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

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

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

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.

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.

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.

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.

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.

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.

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.

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.

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.