Preoperative laser reduces silicone oil use in primary diabetic vitrectomy

INTRODUCTION

Diabetic retinopathy (DR) is the leading ocular complication of diabetes which cause irreversible blindness in working-age adults worldwide

. Approximately 25% of vision loss in DR patients is a result of severe complications of advanced proliferative diabetic retinopathy(PDR)

. Due to the aging population and the increasing prevalence of diabetes, the number of people suffering visionthreatening PDR has significantly increased in recent years

.Pan-retinal photocoagulation (PRP), which prevents the disease progression and reduces the risk of severe visual impairment by 50%, has been the standard treatment of high-risk PDR for decades

. However, in our experience, several patients miss the best time for laser photocoagulation treatment for various reasons and progress to severe PDR-related complications that require vitrectomy surgery. It was reported that 5.6%of patients progress to severe PDR and require a vitrectomy despite having received adequate PRP

.

Vitrectomy has been established as the ultimate treatment of severe PDR-related complications and silicone oil has been used as an effective endotamponade agent that increases the success rate of complicated cases undergoing vitrectomy

.However, once silicone oil is used as intraocular tamponade agent, a subsequent surgery for removal is required. It also brings some disadvantages, such as the progression of nuclear cataracts, poor vision prognosis, increased economic burden and may lead to other postoperative complications

. Having a clearer understanding of the risk factors of silicone oil tamponade in vitrectomy for PDR-related complications might provide novel and more effective preventive strategies. Thus,it is critical to understand the predictive factors of silicone oil tamponade in vitrectomy for PDR-related complications.However, although clinically relevant, the related factors of using silicone oil as intraocular tamponade agent during diabetic vitrectomy still unknown.

Protocol of this cross-sectional, retrospective study was reviewed and approved by the Medical Ethics Committee at Zhongshan Ophthalmic Centre (ZOC) of Sun Yat-sen University (2021KYPJ094). As this was a retrospective study, patient informed consent was waived. The study adhered to the Helsinki Declaration (2008).

The mean patient age at surgery was 52.1±10.5y (range: 18-85y),79 patients (11.4%) were under 40y of age and 158 (20%) were at least 60 years old. Demographics and clinical characteristics of the patients were showed in Table 1.

SUBJECTS AND METHODS

60例自2015年1月—2017年1月收治的肝臟核磁共振檢查患者作為分析樣本，以護(hù)理路徑為前提，分為兩組?；A(chǔ)組30例，患者男女比18：12，年齡23～80歲，平均（51.52±10.36）歲，文化程度：初中10例，高中9例，大專以上11例。分析組30例，患者男女比19：11，年齡24～80，平均（52.07±10.39）歲，文化程度：初中11例，高中10例，大專以上9例。對(duì)比組間數(shù)據(jù)，不統(tǒng)計(jì)學(xué)價(jià)值。

（1）課程結(jié)束后，進(jìn)行考核。理論考核根據(jù)教學(xué)大綱統(tǒng)一命題，統(tǒng)一試卷，統(tǒng)一評(píng)分標(biāo)準(zhǔn)；操作考核統(tǒng)一操作要求和評(píng)分標(biāo)準(zhǔn)，考核成績采用百分制。

Preoperative anti-VEGF combined with PRP therapy was performed in 191 eyes (23.8%),preoperative anti-VEGF without prior PRP in 387 eyes(48.6%), preoperative PRP treatment alone in 62 eyes (7.8%)and 158 eyes (19.8%) received no adjuvant pretreatment. One hundred and forty-four out of the 798 eyes (18.1%) underwent at least three sessions of PRP.

很多時(shí)候，人們的一些過失行為會(huì)導(dǎo)致電力電纜的損壞。這是由于電纜在布置的過程中，有的工作人員由于粗心或者操作方法不當(dāng)，導(dǎo)致其發(fā)生扭曲或者被折，造成了電纜線的損壞，隨著使用時(shí)間的增長，將會(huì)影響電網(wǎng)的正常運(yùn)行。

A standard three-port 23G or 25G parsplana vitrectomy (PPV) was peformed for non-clearing VH,traction retinal detachment (TRD), combined traction and rhegmatogenous retinal detachment (TRRD), or combined VH and RD with a wide-angle viewing system in all the patients.All surgeries were conducted by one of six experienced vitreoretinal specialists, each with more than five years of experience performing vitreoretinal surgery. Intravitreal anti-vascular endothelial growth factor (VEGF) drugs(ranibizumab, aflibercept or conbercept) were administrated 3-7d prior to surgery for active neovascularization (NV) or VH at the surgeon's discretion. The blood or opacified vitreous was cleared, vitreoretinal traction was released, and fibrovascular membrane were removed. Laser was applied for retinal breaks and PRP was used in patients who had not previously undergone laser photocoagulation or in patients in whom previous laser photocoagulation was insufficient. Combined phacomusification was performed as indicated. Whether the intraocular lens was implanted at the same time depends on the fundus status. Endotamponade was achieved using the balanced salt solution, air or silicone oil, mainly according to the status of the retina at the end of the surgery. However, the patient's general condition and visual acuity of the opposite eye were also taken into consideration as silicone oil filling indicators. Balanced salt solution was used as endotamponade in case of no retinal tears was observed. Air endotamponade was used in case of within two retinal tears in a superior location. Silicone oil (5000 mPa.s; RT SIL-OL 5000; Zeiss,Berlin, Germany) was used in case of inferior retinal tears,large and more than two retinal tears, or fibrovascular membrane that could not be cleaned completely. Silicone oil removal was performed at least three months postoperative.Cataract surgery was performed when the lens opacity affects the observation of the fundus.

The medical and surgical data of the patients were retrospectively collected

the electronic medical record system. The preoperative data included patient demographics, duration of symptoms, best-corrected visual acuity, fasting blood glucose, serum cholesterol, triglycerides,serum creatinine, blood urea nitrogen, history of hypertension,use of anti-VEGF agents prior to vitrectomy, and previous treatments for DR (including local laser, PRP and vitrectomy).The operative and postoperative data collected for this study included intraocular tamponade used at the end of the surgery and recurrence of VH or RD that required subsequent surgeries.

The

statistical analyses were performed with SPSS version 25 (IBM, North Castle, NY, USA).

＜0.05 was considered statistical significant. Variables were calculated using basic descriptive statistics, normally distributed continuous variables were presented as mean±standard deviation; nonnormally distributed continuous variables were presented as the median. Categorical variables were presented as number and percentage. A binary Logistic regression test was performed to identify risk factors associated with the use of silicone oil tamponade at the end of vitrectomy.

RESULTS

The aim of the present study was to identify the predictive factors for silicone oil tamponade during primary diabetic vitrectomy. In addition, the clinical characteristics of patients who underwent PPV for PDR-related complications, preoperative treatments and duration of symptoms, were also assessed.

The main indication for primary diabetic vitrectomy surgery was non-clearing VH, followed by VH combined with RD, RD affecting macular, RD threatening macular, and active fibrovascular proliferation (Table 2).

The preoperative corrected Snellen visual acuity of most patients undergoing surgery was ＜0.05,while 58 eyes (7.3%) had visual acuity ＞0.3 before surgery (Table 3).

“天脊化肥專營店”是天脊集團(tuán)市場深耕終端發(fā)力的“橋頭堡”。天脊集團(tuán)以基層網(wǎng)絡(luò)建設(shè)為重要抓手，把“給政策”扭轉(zhuǎn)到“教技能”上來，積極推進(jìn)重點(diǎn)門店向天脊化肥專營店發(fā)展升級(jí)。今年驗(yàn)收通過200家，在三年內(nèi)至少建成1000家以上天脊化肥專營店，讓其成為農(nóng)民豐收交流、科學(xué)種田案例示范、增產(chǎn)增效成果分享、農(nóng)民致富親身體驗(yàn)的“新時(shí)代天脊助力鄉(xiāng)村振興喜悅舞臺(tái)”。

Medical and surgical records of all vitrectomy surgeries at the fundus surgery centre of ZOC from 1 January 2018 to 31 December 2018 were identified and reviewed in the electronic medical record system. A total of 881 consecutive cases of vitrectomy were identified.Patients who underwent primary vitrectomy for PDR-related complications were enrolled. Patients undergoing a secondary vitrectomy for recurrent vitreous haemorrhage (VH) or recurrent retinal detachment (RD), patients with incomplete medical or surgical records, and vitrectomies performed by surgeons with less than five years of experience were excluded from this analysis. The final analysis included 690 consecutive patients (798 eyes; Figure 1).

Nevertheless, Antoszyk

reported that anti-VEGF alone was not inferior to vitrectomy with PRP in the treatment of VH from PDR in the primary outcome of visual acuity over 6mo following initial treatment; however, vitrectomy surgery, which involves the removal of pathological vitreous and clearance of hemorrhage and scarring tissues relieving vitreoretinal traction,remains the cornerstone of treatment for late complications of PDR, even in patients with a history of optimal laser photocoagulation and other medical therapies

. The current surgical concept and techniques used in vitrectomies have dramatically advanced since the surgery reported by Diabetic Retinopathy Vitrectomy Study (DRVS)

, characterizing by the increased use of smaller gauge vitrectomy systems,application of wide-angle viewing system, injection of silicone oil to aid retinal reattachment in complicated cases, and widespread use of anti-VEGF adjuvant therapy for severe PDR-related complications

.

由表1可知，白泥的主要成分是SiO2和Al2O3，其含量分別高達(dá)68.46%和12.98%，二者通過堿液浸出獲得可溶性硅源和鋁源，能夠替代傳統(tǒng)分子篩合成過程中需要的化工原料。

相關(guān)研究表明，當(dāng)?shù)叵滤畡?dòng)力條件改變時(shí)，原來被堵塞的洞隙及其相連的下部排水通道復(fù)活，重新成為地下水集中活動(dòng)的地段；地下水位上升，抗水性差的土強(qiáng)烈崩解，一部分順喇叭口落入溶洞中，初步形成上覆土層的土洞；土洞進(jìn)一步擴(kuò)大，向地表發(fā)展，頂板漸薄，當(dāng)頂板薄到不能支撐上部土層重量時(shí)，便突然發(fā)生塌落。

Vitrectomy was combined with phacoemulsification in 26 eyes (3.3%), and one eye (＜1%) received combined sclera encircling surgery.The most frequent surgical complications during the oneyear follow up period were recurrent RD and recurrent VH.Twenty-nine eyes (3.6%) required reoperation, including 19(2.4%) for stubborn recurrent VH and 10 (1.2%) for recurrent RD. Six eyes (＜1%) developed neovascular glaucoma (NVG)after vitrectomy and underwent shunting device implantation surgery. No patient experienced endophthalmitis and no serious systemic complications occurred after surgery.

During the one-year follow-up period, 201 out of the 313 silicone oil eyes (64.2%) underwent surgery to remove the silicone oil.Ninety-six eyes (30.7%) in the silicone oil tamponade group underwent cataract surgery compared to 19 out of 485 eyes(3.9%) in the non-silicone oil tamponade group (

＜0.01).

DISCUSSION

The demographic and clinical characteristics of Chinese patients who underwent PPV for PDR-related complications were explored in this study. Silicone oil tamponade rate was high although anti-VEGF agents were widespread administrated prior to diabetic vitrectomy. Moreover, we identified that the lack of preoperative laser treatment was the main reason for the high silicone oil tamponade rate during primary diabetic vitrectomy. Thus, in the anti-VEGF era for DR management, PRP still plays an important role and should not be ignored.

This study reviewed a large number of Chinese patients who underwent PPV for severe PDR-related complications. As digital data collection is increasing, the use of database studies to document clinical outcomes in real-world settings is also increasing

. The data used in this study were collected from the electronic medical record system, which represented the patients encountered daily by physicians. Although the results of randomised controlled studies are considered as the highest level of clinical evidence, real-world research results are valuable and applicable.

Silicone oil was used as an intraocular tamponade agent in 313 eyes(39.2%). The silicone oil tamponade ratio of the RD group was 69.4% (240/346); the non-RD group was 16.1% (73/452),and by preforming Chi-square test,

＜0.001. Preoperative photocoagulation treatment [odds ratio (OR)=0.66, 95%confidence interval (CI)=0.48-0.92,

=0.015] and younger age [OR=0.96, 95%CI=0.95-0.98,

＜0.001) were identified as protective factors against the use of silicone oil tamponade during primary vitrectomy for PDR-related complications,while preoperative anti-VEGF therapy did not affect the choice of silicone oil as endotamponade agent (OR=0.64;95%CI=0.64-1.27;

=0.560; Table 4).

Few studies reported the baseline characteristics and trends of preoperative treatments in Chinese patients undergoing diabetic vitrectomy. In our study, the mean age of the patients at surgery was 52y and the most frequent indication for diabetic vitrectomy was non-clearing VH. In one of the largest previously-published studies with a series of 890 consecutive patients regarding vitrectomy for PDR-associated complications, the mean age was 51.9y and the most common indications for vitrectomy were TRD (36.6%) and persistent VH (35.4%)

. Our results are also consistent with those of the Early Treatment Diabetic Retinopathy Study (ETDRS)

.Few studies regarding the preoperative visual acuity of patients with PDR undergoing vitrectomy have been reported. One previous study reported that 11.9% of eyes had visual acuity≥0.1 at baseline

, while 24.8% of eyes in our study had a preoperative visual acuity ＞0.1, including 7.3% of eyes with a preoperative visual acuity ＞0.3. The threshold for performing vitrectomy for patients with PDR has decreased as a result of the advancement of the modern PPV technique, the application of adjuvant therapies, and advances in the management of these patients.

姜夔詞素以清空峭拔稱名，其中《點(diǎn)絳唇·燕雁無心》更是白石詞風(fēng)的代表杰作，抒發(fā)了詞人對(duì)身世的感慨嗟嘆。在《點(diǎn)絳唇》中，關(guān)于首句“燕雁無心”一直有不同的釋義：《全宋詞》中，注釋“燕雁”為“自北方飛來之雁”；《唐宋詞鑒賞辭典》中，釋“燕雁”為“北來之雁”；《唐宋詞選釋》中，俞平伯先生注：“‘燕雁’有兩說：一.‘燕’指玄鳥。仄聲。二.燕為地名，幽燕之燕，平聲”……在當(dāng)下學(xué)術(shù)論文中，也有兩種釋義的偏倚。那么到底是“北地之雁”？還是“燕與大雁”？究其原詞，我們或可得解。

Preoperative anti-VEGF and PRP treatments are common for patients with PDR, which are closely related to the postoperative prognosis

. The adjuvant intravitreal injection of anti-VEGF drugs was first reported in 2006 for the preoperative treatment of patients with PDR with active proliferation

,which made the procedure significantly less challenging,diminished intraoperative iatrogenic complications, and reduced intra- and postoperative bleeding

. In our study, 72%of the eyes received preoperative anti-VEGF treatment and 2.1% of the eyes underwent re-vitrectomy due to recurrent VH within the first postoperative year. The re-vitrectomy rate in our study is significantly lower than previously reported rates of 10.4%-23%

. These differences may be due to a relatively higher rate of preoperative anti-VEGF treatment in our study compared with other studies, which ranged from 17%-53.8%

.

Previous studies have reported that preoperative laser treatment improves visual prognosis and reduces the risk of recurrent bleeding after surgery

. It seems to be the common sense for vitreoretinal surgeons that preoperative laser treatment helps avoid intraoperative complications and reduce the use of silicone oil at the end of the surgery. However, our results provide exact data reference for this conclusion. In this study,only 30% of the eyes underwent PRP treatment prior to surgery, which is significantly less than previously reported PRP rates of 56.8%-83%

. These differences may be due to the poor accessibility to or awareness of regular DR screening and timely laser treatment in Chinese patients with diabetes

. Ophthalmologists and public health policymakers in China should be made aware of these results as China has the largest diabetes mellitus and DR population in the world

.Silicone oil infusion significantly improves the surgical success rate and postoperative visual acuity in complicated cases

; however, its use will inevitably increase the number of operations and postoperative complications, especially postoperative nuclear cataracts

. Iatrogenic injuries should be avoided during DR surgery to reduce the use of silicone oil. The silicone oil tamponade rate was 40% in our study,which was significantly higher than previously reported rates of 5.2%-24.4%

. The higher rate may be attributed to the large number of more serious cases included in this study.The lack of preoperative laser photocoagulation treatment and older age were identified as independent risk factors for the use of silicone oil as endotamponade in this study. The lack of prior PRP treatment may increase the risks of proliferative reticulum and intraoperative iatrogenic holes

. In our study,the preoperative laser treatment ratio was only 30%, which may explain the high ratio of patients who underwent silicone oil infusion.

Several original studies and Meta-analysis have showed that anti-VEGF pretreatment could shorten operation duration,easy the procedure, reduce intraoperative and postoperative complications and even spare the need for postoperative retinal photocoagulation sometimes

. However, controversies regarding the impact of preoperative anti-VEGF drugs on the risk of TRD in eyes with PDR and the use of silicone oil as intraocular tamponade agent in primary diabetic vitrectomy still exist. According to a recent review, the progression to TRD following intravitreal anti-VEGF therapy was noted from 1.5% to 18.4% in different studies, especially common in patients with increased severity of DR with fibrosis

. On the contrary, another study showed that anti-VEGF therapy for PDR does not increase the risk of TRD in eyes with PDR similar to those enrolled in the DRCR.net protocols for which prompt vitrectomy was not planned

. Moreover, Uzel

reported that preoperative anti-VEGF can reduce the use of silicone oil tamponade at the end of surgery in patients undergoing PPV for diabetic TRD. Recently, Chen

evaluated the effects of preoperative ranibizumab intravitreal injection on vitrectomy in patients aged less than 40 years old with PDR-related complications, the results showed that the use of silicone oil tamponade were not affected by preoperative anti-VEGF treatment but affected by the severity of DR. A Meta-analysis also revealed that no significant difference existed between sham control group and preoperative anti-VEGF injection group in reducing the rate of silicone oil tamponade

. In this study, the use of preoperative anti-VEGF was not associated with the choice of using silicone oil as intraocular tamponade agent, which may be attributed to the fact that most patients with aggressive conditions received injections and the treatment makes no significant difference in patients with mild conditions. Our results also support the concept that the incidence of use of silicone oil tamponade were not affected by preoperative anti-VEGF injection.

This study included a relatively large sample size and consecutive primary vitrectomy data from a single tertiary centre during a one-year period, reflecting the current management of PDR-related complications in China. Surgeries performed by inexperienced surgeons were excluded from this study to reduce external causes of variability. However, this study has some limitations. The retrospective nature of the study did not allow for the standardization of the measurements, and loss to long-term follow-up may have resulted in the underor overestimation of the reported outcomes. For example,patients with mild recurrence of VH after surgery that did not require reoperation were not recorded as having recurrent VH. Moreover, some important factors such as: the severity of PDR, the level of glycated haemoglobin, the duration of diabetes and the type of diabetes that may affect the choice of tamponade during the surgery was missing and failed to be evaluated in the present study. And even the patient's general condition and visual acuity of the opposite eye are relevant to the use of silicone oil. Those factors relevant to silicone oil use can be further evaluated.

錯(cuò)誤分析理論的語言學(xué)基礎(chǔ)是轉(zhuǎn)換生成法體系，這一體系認(rèn)為人腦天生具有語言習(xí)得機(jī)制與語言使用能力，從而使得人類具有了其他物種所無法擁有的完備的語言體系。而由于語言的使用往往存在一定的規(guī)則，并且主觀影響較大，因此錯(cuò)誤分析理論的心理學(xué)基礎(chǔ)就是語言遷移理論。而語言遷移理論的核心觀點(diǎn)則是母語的性質(zhì)會(huì)使外語學(xué)習(xí)的某些方面變得容易或困難，即語言遷移有正負(fù)之分。由于受到漢語語義以及表達(dá)順序的影響，在口譯的過程中，許多學(xué)生往往來不及思考正確的英文語序，而是順著漢語語序翻譯所聽到的句子，從而使句子的表達(dá)不符合英語語言習(xí)慣。例如：

In conclusion, the lack of preoperative laser treatment was identified as a significant predictive factor of silicone oil tamponade at the end of primary PDR vitrectomy. Although preoperative anti-VEGF therapy can reduce the time and difficulty of the diabetic vitrectomy procedure, it cannot reduce the rate of silicone oil tamponade. Thus, even in the anti-VEGF era, PRP should not be ignored for the treatment of PDR. The results could be served as a reference for the evaluation and management of patients with PDR.

The authors thank Chen Ning from the medical record statistics department of ZOC for her help in organizing the medical records.

Supported by the National Natural Science Foundation of China (No.82070972); the Natural Science Foundation of Guangdong Province (No.2019A1515011347);the grants from the Guangdong Province High-level Hospital Construction Program (No.303020103); the Key Science&Technology Project of Guangzhou (No.202103000045).

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