Sterilized air tamponade for large idiopathic macular hole

Ya-Nan Hou1*, Ai-Lin You1*, Yi Wang

Abstract

INTRODUCTION

Recently, 25G pars plana vitrectomy (PPV) combined with internal limiting membrane (ILM) flaptuck is widely used in clinic for treating large or refractory macular holes (MHs)[1-4]. After PPV and ILM tucking, different tamponade materials, such as silicone oil[5], perfluoropropane (C3F8)[6], and sulfur hexauoride (SF6)[7], are applied. When using long-acting gas, a patient is required to hold a prone position for at least a week to ensure that the gas bubble is in contact with the MH. For the patients who are unable to hold the prone position and also those who need to travel by air, usually silicone oil is chosen as the main material. The use of silicone oil tamponade leads to some complications, including silicone emulsication, toxic effects, poorer visual outcomes, and ocular hypertension[8-11]. On the contrary, the patients must undergo secondary surgery for oil removal. Recently, sterilized air is also used as intraocular tamponade after PPV and ILM peeling to treat idiopathic macular holes (IMHs)[12-14]. Most successful reports with higher rates of MH closure were based on the small diameter of MH (MH size <400 μm). Few recent studies explored whether air tamponade was sufcient for the recovery of large MH (>700 μm of minimum diameter and >1300 μm of basal diameter). Based on the aforementioned findings, this study focused on the large MHs (taking basal and minimum diameters into consideration) and evaluated the effectiveness of air tamponade for large IMHs.

SUBJECTSANDMETHODS

EthicalApprovalThis study was performed following the tenets of the Declaration of Helsinki, and all the eight participants signed informed consent forms in accordance with the ethical review committee of Chongqing Aier Eye Hospital. Permission was obtained to use patients’ images.

OverviewThis study retrospectively reviewed nine eyes of eight consecutive patients with a large IMH from June 2017 to May 2018 in the Chongqing Aier Eye Hospital. These patients underwent 25G phacovitrectomy, ILM flaptuck, sterilized air tamponade in the vitreous cavity, and intraocular lens implantation to treat large IMHs.

SurgicalProceduresThe 25G PPV was performed under retrobulbar anesthesia by the same surgeon using the Constellation device (Alcon, TX, USA) under a noncontact viewing system Resight 700 (Carl Zeiss, Germany). Phacoemulsication and intraocular lens implantation through a 2.75-mm microcoaxial incision were performed with vitrectomy in the meantime. All the participants underwent a standard 3-port PPV, during which the posterior vitreous was detached from the retina and the vitreous was cut to the peripheral vitreous base. Indocyanine green (1.25 mg/mL; Shenyang, China) dye was injected into the vitreous cavity to just cover the macular area and stain the ILM. Afterward, the ILM was peeled for a diameter of about two optic disks around the MH. During the peeling, the ILM was not removed but a small remnant was left on the margin of MH to invert and fill into the hole. After performing abundantuid-air exchange using sterilized air, the three incisions closed automatically. All patients were requested to maintain a prone position for 3d after the surgery. The postoperative protocol consisted of routine topical antibiotics and anti-inammatory agents for 1mo. Seven days after the surgery, all individuals were recalled to conrm the closure of the hole. The follow up duration was at least 12mo for every individual.

ExaminationsThe diagnosis of large IMH was conrmed by preoperative spectral domain optical coherence tomography (Heidelberg Engineering, Heidelberg, Germany) images and observation during the surgery. All the patients were evaluated by slit-lamp biomicroscopy, indirect ophthalmoscopy, and fundus photography (fundus camera, TRC-50; Topcon, Tokyo, Japan). The Snellen best-corrected visual acuity (BCVA) and intraocular pressure (IOP) of every patient were measured every day during hospitalization. The Snellen BCVA was converted into a logarithm of the minimum angle of resolution (LogMAR) for statistical calculation. The minimum and basal diameters of MH were measured based on the preoperative OCT examination on a horizontal scan. The exclusion criteria were as follows: high myopia (including axial length larger than 26.00 mm or refractive error more than 6.00 D), preoperative MH retinal detachment, traumatic MHs, history of previous vitreous surgery, history of uveitis, choroidal neovascularization, severe cataract, and diabetic retinopathy that could affect the vision.

StatisticalAnalysisSPSS 22.0 (SPSS for Windows, Chicago, IL) was used in all the statistical analyses of this study. The non-parametric paired Wilcoxon signed-rank test was used to compare values before and after surgery. APvalue of less than 0.05 was considered statistically significant.

RESULTS

This study retrospectively analyzed nine consecutive eyes of eight patients with large IMH. All the nine phakic eyes underwent PPV, ILM inversion into the hole,phacoemulsication, and intraocular lens implantation at the same time. The preoperative demographic and baseline characteristics of the nine cases are listed in Table 1. The mean minimum diameter of IMHs was 725.4±147.8(range: 510-872)μm. The mean basal diameter of IMHs was 1320.7±220.2(range: 1028-1556)μm.

All the nine eyes obtained MH closure and stayed in a stable state during a mean follow up of 12mo. No intraoperative and postoperative complications related to the surgery were observed. Specic details of the nine cases about MH closure are shown in Figure 1. Table 1 shows that the mean BCVA converted as LogMAR improved from 1.27±0.28 at baseline to 0.83±0.26 at the last follow up after the surgery (P=0.007). For all individuals, the mean MH closure time was 15±11d. As shown in Figure 1, the fastest closure time was 4d after the surgery, but the longest closure time was 30d.

DISCUSSION

Many studies reported the use of air as a tamponade material for MHs. Usuietal[12]suggested that air tamponade might provide a comparable rate of MH closure compared with SF6 gas tamponade for MH of relatively small diameters. Forsaaetal[13]concluded that air tamponade leads to high closure rates for small and medium-size MHs. This study showed that air tamponade might be considered as a choice of intraocular tamponade for large IMHs. In this study, the minimum diameter ranged 510-872 μm and the basal diameter ranged 1028-1556 μm. The visual recovery of the patients after the surgery was achieved at an average of only 4d as the air bubble was absorbed. Compared with studies using long-acting gas or silicone oil as the tamponade material, the IOP after the surgery in this study was stable and none of the patients had ocular hypertension or ocular hypotony. This study recommended the use of sterilized air as the tamponade material when the minimum diameter of the MH was no more than 800 μm. Whether air tamponade is useful when the minimum diameter is more than 800 μm needs further investigation.

The tucked ILM flap technique may also play an important role in the closure of large MHs. In this study, the tucked

Table 1 Characteristics of patients with large macular hole

Figure 1 For all individuals, the mean MH smallest diameter was 725.4±147.8 μm, the mean MH base diameter was 1320.7±220.2 μm, the mean MH closure time was 15±11d. The fastest closure time was 4d after the surgery, but the longest closure time was 30d.

ILM flap served as a barrier that prevented the entrance ofuid from the vitreous cavity into the MH to maintain the dry condition. On the contrary, the ILM was peeled, inverted, and filled into the hole as a bridge or a chain to stimulate the proliferation of glial cells. The glial cells pulled the retina outer layers, including external limiting membrane (ELM) and ellipsoid zone (EZ), together into the center of the MH to promote the closure rate[15].

All the patients who had an inverted and filled ILMap showed the ELM and EZ together in the middle of the hole, but none of them recovered the original structure. This might berelated to the barrier made by thelled ILMap in the MH. Iwasakietal[16]found that the inverted and filled ILMap in the MH might obstruct the recovery of the ELM line and EZ line during MH repair mechanically. Previous reports showed that postoperative BCVA with restored ELM and EZ lines was better than that without these lines restored after MH surgery[17-20]. In the meantime, PPV combined with ILM peeling without any other steps showed more benefit in the recovery of ELM and EZ. On the contrary, some studies showed that the inverted ILMap technique improved the closure rate compared with the conventional vitrectomy and ILM peeling[1,21]. Balancing of the recovery of ELM and EZ and the closure rate of the MH needs further study. A better surgical method probably could both promote the closure rate and restore the ELM and EZ to acquire the best postoperative BVCA.

This study had some limitations. The sample size was small, and the study did not include controls. In addition, all the patients underwent PPV combined with phacoemulsication and intraocular lens implantation. Hence, whether the improvement in vision was due to the removal of the cataract or closure of the MH was not clear. The influencing factors for the cataract were not excluded in this study. However, this study demonstrated the usefulness of sterilized air as the tamponade material to enable the closure of the large MHs.