Retrobulbar ocular blood flow changes after phacoemulsification in patients

Yin-Ying Zhao, Jun-Hua Li,Ping-Jun Chang, Yun-E Zhao

Foundation item:Supported by Nature Science Foundation of Zhejiang Province(No.LY12H12004)

1School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou 310000, Zhejiang Province, China

2Affiliated Eye Hospital, Wenzhou Medical University, Wenzhou 310000, Zhejiang Province, China

Correspondence to:Yun-E Zhao. School of Ophthalmology and Optometry, Wenzhou Medical University, 270 Xueyuan Road, Wenzhou 325027, Zhejiang Province, China. zye@mail.eye.ac.cn

Received： 2015-09-08　　Accepted： 2016-02-22

白內障超聲乳化術后球后血流動力學變化的研究

趙銀瑩，李軍花，常平駿，趙云娥

(作者單位：1310000中國浙江省溫州市，溫州醫科大學眼視光學院；2310000中國浙江省溫州市，溫州醫科大學附屬眼科醫院)

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Retrobulbar ocular blood flow changes after phacoemulsification in patients

Yin-Ying Zhao1,2, Jun-Hua Li1,2,Ping-Jun Chang1,2, Yun-E Zhao1,2

Foundation item:Supported by Nature Science Foundation of Zhejiang Province(No.LY12H12004)

1School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou 310000, Zhejiang Province, China

2Affiliated Eye Hospital, Wenzhou Medical University, Wenzhou 310000, Zhejiang Province, China

Correspondence to:Yun-E Zhao. School of Ophthalmology and Optometry, Wenzhou Medical University, 270 Xueyuan Road, Wenzhou 325027, Zhejiang Province, China. zye@mail.eye.ac.cn

Received： 2015-09-08Accepted： 2016-02-22

白內障超聲乳化術后球后血流動力學變化的研究

趙銀瑩，李軍花，常平駿，趙云娥

(作者單位：1310000中國浙江省溫州市，溫州醫科大學眼視光學院；2310000中國浙江省溫州市，溫州醫科大學附屬眼科醫院)

Abstract

?AIM:To evaluate retrobulbar ocular blood flow changes after phacoemulsification.

?METHODS:Prospective consecutive study. Forty-six eyes from 46 cataract patients scheduled for phacoemulsification surgery at Affiliated Eye Hospital, Wenzhou Medical College were recruited, of which 22 patients with normal blood pressure and 24 patients with hypertension. All eyes were examined by a color Doppler imaging at before, 4h, 1d after surgery. Resistance indexes(RIs), peak systolic flow velocity(PSV), end-diastolic flow velocity(EDV) were assessed in the ophthalmic artery(OA), central retinal artery(CRA), and short posterior ciliary arteries(PCA).

?RESULTS:RIs of a retrobulbar ocular vessels are stable at 4h and 1d in both group postoperatively. A slight decrease in PSV of PCA in hypertension patients, while a slightly increase in normal patients at 4h postoperatively was observed(10.22±4.39vs11.73±4.69). There were no significant difference between them(P=0.089). PSV and EDV in CRA are lower in hypertension patients but without statistical significance compared with normal patients. There was a statistically significant decrease in EDV of the PCA in hypertension patients at 4h postoperatively compared with preoperatively(3.23±1.10vs3.63±1.15,P=0.036).

?CONCLUSION:Retinal blood flow was disturbed at super-early after phacoemulsification. Age and hypertension are important risk factors to phacoemusification.

KEYWORDS:?phacoemulsification;blood flow;color Doppler imaging;retina

Citation:Zhao YY, Li JH, Chang PJ, Zhao YE. Retrobulbar ocular blood flow changes after phacoemulsification in patients.GuojiYankeZazhi(IntEyeSci) 2016;16(5):793-797

INTRODUCTION

As the most commonly performed cataract surgery, phacoemulsification adopt applicants maximum vacuum to reduce the power and make the surgery efficient and rapid. Nevertheless, most of surgeons ignore the high intraocular pressure during surgery, which may disturb the retrobulbar circulation. Intraocular pressure(IOP) was reported to fluctuate from 66.1 to 196.6 mm Hg during nuclear disassembly of the surgery on cadaver eyes. Moreover, the final pressure was up to 73.2 mm Hg[1]. Zhaoetal[2]described that the static IOP increased to 96 mm Hg during cortical cleanup, while the dynamic IOP fluctuated to 74 mm Hg.

Even though it is the common clinical experience that most eyes do outstandingly well after surgery, there are still few of people discovered visual loss after uneventful phacoemulsification. Several case reports and clinical researches indicated that cataract surgery might be associated with an increased incidence of nonarteritic anterior ischemic optic neuropathy[3-4]. These authors hypothesize that the high IOP associated with cataract surgery maybe a factor to result of nonarteritic anterior ischemic optic neuropathy(NAION). Sprauletal[5]recorded retrobulbar blood flow in humans after phacoemulsification and found cataract extraction temporarily affected ocular hemodynamic. The author postulated that the increased IOP required during phacoemulsification is the main factor. The transient high pressure didn’t seem innocuous completely.

Because of the function referred to as autoregulation, blood flow in retina is stably maintained despite certain fluctuation in ocular perfusion pressure(OPP). However, autoregulation insufficiency leaded inadequate response to changes in perfusion pressure, which may induce ischemia.

This pilot study was set to explore possible changes in ocular blood flow in patients with vascular dysfunction early after the phacoemulsification surgery.

SUBJECTS AND METHODS

This prospective study was of consecutive age-related patients with hypertension and age-matched healthy patients as control group. All subjects were over 60y old and no other systemic pathology that would interfere with ocular or systemic circulation. Hypertension was defined as systolic blood pressure >140 mm Hg or diastolic blood pressure >90 mm Hg, moreover, diagnosed by physician[6]. Patients or controls with ocular conditions that may have affected the blood circulation, such as glaucoma, age-related maculopathy and high degree of myopia were excluded. Patients had phacoemulsification for uncomplicated cataract with IOL implantation. One eye of each subject was randomly selected by a process of alternation.

The procedures conformed with the Declaration of Helsinki and of the local ethical committee of Wenzhou Medical University(Wenzhou, Zhejiang Province, China). All subjects were informed of the procedure and provided written informed consent.

Surgery TechniqueAll surgeries were performed under topical anesthesia by the same surgeon after the pupil was maximally dilated. A 2.2 mm clear corneal incision and 1.0 mm side port paracentesis was made. And a 5.5 mm continuous curvilinear capsulorhexis was created followed by hydrodissection, phacoemulsification, aspiration of cortical masses, with Infiniti Vision System(Alcon, Inc.), and introduction of foldable IOLs. Once the viscoelastic material was removed, the incision was closed by stroma hydration without sutures. Postoperatively, all patients used topical steroid and antibiotic eye drops 4 times a day for 1wk and then tapered.

The intraoperative effective phacoemulsification time(EPT) and energy of the phaco-machine were documented during the surgery. Additionally, the irrigation column height and the maximum vacuum were recorded in different stage of the procedure.

Blood pressure was assessed with an electrocardio-monitor(MP2 IntelliVue, Philips Co., Eindhoven, The Netherlands) on the upper right arm of the patient in different stage of the surgery(before, nucleus removal, I/A stage and endpoint). Noninvasive device to measure systemic hemodynamics.

Color Doppler Imaging MeasurementRetrobulbar hemodynamic evaluation was performed by the same experienced operator in all subjects preoperatively, 4h and 1d postoperatively using Doppler Sonography(MyLab 90, Esaote, Genova, Italy).

After twenty minutes resting in the supine position, the patients were measured with a 7.5 MHz linear-array transducer. The transducer was applied gently to the closed eyelid using a coupling gel without any pressure on the eye. Resistance indexes(RIs), peak systolic flow velocity(PSV), end-diastolic flow velocity(EDV) were assessed in the ophthalmic artery(OA), central retinal artery(CRA), and short posterior ciliary arteries(PCA).

To ensure that the same location was repeatedly measured, patients were asked to keep the head tiled 30° angle, and eye closed during the examination.

Reproducibility of contour line and disc assessment was measured by having the same operator draw contour lines for 30 scans, delete them, and then, on a different day, redraw the contour lines. The differences in area for each contour line were recorded for each eye.

Intraocular pressure was measured before the CDI examination.

Statistical AnalysisStatistical analysis was performed using SPSS software(USA). Student’st-test for unpaired data was utilized for comparisons between groups. RI of retrobulbar vessels, PSV&EDV in CRA were analyzed by pairedt-tests. PSV&EDV in PCA and OA was confirmed by means of non-parametric paired tests. The relationships among variables were analyzed by Pearson correlation analyses.P≤0.05 was regarded as significant.

RESULTS

This study enrolled 46 eyes of 46 patients. Baseline characteristics of patients are presented in Table 1. There were no significant differences between the 2 groups.

The mean IOP at each time point were provided in Table 2. There was no statistical difference between the each time point of IOP in the two groups.

Table 3 shows that RIs of retrobulbar vessels at different time point in hypertension and normal patients. The CRA at 4h

Table 1Clinical and demographic data of patients

ParameterHypertensionNormalPNumberofpatients(eyes)24eyes22eyes>0.05Meanage(a)74±6.7872.4±7.87>0.05Sex(M/F)10/1414/8>0.05Accumulatedenergycomplexparameters10.14±8.227.89±6.29>0.05Visualacuity(before)0.88±0.240.97±0.43>0.05Visualacuity(postoperative)0.11±0.070.20±0.12>0.05

Table 2Intraocular pressure recorded during the follow-up time

GroupBeforeAfter4h1dPHypertension13.24±2.8115.49±4.5414.69±4.53>0.05Normal13.11±2.6217.26±5.5813.45±4.01>0.05

Table 3Resistant index evaluated in retrobulbar blood vessels at different time point

TimeOAHyperNormalPCAHyperNormalCRAHyperNormalBaseline0.821±0.0450.793±0.5960.655±0.0640.638±0.0480.725±0.0430.709±0.0364h0.823±0.0430.790±0.0610.671±0.0620.633±0.0570.744±0.0450.708±0.0351d0.824±0.0440.791±0.0590.661±0.0470.647±0.0510.732±0.0560.707±0.035P10.3800.3570.3780.5140.0820.897P20.2310.7070.5840.3930.5480.817

P1:Comparison of RI between preoperative and 4h postoperative;P2:Comparison of RI between preoperative and 1d postoperative. OA:Ophthalmic artery;PCA:Posterior ciliary artery;CRA:Central retinal artery.

Figure 1PSV observed in different time in retrobulbar blood vessel between hypertension and normal patientsA:Represented ophthalmic artery(OA);B:Represented central retinal artery(CRA);C:Represented posterior ciliary artery(PCA).

postoperative of hypertension patients was slight higher compare with preoperative(0.725±0.043vs0.744±0.045), while there were no significant differences between them. RIs are stable at 4h and one day postoperatively.

The PSV, EDV differences observed in the OA, CRA and PCA before and after the surgery are provided in Figure 1 and Figure 2. There was a statistically significant decrease in EDV of the PCA in hypertension patients at 4h compared with preoperatively(3.23±1.10vs3.63±1.15,P=0.036). All other parameters assessed by CDI measurements in the OA, CRA and PCA appeared to be stable. A slight decrease in PSV of PCA in hypertension patients, while a slightly increase in normal patients at 4h postoperatively was observed(10.22±4.39vs11.73±4.69). There were no significant difference between them(P=0.089). Furthermore, we found PSV and EDV in CRA are lower in hypertension patients but without statistical significance compared with normal patients.

DISCUSSION

Although phacoemulsification made cataract surgery easier and safer, this common surgery continues to carry ocular risks. Several researchers have expressed concerns about IOP elevation during phacoemulsification. Kamaeetal[7]described the peak IOPs exceeded 60 mm Hg during injection of the IOLs. Kreutzeretal[8]evaluated IOP was 60 mm Hg or higher for approximately 1min during the surgery. These researchers proposed the transient IOP may damage eyes with compromised retinal perfusion. However, there is no enough evidence to indicate that such IOP elevation induce retinal damage during phacoemulsification[9]. Azuara-Blancoetal[10]reported that acute changes in IOP affected the cup of the optic nerve head, while the compliance appeared to be

Figure 2EDV observed in different time in retrobulbar blood vessel between hypertension and normal patients. There was a significant decrease of PCA in hypertension group on 4h postoperatively(XP<0.05)A:Represented ophthalmic artery(OA);B:Represented central retinal artery(CRA);C:Represented posterior ciliary artery(PCA).

variable between cases. Schickeetal[11]reported that blood flow can’t be detected during LASIK-ring suction in 90% subjects. Whereas, there is few researches of ocular hemodynamic changes after phacoemusification. Sprauletal[5]reported that ocular blood flow decrease 3d after cataract surgery. However, their participants are all normal patients, and the measure time point was 3d after surgery. According to their result, we speculated that hypertension patients are more affected in early postoperative period. To our knowledge, no study has been reported to investigate the retrobulbar ocular blood flow after early postoperatively.

In the present study, we focus on the effect of phacoemulsification in patients with cataract on ocular hemodynamic parameters. All of the subjects are senile patients. Patients with hypertension were included. Conwayetal[12]suggested that the hemodynamic responses returned immediately to normal as soon as IOP elevated above 85 mm Hg for 90s. However their subjects were young persons with excellent vascular autoregulation. Autoregulation is the ability to maintain blood flow constantly despite alterations in perfusion pressure. Several reports suggested that autoregulation disappeared in the human eye if the IOP is increased above 60 mm Hg[13-14]. Furthermore hypertension alters the structure of blood vessels and disrupts blood flow[15-16]. Patients with hypertension may impair with autoregulation. Moreover, Grohetal[17]indicated that retinal and CRA blood flow decreased approximately 6% to 11% per decade.

In our study, we found RIs in retrobulbar ocular vessels are stable at 4h and 1d after surgery in normal and hypertension patients. PSV are stable in retrobulbar vessels at 4h and 1d after surgery in normal and hypertension patients. In the present study, a significant decreased in EDV of PCA in hypertension patients at 4h postoperatively were found. PCA is important for the perfusion of optical nerve. Most ischemic optic neuropathies are attributed to interference of blood flow originating within the posterior ciliary circulation[18]. It has been reported that CRA showed a faster autoregulatory response than the PCA[14]. This conclusion can explain our result that EDV in PCA is significant decreased at 4h after surgery. It was coincident with our result that the PCA circulation is highly dependent on IOP[19].

It cannot be answered from our data whether the blood flow change seen here is indeed a risk factor for loss of vision in patients after phacoemulsification. Long-term study is required to study whether this retinal blood hemodynamic response in patients with server cataract complies with disease of cardiovascular disease.

In our study, only blood velocities in the CRA are measured, but vessel diameters cannot be quantified because of the limited resolution of ultrasound devices.

Even though it is not possible to examine the blood flow during phacoemusification, we can postulated the changes after the surgery.

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摘要

關鍵詞：白內障超聲乳化手術；球后血流；彩色多普勒超聲成像；視網膜

DOI:10.3980/j.issn.1672-5123.2016.5.01

通訊作者：趙云娥，畢業于溫州醫科大學，碩士，主任醫師，教授；研究方向：白內障. zyehzeye@126.com

作者簡介：趙銀瑩，畢業于溫州醫科大學，博士，住院醫師，講師；研究方向：白內障。

基金項目：浙江省自然科學基金(No.LY12H12004)

目的：觀察白內障超聲乳化合并人工晶狀體植入術后患者的球后血流動力學的變化。

方法：前瞻性對照研究。 選取我院行單眼白內障超聲乳化吸除并植入人工晶狀體患者46例。高血壓組24名，正常血壓組22名，年齡>60歲。分別于術前、術后4h與術后1d行彩色多普勒超聲診斷儀(color Doppler imagining, CDI)檢查患者術眼球后血流。檢測指標包括眼動脈(OA)、視網膜中央動脈(CRA)、睫狀后動脈(PCA)的阻力指數(RI)、最大收縮期血流速度(PSV)、舒張末期血流速度(EDV)。不同時間點比較采用Mann-Whitney Test方法。

結果：兩組球后血流的RI在術后4h及術后1d均保持穩定。術后4h，高血壓患者PCA的PSV輕度降低，而正常血壓患者輕度升高，兩組間無統計學差異(10.22±4.39vs11.73±4.69，P=0.089)。高血壓組患者的CRA的PSV和EDV在各時間點均低于正常血壓組患者，但均無顯著差異。高血壓組術后4h的PCA的EDV較術前有顯著差異(3.23±1.10vs3.63±1.15,P=0.036)。

結論：年齡相關性白內障超聲乳化合并人工晶狀體植入術后，球后血流動力存在一定的波動，年齡及高血壓是重要的影響因素。

引用：趙銀瑩，李軍花，常平駿，趙云娥. 白內障超聲乳化術后球后血流動力學變化的研究.國際眼科雜志2016;16(5):793-797

·Original article·