Horizontal vs Vertical Scleral Tunnels in Flanged IOL Fixation (HORVER)

July 7, 2026 updated by: Sebahattin Celik MD, Yuzuncu Yil University

Horizontal Versus Vertical Scleral Tunnel Orientation in Flanged Intrascleral Fixation: A 2-Year Comparative Study

This study compares the 2-year outcomes of horizontal versus vertical scleral tunnel orientation in flanged intrascleral intraocular lens (IOL) fixation surgery. The primary outcome is the proportion of eyes achieving refraction within ±0.50 diopters of the target at 2 years. Secondary outcomes include IOL tilt measured by anterior segment optical coherence tomography (AS-OCT), iris capture, conjunctival erosion, and other complications. The study aims to determine whether tunnel orientation is associated with differing outcomes in this surgical technique.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

Background: The management of aphakia, crystalline lens luxation, and intraocular lens (IOL) luxation in the absence of adequate capsular support remains challenging. Traditional surgical options include anterior chamber IOLs, iris-fixated IOLs, and scleral-sutured posterior chamber IOLs, each carrying significant long-term risks. In 2017, Yamane and colleagues introduced a sutureless flanged intrascleral IOL fixation technique that rapidly gained worldwide acceptance. A critical yet under-investigated surgical variable is the orientation of the scleral tunnels relative to the limbus. Some surgeons create tunnels parallel to the limbus (horizontal/tangential), others perpendicular (vertical/radial), based on personal preference rather than high-level evidence.

Objective: To evaluate whether horizontal versus vertical scleral tunnel orientation is associated with differing 2-year outcomes in flanged intrascleral IOL fixation.

Study Design: This is a retrospective observational cohort study conducted at a single tertiary referral centre.

Participants: A total of 107 eyes (43 vertical tunnels, 64 horizontal tunnels) with complete 24-month follow-up are included. Surgeries are performed by two experienced vitreoretinal surgeons.

Interventions: All procedures follow the original Yamane flanged intrascleral fixation method with intentional variation in tunnel orientation only. The horizontal tunnel group receives tunnels parallel to the limbus (tangential), while the vertical tunnel group receives tunnels perpendicular to the limbus (radial). A three-piece foldable acrylic IOL (Alcon AcrySof MA60AC) is used in all eyes.

Outcome Measures: The primary outcome is the proportion of eyes achieving mean absolute error (MAE) within ±0.50D of target refraction at 2 years. Secondary outcomes include MAE at 2 years, IOL tilt measured using anterior segment optical coherence tomography (AS-OCT), iris capture, conjunctival erosion, cystoid macular oedema, epiretinal membrane, retinal detachment, vitreous haemorrhage, hypotony, corneal oedema, early IOP elevation, best-corrected visual acuity (BCVA), and vector astigmatism analysis using the Alpins method.

Statistical Analysis: Propensity score matching (1:1) will be performed to address selection bias. Multivariate logistic regression and a multilevel mixed-effects model with surgeon as random effect will be used to adjust for confounders including surgical period, age, and baseline refraction. For the primary outcome, a single pre-specified comparison will be made with a two-tailed significance level of α = 0.05. For secondary outcomes, the False Discovery Rate (FDR) using the Benjamini-Hochberg procedure (q = 0.05) will be applied to control for Type I error inflation.

Timeline: Data were collected from patients who underwent surgery between March 1, 2022, and March 1, 2025. Minimum follow-up is 24 months, with final data collection completed in March 2025.

Study Type

Observational

Enrollment (Actual)

107

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Turkey (Türkiye)
      • Van, Turkey (Türkiye), 65000
        • SBU Van Training and Research Hospital

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Sampling Method

Non-Probability Sample

Study Population

Patients with aphakia, crystalline lens luxation, or intraocular lens luxation in the absence of adequate capsular support who underwent flanged intrascleral IOL fixation surgery at a single tertiary referral centre between March 1, 2022, and March 1, 2025. All patients were aged 18 years or older and completed 24 months of follow-up.

Description

Inclusion Criteria:

  • Age ≥ 18 years
  • Complicated aphakia defined as absence of adequate capsular support following cataract extraction, lens trauma, or previous lensectomy
  • Crystalline lens luxation defined as partial or complete displacement of the natural lens due to zonular weakness
  • Intraocular lens (IOL) luxation defined as partial or complete dislocation of a previously implanted IOL
  • Inadequate capsular support (<180° of intact zonular or capsular support)
  • Ability to complete scheduled follow-up visits
  • Complete follow-up data available

Exclusion Criteria:

  • Previous scleral buckling surgery within 6 months
  • Pars plana vitrectomy within 3 months
  • Active uveitis
  • Active endophthalmitis
  • Uncontrolled scleritis or scleral thinning
  • Corneal decompensation (endothelial cell density <1000 cells/mm²)
  • Uncontrolled glaucoma (IOP >25 mmHg despite maximum therapy)
  • History of penetrating keratoplasty, DALK, DSEK, or DMEK
  • History of corneal refractive surgery
  • Active proliferative diabetic retinopathy
  • Pregnancy or breastfeeding
  • Inability to complete 24-month follow-up

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Cohorts and Interventions

Group / Cohort
Intervention / Treatment
Vertical Scleral Tunnel Group
Patients who underwent flanged intrascleral IOL fixation with scleral tunnels created perpendicular to the limbus (radial/vertical orientation).
Procedure: Flanged Intrascleral IOL Fixation (Yamane Technique)
Sutureless flanged intrascleral fixation of a three-piece foldable acrylic IOL (Alcon AcrySof MA60AC). Two partial-thickness scleral tunnels are created 2.0 mm posterior to the limbus, 180° apart. Haptics are externalized through the tunnels, and a flange is created on each haptic tip using thermal cautery. Tunnel orientation varied intentionally: horizontal (parallel to limbus) or vertical (perpendicular to limbus).
Horizontal Scleral Tunnel Group
Patients who underwent flanged intrascleral IOL fixation with scleral tunnels created parallel to the limbus (tangential/horizontal orientation).
Procedure: Flanged Intrascleral IOL Fixation (Yamane Technique)
Sutureless flanged intrascleral fixation of a three-piece foldable acrylic IOL (Alcon AcrySof MA60AC). Two partial-thickness scleral tunnels are created 2.0 mm posterior to the limbus, 180° apart. Haptics are externalized through the tunnels, and a flange is created on each haptic tip using thermal cautery. Tunnel orientation varied intentionally: horizontal (parallel to limbus) or vertical (perpendicular to limbus).

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Proportion of Eyes Achieving Mean Absolute Error (MAE) Within ±0.50 Diopters of Target Refraction
Time Frame: 24 Months
The proportion of eyes achieving mean absolute error (MAE) within ±0.50 diopters of the target spherical equivalent refraction at 24 months postoperatively.
24 Months

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Mean Absolute Error (MAE) at 2 Years
Time Frame: 24 Months
Mean absolute error in spherical equivalent refraction at 24 months postoperatively.
24 Months
IOL Tilt Angle
Time Frame: 24 Months
Intraocular lens tilt angle measured using anterior segment optical coherence tomography (AS-OCT) at 24 months postoperatively.
24 Months

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Yuzuncu Yil University

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

March 1, 2022

Primary Completion (Actual)

March 1, 2025

Study Completion (Actual)

March 1, 2025

Study Registration Dates

First Submitted

July 1, 2026

First Submitted That Met QC Criteria

July 7, 2026

First Posted (Actual)

July 14, 2026

Study Record Updates

Last Update Posted (Actual)

July 14, 2026

Last Update Submitted That Met QC Criteria

July 7, 2026

Last Verified

July 1, 2026

More Information

Terms related to this study

Keywords

Other Study ID Numbers

  • GOKAEK-2024-04-02 (Other Identifier: Van Training and Research Hospital Ethics Committee)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

Individual participant data will not be shared due to institutional data protection policies and patient privacy regulations. Anonymized aggregate data may be available from the corresponding author upon reasonable request.

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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