In this study, we described the EZ reconstruction process after macula-off retinal detachment surgery. To our knowledge, it has the largest population of cases so far. After retinal detachment, retinal neural cells apoptosis was observed in 24 hours, which peaked by 2 days and dropped to a low level by 7 days 3. Lewis GP found that the inner and outer retinal could regenerate after retina reattached in animal experiment, and recently Ra E also confirmed in vivo that the photoreceptor outer segment could regenerate using adaptive optics fundus camera 4 5. However, this microstructure recovery after successful repair is a time-consuming process. According to the survival function curve in our study, the mid-quartile time was about 14 months, which meant that generally about half of the patients would get their EZ zone fully reconstructed about one year after surgery. Moreover, this recovery rate was much faster in the first two years, and dropped to a much lower level after two or three years postoperatively.
SO has been used world widely in complicated vitreoretinopathy, meanwhile many toxic effects on intraocular structures were substantialized, including iris, ciliary body, trabecular meshwork, retina and optic nerve, etc 6 7. Recently many authors have proved foveal thickness decreasing, EZ disruption, and even choroidal thickness decreasing after SO endotamponade 8–10. The exact mechanism of SO toxicity is still unknown. Slight to moderate immunologic inflammation of SO microbubble in different area is probably acceptable as proved by Wickham L 11. Another explanation is that the ions exchange function of the muller cells between retina and vitreous fluid is barred by the SO which constricts the little space between these two interfaces, reported in vitro-experiments 12. It should be highlighted that postponed SO endotamponade could damage the whole retinal structure, which should be avoided by clinicians.
A posterior staphyloma is an outward protrusion of all layers of the posterior eye, usually occurring in pathological myopia, in which all layers of retina and choroid degenerate irreversibly, from microvasculature to large vessels in fundus. Yuichiro Tanaka has reported extreme thinning or loss of inner neural retina along the edge of staphyloma 13. As a result of the whole eyewall atrophy, the regenerative potential of the neuroretina is very limited obviously, so it is very difficult for those cases to aqcuire a satisfied EZ integrity. Meanwhile, in some previous studies the variable of axis length was revealed as a risk factor for visual function recovery or retinal microstructural integrity, but it was not the case in this study, either in univariate (p = 0.6002) or multivariate analysis (p = 0.7774, not presented). In our point, though posterior staphyloma often accompanies with longer axis, but the damages to retinal structure of them are not parallel. The patient with long axis but without posterior staphyloma could still remain prosperous anatomical outcomes after retina repair, maybe due to less atrophic changes on the fundus structure.
Recently DRIL get its focus in many studies. It was reported that DRIL associated with cystoid macular edema in uveitis, and also correlated with anatomical and functional outcomes of macular epiretinal membrane peeling surgery 14–16. DRIL is a condition of disarrangement of inner retinal layers, which represent the transmission pathway from photoreceptor to ganglion cells. However, the mechanism of DRIL formation is also unclear. DRIL may be a generic finding of tissue damage in a variety of retinal pathophysiological procedures, including ischemia, vasculopathy, and blunt trauma. In this study, we found a strong correlation between DRIL and EZ integrity, however it could not be further clarified whether DRIL was a causative factor for EZ recovery or both of them just shared a common pathogenesis process, which needed future researches
We presumed before this study that postoperative subretinal fluid might affect EZ recovery, as some other authors proposed. However, in this study subretinal fluid was not significantly correlated with EZ integrity. The relatively rare cases of subretinal fluid in this study might contribute to this discrepancy, as we only confirmed 9 cases (9/118) of subretinal fluid (6 in fully reconstruction group and 3 in the other group) through OCT scan, so even larger population should be planned.
As a retrospective study, though we have a relatively large number of cases in this study, it was still not satisfied to comprehensively confirm the risk factors for EZ integrity after RRD repair. Furthermore, as mentioned above, we cannot confirm the causal relationship of some key factors in this study. So, prospective studies or multicenter studies need to be carried out.