Comparison of In-the-bag Stability Between Single-piece and Three-piece Intraocular Lens

Study Overview
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Brief Summary
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Rapid advances of cataract surgery techniques and intraocular lens (IOL) technology have enabled the transition of cataract surgery from blindness relief to refractive correction. An ideal IOL is the critical component to achieve the refractive target of cataract surgery. Biocompatibility, rate of posterior capsule opacification (PCO) and visual quality have all been suggested as the critical factors of an ideal IOL and widely investigated. Recently, stability of IOL position has also been suggested as one of those critical factors due to its close correlation with postoperative visual function. Data suggests that IOL forward movement of 0.29 mm along the visual axis is associated with -0.4D myopic shift. Wang and colleagues recently reported that 0.5mm decentration of an aspheric IOL could eliminate its aberration-correcting effect. Poor stability could even lead to IOL exchange, an additional surgery that put both surgeons and patients in pain. As the supporting element of an IOL, the haptics are crucial to keep the IOL in place. Various haptic designs are being compared in terms of position stability of IOLs. Haptic designs of single-piece versus 3-piece are often compared because they are currently the most commonly used types. Single-piece IOLs have soft and broader haptics which are made of the same material as the optic, usually hydrophobic or hydrophilic acrylic, whereas 3-piece IOLs have rigid haptics which are made of poly methyl methacrylate (PMMA). Clinical studies comparing these haptic designs have yielded controversial results regarding their position stability in the capsular bag, which is the most recommended site for IOL fixation in an uneventful cataract surgery.

Detailed Description
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Rapid advances of cataract surgery techniques and intraocular lens (IOL) technology have enabled the transition of cataract surgery from blindness relief to refractive correction. An ideal IOL is the critical component to achieve the refractive target of cataract surgery. Biocompatibility, rate of posterior capsule opacification (PCO) and visual quality have all been suggested as the critical factors of an ideal IOL and widely investigated. Recently, stability of IOL position has also been suggested as one of those critical factors due to its close correlation with postoperative visual function. Data suggests that IOL forward movement of 0.29 mm along the visual axis is associated with -0.4D myopic shift. Wang and colleagues recently reported that 0.5mm decentration of an aspheric IOL could eliminate its aberration-correcting effect. Poor stability could even lead to IOL exchange, an additional surgery that put both surgeons and patients in pain. As the supporting element of an IOL, the haptics are crucial to keep the IOL in place. Various haptic designs are being compared in terms of position stability of IOLs. Haptic designs of single-piece versus 3-piece are often compared because they are currently the most commonly used types. Single-piece IOLs have soft and broader haptics which are made of the same material as the optic, usually hydrophobic or hydrophilic acrylic, whereas 3-piece IOLs have rigid haptics which are made of poly methyl methacrylate (PMMA). Clinical studies comparing these haptic designs have yielded controversial results regarding their position stability in the capsular bag, which is the most recommended site for IOL fixation in an uneventful cataract surgery. Most previous studies measure the IOL position based on Purkinje reflections. The measurement is time-consuming and patients are reluctant to cooperate during image acquisition. Purkinje measurement does not detect anterior chamber depth (ACD) and as such cannot reveal the IOL position along the axis. Clinical Scheimpflug systems based on rotating Scheimpflug imaging, on the other hand, is able to acquire sufficient 3-dimensioinal data points within a reasonably short period, usually seconds. It was shown that these systems are one of the best methods to estimate IOL position. To better compare the intracapsular stability between single-piece and 3-piece IOLs, the investigators measured IOL positions with rotating Scheimpflug imaging systems and tested the visual quality of patients implanted with these IOLs.

Official Title
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Comparison of In-the-bag Stability Between Single-piece and Three-piece Intraocular Lens Via Scheimpflug Imaging System

Conditions
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Cataract

Intervention / Treatment
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* Procedure: Phacomulsification lens removal cataract surgery with single-piece Intraocular lens(IOL) implantation
* Procedure: Phacomulsification lens removal cataract surgery with three-piece Intraocular lens(IOL) implantation
* Drug: Subconjunctival dexamethasone
* Device: Viscoelastic materials
* Drug: proparacaine


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: diagnosis of bilateral age-related cataract and age between 60 to 85 years Exclusion Criteria: vision-impairing diseases other than cataract, severe refractive error (Preoperative spherical equivalent of either eye >-6.00D or +5.00D) history of ocular trauma, past refractive surgery or other ophthalmic surgery, capsular or zonular disorders that might affect the post-operative centration of IOLs surgical complications including severe hyphema, iris injury, repeated IOL implantation unable to achieve in-the-bag implantation of IOL, corneal sutures during surgery

Ages Eligible for Study
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Minimum Age: 60 Years
Maximum Age: 85 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: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Single-piece IOL Group<br>Age-related cataract patients receive in-the-bag implantation of a single-piece IOL | Procedure: Phacomulsification lens removal cataract surgery with single-piece Intraocular lens(IOL) implantation<br>* The phacoemulsification lens removal cataract surgery is performed with single-piece IOL.During Phacoemulsification.<br>Drug: Subconjunctival dexamethasone<br>* All patients received subconjunctival dexamethasone (2 mg) during surgery. Topical anesthesia, consisting of a single drop of 0.5% proparacaine (Alcaine, Alcon Laboratories), was administered three times at intervals of 5 minutes prior to surgery<br>Device: Viscoelastic materials<br>* viscoelastic materials are used to protect corneal endothelial cells<br>Drug: proparacaine<br>* 0.5% proparacaine (Alcaine, Alcon Laboratories)<br>|
| Experimental: Three-piece IOL Group<br>Age-related cataract patients receive in-the-bag implantation of a three-piece IOL | Procedure: Phacomulsification lens removal cataract surgery with three-piece Intraocular lens(IOL) implantation<br>* The phacoemulsification lens removal cataract surgery is performed with three-piece IOL.During Phacoemulsification.<br>Drug: Subconjunctival dexamethasone<br>* All patients received subconjunctival dexamethasone (2 mg) during surgery. Topical anesthesia, consisting of a single drop of 0.5% proparacaine (Alcaine, Alcon Laboratories), was administered three times at intervals of 5 minutes prior to surgery<br>Device: Viscoelastic materials<br>* viscoelastic materials are used to protect corneal endothelial cells<br>Drug: proparacaine<br>* 0.5% proparacaine (Alcaine, Alcon Laboratories)<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The grade of in-the-bag stability between single-piece intraocular lenses (IOLs) and three-piece intraocular lenses(IOLs) |  | 3 months after the surgery | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The visual acuity between single-piece intraocular lenses (IOLs) and three-piece intraocular lenses(IOLs) |  | 3 months after the surgery | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Intraocular lens