A Randomized Study of Intraocular Caliper-assisted Capsulotomy for Age-related Cataract Patients With Corneal Limbus Opacity

Study Overview
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Brief Summary
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The purpose of this study is to compare the accuracy of capsulotomy assisted by intraocular caliper and Verion navigation system in phacoemulsification surgery and postoperative visual quality for age-related cataract patients with corneal limbus opacity.

Detailed Description
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Continuous curvilinear capsulorhexis (CCC) is an important and technically challenging procedure in cataract surgery. Too large or too small capsulorhexis can increase the incidence of intraoperative and postoperative complications. In recent years, the image projection device Verion navigation system has been reported that it can improve the repeatability and accuracy of capsulorhexis via projecting a pre-set size ring to guide capsulorhexis. However, we found that for the patients with corneal geriatric ring, pterygium or limbal lesions leading to unclear limbal boundary, the projected capsulorhexis will deviate from the center, resulting in capsulorhexis is off center in clinical practice. Our self-developed intraocular caliper, which is modified on the conventional intraocular irrigation needle, can accurately measure the size of capsulorhexis, and mark the position and boundary of capsulorhexis on the lens anterior capsule to guide capsulorhexis, thus significantly improves the accuracy and centricity of capsulorhexis. The purpose of this study is to compare the centricity and accuracy of intraocular caliper-assisted capsulorhexis in phacoemulsification for age-related cataract patients with corneal limbus opacity with that of Verion projection navigation system.

Official Title
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A Randomized Controlled Trial Comparing Intraocular Caliper-assisted Capsulotomy Versus Verion Navigation System-assisted Capsulotomy for Age-related Cataract With Corneal Limbus Opacity

Conditions
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Cataract Extraction

Intervention / Treatment
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* Procedure: Intraocular caliper-assisted capsulotomy
* Procedure: Verion navigation system-assisted capsulotomy


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Adults aged 55 to 80 years with age-related cataract with pterygium, Corneal geriatric ring, and corneal limbus opacity; Pupil diameter ≥ 6.5mm after pupil dilation; Lens nuclear opacity grading score (LOCS III) lower than 4.0. Exclusion Criteria: Patients had previous intraocular surgery; Patients with a diagnosed eye disease that may affect the functions of lens suspensory ligament such as previous ocular trauma, lens subluxation, pseudoexfoliation syndrome, retinal pigment degeneration; Patients had other ocular diseases that impair visual function include optic neuropathy, uveitis, and tumor. Refused to participate the study.

Ages Eligible for Study
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Minimum Age: 55 Years
Maximum Age: 80 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Other
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Intraocular caliper-assisted capsulotomy group<br>In intraocular caliper-assisted capsulotomy group, a modified intraocular caliper with standard calibration on the rinse needle was used to measure and locate the position of capsulorhexis with 5.3 mm diameter and the principle of pupillary margin in concentric circles. The surgeon could gently use the blunt needle in the front of the intraocular caliper to further make corresponding markers on the lens anterior capsule, and then carry out capsulotomy according to the marks. | Procedure: Intraocular caliper-assisted capsulotomy<br>* Intraocular caliper is a modified intraocular caliper with standard calibration on the rinse needle.<br>|
| Active Comparator: Verion navigation system-assisted capsulotomy group<br>In the Verion-assisted capsulotomy group, Verion navigation system was applied to project a 5.3 mm capsulorhexis centered on the corneal vertex. According to the projected capsulorhexis, capsulotomy was performed. | Procedure: Verion navigation system-assisted capsulotomy<br>* Verion Image Guided System (Alcon Laboratories, Inc.) is a digital image guidance system consisting of a diagnostic reference unit and a surgery pilot for intraoperative surgical assistance. The device can be used to align toric intraocular lens during surgery as well as support manual creation of a capsulorhexis with a predefined target diameter.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Distance between pupil center and capsulorhexis center | The primary outcome was the distance between pupil center and capsulorhexis center. Clear images of the edges of IOL and capsulorhexis were taken at the end of the operation, and Image J image analysis software is used to measure the distance between pupil center and capsulorhexis center with the diameter of IOL optical surface (6 mm) as the reference by two independently professional graders at the meantime. | During the surgery | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Uncorrected and corrected visual acuity | Evaluated with ETDRS visual acuity chart. | One month after surgery | 
| Ideal ratio of capsulorhexis | Ideal capsulorhexis is defined as a centered and round capsulorhexis , which can cover the edge of IOL optical surface continuously for 360 degrees with a diameter between 5.0 to 5.5 mm. | During the surgery | 
| Grades of capsulorhexis-IOL overlap | The capsulorhexis-IOL overlap of each patient was graded as 360-degree continuous overlap, 270 360-degree overlap, 180 270-degree overlap, 90 180-degree overlap, and < 90-degree overlap. | During the surgery | 
| Deviation of horizontal and vertical diameter of capsulorhexis from the target diameter (5.3 mm) | Measured by Image J image analysis software. | During the surgery | 
| Horizontal and vertical diameter of capsulorhexis | Measured by Image J image analysis software. | During the surgery | 
| Intraocular lens tilt | Measured by anterior segment OCT (CASIA2). | One month after surgery | 
| Intraocular lens decentration | Measured by anterior segment OCT (CASIA2). | One month after surgery | 
| Intraocular aberrations | Measured by OPD-SCAN III. | One month after surgery | 
| Distance between pupil center and capsulorhexis center |  | One month after surgery |