Presbyopia-Correcting Intraocular Lenses: A Vitreoretinal Perspective

STEPHEN G. SCHWARTZ, MD, MBA · HARRY W. FLYNN, JR., MD (PART 1)
RICHARD M. AWDEH, MD · TERRENCE P. O'BRIEN, MD (PART 2)

To cope with the accelerated pace of medical research and innovation in modern times, physicians have turned to ever-greater subspecialization — carving out smaller and smaller niches, even within subspecialties like retina. This keeps a busy medical practitioner from being overwhelmed with data and allows the physician to develop encyclopedic knowledge of a rather narrow skill set, but could deprive him or her of the benefits to be had from like-minded experts in complementary fields.

Because the retina community is just as susceptible to this as any other subspecialty group, this month we begin an occasional series that invites experts from beyond retina to share their expertise with our readers on a topic that affects both disciplines. Anterior-segment specialists will no doubt figure prominently, but future installments could potentially include experts wholly beyond ophthalmology, such as oncologists, endocrinologists or geneticists.

This month we begin with a discussion of premium intraocular lenses, and have invited several distinguished ophthalmologists from Bascom Palmer Eye Institute in Miami to participate.

This two-part feature begins with retinal specialists Stephen Schwartz, MD, and Harry Flynn, MD, providing commentary about potential visual disturbances in premium IOL patients and the challenges of performing vitrectomy procedures in this population, should the need arise. In part 2, cataract surgeons Richard Awdeh, MD, and Terrence O'Brien, MD, discuss patient expectations and the factors influencing satisfaction with surgical outcomes, then provide many practical "pearls" that can help ensure success.

Readers who have suggestions for future topics are invited to contact the publication at the address below. We welcome your ideas and feedback.

— Jack Persico, Executive Editor
jack.persico@wolterskluwer.com

PART 1 ~ Posterior segment commentary by Stephen G. Schwartz, MD, MBA and Harry W. Flynn, Jr., MD:

Presbyopia-correcting, or "premium" intraocular lenses (IOLs), are gaining in popularity among ophthalmologists and the general public. These include the accommodating Crystalens (Bausch & Lomb) and the multifocals ReStor (Alcon), ReZoom (Abbott Medical Optics, AMO) and Tecnis (AMO) lenses. These lenses offer important benefits to many patients, although they are associated with several disadvantages. From a retinal perspective, these disadvantages primarily manifest as patient dissatisfaction and various technical challenges during subsequent vitreoretinal surgery.

PATIENT DISSATISFACTION

Visual sensations, such as starbursts and halos, are reported by patients receiving multifocal IOLs, and the degree to which these sensations are tolerated is highly variable.¹ In addition, contrast sensitivity may be decreased in patients implanted with multifocal IOLs.² Some of these patients are so symptomatic that they seek additional ophthalmologic consultation, resulting in additional diagnostic testing and increased healthcare expenditures. These IOLs may also be associated with substantial out-of-pocket costs to the patient, which may exacerbate dissatisfaction.

Patients with macular diseases have impaired contrast sensitivity and may be particularly dissatisfied with the visual quality following implantation of a presbyopia-correcting IOL. Macular disease has been suggested as a relative contraindication to premium IOL implantation,³ but the incidence of many maculopathies increases with age. For example, the prevalence of age-related macular degeneration increases from 0.2% in patients aged 55-64 to 13% in patients aged over 85.⁴ Therefore, many patients who are initially satisfied with their premium IOLs may become less so as they age.

SURGICAL CHALLENGES

Pars plana vitrectomy (PPV) in a patient with a presbyopia-correcting IOL is associated with several specific challenges.⁵ These may be subdivided into factors which may make the surgical procedure more technically difficult, and factors which may impair the quality of the vision following surgery.

During vitrectomy, the concentric, differing optical zones of multifocal IOLs can interfere with the surgeon's visualization in several ways. For example, distorted visualization of intravitreal triamcinolone acetonide (used to assist visualization of cortical vitreous) has been reported, and visualization of peripheral retina may be easier around the optic than through it.⁶ During membrane peeling, visualization of fine details on the retinal surface may be relatively more difficult in an eye with a multifocal IOL. In addition, the Crystalens is a silicone IOL, and is associated with disadvantages of other silicone IOLs during PPV, such as adherence to silicone oil⁷ and (in the case of an open posterior capsule) visually significant moisture condensation on the posterior surface of the IOL during fluid-air exchange.⁸

Even following successful pars plana vitrectomy, the patient's quality of vision may be impaired in several ways. PPV may cause subtle displacement of the IOL, such as during fluid-air exchange. A small amount of lens displacement is typically asymptomatic for a patient with a monofocal IOL, but may cause visual disturbance in a patient with a presbyopia-correcting IOL. Lateral displacement (decentration) is of more concern with the ReStor and ReZoom lenses, which feature multiple concentric zones of different optical powers. Decentration of a multifocal IOL by more than 1 mm may cause significant loss of contrast sensitivity.⁹ Axial displacement (vaulting) of the IOL is of particular concern with the Crystalens, which functions by moving along the anteroposterior axis, and may tilt spontaneously (Z syndrome).¹⁰ Furthermore, the refractive state may be altered by vitreoretinal surgery. Although scleral buckling is well known to cause refractive changes (generally induced myopia),¹¹ PPV has been reported to induce corneal astigmatism secondary to the sclerotomy sutures.¹²

Figure 1. Slit-lamp photograph of a ReStor lens.

Figure 2. Slit-lamp photograph of a silicone presbyopia-correcting IOL with adherent silicone oil droplets.

RECOMMENDATIONS FROM A VITREORETINAL PERSPECTIVE

With these considerations in mind, several potential recommendations emerge. First, presbyopia-correcting IOLs should be used with caution in patients judged to be at increased risk for the situations described above. These higher-risk categories include patients with significant risk factors for age-related macular degeneration, retinal detachment, and other diseases requiring vitreoretinal surgery.

Second, when faced with a patient complaining of visual loss following implantation of a premium IOL, the optical qualities of the lens should be considered. Although anatomic abnormalities (such as lens decentration, posterior capsular opacification, and cystoid macular edema) should be sought, it should be recognized that a small but vocal minority of patients receiving these lenses will be dissatisfied with the outcome despite a technically perfect implantation.

Third, the surgeon considering performing vitreoretinal surgery on a patient with a presbyopia-correcting IOL should be prepared for specific challenges related to intraoperative visualization, and the patient should be specifically counseled about possible post-operative visual disturbance secondary to IOL malposition or refractive change. RP

REFERENCES

1. Hunkeler JD, Coffman TM, Paugh J, et al. Characterization of visual phenomena with the Array multifocal intraocular lens. J Cataract Refract Surg. 2002;28:1195-204.
2. Leyland M, Pringle E. Multifocal versus monofocal intraocular lenses after cataract extraction. Cochrane Database Syst Rev. 2006;Oct 18;(4):CD003169.
3. Buznego C, Trattler WB. Presbyopia-correcting intraocular lenses. Curr Opin Ophthalmol. 2009;20:13-18.
4. Smith W, Assink J, Klein R, et al. Risk factors for age-related macular degeneration: pooled findings from three continents. Ophthalmology. 2001;108:697-704.
5. Tewari A, Shah GK. Presbyopia-correcting intraocular lenses: what retinal surgeons should know. Retina. 2008;28:535-7.
6. Kawamura R, Inoue M, Shinoda K, Bissen-Miyajima H. Intraoperative findings during vitreous surgery after implanation of diffractive multifocal intraocular lens. J Cat Refract Surg. 2008;34:1048-9.
7. Kusaka S, Kodama T, Ohashi Y. Condensation of silicone oil on the posterior surface of a silicone intraocular lens during vitrectomy. Am J Ophthalmol. 1996;121:574-5.
8. Eaton AM, Jaffe GJ, McCuen BW 2nd, Mincey GJ. Condensation on the posterior surface of silicone intraocular lenses during fluid-air exchange. Ophthalmology. 1995;102:733-6.
9. Negishi K, Ohnuma K, Ikeda T, Noda T. Visual simulation of retinal images through a decentered monofocal and a refractive multifocal intraocular lens. Jpn J Ophthalmol. 2005;49:281-6.
10. Yuen L, Trattler W, Boxer Wachler BS. Two cases of Z syndrome with the Crystalens after uneventful cataract surgery. J Cat Refract Surg. 2008;34:1986-9.
11. Randleman JB, Hewitt SM, Stulting RD. Refractive changes after posterior segment surgery. Ophthalmol Clin North Am. 2004;17:521-6.
12. Slusher MM, Ford JG, Busbee B. Clinically significant corneal astigmatism and pars plana vitrectomy. Ophthalmic Surg Lasers. 2002;33:5-8.

PART 2 ~ Anterior segment commentary by Richard M. Awdeh, MD, and Terrence P. O'Brien, MD:

A strong desire to improve quality and quantity of vision while reducing or eliminating dependency on glasses has become an increasing attribute among patients with cataract. Over the past few years, improvements in cataract technologies, including an expanding array of refractive intraocular lens designs, has resulted in advanced cataract surgical techniques that merge refractive surgery with cataract surgery. Such "premium" cataract surgery has gained popularity amongst both anterior segment surgeons and the general public. "Premium" intraocular lenses currently include presbyopia-correcting intraocular lenses and astigmatic correcting intraocular lenses.

Currently, there are two broad categories of lenses within the presbyopia-correcting category that have gained FDA approval: (1) Multifocal lenses, which currently includes the ReStor (Alcon), ReZoom (Abbott Medical Optics), and Tecnis Multifocal (Abbott Medical Optics) lenses and (2) Accommodative lenses, which currently includes the Crystalens and Crystalens HD (Bausch & Lomb). There are several other lenses currently in trials, such as the accommodating dual-optic Synchrony IOL (Visiogen). Astigmatic-correcting intraocular lenses currently include the toric IOLs (Alcon; Staar Surgical).

While these refractive intraocular lenses represent a large advancement in technology in the anterior segment arena, there are several important notes to bear in mind when managing cataract patients considering these designs. We have noted that a small but significantly vocal minority of these patients have been very dissatisified post-operatively with outcome; however, these are patients who have been the targets of direct advertising campaigns from the lens manufacturers, practice managers, and eye care providers. Additionally, these are patients who have paid extra money out-of-pocket for a perceived "premium" experience and "premium" results.

Thus, the expectations of patients undergoing "premium" cataract surgery are somewhat different from those undergoing traditional monofocal intraocular lens implantation and highly different from those patients typically seen by a retinologist. In fact, the expectations are sometimes even in excess of those from a younger demographic seeking laser vision correction.

Below we share some pearls that we have appreciated in managing cataract patients seeking a refractive IOL and "premium" experience with cataract surgery.

PATIENT SATISFACTION

Patient satisfaction in this category is highly correlated with two factors: (1) thorough, comprehensive pre-operative counseling and (2) appropriate patient selection. Thorough pre-operative counseling involves listening to the patient's goals, understanding the patient's work-related activities and hobbies, including their ideal distance for near work. This stratification along with an extensive knowledge of the available technology and their limitations allows the anterior segment surgeon to select the most appropriate lens.

We have found that an honest conversation with the each patient regarding the advantages and limitations of the current refractive IOL technology may be time consuming, but is very important in ultimate patient satisfaction. The issues of decreased contrast sensitivity, decreased light to the retina, and a very defined range for near-work have all been raised with the multifocal intraocular lenses and stem from the design of these lenses which allows them to focus light rays onto two different focal points, therefore creating two images in the eye, one from near and one from distance.

Factor two, patient selection, involves a thorough ophthalmic history and examination. Eliciting a history of amblyopia or prior strabismus surgery, prior ophthalmic trauma, neuro-ophthalmic disease, and inflammatory and infectious diseases of the retina are necessary in screening these patients. We advise extensive testing in these patients to both assess disease as well as to document ophthalmic conditions prior to surgery. Topographic analysis of the cornea to assess for irregular astigmatism and high-resolution optical coherence tomography of the posterior pole should be pursued in the pre-operative evaluation of these patients.

Figure 1. Image from a dissatisfied patient who had a Crystalens accommodating implant and then a YAG laser posterior capsulotomy (note pits) for early PCO.

Figure 2. With an open capsule after YAG laser, the same patient remained dissatisfied and underwent an IOL exchange, cutting the hinges of the Crystalens and resting a Monofocal Aspheric IOL on the residual IOL fragment within the capsular bag. Due to weakened zonular support, the entire Crystalens implant could not be explanted, necessitating cutting out the optic at the hinges.

IOL AS PART OF AN OPTICAL SYSTEM

Cataract surgery with insertion of a traditional monofocal IOL is somewhat more "forgiving" in that the lens is a uniform structure and spatial variation across the lens occurs on a very large scale (millimeters), thus rendering the lens insensitive to minute aberrations in other parts of the visual system (as noted by Ming Wang, MD, PhD). Presbyopia-correcting IOLs, on the other hand, require proper centration in the capsular bag and are more sensitive to posterior capsular opacification. Additionally, these IOLs are more sensitive to aberrations elsewhere in the optical system. Irregular corneal astigmatism, anterior chamber depth, and posterior pole pathology (specifically epiretinal membrane/macular pucker) can all contribute to suboptimal final visual acuity.

SURGICAL CHALLENGES

Particular attention to the creation of a centered capsulorhexis, as well as an appropriately-sized capsulorhexis (ie, 6.0 mm for the Crystalens) is required when inserting these IOLs. Some surgeons prefer slightly off-centering the IOL in the nasal direction in order to ensure that the center of the IOL is aligned with the center of the visual axis. However, even when particular attention is paid to proper capsulorhexis creation and patient selection, dissatisfied post-operative patients are seen and can present a management dilemma to both the anterior segment surgeon and retina specialist.

Some of these patients may require an IOL exchange, and an elevated level of technical expertise is required as the dual optic and accommodative IOLs can be difficult to remove from the capsular bag. Additionally, a large number of patients with presbyopia-correcting IOLs will have undergone laser capsulotomy of the posterior capsule, as these lenses are more sensitive to trace amounts of posterior capsular opacification, making IOL exchange even more difficult. A recent study by our group demonstrates good best-corrected visual acuity following IOL exchange in dissatisfied premium IOL patients.

RECOMMENDATIONS FROM AN ANTERIOR-SEGMENT PERSPECTIVE

For anterior segment surgeons, it is recommended to heed the following suggestions:

• Avoid excessive promotion or "selling" of refractive IOLs to reduce excessively high patient expectations. Talk with the patient. Get to know the patient in terms of their particular personality, desires and expectations up front.

• Don't just select a single type of refractive IOL as a "one size fits all" because of familiarity with a particular IOL design or insertion method. Customize the selection based on as much objective as well as subjective pre-operative data.

• Educate pre-operatively with as much information to ensure an informed patient and informed choice for the operative plan. Be prepared to say "no" to an individual with excessively high or unrealistic expectations. Just because their neighbor may have had a particular refractive IOL that "worked great" doesn't meant that design is necessarily fit for them.

• Screen for subtle macular pathology with high resolution optical coherence tomography. Have a low threshold for consultation with a retinal specialist pre-operatively, especially if the media opacity doesn't quite match the visual acuity.

• Manage the ocular surface in advance of the procedure.

• Develop a comfortable plan for addressing astigmatism with an aggressive approach.

• Strive for perfection with surgical techniques including aggressive cortical clean-up and polishing of the posterior capsule.

• Have a back-up plan for intraoperative complications, including an eccentric or incomplete capsulorhexis, discission of the posterior capsule or vitreous loss.

• Plan for additional chair time with these refractive IOL patients in the early post-operative period.

• Look for tear film and ocular surface abnormalities and treat aggressively. Avoid excessive preservative-containing medications.

• Consider laser vision correction for significant residual ametropia, especially residual astigmatism.

• Assess the posterior capsule clarity and be prepared for possible earlier YAG laser capsulotomy given earlier opacification. Defer if the patient is complaining significantly or if there is a possibility of need for an intraocular lens exchange.

• Identify patients at risk for development of cystoid macular edema and treat pre-emptively prior to and for an extended period after the procedure with topical non-steroidal anti-inflammatory agents. Use high resolution OCT post-operatively to screen for subtle cystoid macular edema or epiretinal membrane formation.

• Involve the vitreoretinal specialist early on post-operatively in the event that intervention with intraocular medication delivery or surgical therapy will be required.

With prior proper planning, it is possible for the modern advanced refractive cataract surgeon to prevent poor outcomes with selection and implantation of refractive IOLs. RP