Horizontal Versus Vertical Scleral Tunnel Orientation in Flanged Intrascleral Fixation: A 2-Year Comparative Study
Trial Snapshot
- Phase
- Not Applicable
- Status
- Completed
- Sponsor
- Enrollment
- 107
- Locations
- 1
- Primary Endpoint
- Proportion of Eyes Achieving Mean Absolute Error (MAE) Within ±0.50 Diopters of Target Refraction
Study Overview
Brief Summary
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.
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.
Study Design
- Study Type
- Observational
- Observational Model
- Cohort
- Time Perspective
- Other
Eligibility Criteria
- Ages
- 18 Years to — (Adult, Older Adult)
- Sex
- All
- Accepts Healthy Volunteers
- No
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
Arms & Interventions
Vertical Scleral Tunnel Group
Patients who underwent flanged intrascleral IOL fixation with scleral tunnels created perpendicular to the limbus (radial/vertical orientation).
Intervention: Flanged Intrascleral IOL Fixation (Yamane Technique) (Procedure)
Horizontal Scleral Tunnel Group
Patients who underwent flanged intrascleral IOL fixation with scleral tunnels created parallel to the limbus (tangential/horizontal orientation).
Intervention: Flanged Intrascleral IOL Fixation (Yamane Technique) (Procedure)
Outcomes
Primary Outcomes
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.
Secondary Outcomes
- Mean Absolute Error (MAE) at 2 Years(24 Months)
- IOL Tilt Angle(24 Months)
Investigators
Sebahattin Celik MD
Clinical Professor
Yuzuncu Yil University