Clinical trial NCT02609997: Comparison of In-the-bag Stability Between Single-piece and Three-piece Intraocular Lens
Official title: Comparison of In-the-bag Stability Between Single-piece and Three-piece Intraocular Lens Via Scheimpflug Imaging System
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: NA
Conditions: Cataract
Keywords: Intraocular lens
Lead sponsor: Sun Yat-sen University
Sponsor class: OTHER
First posted: 2015-11-20
Enrollment: 65
Sex: ALL
Minimum age (years): 60
Maximum age (years): 85
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: no
Allocation: RANDOMIZED
Intervention model: PARALLEL
Primary purpose: TREATMENT

Brief summary: 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: 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.

Eligibility criteria: 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

Primary outcomes:
measure: The grade of in-the-bag stability between single-piece intraocular lenses (IOLs) and three-piece intraocular lenses(IOLs)
timeFrame: 3 months after the surgery
Secondary outcomes:
measure: The visual acuity between single-piece intraocular lenses (IOLs) and three-piece intraocular lenses(IOLs)
timeFrame: 3 months after the surgery
Other outcomes:
Locations:
city: Guangzhou
country: China
facility: Zhognshan Ophthalmic Center, Sun Yat-sen University
state: Guangdong
Study officials:
affiliation: Zhongshan Ophthalmic Center, Sun Yat-sen University
name: Haotian Lin, M.D., Ph.D
role: PRINCIPAL_INVESTIGATOR
affiliation: Zhongshan Ophthalmic Center, Sun Yat-sen University
name: Yizhi Liu, M.D., Ph.D
role: STUDY_CHAIR
affiliation: Zhongshan Ophthalmic Center, Sun Yat-sen University
name: Weirong Chen, M.D.
role: STUDY_DIRECTOR
References:
citation: Korynta J, Bok J, Cendelin J. Changes in refraction induced by change in intraocular lens position. J Refract Corneal Surg. 1994 Sep-Oct;10(5):556-64.
citation: Wang L, Koch DD. Effect of decentration of wavefront-corrected intraocular lenses on the higher-order aberrations of the eye. Arch Ophthalmol. 2005 Sep;123(9):1226-30. doi: 10.1001/archopht.123.9.1226.
citation: Rosales P, Marcos S. Phakometry and lens tilt and decentration using a custom-developed Purkinje imaging apparatus: validation and measurements. J Opt Soc Am A Opt Image Sci Vis. 2006 Mar;23(3):509-20. doi: 10.1364/josaa.23.000509.
citation: de Castro A, Rosales P, Marcos S. Tilt and decentration of intraocular lenses in vivo from Purkinje and Scheimpflug imaging. Validation study. J Cataract Refract Surg. 2007 Mar;33(3):418-29. doi: 10.1016/j.jcrs.2006.10.054.
citation: Zhong X, Long E, Chen W, Xiang W, Liu Z, Chen H, Chen J, Lin Z, Lin H, Chen W. Comparisons of the in-the-bag stabilities of single-piece and three-piece intraocular lenses for age-related cataract patients: a randomized controlled trial. BMC Ophthalmol. 2016 Jul 8;16:100. doi: 10.1186/s12886-016-0283-4.