Efficiency of modified hydrodissection vs traditional method in age related cataract surgery: a randomized clinical trial

doi:10.21203/rs.3.rs-2246959/v1

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Efficiency of modified hydrodissection vs traditional method in age related cataract surgery: a randomized clinical trial

https://doi.org/10.21203/rs.3.rs-2246959/v1

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Purpose

To investigate whether our modified hydrodissection is safe and efficient in age related cataract surgery.

Methods

A prospective, randomized, single-blind clinical study was performed in Chongqing Bishan Old Town Hospital from May 16 to August 31, 2022. Age related cataract patients without any other ocular disease were included. They were randomly allocated into modified hydrodissection and traditional hydrodissection groups. Hydrodissection was performed using modified or traditional method. It kept the same procedures as routine in incision, continuous circular capsulorhexis, phacoemulsification, irrigation-aspiration. Hydrodissection time and Oscar score are the main measurement to evaluate the efficiency of the modified method. Descemet membrane detachment, unstable anterior chamber and posterior capsular rupture were the main measurements to evaluate the safety.

Results

There were 156 patients (age:71.39 ± 7.17 years old; gender: 90 (57.7%) female, 66(42.3%) male) with age related cataract participating in this study. The hydrodissection time was 12.23 ± 1.84s and 18.72 ± 1.69s in the modified hydrodissection group and traditional group, respectively (P༜.001). 89.7% of eyes in modified hydrodissection group achieved Oscar score 5, which was achieved by only 75.6% eyes in traditional group (P = .033). There was no complication occurred in these patients.

Conclusions

This study demonstrated that the modified hydrodissection was as safe as traditional method but with more efficiency.

Health sciences/Diseases/Eye diseases/Lens diseases

Health sciences/Medical research/Study design/Randomized controlled trials

modified hydrodissection

age related cataract

surgical technology

Hydrodissection is the crucial step to cleave lens and capsular, but with risky of post capsular rupture and inefficiency sometimes, especially in unexperienced surgery.

What This Paper Adds

Hydrodissection can be modified simple and practical in cataract surgery.

An unblocked channel between the capsular and primary incision contributed to

balance capsular pressure, that may improve efficiency and safety.

Phacoemulsification is the commonly cataract surgery nowadays since it was invented by Charles Kelman in 1960’s¹. Hydrodissection is a crucial step to cleave lens cortex and capsular, also one of the most difficult steps in phacoemulsification surgery². It is risky for incomplete cleavage which may lead intraocular pressure increase, post capsular rupture or zonular dehiscence, even dropped nucleus^3,4. Inexperienced surgeons may perform hydrodissection followed phacoemulsification step by step, but usually need repeat hydrodissection to ensure cleavage complete especially in trainees, that remains risk as well as reduces efficiency in traditional method^5,6. Hence, we modified hydrodissection method, to compare and analysis whether it’s safety and efficiency during cataract surgery.

There were totally 156 patients (age:71.39 ± 7.17 years old; gender: 90 (57.7%) female, 66(42.3%) male) with age related cataract participating in this study, and randomly allocated into two groups with 78 eyes in each group. Nucleus hardness had no difference between groups (Table 1). Post capsular rupture, DMD did not occur in these patients, and anterior chamber was always stable. There were no other complications such as zonular dehiscence, nucleus drops.

Table 1

demographic and clinical characteristics of patients
	Modified	Traditional	p
Eyes, No.	78	78	/
Age, y	70.72 ± 6.87	72.06 ± 7.44	.49^a
Sex, No. (%) Female Male	46(29.5%) 32(20.5%)	44(28.2%) 34(21.8%)	.75^b
Nucleus hardness, No. (%) level 2 level 3 level 4 level 5	16(10.3%) 39(25%) 21(13.5%) 2(1.3%)	14(9%) 36(23.1%) 24(15.4%) 4(2.6%)	.80^b
Nucleus hardness (level 2/3/4/5) according to The Lens Opacities Classification System III. ^a Independent-samples T test; ^b Chi-square test.

Average hydrodissection time cost was shorter in modified group than that in traditional group (12.23 ± 1.84s vs 18.72 ± 1.69s; difference, 154; 95%CI, -7.05- -5.93; P༜.001). Oscar score 5 achieved 89.7% (70 of 78) and 75.6% (59 of 78) in modified hydrodissection and traditional group, respectively (P = .033) (Table 2).

Table 2

Efficiency of modified hydrodissection vs traditional method in age related cataract surgery
	Modified	Traditional	p
Oscar score, No. (%) Score 4 Score 5	8(5.1%) 70(44.9%)	19(12.2%) 59(37.8%)	.03^a
Hydrodissection time, s	12.23 ± 1.84	18.72 ± 1.69	.33^b
Oscar score 4: fluid injected in appropriate location, able to rotate nucleus but encounters more than minimal resistance. Oscar score 5: ideally see free fluid wave but adequate if free nuclear rotation with minimal resistance is achieved. ^a Chi-square test; ^b Independent-samples T test.

Complete hydrodissection guarantees lens dissociative from the capsular to protect capsular and zonular fibers during phacoemulsification and extracapsular cataract extraction⁹. Several objective surgical evaluations were developed, in which ICO-OSCAR has international validation with inter-rater reliability and construct validity and focused on each step of ophthalmology surgical competency assessment¹⁰. Uncomplete hydrodissection, in other words hydrodissection step that could not achieve ICO-OSCAR score 5, may need multipoint injection or repetition of instruments entrance into the anterior chamber. Therefore, it increase intraoperative risk such as DMD, iris prolapse, capsular block syndrome, capsular tears, vitreous prolapse, difficulty in aspirating the cortex, zonular dehiscence and so on^11–15. This not only consumes more time to reduce the efficiency of surgery, but also increases the risk of surgery and intraoperative and postoperative complications.

Surgeons endeavor to ameliorate this key step. Lin et al performed a minimal fluid technique as less as 0.2cc BSS squirting into lens equator, separating nucleus by a 27G cannula with 1 or 3-mL syringe¹⁶. Blumenthal and Mimouni created a remote hydrodissection utilizing an ending right angel (Chang) cannula with its opening central to the capsulorhexis edge and above the cortex¹⁷. It is obviously both of them innovated hydrodissection cannula, but the present study modified the method itself simple and practical.

Our modified hydrodissection just need 3 steps: first cannula reaches the point to injection a little fluid, second drives the lens locally, and third rotates the lens to complete cleave the lens and capsular. The key of this method is that the point of water injection between primary incision is acute angle, which could provide an unblocked channel between the capsular and primary incision. That channel contributed to balance the pressure within endocapsular and the space between posterior chamber and anterior hyaloid membrane¹⁸. Also, the fluent motion without instruments repeatedly entrance and friction to the incision would reduce DMD, prevent wound expansion¹⁹ and better maintenance of the anterior chamber stability. As the results of no posterior capsular rupture occurred in this study, it suggested that the modified hydrodissection may be as safe as traditional method.

Moreover, the reduced hydrodissection time not only demonstrated shorter operation time, but also suggest its ease of operation. Harb and Sadiq reported their safe and reliable “Tilt-and-crush” technique, which was energy-efficient in removal soft cataract compared with “divide-and-conquer” and “phaco-chop” techniques¹². Our modified hydrodissection method was similar to their describe about cannula introduced position but with neither larger opposite the main incision of CCC nor prolapse the nucleus into the anterior chamber. In addition, they statistic the phaco time which demonstrated its efficient in emulsifying soft cataracts. Furthermore, we compared the hydrodissection time and the rate of Oscar score 5 to sufficiently verify its efficient. Certainly, our modified hydrodissection was a small detail in age related cataract surgery, and most of them had nucleus hardness above level 3. It may be explored in other cataract such as soft nucleus. At the same time, it is also necessary to test whether the method is suitable for other complex cataract, such as pseudoexfoliation, glaucoma and subluxation, etc^20–22.

This study limited to one experienced surgeon to keep the consistency, but as we described the modified method was suitable for unexperienced ones. Hence, two training cataract surgeons were taught to perform the modified hydrodissection. Both of them had good command of this technology in several cases to cleavage lens and capsular, achieving Oscar score 5 in a little bit easier compared with traditional method. Data were not shown for the different grade of the two training surgeons. Next, our modified hydrodissection should be verified and ameliorated by multi clinic centers and specialists to standardize this procedure, then to train residents.

This study suggests that our modified hydrodissection method is safe and efficient in age related cataract surgery. It may be verified and ameliorated to standardize training procedure in the future.

Participants

This parallel randomized study recruited patients aged between 40–100 years old with age related cataract and undergoing phacoemulsification with intraocular lens implantation in Chongqing Bishan Old Town Hospital from May 16 to August 31, 2022. Only right eyes were included for patients undergoing surgery in both eyes. Exclusion criteria are lens dislocation or subluxation; posterior subcapsular cataract; class I and V nuclei; diabetes; previous intraocular surgery for the same eye; moderate to severe corneal opacity; inability of the pupil to dilate to 6mm or larger. This study was approved by the Institutional Review Board of Bishan Old Town Hospital and registered in Chinese Clinical Trial Registry with No. ChiCTR2200060052 (ULR: http://www.chictr.org.cn/edit.aspx?pid=169728&htm=4) on 16/05/2022, conducted in accordance with the principles of the Declaration of Helsinki and obtained written informed consent from all participants. Subjects were allocated into two groups according to block random number.

Sample size calculation and allocation

This study was designed for non-inferiority. The sample size was calculated according to the main efficacy evaluation index of hydrodissection time. We observed cost of hydrodissection time was about 12s and 18s in modified and traditional methods respectively. A 1:1 randomization allocation with block size of 4 was generated on line and reserved in excel of sequentially number, the non-inferiority margin was − 5, the one-sided α = .05, and the test power was 80%, so the sample size required 156 cases. Only participants were masked to interventions until trial completion.

Operative procedures

All procedures except hydrodissection of the cataract surgery were performed as routine by one experienced surgeon. Compound tropicamide was dropped to the surgical eyes to get pupil dilate to 6mm or larger, and oxybuprocaine was used to get satisfied topical anesthesia. The main and second corneal incisions were created at 10:30 and 2:30 o’clock. Viscoelastic was injected into anterior chamber followed by continuous circular capsulorhexis. Then hydrodissection was performed. The modified hydrodissection group accepted the method with cannula tip inserted into the capsulorhexis edge near the primary incision by cannula bar resist on the primary incision upper lip (Fig. 1). Traditional hydrodissection group received routine method with cannula tip run through anterior chamber to the opposite site to cleavage cortex and capsular. Lens was rotated to leave capsular. Phacoemulsification and irrigation-aspiration carried on Centurion Vision System were used to extract nucleus and cortex. Intraocular lens was implanted in the capsular. Viscoelastic was aspiration. Perfusate was filled with anterior chamber and watertight incisions.

Recoding and measurement

Intraoperative videos were recoded and collected. Two observers recorded the hydrodissection time and Oscar score of this procedure. Hydrodissection time was defined as the time from cannula tip accessing main incision to jet fluid rotating lens until the tip retreating from the incision. The performance was scored according to ICO-OSCAR phaco⁷. Nucleus hardness was graded according to LOCS III classification⁸. Descemet membrane detachment (DMD), unstable anterior chamber, posterior capsular rupture and other complications were also recorded during whole operations.

Statistical analysis

All randomized assigned participants who received intended treatment were analyzed for the outcomes. SPSS 22.0 was conducted to analysis the data. Chi-square test was used to compare gender and Oscar score, with described as percentages for categorical variables. The Kolmogorov-Smirnov test was used to verify the normality of the continuous variable distribution, which was described as means and SDs. The independent-samples T test was used to compare the hydrodissection time. P value༜.05 was recognized as statistical significance.

Authors contributions: Zhen Liu and Zeli Chen drafted this work and acquainted data; Changjun Lan analyzed and interpretated results; Xuan Liao designed of this study.

Data availability statement: The data that support the findings of this study are available from the corresponding author X.L., upon reasonable request.

Conflict of Interest Disclosures: None reported.

Financial Support: This study was supported by grant No.22XFWDF0003 from Project of the Strategic Cooperation of City and College, Nanchong.

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No competing interests reported.

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Efficiency of modified hydrodissection vs traditional method in age related cataract surgery: a randomized clinical trial

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Results

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