Extending the limbus-to-cannula distance to 6.0 mm during pars plana vitrectomy in highly myopic eyes

Purpose To evaluate the utility of extending the limbus-to-cannula distance to 6.0 mm during pars plana vitrectomy (PPV) for highly myopic eyes. Methods Four eyes with axial lengths exceeding 31.0 mm, that underwent 25-gauge PPV were retrospectively evaluated. Assuming that cannulas were inserted 3.5 and 6.0 mm from the corneal limbus, the distance from the cannula to the fovea (CF distance) was preoperatively evaluated using anterior segmental optical coherence tomography. Surgical complications were also investigated. Results The CF distance was shortened by 1.22±0.05 mm and 1.22±0.09 mm on the temporal and nasal sides, respectively, by inserting the cannula at 3.5 to 6.0 mm from the corneal limbus. As per the preoperatively measured CF distance, one of the cannulas was inserted 6.0 mm from the corneal limbus in 3 eyes. Their cannulas were confirmed to be inserted at the pars plana, and no surgical complications associated with this technique were observed. Conclusion Extending the limbus-to-cannula distance to 6.0 mm during PPV could be one of the options to reach the posterior pole in highly myopic eyes. A preoperatively measured CF distance can be a clinical criterion in determining the cannula position.