CO-MANAGEMENT
Refractive Surgery with the Crystalens IOL
This accommodative lens technology will impact your practice and presbyopic patients.
By Neil Martin, M.D., F.A.C.S., Chevy Chase, Md.

Refractive surgery has entered an exciting new era of intraocular lens (IOL) surgery that can correct presbyopia. Accommodating IOLs like the crysta-lens may help patients with and without cataracts see naturally and seamlessly from reading to computer to driving distance. These IOLs also generate many questions for the optometric patient. This article will explain the crystalens technology, discuss patient selection and introduce postoperative management.

No more "readers"

The advent of technology to cure presbyopia presents an enormous opportunity. Satisfying the presbyopic needs of the aging baby boomer population will be essential to the future success of our practices. The number of boomers over 50 will reach a high of 106 million by 2015. Boomers have had many of their rejuvenation needs met by such products as Viagra and Rogaine and by plastic surgery. Little reminds one of the pas

sage of time more than reading glasses, so boomers demand more than distance vision correction with LASIK. In addition, accommodative lens technology will benefit the senior on Medicare contemplating cataract surgery and seeking to maintain full function and vitality.

Understanding Crystalens

Crystalens is the first and only FDA-approved IOL for the treatment of presbyopia that focuses like the eye's natural lens, allowing for continuous near, intermediate and distance vision. The IOL is made of a solid silicone, Biosil. The lens has modified plate haptics with a biconvex optic. The lens is hinged adjacent to the optic and has small looped polyimide haptics. The overall length is 11.5mm. The lens is implanted with standard small incision techniques through a 3.5mm to 3.7mm incision.

How does It work?

The crystalens is designed for implantation in the capsular bag. The bag encapsulates and holds the lens in a posterior position against the vitreous face. The accommodative action of the crystalens is thought to depend upon the displacement of the vitreous mass anteriorly in response to the contraction of the ciliary muscle during accommodation. Optimal accommodative amplitude is achieved when the lens is well-centered in the capsule and the capsule is in its most posterior position in the non-accommodative state. By using the eye's muscle to move the lens backwards and forwards naturally in response to the brain's desire to see at different distances, crystalens enables the eye to focus continuously and seamlessly through near, intermediate and distance vision.

Other mechanisms have been suggested to explain the accommodative effect of the crystalens. Forward displacement of the ciliary body during accommodation may move the lens forward, increasing its effective power and providing accommodation. In addition, flexion of the optic appears on wave scan studies to provide an accommodative effect.

A unique IOL

With bilateral implantation of the crystalens, some of the disadvantages with multifocal lenses or standard monovision are avoided. In some studies, crystalens has a similar incidence of glare and halos as traditional IOLs and a somewhat greater incidence in other comparisons. However, my patients have found these symptoms to be minor and to improve over time. A particular strength of the full vision crystalens: it appears better than pseudo-accommodative IOLs at intermediate vision. The crystalens directly utilizes the ciliary muscle to adjust for all distances, especially intermediate.

Rejuvenation of intermediate vision is of paramount importance as many daily activities rely on intermediate vision: computer use, cell phones, PDAs, shopping.

Crystalens long-term data demonstrates efficacy over a three-year period. Bilateral uncorrected distance vision at one and three years demonstrates a significant improvement in visual acuity. Over 90% of patients are seeing 20/25 or better without correction and these outcomes appear to be consistent over the three-year analysis of the data. With both eyes implanted, over 70% of patients see J1 or better and over 98% see J3 or better. Intermediate vision through the distance correction is excellent in binocular patients with 100% of patients seeing J1 or better at 3 years.

Patient selection

Crystalens is approved for presbyopia correction in patients with cataracts, although the lens may be used off-label in patients without cataracts who seek correction of their distance vision and presbyopia. It is important to choose the right lens and the right patient. The best patient is about 50 years old or older, has normal eyes (other than the cataract) and has realistic expectations. The hyperopic presbyope from +1.00 or more is the "sweet spot" for crystalens. The lens can correct most patients with preoperative refractions of -10.00 to +7.00 diopters. Exhibit caution with emmetropes and low myopes as they provide a very small target for success. Corneal cylinder of one or more diopters must be corrected for

good visual results using astigmatic keratotomy (limbal relaxing incisions) or LASIK. Patients with previous RK or LASIK may require enhancement because of the effect of refractive surgery on IOL power predictability. Patients whose correction is beyond the powers available for the crystalens may be further corrected by LASIK, PRK or a piggy-back IOL.

Crystalens surgery does not appear to have the same concern for potential exacerbation of dry eye as LASIK because crystalens surgery does not require a corneal flap and does not steepen the cornea as does hyperopic LASIK.

In-depth patient consent is required for adequate patient understanding of the benefits, risks and alternatives when considering the crystalens. Excellent patient education materials are available from Eyeonics, the maker of the crystalens. In addition, patient education materials and DVDs are available from Patient Education Concepts and may be made available through the co-managing surgeon. Elab

orate consent forms have been developed to document the doctor's and surgeon's patient education process and the patient's understanding. It is wise to avoid patients who are demanding immediate perfect vision and are not willing to accept the concept that near vision improves over time. IOL exchange, piggy back IOLs or LASIK may be required to give optimal results. Some patients will benefit from postoperative vision rehabilitation and accommodative training that includes challenging one's vision incrementally over time.

There are some patients who would be better suited to other types of IOLs. Crystalens is not appropriate for patients with active disease such as uveitis or diabetic retinopathy, certain retinal diseases, unrealistic expectations, poor visual potential, amblyopia or large pupils (>7 mm or so). Glaucoma patients should be avoided if a filter procedure may be part of their future management.

Patients must understand that although crystalens has the same safety as traditional cataract surgery, it possesses the same risks. An eye can be lost from complications such as infection, hemorrhage or retinal detachment, although the risks may be very low. Understanding risks is especially important for the refractive lens exchange patient. Crystalens patients should understand that they will still need eyeglasses, although they will hopefully find that the eyeglasses usually stay in their pockets.

Diagnosis and pre-op

There is no standard visual acuity for when cataract surgery is indicated. Cataract surgery may be indicated when the patient's vision is not adequate for his visual needs. The referring optometrist needs to be certain that the cataract explains the patient's vision loss and certain that corneal, retinal or optic nerve pathology do not contribute to the vision loss. When cataract is diagnosed and cataract surgery is indicated, the patient is given options regarding IOLs.

Preoperative evaluation for the crystalens includes uncorrected and best corrected distance and near vision, monocularly and binocularly. Careful manual keratometry may be more accurate than automated keratometry and is used for IOL power calculation. Astigmatism must also be assessed with automated topography and pachymetry obtained in case limbal relaxing incisions or future LASIK is needed. Biometry is performed with either or both immersion A-Scan and IOL Master. Contact biometry may give erroneously short results and is not recommended. If measurements are not consistent, the patient may need to return for repeat scans or keratometry. If the patient has a contact lens history, preoperative corneal rehabilitation may be needed.

Eye dominance is recorded as the surgeon prefers to operate on the non-dominant eye first, pending degree of cataract. The refractive outcome of the first eye aids in selection of the IOL power for the second eye. Planned visual outcome targets emmetropia and adjustments must be made for biological variation as evidenced by the results of the first eye.

The full potential of the crystalens can only be achieved if all of the accommodative effect can be applied to intermediate and near vision. Post-operative hyperopia should be avoided because residual hyperopia will decrease accommodative amplitude by the amount of accommodation being used to correct distance vision.

Scotopic pupil size is recorded and large pupils disallow many patients from being crystalens candidates. Pupil size of greater than 7.0mm may make a patient a better candidate for other lens technologies or at least necessitate additional verbal and written consent concerning risks of glare and night vision. All evaluations and counseling must be in context with the patients' vocational needs. The doctor should exercise caution in suggesting surgery to engineers and obsessive-compulsive personalities.

Crystalens Surgery

Crystalens surgery is demanding and requires subtle modifications of a standard phacoemulsi fication technique. A water-tight incision is made to maintain proper IOL position. Scleral-tunnel or sutured clear-corneal incisions are recommended. The preferred rhexis is circular and generally 5.5mm. Immaculate cortical cleanup is essential as capsule fibrosis may affect posterior vaulting of the lens. Most breaks in the posterior capsule and radial capsular tears will prevent crystalens from being used and the patient needs to be aware of this possibility preoperatively. Surgical technique must be of the highest quality to meet patient expectations.

The ophthalmologist will examine the patient immediately following surgery to make sure the lens is well-centered, the haptic plates are covered by the anterior leaflet of capsule, and the optic is vaulted in the posterior position. Atropine 1% will be instilled in the OR and in recovery to ensure the ciliary body is at rest, and help maintain the optic in proper position in the capsular bag.

Postoperative Follow-Up

The optometrist's role pre- and post-op is crucial in positive patient outcomes. Patients should be instructed not to touch or rub the eye and use an eye shield when sleeping. Cyclopentolate 1% is used four times a day for 10 to 14 days to aid in proper crystalens positioning. Prednisolone acetate 1% is used four times a day for about a month and slowly tapered. A fluorquinolone antibiotic is usually used for five to seven days postoperatively. Like their retino-vitreous colleagues, most accommodative lens surgeons will probably not return the patient to his eye doctor immediately because of the multitude of healing changes that may affect outcome and will follow the patient closely during this post operative time. Patient management must be fine tuned to meet high expectations.

Lens position, vaulting, capsule reaction and refractive outcomes will be assessed. If the patient's uncorrected vision is below expectation an early response may be needed with modification of medical regimen or a surgical procedure including YAG laser, IOL exchange, or repositioning of IOL haptics. If the patient requires an IOL exchange or repositioning, these procedures must be accom-plished by the first three to four weeks after surgery.

Myopic regression after the first two weeks may require a repeat course of cycloplegia. Capsule contraction is closely followed as it affects lens position which changes refraction causing myopia and possibly astigmatism. Capsule contraction or opacity may require early and timely YAG laser intervention is some cases. Topical steroids are often prolonged to two to three months to limit capsule reaction. Slit lamp exams and IOP are closely followed.

Crystalens has unique features of capsule response that can significantly affect refraction at three to even six months postoperatively. Many optometrists may prefer to wait until three months postoperatively before assuming care of their patient.

The optometrist should evaluate the patient's reading ability in a lighted room. Slit lamp examinations require observations and judgments unique to the crystalens. Distance, intermediate and reading vision are usually very good.

There may be an individual response initially to near vision. Measuring accommodative amplitude is always accomplished through the distance correction. For patients awaiting the second eye, remind them that the crystalens functions better as a "matched set" since accommodation is a consensual response.

It is not recommended to automatically offer readers, but rather challenge the patient to increase their reading ability by reading smaller and smaller print without assistance. One practice uses a formalized system comprised of six workbooks to be used over 12 weeks. Each workbook uses smaller print providing an entertaining accommo- dative exercise. If eyeglasses are offered, they typically only need a +1.0 add, and this should be reduced incrementally over time. The optometrist's refraction, accommodation exercise and supportive skills are key.

Generally the covered postoperative period for crystalens is 90 days. Some optometrists may prefer to start postoperative care, accommodative exercises (if necessary), refraction and spectacle dispensation at this point in time where they can charge for their services.

Accommodating cost

The crystalens accommodative lens is a premium technology that provides an unparalleled level of visual functioning and rejuvenation value for the patient. The average cost is about $ 5,000 per eye including surgeons and anesthesiologist's fees, the eye surgery center, the cost of the lens, post operative follow-up and early postoperative additional surgeries, such as lens exchange or LASIK. The cost of clear lens extraction would be out of pocket for the patient. When a cataract is present, insurance usually covers slightly less than half of the cost. Defined benefit plans and financing may make the surgery more affordable.

Conclusions

Becoming familiar with new technology is a necessity. The final outcome is dependent on obsessive accuracy in preoperative measurements, flawless surgery and attentive postoperative care with timely intervention. Careful post-op refraction, accommodation work and moral support are indispensable adjuncts to a happy outcome. Building a good network with ODs and MDs in a cooperative and mutually supportive environment leads to success for both healthcare provider and patient.