Clinical application of a shape-preserving rapid corneal donor dehydrater

INTRODUCTION

Corneal blindness has been reported as the second only to cataract in the leading causes of blindness, 10 million of the patients having bilateral corneal blindness

. Keratoplasty is the main method for the treatment of corneal blindness

.At present, corneal materials from donors are in short supply worldwide with the exception of a few countries, such as the United States and European countries. An estimated 12.7 million patients are placed on a long waiting list and the number is still growing

. Due to the paucity of trained keratoplasty surgeons and the shortage of cornea donors in some areas, cornea donations obtained cannot be used in reasonable time and efficiently

.

慢性胸、肺疾病会引起呼吸功能障碍,随着病情的发展会加重,最终引起呼吸衰竭,近年临床各医院对慢性呼吸衰竭报道逐渐增多。患者多表现为高碳酸血症、低氧血症等,严重的会出现全身系统紊乱[1-2]。适当的护理干预,可预防并发症出现,改善治疗效果。笔者为分析循证护理价值,报道如下:

甲洛洛嘴上的条条皱纹挤在一起，后背冒出汗，他翻了个身，整个身子缩成一团，再度沉入思虑：我虽然只是一个守仓库的，但在营业部里我的年岁最大，人缘也不错，不管别人当面怎么说也好，背面怎么说也好，管我叫甲洛洛（汉人坨子）也行，但我还是笑脸相迎，从没得罪过任何人啊。就算所有人管我叫甲洛洛，可部里无论遇到打架斗殴的，还是小偷小摸的，都是我去息事宁人，大家虽然表面不说，可暗地里还是对我有几许佩服的，更别说小瞧了我。

To solve the problem of shrinkage and deformation of corneas during dehydrating, the second innovation we proposed involves dehydrating donor corneas on 304 stainless steel beads that are the same diameter. Positioning holes are located in the dehydrating box that hold stainless steel beads of different diameters. When dehydrating, the donor cornea is laid flat on the stainless-steel bead with the endothelium facing downward. Given that the cornea and the bead have the same diameters, the cornea completely fits the circumference of the steel ball, thus maintaining the normal shape of the donor cornea.

SUBJECTS AND METHODS

This study was adhered to the tenets of the Declaration of Helsinki and approved by the Institutional Review Board of Shandong Eye Hospital, Jinan, China.ID:201904. All patients signed an informed consent approved by the Institutional Review Board.

由此可知，实验组巨大儿、新生儿高胆红素血症等并发症发生率低于对照组，差异有统计学意义（P<0.05）。实验组新生儿低血糖、低胎龄儿、呼吸窘迫综合征等并发症发生率与对照组相比，差异无统计学意义（P＞0.05）。

The corneal dehydrater that can be assembled quickly is made of high transparent plastic material. The box body is a vertical rectangular structure. The external size is 530×390×320 mm

, and the specification is 45 liters. The system is composed of ultraviolet lamp tube,powerful silent circulating fan, color-changing silica gel,dustproof filter net, dehydrating box, and 304 steel balls(Figures 1 and 2).

The rated voltage of the power supply is 220 V, and the rated frequency is 50 Hz. There are two ultraviolet lamp tubes that are 4 W and 6 W, separately. The lamps are used to sterilize the inner space of the dehydrater and keep the air sterile.Rapid dehydrating of donor corneas is primarily achieved using color-changing silica gel and a strong silent circulating fan. A rechargeable hygroscopic card monitors air humidity and ensures the use of dehydrated air in the dehydrater. The specification of the strong silent circulating fan is 100 mm, the input power is 25 W, and the rated speed is 2800 r/min. The fan is used to circulate the air inside the dehydrater forcibly and then transmit the dry air to the dehydrating box through the circulating pipe (110 PVC pipe, after reducing diameter to 50). In addition, to ensure that the circulating air is free of impurities, the fan side of the circulation fan and the circulation pipe are equipped with a 3-mm thick dustproof screen.

The dehydrating box is a semienclosed space that is 170×110×9 mm

in size. The dehydrating box is provided with 8 positioning holes to hold stainless steel beads of different diameters (10-20 mm in diameter). During dehydrating, the corneal donor is placed on 304 steel balls of the same diameter as the cornea to maintain the normal shape of the cornea and solve the problem of corneal tissue shrinkage and deformation during dehydrating.

The process of rapid shaping and dehydrating of the corneal donor: The indoor temperature and humidity were adjusted to 22℃-23℃ and 48%-50%, respectively. First, the inner wall of the dehydrater was wiped with 75% alcohol, and then the ultraviolet lamp is turned on for 30min for disinfection. An agar plate was placed in the dehydrater for air detection. After the system was validated, the corneal donor was dehydrated.The corneal donor was removed using surgical forceps, and the endothelium was placed downward on 304 stainless steel beads that were the same diameter as the cornea. The cornea was leveled using surgical forceps. The strong silent circulation fan was turned on for dehydrating, and the dehydrating time is approximately 103±11min. After the completion of dehydrating, the cornea was transferred to a storage container and stored in a refrigerator at 4℃ after vacuum pumping(Figure 3).

For the dehydrated corneal materials, the average dehydrating time was 103±11.2min. After the completion of dehydrating,all the donor corneas maintained a normal shape without any shrinkage or distortion, and the average intraoperative rehydration time was 43.3±12.1s during operation.

实验界面由4部分组成,对应简化模型的4个功能区,如图4所示,功能区(左上)模拟雷达目标搜索界面,功能区(右上)模拟表格显示界面,功能区(左下)模拟图标搜索点击界面,功能区(右下)模拟菜单状态显示界面.所有界面元素(文字、图标、图形符号)不针对任何现存显示界面,均为实验需求模拟制作.

Donor corneas cannot be preserved in Optisol corneal storage medium for more than two weeks

. To properly preserve donor corneas and avoid waste, dehydration treatment is often required for lamellar keratoplasty. At present, the main preservation methods of inactive corneal materials include glycerol preservation and dehydration preservation

. The most common disadvantage of glycerol preservation is that the glycerol molecules cannot be completely removed from the corneal donor after rehydration, thereby generating high water content and poor transparency of the corneal button

.

The dehydrater group was followed for an average of 8.5±2.0mo, whereas the control group was followed for an average of 8.3±1.7mo. The age, sex,and preoperative BCVA of the two groups of patients were comparable, and intergroup comparisons showed no significant differences.

The standard of postoperative corneal button transparency: 0:The corneal buttons is transparent; 1: Small superficial noninterstitial opacity, and the pupillary margin and iris vessels are visible through the corneal buttons; 2: Small, deep interstitial opacity with visible pupillary margin and iris vessels; 3:Moderate interstitial opacity, visible only at pupillary margin;4: Large interstitial opacity with only part of the pupillary margin visible; 5: Very large interstitial opacity with no anterior chamber visible.

Statistical analyses were performed using SPSS 21.0 (SPSS,Chicago, Illinois, USA). The demographics between the two groups were compared with independent samples

-test and Chi-square analysis. The BCVA, transparency of corneal buttons, thickness of the corneal buttons and the time of epithelium completely healed were compared between the two groups using independent samples

-test. A

value of ＜0.05 was considered statistically significant.

在运营管理方面，建立现代化的绿色矿业集团，构建“互联网+矿业”模式，建设矿山生产自动化系统，打造智慧矿山。

RESULTS

All patients were observed daily during the first week after surgery, weekly during the next 2mo, and monthly thereafter. The best corrected visual acuity (BCVA)and the thickness of the corneal buttons were evaluated at 1wk,1, and 6mo after surgery. The transparency of corneal buttons were evaluated at 1d, 1wk, and 1mo.

The age, sex, and mean preoperative BCVA of the two groups of patients were comparable, and intergroup comparisons showed no significant differences (

＞0.05; Table 1).

A consecutive series of 83 eyes (83 patients)underwent deep anterior lamellar keratoplasty (DALK)using corneal donor tissue preserved with corneal dehydrater(dehydrater group) for fungal keratitis at the Shandong Eye Hospital from January 1, 2019 to October 1, 2020. To compare the postoperative outcomes, 60 patients (60 eyes) who received DALK using corneal donor tissue preserved with glycerol for fungal keratitis by the same surgeon were included in the control group (glycerol group).

All of the 143 corneal materials were used in DALK surgery

,and all surgeries were performed by a single surgeon (Gao H).

The mean BCVA was 0.30±0.18 at 1wk and 0.32±0.16 at 1mo in the dehydrater group; these values were significantly better than those in the glycerol group, which were 0.14±0.09 and 0.23±0.09,respectively (

＜0.001). However, no statistically significant difference was obtained at 6mo between the two groups in BCVA (Table 2).

The score of transparency of corneal buttons in dehydrater group was lower than that of the control group at 1d (1.3±0.8

2.8±0.7) and 1wk (0.4±0.5

2.0±0.4), which means postoperative corneal button transparency rate was higher in the dehydrater group, with statistical difference (

＜0.001,Table 2). The epithelium completely healed at 3.3±0.6d after surgery (negative for fluorescein sodium staining; Figure 4).

After the surgery, the thickness of corneal buttons was 588±18 μm at 1wk and 544±41 μm at 1mo in the dehydrater group; these values were significantly better than those in the glycerol group, which were 654±30 and 585±49 μm, respectively(

＜0.001). But no statistically significant difference wasobtained at 6mo between the two groups (

＞0.05). These values indicate that the corneal buttons were stable and reached the normal level after 6mo (Table 2).

全面预算管理要以公司组织结构为基础，合理确定预算控制主体。遵循“谁使用、谁承担、谁管理、谁控制”的原则，充分发挥归口管理部门在预算控制中的作用。同时制定一套科学完善、严谨规范的组织制度为全面预算管理的有效实施提供保障。在制度建立的过程中，要对相关部门的权责进行明确，同时阐明预算目标，并对预算编制、审批、执行、考核等一系列程序进行合理的制定。在制度构建完成后，要将制度的落实和企业文化建设有机的结合起来，使其逐渐成为一种文化，渗透到广大员工的行为习惯中。

The surgery was smooth and lacked implant bed microperforations, posterior elastic layer ruptures and other complications.

DISCUSSION

Keratoplasty is the main method used to restore vision in patients with corneal blindness

. At present, many developing countries, including China, lack corneal donors due to traditional, cultural, and religious reasons

. In addition to the shortage of corneal donors, there are some practical problems in clinic, such as patients waiting for donors and donors waiting for corneas

. The utilization rate of donor corneas cannot reach the ideal level, and some freshly corneal donors may not be immediately used in patients. This phenomenon aggravates the shortage of donors

. If a freshly corneal donor is discarded towards the end of the preservation period, donor resources will be wasted. If the cornea is dehydrated, it can be used for lamellar keratoplasty in the future. Therefore, a high-quality, long-term dehydrating and preservation method is helpful to make full use of the limited corneal donor resources.

Some problems are associated with traditional glycerol preservation and anhydrous calcium chloride dehydrating preservation, such as incomplete dehydration and donor shape changes after dehydration. These limitations prevent the clinical application of these methods. Compared with the traditional dehydrating and preservation methods, the dehydrater described in this study has two advantages: fast dehydrating and maintaining the original shape of the cornea.The rapid dehydrating of corneal donors is mainly dependent on the hydroscopicity of discolored silica gel and a strong silent circulation fan. Discoloration silica gel is a fine porous silica gel with high active adsorption capacity that is combined with cobalt chloride on the internal pore surface of silica gel using specific technological steps. The gel has a strong adsorption effect on water vapor in the medium and is nontoxic and harmless, odorless, and highly safe for clinical application.We placed the discolored silica gel at the bottom of the dehydrating box to directly absorb the volatile water from the donor corneas. In addition, the strong silent circulation fan continuously circulates the air in the dehydrating box,thus ensuring that the corneal donor dries quickly within 2h,avoiding donor pollution, autolysis and other problems caused by long-term separation.

In addition, postoperative complications, such as interlamellar effusion and double anterior chamber, easily occur. The traditional dehydrating preservation uses anhydrous calcium chloride, which exhibits strong water absorption and releases a considerably amount of heat in the process, which damages and deforms the cornea, thus limiting its clinical application.This paper introduces a new type of corneal dehydrater that can be used to quickly dehydrate and still maintain the shape of the cornea. Using this system, the cornea dries fast without wrinkling and deforming. This system solves the problem of high-quality preservation of corneal donor tissue and is a new method worthy of clinical application.

All patients met the following inclusion criteria for surgery

:1) clinically diagnosed as fungal keratitis confirmed by the presence of fungus in potassium hydroxide preparations,confocal microscopic images, or positive culture results; 2)antifungal medication as reported in our previous studies was given for at least 2wk but was ineffective; 3) slit-lamp examination and RTVue optical coherence tomography(Optovue; Fremont, CA, USA) scans displaying stromal layer pathological changes with fusion and diffuse opacity reaching more than 3/5 of the depth of the stroma but without reaching Descemet’s membrane (DM)

; 4) a complete follow-up of at least 6mo.

Based on the results, the dehydrater can efficiently dehydrate the corneal material and maintain the original shape. Cases of shrinkage and deformation were not observed. A significant improvement in the BCVA was noted with an average increase of more than two lines. In terms of the transparency of corneal buttons, the corneal buttons exhibited mild edema on the first day after DALK. The edema generally disappeared one week after operation. The epithelium healed quickly after the operation. In terms of the thickness of corneal buttons, the central thickness of corneal buttons was 588±18 μm 1wk after operation and 544±41 μm 1mo after operation. These results indicate that the corneal buttons were stable and reached the normal level.

In summary, the cornea dehydrater with rapid dehydrating and shaping quickly dehydrates the corneal donor, and significantly reduces early complications, such as interlamellar effusion and double anterior chamber after operation. It can also maintain the original shape of the cornea during the process of dehydrating. This dehydrater solves the problem of long term and high-quality preservation of corneal materials, and this new method is worthy of clinical application.

The authors would like to thank Ms. Tong Liu for her editorial assistance.

本文通过Eviews 6.0软件，采用普通最小二乘法基于截面数据进行多元线性回归分析.首先，对浙江省对外直接投资的出口效应进行检验，回归结果如下：

④继续使用的水工建筑物、厂房及水工金属结构等，这些固定资产设施已使用30多年，应只考虑剩余价值的效益贡献。

Sun Y, Qi XL and Gao H was responsible for its design. Sun Y wrote the first draft of the manuscript. Lin X and Zhang XY participated in its design of manuscript. Zhang XY and Gao L helped revise of manuscript.Sun Y and Lin X was involved in data collection and statistical analysis. All authors have read and approved the final manuscript.

Supported by National Natural Science Foundation of China (No.81870639; No.82070923;No.81900907); Taishan Scholar Program (No.tspd20150215;No.tsqn201812150); the Academic Promotion Program of Shandong First Medical University (No.2019RC009).

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