MH coexisting with RRD with peripheral causative breaks was uncommonly noted. It is different from MH induced RRD in high myopia, in which MH is the causative break for RRD. In contrast, in eyes of MH coexistent with RRD, the retina could be well attached by only addressing the peripheral causative breaks, either with scleral buckle or vitrectomy. Before the introduction of ILM peeling, the closure rate of macular hole was around 30% after vitrectomy and air-fluid exchange. With the technique of ILM peeling, about 80% of eyes could achieve MH closure.
According to previous reports, most eyes of MHRD were macula off.1,2,4,5 Since macula attachment status would affect the pre- and postoperative visual outcome, to make the comparison more meaningful, we only include eyes with macula off RRD both in the study group and control group.
The pathogenesis of MH concomitant with macular off RRD is still unknown. Some authors believed that the acute posterior vitreous detachment process, which was responsible for the formation of peripheral retinal breaks and hence the RD, also contributes to the formation of the full-thickness macular hole.3 Some authors believe that tangential traction by the pre-retinal membrane may contribute to the development of MH,1 which could be supported by the high incidence of PVR and presence of ERM in 5 of our patients with pre-operative OCT. The tangential traction on fovea from epiretinal membrane may further be aggravated by the stretching force of retinal detachment which induce an inward bulging of macula.6 Other possible pathogenesis including foveal cystoid changes secondary to hypoxia and inflammatory changes induced by neuroretinal detachment, which weaken the fovea structure. In this study, we noticed that most of the MH in MHRD had EZ lining the bottom of macular hole. This possible explanation would be that an attached retina is in a concave shape and has the inner neuroretinal surface smaller than the outer neuroretinal surface. When the retina is detached, the retina becomes convex in shape, thus the inner neuroretinal surface area expands and suffers from tangential traction, in contrast, the outer retina becomes concave and the surface are relatively more redundant than the inner retinal surface. Besides, the hypoxia induced outer retina edema and secondary corrugation, which was observed in all eyes of EZ lining in our cases, may further increase the redundancy. (Fig. 2) The difference of geometry and structural changes of detached retina may well explain the breaking point of MH would start from the inner surface with the ellipsoid zone still bridging the fovea as shown in most of the preoperative OCT in our series, which is different from the idiopathic macular hole from anterior-posterior traction, that the outer retinal defect generally precedes the inner retina defect.7,8
In the current study, we noted that eyes of MHRD had higher chance of PVR, CD, more extensive RRD and recurrent RRD. Poor initial and final BCVA in eyes with concomitant MH than eyes without MH had also been reported in previous literature, even though the holes were successfully repaired, 5 The poor visual outcome may be explained by that the presence of MH itself has negative impact on vision recovery, besides, the possible different pathogenesis of MH in MHRD including cystoid macular changes, which may cause permanent tissue damage and further aggravate the vision recovery. PVR has been reported of higher incidence 1, 2 and as a risk factor for macular hole eyes with RRD.2 The presence of PVR surface membranes is very likely to induce additional tangential forces, thus may play a role in the simultaneous occurrence of a MH and RRD.
Previous reports have shown that MH was a risk factor for CD. 9, 10,11 In this study, we further showed that the incidence of CD is significantly higher in eyes with concomitant MH..Presence of CD would markedly increase intraocular inflammatory cytokine,12 which may aggravate the cystoid changes of the already compromise macula, and the development of PVR,13 thus facilitate the formation of MH. More extensive RRD was also noted in our series of MHRD. Previous report1 had also shown a high incidence of subtotal or total RRD (91%) in eyes of MHRD. Eyes of RRD had been shown to have elevated inflammatory and ischemic cytokines including VEGF, IL-8 in the vitreous.14 Besides, elevated levels of tumor necrosis factor α (TNF-α), monocyte chemotactic protein-1 (MCP-1), and basic fibroblast growth factor (bFGF) were also detected in detached neural retina.15 A more extensive retinal detachment may induce more cytokine release, with more severe secondary cystoid changes and retina apoptosis, which may also help the formation of MH. The current study showed increased incidence of recurrent RRD in eyes with concomitant MH, which is in line with the previous report2, and was within the expectation, as patients in this group had higher chance of PVR, CD, and extensive RRD, all of which would increase the incidence of recurrent RRD.16 Echos with previous studies, our study showed that eyes of MH had worse initial and final BCVA, which is fairly reasonable, as MH, PVR, extensive RRD, and recurrent RRD all contributed to poor initial and final BCVA.
The limitations of this study include the retrospective nature and lack of intraoperative and preoperative OCT in most cases; as a thin fovea surrounded by edematous retina during intraoperative observation may give the false impression of a macular hole, though the Schlieren phenomenon,and application of dye may easily tell the presence of MH.. With the more widely use of intraoperative OCT in the future, the presence of MH maybe more confirmative and the morphology of MH concomitant with RRD could be more thoroughly appreciated in eyes without preoperative OCT. Besides, though we try to exclude eyes with preexisting MH before the event of RRD by tracing back the patients’ history, it is possible that some of our patients had MH previous to this event of RRD.
In conclusion, patients with MHRD had both worse initial and final visual acuity, higher incidence of PVR and CD, more extensive RRD and higher chance of recurrent RD. Besides, most of the MH obtained preoperatively had ellipsoid zone bridging the bottom of MH, cystoid macular changes and changing of retinal curvature from submacular fluid may be one of the major pathogenic factors for MH formation.