Crystalens AO IOL Indications and Safety Information
INDICATIONS FOR USE
The Crystalens accommodating posterior chamber intraocular lens (IOL) is intended for primary implantation in the capsular bag of the eye for the visual correction of aphakia secondary to the removal of a cataractous lens in adult patients with and without presbyopia. Crystalens provides approximately one diopter of monocular accommodation which allows for near, intermediate, and distance vision without spectacles.
- Some patients may still require glasses to perform certain tasks.
- There is no clinical data to support placing this lens in the ciliary sulcus.
- The safety and effectiveness of this lens have not been evaluated in patients under 50 years of age.
- The effect of vitrectomy on accommodation is unknown.
- Small amounts of lens decentration occurring with an IOL having a narrow or small optic (<5.5 mm) may cause glare or other visual disturbances under certain lighting conditions. Surgeons should consider this potential complication before implanting an IOL with a small or narrow optic. This lens incorporates a 5.0 mm optic.
- YAG-laser posterior capsulotomies should be delayed until at least 12 weeks after the implant surgery. The posterior capsulotomy opening should be limited to no more than 4 mm. Consistent with other IOLs, there is an increased risk of lens dislocation and/or secondary surgical re-intervention with early or large YAG capsulotomies.
- Crystalens should not be implanted if the capsular bag is not intact or if there is any zonular rupture.
- The safety and effectiveness of the device has not been established in patients with the following ocular conditions:
- Chronic drug miosis
- Diabetic retinopathy
- Previous corneal transplant
- History of retinal detachment
- Congenital bilateral cataracts
- Recurrent anterior or posterior segment inflammation of unknown etiology, or any disease producing an inflammatory reaction in the eye
- Patients in whom the intraocular lens may interfere with the ability to observe, diagnose or treat posterior segment diseases
- Surgical difficulties at the time of intraocular lens implantation which might increase the potential for complications (e.g., persistent bleeding, significant vitreous prolapse or loss)
- Corneal endothelial dystrophy
- Pseudoexfoliation syndrome
- Suspected microbial infection
- Surgeons considering lens implantation in such patients should explore the potential risk/benefit ratio.
- Mechanical hinge testing has been evaluated in a laboratory setting. Hinge movements of 1,000,000 cycles at 10 cycles per second have been documented with no degradation of hinge integrity or stability. However, long-term stability in the human eye has not been established. Therefore, surgeons should continue to monitor implant patients postoperatively on a regular basis.
- The effectiveness of ultraviolet light absorbing lenses in reducing the incidence of retinal disorders has not been established.
- The rate of cystoid macular edema may increase with sulcus-bag placement of the haptics.
- Do not implant this lens in the anterior chamber or sulcus.
- Unlike most other IOLs, the Crystalens AO IOL optic has hinges connecting it to the haptic. There are adverse events in which the optic becomes stuck in an anterior, posterior, and/or tilted (asymmetric) or decentered position and the hinges become fixed in a displaced configuration. These events are referred to as cases of “lens vault” or “vaulting” and typically cause blurry vision and unexpected myopia, hyperopia, and/or astigmatism, and possibly higher order aberrations. When vaulting occurs, secondary surgery is often required to restore the correct optic position or sometimes to remove the lens. The following are important considerations:
- Vaulting is sometimes associated with excessive postoperative capsular fibrosis. Consider surgical techniques and medication to minimize this inflammation and implementing an appropriate follow-up schedule to detect early signs of excessive capsular fibrosis.
- Ensure proper IOL placement through rotation and visual inspection.
- A wound leak could cause anterior vaulting of the optic. Therefore a scleral tunnel or long multiplane limbal/corneal incision is recommended with long narrow paracenteses. Ensure all incisions are watertight and do not leak.
- During surgery, the optic should be vaulted backward to a position corresponding to the normal location of the posterior capsule. Attempts to position the lens further posteriorly by hyper-inflating the globe with BSS could lead to posterior vaulting and hyperopic outcomes, and should be avoided.
- Asymmetric and excessive fibrosis of the capsule may be associated with asymmetric vaulting. Contributing factors may include decentration or tear of the anterior or posterior capsule, or ruptured zonules. If any of these are present before lens implantation, do not implant the Crystalens IOL.
- Do not resterilize this intraocular lens by any method.
- Do not store lenses at temperatures over 45°C (113°F).
- In cases where patients are monocular or have much poorer acuity in the fellow eye, they should exercise extreme caution if this happens in potentially hazardous situations (such as driving). If the patient experiences blurred vision, they should contact their physician promptly, as this may indicate a problem with lens positioning.
The incidence of adverse events experienced during the clinical trial was comparable to or lower than the incidence reported in the historic control (“FDA grid”) population. As with any surgical procedure, risk is involved. Potential adverse events accompanying cataract or implant surgery may include, but are not limited to, the following: lens subluxation, corneal endothelial damage, non-pigment precipitates, cystoid macular edema, infection, retinal detachment, vitreous loss, pupillary block, secondary glaucoma, iris prolapse, vitreous-wick syndrome, uveitis, and pupillary membrane.
Vaulting is a post-operative adverse event where the Crystalens AO IOL lens optic hinges move into and remain in a displaced configuration. Vaulting events occurred at a rate of 0.3% (1 events / 324 subjects) in the clinical study conducted for the original Crystalens IOL (Model AT-45), and at a rate of 0.9% (2 events / 227 subjects; both arms combined) in the clinical study conducted for the Trulign Toric IOL (a modification having the same hinged haptic design; Model AT50T). The optic may be displaced anteriorly, posteriorly, or tilted / decentered. Vaulting takes three forms: anterior vault (both hinges are displaced anteriorly), posterior vault (both hinges are displaced posteriorly), and asymmetric vault (z-syndrome) (one hinge is displaced anteriorly and one hinge is displaced posteriorly).
- Vaulting typically presents with blurry vision, which may either gradual or acute in onset.
- Blurry vision after cataract surgery may be due to various other conditions and patients are advised to contact their surgeons if they notice a change in vision.
Diagnosis of vault is based on the IOL configuration, which can be visualized with a slit lamp.
- Anterior vault – both hinges and optic are displaced anteriorly, away from the posterior capsule.
- Posterior vault – both hinges and optic are displaced posteriorly, causing excessive posterior bowing of the posterior capsule.
- Asymmetric vault – one hinge is displaced anteriorly and one is displaced posteriorly, causing the optic to tilt.
Additional clinical findings that support the diagnosis of vault include:
- Excessive capsular contraction – fibrotic bands, striae, and opacification visualized at slit lamp
- Changes in refractive error – measured through manual or automatic refraction
- Anterior vault – optic is displaced anteriorly, resulting in myopic shift
- Posterior vault – optic is displaced posteriorly, resulting in hyperopic shift
- Asymmetric vault – optic is tilted, resulting in astigmatism along the axis of the tilt
Slit lamp photographic images of as asymmetric vault are included in the Directions for Use (DFU).
Definitive causes of vaulting have not been established. Factors that have been suggested as potentially contributing to vaulting include the following:
- Asymmetric anterior capsulotomy – The Crystalens AO IOL is symmetric and the lens optic is intended to rest in the center of the capsular bag post-implantation. Asymmetric capsulotomy may result in asymmetric amount of capsular contact with the IOL which, during post-operative capsular contraction, may lead to asymmetric forces acting upon the IOL hinges.
- Incomplete removal of lens material – Extensive medical literature has established that residual lens material can incite an exuberant post-operative inflammatory reaction. Post-operative inflammation can precipitate excessive capsular fibrosis, which may lead to excessive capsular contractile forces acting upon the IOL hinges.
- Capsular defect – A defect in the capsule will result in asymmetric capsular support for the IOL and possibly decentration or tilt of the IOL. During post-operative capsular fibrosis, these factors may lead to asymmetric contractile forces acting upon the IOL hinges and worsening of decentration / tilt.
- Zonular defect – Zonules provide support and balance for the capsular bag / IOL. Loss of zonular support can lead to decentration or tilt of the capsular bag and asymmetric forces acting upon the IOL hinges.
- Incorrect IOL placement – Examples of incorrect placed include: IOL haptic footplates not evenly placed around the capsular equator, one or more haptic footplates placed in the sulcus instead of the capsular bag, IOL placed in an upside-down configuration. Each of these scenarios may cause the IOL to move in as asymmetric manner or the hinges to remain “stuck” in a flexed configuration.
- Wound leak – Wound leak allows fluid to egress from the anterior chamber to the external corneal surface, resulting in low and fluctuating levels of anterior chamber stability. Low anterior chamber pressure relative to posterior vitreous pressure may push the IOL optic anteriorly, resulting in anterior vault.
- Excessive postoperative inflammation and excessive capsular fibrosis – Persistent postoperative inflammation is associated with excessive capsular fibrosis. Capsular fibrosis may cause contractile forces to act upon the IOL hinges.
If any of the vaulting risk factors are present before lens implantation, do not implant the Crystalens AO IOL.
Potential Sequelae of Vaulting:
- Vaulting commonly induces refractive error (e.g. myopia, hyperopia or astigmatism) which may be reversible if the Crystalens AO IOL can be restored to its normal position.
- Vaulting commonly presents as blurry vision, which can be either gradual or acute in onset. Vaulting may be reversible by restoring the IOL to its normal position, which may require surgery.
- The treatment for vaulting may require secondary surgical intervention.
Physicians should consider the characteristics of each individual vaulting case prior to determining the appropriate treatment. Data on long-term follow-up after treatment of vaulting is not available.
ATTENTION: Refer to the Directions for Use labeling for a complete listing of indications, warnings and precautions, clinical trial information, etc.
CAUTION: Federal (USA) law restricts this device to the sale by or on the order of a physician.