Background
Perfluorocarbon liquid (PFCL) is now in wide and critical use in vitreoretinal surgery. The presence of submacular PFCL is a significant surgery-associated complication and can lead to functional visual loss, central scotoma and irreversible retinal structural damage [
1]. Removal of submacular PFCL is generally recommended. However, there is no expert consensus or reference for the standard surgical treatment. Here, we report four cases of surgical removal of retained submacular PFCL bubbles using a 38-gauge flexible cannula combined with internal limiting membrane (ILM) peeling and intravitreal air tamponade.
Discussion
Subretinal PFCL is a relatively rare but serious complication secondary to surgical repair of rhegmatogenous retinal detachment. Temporary exposure to PFCL has been reported to be clinically safe, however, retained PFCL has the potential toxic effects on various structures of the retina [
2]. Actually, it is optimal to notice the PFCL bubbles intraoperatively and remove subretinal PFCL immediately. However, subretinal retention of PFCL cannot be detected in 0.9 to 11.1% of cases until follow-up visits [
3].
During vitreoretinal surgery, especially for macular-off retinal detachment or giant retinal tears, unnoticed small droplets could migrate into the subretinal space via retinal breaks during PFCL injection. The high jet stream of the injection may induce turbulence in the vitreous cavity, causing disruption of the PFCL surface tension, thus increasing the possibility for PFCL bubbles to migrate towards the subretinal space. If the end of the injection needle is not completely submerged into the growing bubble, subretinal PFCL droplets may also occur. Once PFCL was displayed in the subretinal space, long-term retention may induce progressive retinal pigment epithelial and photoreceptor damage, resulting in irreversible visual impairment [
4]. Visual prognosis of residual PFCL depends on the location, size and exposure time. Since the removal of the retained subretinal PFCL is challenging and may cause significant damages, prompt intervention appears to be recommended particularly in the submacular location.
In our cases, a modified minimally traumatic technique was used for direct aspiration of the retained PFCL bubbles. A standard three-port pars plana vitrectomy was performed in all patients. The ILM of the retina was stained with the use of ICG and then peeled to the vascular arcades. Subsequently, a 38-gauge flexible cannula was used to carefully aspirate the PFCL droplets, with the tip in a substantially perpendicular position. Additional file 1: Video S1 shows the procedure in more detail. Postoperatively, the patients achieved both an anatomic success and an improvement in visual acuity. Despite in one case, the patient developed a macular hole which was successfully resolved with another surgical intervention, this method should be considered as alternative for the treatment of retained submacular PFCL. Further studies with larger patient population and longer follow-up are warranted to verify and extend our findings. Moreover, it is worth noting that, in case 4, direct ILM peeling was not attempted at the beginning as silicon oil had already been injected into the vitreous cavity. We observed the development of epiretinal membrane postoperatively, which could be due to the perifoveal retinal puncture and a predisposition in young patients [
5]. More specifically, PFLC aspiration could make an open break, facilitating the access of retinal pigment epithelial cells or fibroblast-like cells to the epiretinal surface and to produce collagen. Further histopathologic studies on epiretinal membrane are needed to better demonstrate this problem.
There are several issues that deserve further discussions. First, there is no consensus about the optimal timing for submacular PFCL removal. But in general, earlier removal seems to be more appropriate to improve visual functions and to avoid further retinal damages. As we all know, the photoreceptor inner segment/outer segment (IS/OS) junction has been found to be an important prognostic factor for visual acuity. In our current cases, we noticed that the appearance of photoreceptor layers seemed to be defective, thus necessitating earlier surgical interventions. If we don’t consider the time periods when submacular PFCL is detected, and the patient is willing to accept the surgical intervention, the procedure is recommended in 2 weeks after the initial surgery. Based on our results and the limited number of previously published case reports [
6‐
8], follow-up results indicated that early surgical removal generally showed a good prognosis. Second, ILM peeling is a technical procedure applied to release tangential traction, thus minimizing the risk of an iatrogenic macular hole. On the other hand, since the inner retina seems to be more rigid when the ILM exists, ILM peeling might weaken the force acting to confine PFCL in the subretinal space and increase retinal flexibility. Cillà et al. [
9] also affirmed the significance of ILM peeling and further demonstrated that performing the procedure immediately before or shortly after the PFCL aspiration did not seem to influence anatomic results. Third, different sizes of cannulas were used for PFCL aspiration in previous reports, ranging from 36-gauge to the smallest 50-gauge [
10‐
13]. It is challenging to select the most suitable cannula and the choice will largely depend on the size and location of PFCL, as well as the technical considerations of the surgeons. While aspirating the subretinal PFCL, the tip of the cannula should be placed exactly on the top of the bubble in a substantially perpendicular position, so as to minimize the potential damage to retinal functions. Fourth, since the risk of postoperative macular hole could not be excluded, all patients were finally treated with intravitreal air injection and instructed to maintain a face-down position for at least 3 days. Intravitreal gas tamponade is supposed to be beneficial for macular hole closure after elimination of the tangential force. In addition, it provides a template for glial cell proliferation and migration.
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