FormalPara Key Summary Points

3D visualization system-assisted vitrectomy provides a PFCL-free way to perform PPV.

3D visualization system provides a clear and bright view, allowing surgeons to operate comfortably.

RRR and VA improvement can be achieved without the use of PFCL.

The 3D visualization system-assisted PFCL-free technique simplifies surgery, shortens operation time, and lessens complications.

Digital Features

This article is published with digital features, including a video, to facilitate understanding of the article. To view digital features for this article go to https://doi.org/10.6084/m9.figshare.22093544.

Introduction

Pars plana vitrectomy (PPV) is now considered a primary strategy to restore vision for patients who have rhegmatogenous retinal detachment (RRD). During PPV surgery, perfluorocarbon liquid (PFCL) is a frequently used aid to flatten the detached retina and drain subretinal fluid (SRF). Without PFCL stabilizing the detached retina, peripheral vitrectomy may cause iatrogenic retinal breaks (IRB). However, its unintended intraocular retention would cause retina toxicity and thus lead to possible postoperative complications. To avoid such complications, some scholars have performed internal SRF drainage by posterior retinotomy [1]. Unfortunately, this is an invasive procedure that can lead to additional complications (e.g., intraoperative hemorrhage, subretinal neovascularization, proliferation, and visual field defect) [2, 3] and cause more unnecessary postoperative care.

Another way to avoid the complications of PFCL is incomplete SRF drainage through the preexisting retinal breaks, which does not avoid either the use of PFCL nor the performance of posterior retinotomy for SRF drainage [2, 4]. However, the intraocular manipulations are usually disturbed by the poor visibility of traditional microscopes in gas-filled eyes.

Compared with the traditional microscope, a 3D digital visualization system has superior visual qualities, with much clearer intraoperation visualization, a wide field of view, and increased depth of field [5, 6], which should be sufficient for intraocular manipulations in gas-filled eyes. Therefore, as early as 2016, Eckardt and Paulo first applied the 3D digital visualization system in vitreoretinal surgery [7]. Since then, the 3D visualization system has been used in PPV for various vitreoretinal diseases with good efficacy and safety [8, 9].

On the premise of the good visual clarity provided by the 3D visualization system, we discuss the possibility of omitting PFCL and the following posterior retinotomy during the PPV operation for RRD. The 3D visualization system offers a clear vision for intraocular manipulations after fluid–air exchange, and a series of cases are presented here to demonstrate our experiences and the surgical outcomes of this technique.

Methods

This retrospective study included 60 consecutive cases of RRD, all of whom had undergone a 3D visualization system-assisted PPV by a same surgeon at Xuzhou First People’s Hospital, between October 1 2021 and March 31 2022. All the participants were over 18 years old, and written informed consent was obtained prior to surgery. Cases with giant retinal tear, macula hole, or proliferative vitreoretinopathy (PVR) worse than grade C1 (updated Retina Society Classification of PVR, 1991) were precluded. The study was performed according to the Declaration of Helsinki and approved by the Ethics Committee of Xuzhou First People’s Hospital.

All 60 patients underwent 23-gauge (23 G) PPV by the same surgeon, with the assistance of a Constellation Vision System (Alcon Laboratories, Inc.). The PPV was assisted by a NGENUITY 3D Visualization System (Alcon Laboratories, Inc.) and a BIOM 5 wide-field viewing system (Binocular Indirect Ophthalmology Microscope; Oculus, Wetzlar, Germany) mounted on a Proveo 8 (Leica Microsystems, Wetzlar, Germany) microscope.

Since January 1 2022, under the influence of the Chinese medical insurance policy, doctors in China have tried several ways to save on medical expenses. One of the most effective ways is to omit PFCL in the vitrectomy of RRD. Therefore, the 3D visualization system-assisted procedure is routinely carried out in patients who meet the conditions for enrollment, and no PFCL has been used during the operations. The cases of traditional PFCL operations were selected retrospectively. The patients were divided into two groups: the PL group (30 cases that used PFCL to assist the drainage of SRF) and the NPL group (30 cases that excluded the usage of PFCL, and SRF was aspirated through the original retinal breaks). If the patient had significant cataract, then lensectomy with phacoemulsification was performed at the same time during the PPV. Secondary intraocular lens was implanted after the perfluoropropane (C3F8) gas was absorbed or during the silicone oil removal. The procedure of core vitrectomy and triamcinolone-assisted posterior vitreous detachment induction was the same in both groups.

In the PL group, PFCL was injected up to the posterior margin of the break to partially discharge the SRF and stabilize the detached retina. After peripheral vitrectomy, the residual SRF was drained by fluid–air exchange. Then, the remaining PFCL was injected, and endolaser photocoagulation was performed under fluid. Finally, the PFCL was removed by fluid–air exchange.

In the NPL group, peripheral vitreous was thoroughly shaved using scleral depression, then the SRF was aspirated through the original retinal breaks using a flute needle by fluid–air exchange. Little residual SRF at the posterior pole was tolerable, as long as the SRF around the breaks was completely drained. Then, endolaser photocoagulation was performed around the degenerative areas and retinal breaks under air. Video 1 reveals the key steps of the technique procedure.

Video 1: Key Steps of the Operation Procedure (MP4 38847 KB)

In both groups, after the above procedure, C3F8 or silicone oil was selected as tamponade, and patients were instructed to position themselves face down. The patients were advised routine postoperative follow-up on day 10, 1 month, and 3 months. The minimum follow-up period was 3 months. Spectral-domain optical coherence tomography (SD-OCT) was performed to detect the SRF retention in each patient at 1 month follow-up, if the SRF was unabsorbed, the follow-up was prolonged to 3 months.

Data such as retinal reattachment rate (RRR), operation duration, tamponade, IRB, and preoperative and final BCVA were collected. The decimal visual acuity (VA) was converted to logarithm of the minimum angle of resolution (logMAR) equivalents for analysis following the formula: logMAR =  −log(decimal VA) [10]. The VA of counting fingers, hand movement, and light perception were converted to 2.10, 2.40, and 2.70, respectively [11].

Statistical analysis was performed using Graphpad Prism 9.0 Software. Continuous data were expressed as mean ± standard deviation. Normality and lognormal distribution were used to check whether the data conformed to normal distribution. If not, the nonparametric Wilcoxon test was applied. The Mann–Whitney U test was used to compare the VA between the two groups. The comparison of preoperative and final VA was performed using a paired t-test. The chi-square test was used for comparisons of the following data: gender, macula status, phacoemulsification, IRB, tamponade, and SRF residual. The level of statistical significance was defined as p < 0.05.

Results

This study included 60 eyes of 60 patients, 30 cases in each group. As presented in Table 1, the baseline data (i.e., age, gender, BCVA, macula status, extent and duration of RRD) were not statistically different between the two groups. It should be noted that lensectomy with phacoemulsification was performed in eight cases (26.67%) in the NPL group and ten cases (33.33%) in the PL group during the operation. There were no statistical differences between the two groups (chi-square = 0.3175, p = 0.5731), therefore, the operation time was calculated without excluding the phacoemulsification time. In the NPL group, 19 eyes (63.33%) were filled with C3F8 and 11 eyes (36.67%) with silicone oil, while in the PL group, 14 eyes (46.67%) were filled with C3F8 and 16 eyes (53.33%) with silicone oil; the statistical analysis showed no significant difference (chi-square = 1.684, p = 0.1945).

Table 1 Comparison of baseline data in the two groups
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The mean operation time of the NPL group was 52.67 ± 8.58 min, which was significantly shorter than the 66.33 ± 11.21 min in the PL group (p < 0.0001 and t = 5.301) (Table 2; Fig. 1). During the operation, IRB was encountered in three cases (10.00%) in the NPL group and in one case (3.33%) in the PL group, but there was no significant difference (chi-square = 1.071, p = 0.3006).

Table 2 Comparison of the outcomes of the two groups
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Fig. 1
figure 1

Operation time of the two groups

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The average follow-up duration was 3.80 ± 0.71 months in the NPL group and 4.13 ± 0.82 months in the PL group (U = 346, p = 0.1326). After 1 month of follow-up, SRF residual was detected in two eyes (6.67%) of the NPL group and one eye (3.33%) of the PL group by SD-OCT (chi-square = 0.3509, p = 0.5536), but all were absorbed by the 3 month follow-up. None of the 30 eyes in the PL group had intraocular or subretinal PFCL retention. The retina in all cases were reattached (RRR = 100%) and significant gain in VA was noted at the end of follow-up in both groups: the difference in BCVA preoperation and at the end of follow-up was calculated to be p < 0.0001 and t = 6.756 in the NPL group, and p < 0.0001 and t = 8.498 in the PL group. The mean final BCVA was 0.479 ± 0.316 logMAR in the NPL group, slightly better than the 0.650 ± 0.371 logMAR in the PL group (Table 2; Fig. 2).

Fig. 2
figure 2

BCVA (Log MAR) preoperation and at the end of follow-up of the two groups

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Discussion

At present, PPV is the most commonly used and effective treatment for RRD. Thanks to recent innovations and improvements in high-speed cutters, the development of powerful light sources, and wide-angle viewing systems, the success rate of RRD reattachment has risen to 90% [2, 12]. PFCL has specific physical properties, including optical transparency, low viscosity, high gravity, and immiscibility in water. It is commonly applied to displace SRF and flatten the detached retina in RRD.

However, the intraoperative application of PFCL may lead to complications such as postoperative intraocular retention toxicity, and the PFCL could squeeze any remaining SRF that may not be fully drained during the fluid–air exchange into the peripheral subretinal space, resulting in failure of the laser in the peripheral degenerative areas. Large peripheral retinotomies and lack of saline rinse after PFCL removal are the main risk factors for retention [13]. Thus, during operations using PFCL, the PFCL should be rinsed two to three times with balanced salt solution after fluid–air exchange, while the peripheral laser also needs to be replenished after the complete removal of SRF by the second round of fluid–air exchange. These procedures definitely increase operation steps and prolong the operation time. The summary of our operation results showed that the mean operation time was 52.67 ± 8.58 min for the NPL group and 66.33 ± 11.21 min for the PL group, with the 20% decrease in mean operation time due to the above reasons.

PPV for RRD in the absence of PFCL is executable, but it has two main drawbacks. First, without PFCL stabilizing the detached retina, the following peripheral vitrectomy may cause IRBs. With the development of instruments and machines, microincision vitrectomy systems can decrease the rate of IRBs associated with traction at sclerotomy entry sites, compared with conventional 20-gauge vitrectomy [14]. In this case, we recommend the following precautions to reduce the incidence of IRBs. Peripheral vitrectomy can be performed at a higher speed and lower vacuum pressure to reduce the traction from instrumentation, as higher cut rates cause decreased retinal traction [15]. After most of the vitreous around the retinal breaks are removed, part of the SRF can be drained out through the original breaks to flatten the retina and reduce the motility.

Second, air-filled eyes, especially phakic or pseudophakic eyes [1], have poorer visualization under a microscope, which hinders the application of PFCL-free technology. The 3D visualization system is a good strategy to overcome this difficulty. It is superior to traditional microscopy in many aspects, such as clearer intraoperation visualization, lower endoillumination level, wide-field view, and optimized ergonomic design. The 3D visualization system can improve the magnification (48% higher than conventional microscopy), depth perception (five times better), and resolution (42% increase) by real-time digital signal processing. The digital amplification tool allows sharper, clearer images of high resolution at half the endoillumination levels used in traditional microscopes, reducing the phototoxic damage to the retina [5, 6]. In our experience, at least 50–55% light intensity was required for the conventional microscope to perform PPV, while 30–35% light intensity was enough in the 3D surgeries, and the visual field was much brighter than the conventional microscope. In this study, the 3D visualization system offers a good vision in an air-filled eye, so that intraocular manipulations under air are feasible. After peripheral vitreous is thoroughly shaved, a careful peripheral search with scleral depression and endoillumination is performed. Laser photocoagulation of the degenerative area within the attached retina is completed first, then the SRF is aspirated by fluid–air exchange, followed by laser photocoagulation in the detached region (Fig. 3).

Fig. 3
figure 3

Images of fluid–air exchange and laser photocoagulation. A SRF is aspirated by fluid–air exchange through the original retinal break; B, C laser photocoagulation around the retinal break and degenerative area

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In the NPL group, SRF is drained out as much as possible by fluid–air exchange through the original retinal breaks. Complete drainage of SRF throughout the fundus is not necessary. As long as the SRF around the retinal breaks is cleaned out, sufficient laser photocoagulation can be carried out, and the residual SRF can be pumped out by retinal pigment epithelium (RPE) through active transport after the operation [16]. This accounts for the fast reattachment observed on the first postoperative day, indicating that the retinal breaks are blocked. Therefore, thorough drainage of SRF by posterior retinotomy is not necessary. In this study, SD-OCT detected no SRF residue in the macular area due to the compromised visibility in C3F8-filled eyes at the early postoperative stage. After 1 month follow-up, SRF residue was detected in three eyes with silicone oil tamponade, two eyes in the NPL group, and one eye in the PL group: all were absorbed after 3 months without medication. We attribute this delayed absorption to the duration of RRD. Limited by the small sample size, we cannot confirm whether the delayed absorption is related to the patient’s age or surface tension of intraocular tamponade.

In our study, the retinas in all 60 cases in both groups were reattached (RRR = 100%), and VA gained significant improvement at final follow-up. Attributed to the 3D visualization system, all the 60 cases of our study were completed without complications, and no case in the NPL group was converted to traditional microscope or the PFCL-included procedure due to the intraoperation visualization. Moreover, the 3D visualization system has optimized ergonomic design, which enables surgeons to lift their heads and relieve musculoskeletal discomfort. It also allows surgeons to operate at a higher magnification on larger display screens, and view with equal comfort, all regions of the surgical field, which can effectively alleviate visual fatigue [17].

We recommend that in PPV that uses only the original retinal breaks for SRF drainage, instead of using PFCL can be realized with the help of a 3D visualization system. The 3D visualization system can provide a clearer and brighter view, and allow surgeons to operate comfortably at a higher magnification level and on larger display screens, thus providing a perfect circumstance to exclude the use of PFCL. Consequently, adequate anatomical reattachment and VA improvement can be achieved without the use of PFCL, with a simplified surgical procedure, shortened operation time, and a reduction of potential complications. The 3D visualization system provides a feasible PFCL-free technique.

Conclusions

The 3D visualization system-assisted PPV provides a PFCL-free way to restore vision for RRD patients. Perfect RRR and VA improvement can be achieved without the inclusion of PFCL. Due to the high-definition advantage of the 3D system, the intraoperative visual effect is satisfactory, the operational steps are reduced, and the operation time is shortened. The 3D visualization system allows surgeons to operate easily and comfortably, and thus is highly recommended for PPV surgery. This is a retrospective and nonrandomized study, the results of which will be further confirmed in a prospective, randomized trial.