision. All authors agree to be accountable for all aspects of the work in the manuscript.