In this study, we assessed the efficacy and safety of PSR for the treatment of MFS. Our results showed a slight increase in AL in the first 6 months after surgery; however, the mean AL stabilised after 6 months. This finding is similar to those reported by Zhu et al17. MFS is the main cause of vision loss in patients with pathological myopia. Although the pathogenesis of MFS is unknown, it is presently considered to be related to two factors, which are as follows9, 18, 19: The tangential traction between the posterior vitreous cortex and the inner limiting membrane, and the mismatch between the retina and the externally expanded scleral tissue. The latter is considered to be the main cause of MFS. AL stability is important for the treatment of MFS, as well as for the prevention of recurrence.
Data recorded at the last follow-up in the present study showed that the fovea was essentially reattached in 30 eyes (93.75%) and partially reattached in two eyes (6.25%). Several studies20–22 have shown reattachment rates of 83.3–100% for MFS treated using PSR, with variances occurring due to differences in the shape and material of the strips used intraoperatively and due to variations in the duration of the study observations. Micol et al.7 found that resolution of foveoschisis, retinal reattachment, and MH closure seem to be achieved more frequently with macular buckle than with PPV. The duration of retinal reattachment may be related to the position of the intraoperative strip, the duration and diameter of the foveal retinoschisis, and the shape of the posterior scleral staphyloma. The strip material used in this study was chosen from donor sclerae and sterilised and cross-linked with genipin for increased strength and resistance to degradation, which is beneficial for the prevention of posterior scleral expansion and maintenance of long-term surgical outcomes23. The length and width of the strip should be pre-designed before PSR to ensure that it can completely wrap around the macula and posterior scleral staphyloma5, 10. The vortex vein, optic nerve, and other important tissues should be avoided while positioning the strip to avoid disrupting the blood supply to the eye and affecting vision. The mean duration of follow-up in the study was 17.80 ± 8.74 months, which indicates that the surgical outcomes were stable 1 year after surgery. However, further follow-up is needed to determine the long-term outcomes of the surgery. The MH in seven eyes (77.78%) in the present study closed after surgery. Ikuno et al.24 reported that the rate of MH closure in patients with high myopia who underwent PPV surgery in their study was 25%. The two patients in the present study who had no MH closure showed improved visual acuity and retinal reattachment. Thus, we believe that we can continue to observe fundus changes and that no further surgical intervention is needed.
Several authors25–26 concluded that high myopia causes a decrease in ERG a-wave and b-wave amplitudes in patients and that photopic readings reflect the cellular electrical activities of the retinal layers, from the photoreceptor cells in the macular region to the amacrine cells. Westall et al.27 concluded that altered retinal cone cell responses appear earlier and are more impaired than those of optic rods in patients with MFS. Therefore, we used photopic ERG to determine whether surgery could offer an improvement in retinal function. Our results showed that the postoperative a-wave and b-wave amplitudes of the patients were significantly improved compared with the preoperative data and that the difference was statistically significant (p<0.05). This indicates that retinal function could be improved using PSR. The preoperative BCVA of the patients in the present study was 0.80 ± 0.49, whereas the postoperative BCVA was 0.62 ± 0.50 (p༜0.05). This increase in BCVA may be attributed to the effect of mechanical pressure on the sclera in the posterior pole by the PSR, which can reattach the fovea and delay the increase in AL. In addition, due to the stimulating effect of the allograft sclera, neovascularisation develops in the sclera and the blood supply to the corresponding parts of the retina and choroid is improved, thereby promoting metabolism in the optic cells.
All transient elevations in IOP during the early postoperative period subsided with the use of IOP-lowering drops. The difference between the IOP recorded at the last postoperative follow-up and that recorded during the preoperative period was not statistically significant (p༞0.05), suggesting that the shortening of the AL during surgery did not affect the circulation of aqueous humour. The postoperative visual distortion is related to the macular fold caused by the PSR, which is a direct confirmation of the effectiveness of the surgery. As the foveal retinoschisis gradually repairs and the folds gradually flatten, the visual distortion progressively improves and eventually disappears. No serious postoperative complications, such as retinal detachment and vitreous haemorrhage, occurred in the present study, indicating the safety of the surgery.
This study has some limitations. First, the observation period was short and the sample size is small. Second, no control group was established and few indicators of fundus function were evaluated. Considering the complicated pathogenesis of MFS, a large number of long-term clinical studies are needed to verify the long-term efficacy of PSR. In addition, the difference between the efficacy of PSR treatment alone and PSR combined with PPV for MFS needs to be evaluated.