Purpose: To evaluate the effect of pars plana vitrectomy (PPV) and internal limiting membrane (ILM) peeling for lamellar macular hole (LMH) with or without macular retinoschisis in highly myopic eyes. Methods: In this retrospective, consecutive case-control study, 21 highly myopic patients (22 eyes) with LMH were divided into two groups based on preoperative optical coherence tomography (OCT): the “flat group” had no macular retinoschisis (n = 10), and the “retinoschisis group” had macular retinoschisis (n = 12). The average follow-up time was 17.2 ± 12.6 months. Outcomes were based on 6-month postoperative best-corrected visual acuity (BCVA), integrity of the ellipsoid zone (EZ), external limiting membrane (ELM), and residual foveal thickness (RFT). Results: The appearance of the macula on OCT was normalized in 19 eyes (86.3%) at the final follow-up visit. Compared to the flat group, the retinoschisis group presented a significantly higher incidence of epiretinal membrane (p = 0.046) and lower refractive error (p = 0.033), shorter axial length (p = 0.0009), better integrity of ELM and EZ (p = 0.005 and p = 0.005, respectively), and better preoperative and postoperative BCVAs (p = 0.015). Conclusions: PPV is an effective method to achieve a high anatomical success, improve postoperative vision, and prevent foveal thinning in highly myopic eyes with LMH. In these eyes, the presence of retinoschisis strongly indicates the need for vitrectomy.