Simple method of measuring ocular rotation in supine position during small incision lenticule extraction

INTRODUCTION

Static cyclotorsion has been a major concern in surgery since the infancy of refractive surgery, and it has been emphasized that rotation of the eyeball during refractive surgery is an important cause of refractive errors left after surgery.Swami

suggested that an average misalignment of 4°could result in 14% of astigmatism not being treated properly,and a 6° difference visible in more than 25% of the eye would result in a 20% undercorrection, and a misalignment of 16° would lead to undercorrection in more than 50% of astigmatism. Previously, static cyclotorsion was measured using various methods, such as using a double Maddox rod

and video-oculography

, and the position change did not have a significant effect on ocular torsion. After the introduction of the eye-tracking system in refractive surgery,research on cyclotorsion has been active. Chernyak

measured the difference in cyclotorsion before and during surgery.The average cyclotorsion of both eyes was approximately 2.0°, and 19 out of 24 patients had binocular excyclotorsion.Subsequent studies generally showed a pattern of binocular excyclotorsion

.

Compared to conventional laser-assisted

keratomileusis,small incision lenticule extraction (SMILE), which has no flap-related complications, provides rapid patient recovery,and has low incidence of dryness, is gaining worldwide popularity and taking over conventional refractive surgery

.However, since its surgical procedure is different from the existing surgery, there is absence of an eye-tracking system in SMILE. Therefore, errors may occur in centering and in the accurate setting of the astigmatism axis during surgery. There are several studies on how to correct these errors; however, all these techniques are manual methods

.

There have been several studies in measuring static cyclotorsion,and among them, Jackson cross cylinder

, Maddox double-rod test

, videokeratography

, and intraoperative measurement were used

. No methods associated to SMILE were reported.In this study, we investigated a method to simply measure the amount of cyclotorsion without the need for extra hardware through anterior slit photography and surgical parameter comparison. In addition, the effect of the amount of cyclotorsion on the surgical results was investigated.

SUBJECTS AND METHODS

Statistical analysis was performed using SPSS software (version 22, SPSS, Inc., USA). Excyclotorsion was indicated by positive values and incyclotorsion by negative values. The mean cyclotorsion indicates the average of these positive or negative values. The absolute value of cyclotorsion indicates the amount of rotation of the eye,regardless of the direction of the cyclotorsion. Chi-square test, Mann-Whitney

test, Wilcoxon signed-rank test,Friedman test, and Pearson’s correlation analysis were used for preoperative and postoperative comparisons. Differences were considered statistically significant at

values less than 0.05.

總之，綜上所述，水肥一體化在我國有著良好的發(fā)展前景，雖然目前在操作中遇到一些問題。但隨著該項(xiàng)技術(shù)的發(fā)展和國內(nèi)環(huán)境的支持，這些問題終將得到解決。本文正是基于對這方面的認(rèn)識，對葡萄種植中水肥一體化推廣和應(yīng)用進(jìn)行較為詳細(xì)的分析，并以此闡述該項(xiàng)技術(shù)在應(yīng)用中的各種優(yōu)勢。

In this study, we measured intraocular rotation through anterior slit photographs after surgery. The absolute value of the torsional angle was 3.141°±2.256°, and the range of torsion was 0.5°-11.4°. The right eyes tended to be excyclotorted,and the left eyes tended to be incyclotorted. This result is consistent with the results of Park

, Zhao

, and Terauchi

. Zhao

suggested that this result may be due to eye laterality; that is, since the right eye is predominant in many cases, the strength of the oblique muscles of the right eye is stronger and there will be a difference between the two eyes. In correlation analysis, preoperative values such as gender, preoperative corneal thickness, and preoperative intraocular pressure were not correlated with the amount of cyclotosion and the direction of cyclotorsion, and these results are consistent with previous studies.

Anterior slit photographs were taken 1d, 1, 3, and 6mo after surgery. Photographs were taken using a Haag-Street BQ 900 illumination system with the EyeSuite IM 600 imaging module (Haag-Streit International, Koeniz,Switzerland). Photographs were taken by an experienced photographer under indoor lighting. When this picture was taken, the patient kept their eyes straight, the slit beam width was 1 mm, the light source intensity was 60%, and the slit beam angle was 30°. This procedure is represented schematically in Figure 1. Photographs in which the flap was torn during surgery or the incision margins were difficult to distinguish were excluded.

After obtaining the pictures, we calculated the cyclotorsion from the margin of the corneal incision. These calculations were performed using the Image J software (version 1.53i, NIH, USA). First,we checked the upper end of the corneal incision line and drew an imaginary circle along the incision line. A straight line was drawn connecting the upper end of the incision line to the center of the imaginary circle. This straight line was moved counterclockwise to the center of the corneal incision line. The length of incision was 2.5 mm, so it actually moved at a 1.25-mm distance along the contour of the circle. Because the diameter of the circle was 7.5 mm, the counterclockwise shift was calculated to be 19.1°. Theoretically, if there was no cyclotorsion during the surgery, the angle between this straight line and the horizontalline would be 135°. Therefore,by measuring the actual degree of this angle, we could measure the degree of torsion. The method of calculating the cyclotorsion is represented in a schematic diagram in Figure 2.We evaluated the cyclotorsion using photographs taken at 1mo.

To investigate the effect of preoperative parameters on the cyclotorsion, eyes were divided into a group with the amount of cyclotorsion 4 degrees or more and a group with the amount of cyclotorsion less than 4 degrees and analyzed (Table 2).There was no correlation between gender, preoperative corneal thickness, preoperative intraocular pressure, amount of rotation, and direction of rotation. It was found that the smaller the preoperative sphere, the higher the amount of cyclotorsion (

=0.11,

=0.016; Figure 8). There was no significant association between the amount of cyclotorsion and preoperative astigmatism (

=0.758; Figure 9).

To investigate the reproducibility of this measurement method, we measured the cyclotorsion at 1d, 1, 3, and 6mo postoperatively in one patient, and these consecutive data were compared.

本組患者中，累及1個(gè)椎體324例，2個(gè)椎體96例，3個(gè)及以上椎體54例；胸椎384個(gè)，腰椎330個(gè)。骨密度為（-3.43±0.36）SD。其中OVCF 489個(gè)椎體、OVBF 140個(gè)椎體、Kummell病85個(gè)椎體。具體手術(shù)部位分布詳見表1。

This study was performed in accordance with the tenets of the Declaration of Helsinki and was approved by the Institutional Review Board/Ethics Committee of Chungbuk National University Hospital, Cheongju, Korea.This retrospective study included 484 eyes from 242 patients who underwent SMILE procedures between November 2018 and December 2020 at the Seoul Daabom Eye Center,Cheongju, Korea. The inclusion criteria for this study were corrected distance visual acuity of 20/20 or better, myopia of-1.00 diopters (D) to -9.00 D with astigmatism of 0 to -4.00 D,and stable refraction for more than 1y. The exclusion criteria were the suspicion of keratoconus on corneal topography,severe dry eye, progressive corneal degeneration, the presence of systemic diseases and severe ocular diseases, and a history of intraocular or corneal surgery.

RESULTS

Of the 242 patients, 124 (51.2%)were men and 118 (48.8%) were women, and all patients underwent SMILE surgery in both eyes. The mean age was 28.47±6.44y, and the mean intraocular pressure was 17.55±2.19 mm Hg. The preoperative mean spherical equivalent (SE) was -4.10±1.64 D, the preoperative mean spherical power was -3.70±2.18 D, and the mean astigmatism was -0.82±0.74 D. The mean corneal thickness measured before surgery was 552.64±30.01 μm (Table 1).

UCVA and SE improved significantly after the surgery. The postoperative logarithm of the minimum angle of resolution (logMAR) UCVA was-0.04±0.08 at 1wk, -0.07±0.07 at 1mo, -0.08±0.07 at 3mo, and-0.09±0.07 at 6mo (Figure 3). The mean postoperative SE was 0.03±0.29 at 1wk, 0.01±0.29 at 1mo, -0.04±0.24 at 3mo and-0.03±0.17 at 6mo (Figure 4).

In 484 eyes, 219 (45.2%) eyes had excyclotorsion,235 (48.6%) eyes had incyclotorsion, and 30 (6.2%) eyes had no torsion. In the right eyes, excyclotorsion was 55.0%,incyclotorsion was 38.0%, and no torsion was observed in 7.0% of eyes. In the left eyes, excyclotorsion was 35.5%,incyclotorsion was 59.1%, and there was no torsion in 5.4% of the eyes. Figure 5 is a series of photographs of a representative case. The right eyes tended to be excyclotorted, and the left eyes tended to be incyclotorted and statistically significant(

<0.01, Chi-square test; Figure 6). The mean cyclotorsion was 1.18°±3.69°, and the absolute value of the torsional angle was 3.14°±2.26°. The range of cyclotorsion was 0.5°-11.4°.The distribution of the cyclotorsional angle is shown in Figure 7.In a single patient, the direction and amount of cyclotorsion in the right and left eyes were not correlated with each other(

=0.15,

=0.14, respectively).

Preoperative data such as age, sex,uncorrected distance visual acuity (UCVA), best corrected distance visual acuity (BCVA), manifest refraction, corneal thickness, and intraocular pressure were collected. Patients were examined at 1d, 1, 3, and 6mo postoperatively. When patients visited the clinic, objective and subjective refraction tests were performed, and UCVA and BCVA were recorded.

我國早在2000年就開始實(shí)施了國庫管理制度。這一項(xiàng)制度的實(shí)施就實(shí)現(xiàn)了國庫資金的統(tǒng)一管理，同時(shí)，還實(shí)現(xiàn)了將財(cái)政資金進(jìn)行直接的劃撥。例如稅收和非稅收的繳費(fèi)都統(tǒng)一納入財(cái)政專戶之中，國庫管理制度的實(shí)施，規(guī)范了財(cái)政資金的收支，提高了財(cái)政資金的管理效率。與此同時(shí)，對于預(yù)算的執(zhí)行也建立了動(dòng)態(tài)的監(jiān)控機(jī)制，從而對其進(jìn)行全面的監(jiān)督，這能夠有效地對預(yù)算的執(zhí)行起到警示的作用。

There was no significant association between the amount of cyclotorsion and postoperative UCVA, refractive outcomes(Table 3). In 98 eyes with astigmatism greater than -1.50 D,correlations between the amount of cyclotorsion, residualastigmatism, and BCVA after surgery were investigated, but there was no statistical correlation.

The ratio of right eye excyclotorsion and left eye incyclotorsion on 1d was higher than that at 1, 3, and 6mo, and this was statistically significant (all

<0.01; Table 4).There was no difference between the 1, 3, and 6mo results in the right and left eyes (

=0.15,

=0.16, respectively).

DISCUSSION

Since SMILE was first announced, it has opened a new horizon of refractive surgery

. It is known that the visual acuity results are comparable to those of conventional surgery, but there have been studies showing that astigmatism and highorder aberration results are inferior

. This result is thought to be influenced by the fact that the contact between the eyeball and the patient interface of the surgical device is required for suction during surgery, which is a deep-seated problemof SMILE, and undesirable decentration may occur during this process. Likewise, due to the absence of an eye-tracking system, errors in the astigmatism axis may occur, which may lead to errors in astigmatism correction

.

In refractive surgery, it is important to precisely cut or ablate the corneal tissue according to the target surgical parameters. Axial misalignment is known to affect the surgery outcomes, and it can induce from the undercorrection of the astigmatism to the formation of a new cylinder axis in severe cases

. Astigmatism axis measurements are performed in an upright position; however, the surgery is performed in a supine position. Therefore, if an eyeball rotation occurs attributed to a change from an upright position to a supine position, axial misalignment can be induced, and the postoperative visual acuity might be affected as a result of axial misalignment.Eyeball rotation through a change in posture is called static cyclotorsion, and numerous studies have been conducted on how it affects the surgical outcome of refractive surgery

.Static cyclotorsion is a major concern in the field of refractive surgery, and various eye-tracking systems have been developed to correct astigmatism axis error

.

All SMILE procedures aimed to obtain emmetropia. All patients received topical anesthesia, standard sterile draping, and speculum insertion. SMILE surgery was performed using a Visumax femtosecond laser (Carl Zeiss Meditec AG, Jena, Germany) with a repetition rate of 500 kHz and pulse energy of 110-140 nJ and followed a previously published surgical procedure. The cap diameter was 7.5 mm,the lenticule diameter was 6.5 mm, and the cap thickness was 120 μm. A single 2.5-mm side cut was made at 135° position.No manual corneal marking or manual compensation of the cyclotorsion was performed. The lenticule was then dissected,separated through the side cut, and manually removed.

數(shù)學(xué)全息定義和非全息定義的教學(xué)目標(biāo)是不同的．按照布魯姆的認(rèn)知水平的層次(“記憶”、“理解”、“運(yùn)用”、“分析”、“評價(jià)”、“創(chuàng)造”)來分類.數(shù)學(xué)定義的教學(xué)目標(biāo)可分為三個(gè)層次，即初級目標(biāo)、中級目標(biāo)、高級目標(biāo)．本文將“運(yùn)用”分為三個(gè)層次，即“很簡單的運(yùn)用”(相當(dāng)于直接運(yùn)用或直接套公式)、“簡單運(yùn)用”(包括逆用、變用等)、“靈活運(yùn)用”．全息定義教學(xué)的初級目標(biāo)是達(dá)到“記憶”、“理解”、“很簡單的運(yùn)用”等層次的要求，中級目標(biāo)是在達(dá)到初級目標(biāo)的基礎(chǔ)上還應(yīng)達(dá)到“簡單運(yùn)用”、“分析”層次的要求，高級目標(biāo)是在達(dá)到初級目標(biāo)和中級目標(biāo)的基礎(chǔ)上還應(yīng)達(dá)到“靈活運(yùn)用”、“評價(jià)”、“創(chuàng)造”層次的要求．

Recently, studies on the results of manual compensation in SMILE have been published

. Chen

reported that 84 patients were treated with standard SMILE for 30 patients and SMILE with manual cyclotorsion compensation for 54 patients. The SE of the two groups was the same, but better results were obtained in the vector analysis of astigmatism.Xu

compared the surgical results of the group with and without manual compensation in SMILE and found no difference between the two groups in terms of visual acuity and refractive outcomes, even in high astigmatism. According to this result, Xu

reported that manual compensation could reduce alignment error, but the average amount of cyclotorsion was too small to affect astigmatism, so it was not compulsory. K?se

proposed a method of compensating cyclotorsion by overlapping an image taken in an upright state on a surgical screen using an image-guided system and rotating the patient’s head. Standard SMILE for 62 eyes and SMILE with cyclotorsion compensation were performed for 62 eyes, and better results were obtained in UCVA and residual astigmatism. The mean astigmatism error was -0.19±0.17 D in the cyclotorsion compensation group and -0.45±0.38 D in the standard group. As described above, there are various opinions about the results of manual compensation. In our study, surgery was performed without cyclotorsion correction;however, satisfactory results were obtained after surgery. There was no difference in the amount of astigmatism according to the degree and direction of cyclotorsion. There was no difference in final residual astigmatism and UCVA, and even in the analysis of cases with astigmatism greater than-1.50 D, cyclotorsion did not affect the residual astigmatism and UCVA. Therefore, our results support the suggestion that manual compensation is not obligatory. However, there are studies that the results of manual compensation were favorable, so additional research is needed. The methods of manual compensation during surgery in the above studies were to correct the patient interface by rotating the suction cone directly after applying the suction after limbal marking, and rotating the head according to upright images. Rotating the suction cone, limbal marking processes and rotating the head have limitations due to the possibility of human error, and there is a risk of suction loss when rotating the cone; therefore,caution is required for manipulation. Further research is needed to see if it’s worth taking the risk.

One of the merits of this study is that it does not require any additional equipment to measure the cyclotorsions.Although most recent studies measured cyclotorsions through eye tracking systems, our study has clinical advantages for analyzing cyclotorsions that can be easily measured in clinical settings without additional devices. Another advantage of this study is that this method has sufficient reproducibility, even though it is a very simple method. In this study, there was no significant difference in the results of our surgery at an average of 1, 3, and 6mo. Although it was found that, on average,the right eye excyclotorsion and left eye incyclotorsion were more evident on the 1

day, these results are attributed to the unclear wound margins in the immediate postoperative period,or delayed adaptation to the refractive changes immediately after surgery. There is a study result that the accommodative response increases after refractive surgery for myopia

, also there is a paper that cyclotorsion occurs when accommodative response occurs

. In our study, the increased accommodative response may have caused cyclotorsion in the very early stage of surgery, and it is possible to hypothesize that the gradual change of accommodative state affects the degree of cyclotorsion. Further research is needed in this point.

This study has some limitations. First, this method can only measure cyclotorsions but cannot measure decentrations, so the effect of decentration cannot be confirmed. However, studies have shown that the effect of decentration is not thought to be significantly related to surgical outcomes. Huang

divided their subjects into two groups with an astigmatism of 2.5 D or more and less than 2.5 D and investigated the amount of decentration and the surgical outcome. They showed that coma and spherical aberration were more frequently induced in the high astigmatism group. However, according to the results of this study, the effect of decentration was considered insignificant. Second, one examiner directly set the endpoint of the incision manually without using an automated program, hence subjective errors may occur. There is room for improvement when using an automated method using an image-tracking program, and further studies are needed. Third,our study investigates reproducibility with photos taken over a long period of time and we used only one photo each day.So long-term reproducibility can be investigated, but shortterm reproducibility cannot be determined. This should be supplemented through additional research.

In conclusion, the newly devised ocular cyclotorsion measurement method used in this study is a suitable test method for evaluating ocular cyclotorsion after SMILE. In addition, this new technique is easy to perform and does not require additional equipment; therefore, so we believe it can be widely used. Because this method is based on actual surgical results, it is more realistic than the previous measurement method. With this method, we were able to measure ocular cyclotorsion according to the operating posture and showed that ocular cyclotorsion did not significantly affect visual acuity and refraction after surgery.

1.2 臨床診治及保肢方案 所有患者首先判斷生命體征是否平穩(wěn)，有無重大合并傷。予糾正失血性休克、補(bǔ)充血容量，在維持基本生命體征、全身情況穩(wěn)定后，評估肢體損傷程度，進(jìn)行保肢手術(shù)。一期徹底清創(chuàng)，清除壞死組織，尤其是失活的肌肉組織不能姑息，清創(chuàng)時(shí)注意保護(hù)血管和神經(jīng)。先恢復(fù)骨組織的連續(xù)性和穩(wěn)定性，采用外固定支架和鋼板內(nèi)固定。血管修復(fù)是保肢的關(guān)鍵，需要時(shí)移植血管。骨骼、神經(jīng)、血管修復(fù)后，予以皮膚軟組織覆蓋，如皮膚軟組織缺損較多，行鄰近皮膚肌肉轉(zhuǎn)位，優(yōu)先覆蓋血管神經(jīng)骨骼，殘余較大創(chuàng)面予創(chuàng)面封閉負(fù)壓引流(vaccum sealing drainage,VSD)治療；二期行植皮或皮瓣修復(fù)。

None;

None;

自2003年8月正式投入發(fā)電運(yùn)行以來，沙集泵站積極利用徐洪河行洪棄水開發(fā)水力發(fā)電，創(chuàng)造了可觀的經(jīng)濟(jì)效益，對2003—2011年發(fā)電運(yùn)行數(shù)據(jù)統(tǒng)計(jì)，年平均發(fā)電340.4萬kWh，機(jī)組年平均運(yùn)行14 183.3臺時(shí)（按照單臺機(jī)組平均出力240 kW）。經(jīng)測試進(jìn)行降低轉(zhuǎn)速后，每臺機(jī)發(fā)電功率增加約100 kW，全站共增加發(fā)電功率500 kW。考慮變頻機(jī)組等相關(guān)設(shè)備消耗電量約40 kW，改造后泵站年均發(fā)電量可增至470.9萬kWh，相當(dāng)于火電廠燃燒578.7 t標(biāo)準(zhǔn)煤產(chǎn)生的電量，無論是經(jīng)濟(jì)效益還是社會效益均比較顯著。

None;

None.

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