A retrospective Cohort Research of the Impact of Intraocular Lens (IOL) Loading Methods on the Adhesion Phenomenon during Cataract Surgery

doi:10.21203/rs.3.rs-4894287/v1

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A retrospective Cohort Research of the Impact of Intraocular Lens (IOL) Loading Methods on the Adhesion Phenomenon during Cataract Surgery

https://doi.org/10.21203/rs.3.rs-4894287/v1

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Purpose

This study aims to observe the optic and haptic adhesion phenomenon of different intraocular lens (IOL) and the impact of different methods of IOL loading on the occurrence of adhesion phenomena.

Methods

253 patients (253 eyes) undergoing routine cataract surgery combined with IOL implantation at Peking University Third Hospital from July 2021 to July 2022 were enrolled. As an observative retrospective study, the Trial Registration Number (TRN) is not applicable for our research. Five types of IOLs including Tecnis ZCB00, Tecnis ZXR00, Tecnis ZMT, A1UV, and A1UL22 were selected and loaded using 7 different methods to compare the incidence of different IOL adhesion types and additional device assistance.

Results

The incidence of adhesion and additional device assistance in A1UV and A1UL22 groups were significantly higher than that in other three groups (P < 0.05). Routine loading method group exhibited the highest incidence of haptic adhesions (55%), while balanced salt solution (BSS) group presented the lowest incidence of haptic adhesions (5.9%, P < 0.05). BSS and viscoelastic group showed the highest incidence of double haptic loop adhesions (33%) among all the loading ways groups.

Conclusions

A1UV and its preloaded A1UL22 IOL presented the highest incidence of adhesion, compared with the other three IOLs (Tecnis ZCB00、Tecnis ZXR00、Tecnis ZMT). The application of BSS during IOL loading was effective in reducing the adhesion incidence.

Health sciences/Diseases/Eye diseases/Lens diseases

Health sciences/Health care/Therapeutics/Surgery

intraocular lens

optic and haptic adhesion

loading methods

With the development of cataract surgery equipment, intraocular lens (IOL) and the increasing demand of patients for visual quality, cataract surgery has transformed from the era of traditional restorative surgery to the era of refractive surgery, which brings more opportunities and challenges to cataract surgeons.^1–3 The success of the cataract surgery and patients’ postoperative cisual quality can be influenced by many factors, of which the material and characteristics of the IOL are of great imprtance.^4–5

Hydrophobic acrylate IOLs are composed of polymers of phenylacetate and phenylethylacrylate, which have the characteristics of lighter mass, high flexibility, high refractive index, and high surface viscosity⁶, and are now widely used in clinical practice. The characteristics of large surface viscosity make it easier to adhere to the lens capsule, especially bringing the posterior capsule into close contact with the optical part. Thus, this type of IOLs can prevent the migration of lens epithelial cells, and reduce the incidence of posterior capsule opacification.^7–9 However, this property leads to an increased risk of adhesion of the haptic part to the optical part during IOL implantation, which may prolong the operation, and increase the unforeseen risks of the surgery. Yiping Hu et al.¹⁰ showed that hydrophobic acrylate IOLs have a higher risk of adhesion of haptic part to the optical area, and the use of viscoelastic during loading can shorten the adhesion time. They also found the application of polymethyl methacrylate (PMMA) in the haptic part can reduce the risk of the adhesion. In our research, we compared the hydrophobic acrylic IOLs with a high incidence of adhesion: A1UV and its preloaded form A1UL22 of Eyebright Medical Technology, with 3 other hydrophobic acrylic IOLs: Tecnis ZCB00, Tecnis ZXR00, and Tecnis ZMT of Advanced Medical Optics. Furthermore, we explored the effectiveness and safety of different IOL loading methods to prevent the occurrence of adhesion.

Subjects

This research is an observative retrospective study, approved by the Institutional Review Board of Peking University Third Hospital and conducted in accordance with the tenets of the Declaration of Helsinki. The ethics number of our research is D2016035. Informed consents were obtained from each patient. 253 patients (253 eyes) undergoing routine cataract surgery combined with IOL implantation at Peking University Third Hospital from July 2021 to July 2022 were enrolled, with implanted IOLs: Tecnis ZCB00 (45 eyes), Tecnis ZXR00 (29 eyes), Tecnis ZMT (28 eyes), A1UV (87 eyes) and A1UL22 (64 eyes) (The IOL parameters can be seen in Table 1).

Table 1

Basic parameters of five kinds of IOLs
	Tecnis ZCB00	Tecnis ZXR00	Tecnis ZMT	A1UV	A1UL22
Optic material	Hydrophobic acrylic
Haptic material	Hydrophobic acrylic
Square edged	Yes
Heparin coated	No
Blue light-filtering	No
Optic dimension (mm)	6
Total dimension (mm)	13
Index of refraction	1.47	1.47	1.47	1.48	1.48
Haptic angle (°)	Tri-Fix	Tri-Fix	Tri-Fix	1.5	1.5
A-constant	118.8	118.8	118.8	118.2	118.2
A1UL IOL is the preloaded type of A1UV IOL

Inclusion and exclusion criteria

Our inclusion criteria were as follows: (i) regular cataract surgery combined with IOL implantation; (ii) the implanted lens was one of Tecnis ZCB00, Tecnis ZXR00, Tecnis ZMT, A1UV, and A1UL22; and (iii) the procedure was performed successfully without IOL-related complications. Exclusion criteria were as follows: (i) special cataract surgery, such as traumatic cataract, pediatric cataract, dislocation of the lens, and cataract surgery in combination with other surgeries; (ii) unexpected events such as IOL rupture.

IOL loading methods

5 non-preloaded IOLs, Tecnis ZCB00, Tecnis ZXR00, Tecnis ZMT, and A1UV, were loaded using 6 methods and the preloaded IOL A1UL22 was counted as the Looading methods VII. All the 6 manual loading methods were listed as follows.

Loading method I (routine loading): The loading protocol in the instruction manual¹⁰ was set as the control group: about 0.4 mL of sodium hyaluronate gel (Maxigen Biotech Inc.) was injected into the introducer head, the edge of the optical surface of the IOL was gripped with IOL forceps (Suzhou Xiehe Medical Instrument Co., Ltd.), and the crystal was gently placed in the reverse "S" shape to the posterior part of the introducer head, so that half of the optic surface enters the introducer head and the front haptic part covers the top of the optic surface, then hold the posterior haptic part so that it also covers the top of the optic surface, and gently push the IOL into the marking position of the introducer head with the IOL forceps against the root of the crystal. Then connect the pusher and consider the installation successful if there is no resistance to pushing.

Loading method II (BSS loading): Cover the IOL surface with BSS (Shenyang Xingqi Pharmaceutical Co., Ltd.), and then load IOL according to loading method I.

Loading method III (viscoelastic loading): Cover the IOL surface with sodium hyaluronate gel (viscoelastic) and then load IOL according to loading method I.

Loading method IV (haptics interval loading): Load the front haptic first, and then load the posterior haptic after an interval of 1 minute.

Loading method V (BSS + viscoelastic loading): Cover the IOL surface with BSS and viscoelastic, and then load IOL according to loading method I.

Loading method VI (BSS + viscoelastic + haptics interval loading): Cover the IOL surface with BSS and viscoelastic, and then load the front haptic first, after an interval of 1 minute load the posterior haptic, which we called interval loading.

Loading method VII (preloaded): The A1UL22 IOL is a preloaded IOL that is implanted directly into the eye without manual loading during the surgery and is operated according to the instructions[4].

Evaluation

Incidence and type of adhesion: there are 4 types of adhesion: single haptic adhesion to the optical part (Fig. 1A), two haptics adhesion to the optical part (Fig. 1B), two haptic parts adhere to each other (double haptic loop adhesion, Fig. 1C), and no adhesion (Fig. 1D).

Duration of IOL folding: The time from when the IOL in a folded and curled position at the front of the inducer until the entire IOL is pushed into the anterior chamber.

Duration of IOL unfolding: The time from the curled position to the fully deployed position after the IOL is pushed into the anterior chamber from the inducer.

The incidence of the need for additional instrument assist: The incidence of the situation where the surgeon needed to use additional instruments to assist in IOL deployment because of a certain type of IOL adhesion. (Fig. 2)

Statistical analysis

All statistical analyses were performed using IBM SPSS version 26.0 (IBM Corp., Armonk, NY, USA). The statistical data are expressed as rate (%), using the chi-square test, with P < 0.05 being a statistically significant difference and P < 0.001 being a highly significant difference.

Comparison of the adhesion incidence among the IOL groups when using Loading Method I

After loading the IOLs according to Loading method I (routine method) [3], we observed a significant difference in the incidence of adhesion among 4 types of IOLs (P < 0.01), as detailed in Table 2. The incidence of adhesion in the A1UV and A1UL22 IOL groups ware significantly higher than that in the other 3 groups.

Table 2

Incidence of adhesion in different types of IOLs
Type of IOLs	Adhesion	No adhesion	P value
A1UV	30 (34.5%)	57 (65.5%)	0.003**
A1UL22	19 (29.7%)	45 (70.3%)
ZCB00	7 (15.6%)	38 (84.4%)
ZXR	1 (3.4%)	28 (96.6%)
ZMT	4 (14.3%)	24 (85.7%)
: P < 0.05, : P < 0.01, **: P < 0.001.

Comparison of the incidence of additional instrument assistance

We conducted χ2 analysis on the percentage of additional instrument assistance among the 5 IOL groups. At room temperature of 25°C, there was a significant difference (P < 0.01) in the percentage of additional instrument assistance during implanting the IOL into the anterior chamber in each group (Table 3). The percentage of additional instrument assistance in A1UV and A1UL22 groups were significantly higher than that in the other 3 groups.

Table 3

The incidence of the need for additional instrument assistance of different types of IOLs
Type of IOLs	Adhesion	No adhesion	P value
A1UV	21 (24.1%)	66 (75.9%)	0.001**
A1UL22	10 (15.6%)	54 (84.4%)
ZCB00	1 (2.2%)	44 (97.8%)
ZXR	0 (0.0%)	29 (100%)
ZMT	2 (7.1%)	26 (92.9%)
: P < 0.05, : P < 0.01, **: P < 0.001.

Comparison of the incidence of adhesion between different loading method groups in A1UV and A1UL22 groups

We also conducted χ2 analysis on the incidence of adhesion among the 7 loading method groups. There was a significant difference in the incidence of adhesion among the 7 groups (P < 0.01), with Loading method I (routine loading) showing the highest incidence of adhesion (55%), and Loading method II (BSS loading) showing the lowest incidence of adhesion (5.9%), as shown in Table 4.

Table 4

The incidence of adhesions in different loading method
Loading method	Adhesion	No adhesion	P value
I (routine loading)	11 (55.0%)	9 (45.0%)	<0.001***
II (BSS loading)	1 (5.9%)	16 (95.1%)
III (viscoelastic loading)	3 (10.0%)	27 (90.0%)
IV (haptics interval loading)	5 (8.9%)	51 (91.1%)
V (BSS + viscoelastic loading)	6 (40.0%)	9 (60.0%)
VI (BSS + viscoelastic + haptics interval loading)	16 (31.4%)	35 (68.6%)
VII (preloaded)	19 (29.7%)	45 (70.3%)
: P < 0.05, : P < 0.01, **: P < 0.001.

Relationship between loading methods and the types of adhesion

The types of adhesion significantly varied between different loading methods (P < 0.01). The incidence of single haptic adhesions was lowest in Loading method V group(0%), and highest in Loading method I group (25.0%). The incidence of double haptic-optic adhesions was the lowest in Loading methods II and III groups (0%), and highest in Loading method I group (10.0%). The incidence of double haptic loop adhesion was found lowest in Loading method II group (1%), and highest in Loading method V group (33.3.%). The incidence of unglued was found highest in Loading method II group (88.2%), and the lowest in Loading method I group (35.0%), as shown in Table 5.

Table 5

The incidence of adhesion types in different loading method
Loading method	Single haptic adhesion	Two haptics adhesion	Double haptic loop adhesion	No adhesion	P value
I (routine loading)	5(25.0%)	2(10.0%)	6(30.0%)	7(35.0%)	0.031*
II (BSS loading)	1(5.9%)	0(0.0%)	1(5.9%)	15(88.2%)
III (viscoelastic loading)	2(6.7%)	0(0.0%)	3(10.0%)	25(83.3%)
IV (haptics interval loading)	7(12.5%)	2(3.6%)	5(8.90%)	42(75.0%)
V (BSS + viscoelastic loading)	0(0.0%)	1(6.7%)	5(33.3%)	9(60.0%)
VI (BSS + viscoelastic + haptics interval loading)	2(3.9%)	2(3.9%)	12(23.5%)	35(68.6%)
VII (preloaded)	9(14.1%)	4(6.3%)	14(21.9%)	37(57.8%)
: P < 0.05, : P < 0.01, **: P < 0.001.

The various advantages of hydrophobic acrylate make it one of the most commonly used materials for IOLs.^12–13 However, its viscosity leads to adhesion during implantation of IOLs, which needs extra equipment to deploy the IOLs, thus prolonging the surgery and increasing the difficulty and risk.

In this study, we compared the incidence of adhesion of different types of hydrophobic acrylic IOLs and found that the incidence of adhesion of A1UV and A1UL22 IOLs was significantly greater than that of Tecnis ZCB00, Tecnis ZXR00, and Tecnis ZMT IOLs. Meanwhile, we investigated different loading methods in the effectiveness of prevention of adhesion. Our results showed that the incidence of adhesion and additional instrument assistance can be significantly reduced by applying BSS on the surface of the IOL during the loading.

In the case of the same hydrophobic acrylic material and the same total length of the lens body, the angle between the haptic and optic of A1UV and A1UL22 is slightly smaller than that of ZCB00, ZXR00, and ZMT, and the area of the base of the haptic in the A1UV and A1UL22 is narrower than that of the others, resulting in a smaller rebound force of the haptic when the IOL is folded and the haptic is attached to the body, thus increasing the incidence of haptic and optic adhesion of the IOL and the time of adjustment, resulting in longer surgery time. Yiping Hu et al.¹⁰ demonstrated that the base of the haptic of the Tecnis ZCB00 was 0.35 mm × 0.45 mm and that of the IQ SN60WF was 0.30 mm × 0.41 mm, suggesting that the width and thickness of the haptic base of the Tecnis ZCB00 is larger than that of the IQ SN60WF, thus the Tecnis ZCB00 has a greater resilience, resulting in easier separation of haptic and optic part.

Another reason of the higher adhesion rate A1UV and A1UL22 is that the special haptic design, sanding treatment at the end of the haptic increases the friction. Once the IOL is folded, the contact between the loop and the optical part or between the two haptics will lead to adhesion, which is difficult to separate.

In addition, our results showed no significant difference in adhesion rate between A1UV and A1UL22, indicating that preloading does not avoid adhesion compared to manual loading. However, the use of preloaded IOLs almost avoids the occurrence of rupture of haptic during IOL implantation¹⁷, so considering the safety of IOL implantation and the rational use of medical resources, preloaded IOLs have some value for clinical use.

In this study, 7 different IOL loading methods were designed and experimented. The results showed that adding BSS showed the lowest adhesion incidence, and adding viscoelastic was the second, haptics interval loading was the third, and combining multiple methods was not as effective as the above three. And all these five methods we experimented were better than the control group (routine loading). We speculated that the viscosity of water is less than that of viscoelastic, which is less likely to cause adhesion compared to viscoelastic for hydrophobic IOL; the weaker effect of the combined method is considered to be due to the excessive volume of the added medium, which increases the pressure of the haptic on the optic part when the IOL is in the folded state inside the inducer, causing an increase in the incidence of adhesion. Our results indicated that the loading methods used in this study to prevent adhesion were effective, of which loading the IOLs with a small amount of BSS was the best.

Previous studies have shown that the prolonged duration of the procedure increases the risk of Iatrogenic infection.^14–16 The results showed that adhesion was more severe in the A1UV and A1UL22 groups than that in the others, which increases the difficulty of surgery and the risk of surgical infection for less experienced surgeons.

In conclusion, this study compared 5 hydrophobic acrylic IOLs using different loading methods to prevent adhesion of haptic and optic part, and loading hydrophobic acrylic IOLs with a small amount of BSS on the lens surface was the most effective. In addition, increasing the base area between the optic part and haptic part can effectively increase the resilience of the haptics and reduce the occurrence of adhesion. Preloading does not reduce the adjustment time compared with manual loading, but considering the safety of surgery and the rational use of medical resources, the preloading IOLs is worth promoting.

Ethics approval and consent to participate

Consent for publication

Not applicable.

Data availability

The datasets used and/or analysed during the current study available from the corresponding author on reasonable request.

Funding

There is no conflict of interest between this study and any commercial institution or company. There are no commercial or financial relationships that may create conflicts of interest in this study. We did not sign any agreements with any sponsoring units that may result in biased research results. All authors declare that they have no conflict of interest.

Author Contribution

Li Yanan and Zhang Li carried out the idea and designed the research. Liu Jing, Li Yanan, Miao Jinsong and Zhang Li collected the data. Wang Yiren wrote the main manuscript and all the authors reviewed the manuscript.

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No competing interests reported.

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You are reading this latest preprint version

A retrospective Cohort Research of the Impact of Intraocular Lens (IOL) Loading Methods on the Adhesion Phenomenon during Cataract Surgery

Status:

Version 1

Abstract

Purpose

Methods

Results

Conclusions

Figures

INTRODUCTION

MATERIALS AND METHODS

Subjects

Inclusion and exclusion criteria

IOL loading methods

Evaluation

Statistical analysis

RESULTS

Comparison of the adhesion incidence among the IOL groups when using Loading Method I

Comparison of the incidence of additional instrument assistance

Relationship between loading methods and the types of adhesion

DISCUSSION

Declarations

Author Contribution

References

Additional Declarations

Status:

Version 1