Our study showed that patients with MF may obtain anatomical and functional improvement from 23-gauge vitrectomy with ILM peeling at least 6 months following (p < 0.001). Many earlier studies confirmed that PPV with ILM peeling results in better BCVA and anatomic outcomes compared with PPV alone [6, 9, 10, 14, 15, 24–26]. However, some researchers hypothesized that total ILM peeling could increase the risk of developing a FTMH, macular shift and inner retinal dimples [6, 27]. 'Fovea-sparing ILM peeling' method was raised by Ho[8] and Shimada[6] to prevent the formation of FTMH and to reduce the damage to the structure of macular after vitrectomy. Although it's extremely challenging to preserve a small size of spared-fovea ILM with long axial length. If the size is not small enough or the margin is not sharp, the preserved ILM itself may cause a late contraction [6].
In our study, the eyes with FD had a thicker baseline mean CFT and a thinner postoperative mean CFT, compared with those without FD, probably due to EZ disruption preoperatively related to the foveoschisis and FD. This disruptive change may bring about worse preoperative VA and postoperative VA, compared with those eyes without FD at baseline [28]. Our study showed that a better baseline BCVA and absence of FD were significantly correlated with a better visual prognosis (p < 0.001), similar to the results by Lee et al.[29] and Al-Badawi et al.[30]. Nonetheless, even eyes with FD achieved as much improvement in vision and macular structure as eyes without FD from baseline. Therefore, when the central fovea is affected, with vision decline, it is effective to take surgical treatment of vitrectomy in time to restore the foveal configuration and prevent macular hole and retinal detachment. For eyes with FD with long-term low vision, surgery is still an effective way to improve VA.
Whether or not to use gas tamponade and which gas is more suitable for tamponade has been controversial [15, 21, 31]. We insist on the application of gas tamponade to achieve more rapid MF resolution to protect macular function. Jiang et al.[32] considered that C3F8 was more effective in patients than air. Hwang et al.[19] reported that there was no significant difference in postoperative BCVA between air tamponade group and C3F8 group. In this study, air, C2F6 and C3F8 tamponade were divided into three groups according to different tamponade material. There was no significant difference in FD and combined cataract surgery between the three groups (P = 0.45 and P = 0.46), which could exclude the effect of both on the statistical results. All eyes of the three groups showed significant visual improvement after vitrectomy. The air tamponade group showed a greater improvement in postoperative BCVA compared with the C3F8 tamponade group. This disparity can be explained to some extent by the expansion and long retention time in eyes, which may lead to lens opacity and high intraocular pressure [15]. The postoperative complications showed that 1 case of secondary glaucoma and 12 cases of complicated cataract were with C3F8 tamponade, 2 cases of complicated cataract with air tamponade. The results indicated that air tamponade was more effective than C3f8 tamponade, with fewer side effects. Compared with C3F8, air tamponade can provide faster visual recovery and reduce the occurrence of postoperative complications.
FTMH is a common complication after PPV with ILM peeling for MF, with an incidence of about 12.5%ཞ27.3%. ILM peeling, gas tamponade, and preoperative ellipsoid disruption may be risk factors [14–16, 21, 23, 28, 33]. In our study, 2 of 62 eyes (3.2%) developed FTMH with total ILM peeling, similar to the incidence of PPV without ILM peeling studies and fovea-sparing ILM peeling studies [34–36]. It has been reported that postoperative FTMH is more common in MF with FD [2, 37, 38]. Preoperative lamellar MH was observed in the two cases of our study that developed postoperative FTMH (one case with C3F8 tamponade, the other one with C2F6 tamponade). Tian's research showed that the only risk factor for development of postoperative FTMH was preoperative outer lamellar MH [36]. We hypothesized that the foveal tissue with lamellar MH or EZ defect is fragile and is more easily damaged, regardless of the surgical procedure selection, fovea-sparing or total ILM peeling. How to reduce the occurrence of postoperative MH requires further study.
There are several limitations to this study. First, although our surgical technique was standardised, the decision to use either air or expansive gas intraocular tamponade depended on the surgical period (by June 2017) and the surgeon's experience rather than being driven by particular guidelines. Second, we didn't note EZ disruption in the study, because some OCT scans were of poor quality caused by lens opacity and extreme axial length. Third, the sample size was not enough, and the patients were not randomized into groups.