Features Involved in the Healing Process of Macular Holes

Abstract

The mechanism of closure of a macular hole (MH) is not yet fully understood. Spontaneous closure in nontraumatic cases is possible, but quite rare. 1 Alternatively, vitrectomy and gas tamponade, with or without internal limiting membrane (ILM) peeling, achieve anatomic success in 80% to 95% of cases. During recent years, different techniques have been attempted to improve the closure rate of MH and bring it closer to 100%.The addition of autologous serum does not appear to alter the prognosis of surgery, 1 while the addition of platelet-rich plasma seems to work better, 2 even in challenging cases, such as myopic MH. More recently, the ILM flap technique was introduced for cases of MH that pose a high risk of persistence, such as myopic, chronic, or large holes. Initially, many surgeons thought that it would be necessary to put the ILM inside the hole to create a kind of plug. Subsequently, the pioneers of this technique stated that it would be sufficient to cover the hole with a single ILM layer, and they proposed performing the peeling only on the temporal side. 3 An MH can be considered a small laceration in the weakest point of the retina, the fovea. The formation of a blood clot is the first step in the repair of a skin wound, which creates a closed environment, within which the repair mechanisms can act. Similarly, there is some evidence that anything that covers the MH and can separate the vitreous cavity from the intraretinal and subretinal space could facilitate its closure. This might explain why a single layer of ILM covering a myopic MH makes such a significant difference in the rate of closure of myopic MH. 4 Moreover, the ILM flap was found to be displaced or not present in all MHs that failed to close. For the same reason, platelet-rich plasma is likely to work better than autologous serum that does not stick at the edges of the MH.We could even speculate that the main role of a tamponade might be the formation of a cover over the MH that can promote the maintenance of the homeostatic conditions necessary for the healing process. Silicone oil has been found to be an effective tamponade for the treatment of MH. This is surprising, as it is a lasting, but weaker, tamponade compared with gas. A possible explanation for its positive effect in promoting MH closure is that it creates a kind of bursa inside the edge of the MH and, therefore, compartmentalizes chemotactic and nutrient substances that may support its closure.The ILM flap also acts as substrate for a secondary intention wound-healing mechanism. When the hole is large, the edges are stiff, or the retina is not elastic enough, the ILM plug can support the closure without complete reapposition of the edges. In some cases, this step is followed by further anatomical and functional improvements during follow-up: the plug is slowly dis-VIEWPOINT

Macular Hole in Myopic Eyes: A Narrative Review of the Current Surgical Techniques

“…At the beginning, many surgeons believed necessary to insert the flap into the hole like a plug. Now it is thought sufficient to cover the hole with the peeled ILM flap in order to obtain a division between the vitreous cavity and the intraretinal spaces and to promote the MH repair mechanism [82]. The original procedure consisted of circumferentially 2-disc-diameter ILM peeling around the MH to preserve the adhesion between the inner ILM outline and the MH edges.…”

“…These strategies include the use of viscoelastic [83] or perfluorocarbon [84] before balanced saline solution-air exchange, fluid-air exchange with low intraocular pressure and passive aspiration [75], and the addition of autologous serum [14, 22] or platelet-rich plasma [85]. Platelet-rich plasma seems to achieve better anatomical results compared to the autologous serum due to its greater adhesiveness to the edges of the hole [82].…”

“…It has been demonstrated that silicone oil creates a bursa inside the MH with a compartmentalization of chemotactic and nutrient substances. These substances might promote reparative mechanism which supports the closure of the hole [82].…”

Inverted ILM Flap for the Treatment of Myopic Macular Holes: Healing Processes and Morphological Changes in Comparison with Complete ILM Removal

“…This observation may support the ILM flap's role as a scaffold for retinal layer repair after surgery for both idiopathic and myopic MHs [19, 39, 40]. Moreover, we hypothesized that the ILM, creating a separation between the vitreous cavity and the intraretinal environment, can promote the restoration of a favorable homeostatic condition for hole closure [41].…”

Refractory Myopic Retinal Detachment and Macular Hole Closure with Autologous Neurosensory Retinal Free Flap

“…The bimanual approach is one of the key steps of this surgery because of the difficulties in dealing with a floating retina. Besides, the use of silicone oil is useful as it seems that retinal grafts tend to shrink in size [8] and the oil keeps the flap well over the MH, allowing time for retinal cells proliferation and migration [10]. Oil removal should be performed 6 months after surgery if one looks for a better visual outcome.…”