Comparison of the Concordance Between Digital Marking and Manual Marking for Toric Intraocular Lens Positioning

Comparison of the Concordance Between Digital Image-Guided Navigation and Manual Peripheral Corneal Marking for Toric Intraocular Lens Positioning

This cross-sectional comparative study evaluated patients from a single cataract center. In each eye, manual horizontal meridian axis line was marked on the cornea using the manual peripheral corneal marking technique (Horizontal Slit Beam Marking ), while the Verion digital image-guided navigation system provided a reference axis fixed at the horizontal meridian (0°/180°). The primary outcome measure was the difference in degrees between the digital marker and the manual marker horizontal meridian as measured intraoperatively. Agreement was assessed using Bland-Altman analysis, reporting the mean bias (systematic error) and 95% limits of agreement (LoA, mean ± 1.96 SD). A misalignment of ±10° was defined as the threshold of clinical significance.

Study Overview

• Status: Not yet recruiting
• Conditions: Cataract Surgeries
• Intervention / Treatment: Other: Verion Digital Marking

Detailed Description

Patients with visually significant cataract and regular corneal astigmatism who were scheduled for phacoemulsification were screened for eligibility. Inclusion criteria were adults (18 -90 years of age) that were candidates for uncomplicated cataract surgery. The exclusion criteria were irregular corneal astigmatism, lens subluxation, uveitis, glaucoma, trauma, history of retinal disease or optic neuropathy, previous intraocular or corneal surgery and corneal disease that could not be evaluated by the ARGOS or VERION systems.

Preoperative assessment included best-corrected visual acuity (BCVA), which were determined by Snellen's chart and converted to logMAR. Spherical equivalent (SE) and astigmatic refraction (AR) were examined by Full Auto Ref-Keratometer (RK-F2, Canon). Evaluation for corneal astigmatism and axial length with ARGOS® Biometer. Slit lamp examination (BP 900®, Hagg-Streit) intraocular pressure measurement (Canon TX-20P), and dilated retinal examination was performed on all of the patients.

For manual technique a slit-lamp was used. Patients were seated with their head fixed with the horizontal supporting band and their chin placed in the center of the chinrest. A thin horizontal slit beam is projected onto the cornea and moved vertically (up and down) until the area of maximum light concentration (brightest reflection) on the corneal surface is identified. For each eye, after identifying the point of maximum light reflex, under topical anesthesia with 0.5% proparacaine hydrochloride eye drops, the corneal limbus was marked at the 0° and 180° meridian (3 and 9 o'clock) positions using a blunt tip of the Sinskey hook coated with sterile gentian violet ink, using light pressure as a single touch of approximately one second, in order to standardize ink deposition and minimize ink spread. The marking was maintained horizontally without any movement during the marking. The thickness of marks was routinely less than 0.25 mm

For the digital technique, preoperative biometry data obtained from the ARGOS Biometer were entered into the Alcon Vision Planner v1.6, which was paired with the VERION Image-Guided System (Alcon Laboratories, Inc., Fort Worth, Texas, USA) to project the digital overlays directly into the operating microscope. This module captures a high-resolution preoperative reference image of the eye which can be used to document the center of the undilated pupil, corneal reflex position or eccentricity of the visual axis, scleral vessels and iris structures. All marking was performed by the same experienced surgeon (W. Tattiyakul) who was experienced with using all techniques, performed all procedures and measurements. No complications had occurred.

With both the manual and digital marks visible intraoperatively, the angular deviation along the horizontal meridian (in degrees) between the manual mark and the digital reference was recorded from the operating-microscope display for each eye by two trained observers independently, each blinded to the other's readings, using the same standardized display. The mean of the two observers' readings was used for all subsequent analyses, and inter-observer agreement was assessed using the intraclass correlation coefficient (ICC) and Bland-Altman analysis

• Study Type: Observational
• Enrollment (Estimated): 100

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

Cataract Patients at Thammasat University

Description

Inclusion Criteria:

• candidates for uncomplicated cataract surgery

Exclusion Criteria:

• irregular corneal astigmatism, lens subluxation, uveitis, glaucoma, trauma, history of retinal disease or optic neuropathy, previous intraocular or corneal surgery and corneal disease that could not be evaluated by the ARGOS or VERION systems

Study Plan

How is the study designed?

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Mean signed angular deviation in degrees of the manual slit-lamp horizontal reference mark from the VERION digital reference meridian	For each eye, the signed angular difference (degrees) between the horizontal reference meridian (0-180°) marked by the manual slit-lamp peripheral corneal marking technique and the corresponding meridian identified by the VERION Image-Guided System (reference standard) is measured intraoperatively. Clockwise deviation is coded positive and counterclockwise negative. Agreement is summarized across eyes as the mean signed angular deviation with 95% Bland-Altman limits of agreement. Reported in a single unit (degrees).	6 months

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Proportion of eyes within ±5° of the VERION digital reference meridian, measured intraoperatively	For each eye, the absolute angular difference (degrees) between the horizontal reference meridian marked by the manual slit-lamp peripheral corneal marking technique and the meridian identified by the VERION Image-Guided System (reference standard) is measured intraoperatively. The outcome is the proportion of eyes with an absolute deviation of 5° or less, reported as a percentage (%) of eyes assessed. ±5° is the pre-specified threshold of clinically acceptable agreement for the marking step.	6 months

Collaborators and Investigators

• Sponsor: Thammasat University

Study record dates

Study Major Dates

• Study Start (Estimated): July 10, 2026
• Primary Completion (Estimated): September 30, 2026
• Study Completion (Estimated): October 30, 2026

Study Registration Dates

• First Submitted: July 8, 2026
• First Submitted That Met QC Criteria: July 13, 2026
• First Posted (Actual): July 17, 2026

Study Record Updates

• Last Update Posted (Actual): July 17, 2026
• Last Update Submitted That Met QC Criteria: July 13, 2026
• Last Verified: July 1, 2026

More Information

Terms related to this study

• Keywords: toric intraocular lens; manual marking; digital marking
• Other Study ID Numbers: MTU-EC-OP-0-162/69

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No