In the June 2010 issue of EyeWorld magazine, a panel of experienced refractive surgeons discussed their opinions about the latest presbyopia-correcting intraocular lenses (IOLs) used in refractive cataract surgery and refractive lens exchange (RLE) to improve vision and reduce the need for prescription glasses.

The panel comprised the following eye surgeons: Carlos Buznego, MD, and David A. Goldman, MD, (Bascom Palmer Eye Institute, Miami, Fla.); Jack L. Weiss, MD (San Diego, Calif.); David F. Chang, MD (University of California, San Francisco); Dimitris Bouzoukis, MD (University of Crete, Heraklion, Greece); John A. Vukich, MD (Madison, Wisc.); Scott M. MacRae, MD (University of Rochester Medical Center, Rochester, N.Y.)

Current presbyopia-correcting IOL options available in the United States include multifocal IOLs, such as ReSTOR (Alcon, Fort Worth, Texas), Tecnis Multifocal (Abbott Medical Optics, Santa Ana, Calif.) and ReZoom (also by Abbott Medical Optics).

Presbyopia also can be corrected with accommodating IOLs. Currently the only brand of accommodating IOL that is FDA-approved for use in the United States is Crystalens (Bausch & Lomb, Rochester, N.Y.)

Among the comments the surgeons made about these lenses and the surgical correction of presbyopia:

• Refractive surgeons are becoming more familiar with presbyopia-correcting IOLs and a greater selection of these premium lens implants is now allowing surgeons choices for a wider range of patients, said Dr. Buznego.
• No presbyopia-correcting IOL is perfect, said Dr. Goldman. Multifocal IOLs usually have some degree of glare or halos, and accommodating IOLs may not provide near vision for some patients, he added.
• Dr. Weiss said the ReSTOR +3.0 multifocal IOL is his “go-to” presbyopia-correcting IOL, and that halos don’t seem to be a major issue with this lens, in his opinion.
• Dr. Chang said he also prefers the ReSTOR +3.0 multifocal IOL for most patients who desire presbyopia correction with an intraocular lens, though he also frequently uses the Tecnis Multifocal IOL for patients whose top priority is freedom from reading glasses.
• Dr. Weiss said he has had success with mixing multifocal IOLs when patients need surgery in both eyes — specifically, using The ReSTOR lens in one eye and the Tecnis Multifocal IOL in the other. Dr. Bouzoukis concurred, saying this approach often provides the best combination of uncorrected distance, intermediate and near vision.
• Dr. Vukich praised the excellent distance vision provided by the Crystalens accommodating IOL, but added that some patients do not get enough added power for uncorrected near vision with this IOL, and to compensate, he sometimes implants Crystalens IOLs in both eyes in a modified monovision approach to improve near vision.
• Dr. Chang agreed that patients opting for Crystalens accommodating IOLs can benefit from monovision, and Dr. Weiss said Crystalens is a good choice for patients who are worried about glare and halos.
• The surgeons agreed that patient education about presbyopia-correcting IOLs prior to surgery is very important so patients understand that all multifocal and accommodating IOLs involve some compromise in vision.
• Dr. MacRae said a recent study he conducted showed that mild uncorrected astigmatism can more significantly affect visual performance with multifocal IOLs, compared with accommodating or conventional monofocal IOLs.
• Dr. Buznego said that if patients have pre-existing dry eye, it is important to successfully treat this condition prior to implantation of a presbyopia-correcting IOL to be able to fairly evaluate the visual performance of the IOL.

The surgeons said they are looking forward to the introduction of new presbyopia-correcting IOLs currently in development to see how these lenses compare with currently available multifocal and accommodating IOLs.

Dr. Bouzoukis added that new surgical techniques being introduced in femtosecond laser-assisted cataract surgery may play an important role in optimizing the visual outcomes of intraocular lens surgery for the correction of presbyopia.

SOURCE:  Presbyopia-correcting IOLs: evolving options. EyeWorld. June 2010.

So says experienced refractive surgeon David Hardten, MD, of Minnesota Eye Consultants (Minneapolis, Minn.) in this month’s issue of Review of Ophthalmology.

To produce optimum visual outcomes and excellent patient satisfaction after premium IOL surgery for presbyopia correction, Dr. Hardten says a laser vision correction enhancement procedure such as LASIK or PRK may be needed.

Clinical pearls Dr. Hardten offers in the article directed to fellow ophthalmologists and refractive surgeons include:

• In cases of mediocre vision after cataract surgery, check for post-operative eye conditions such as cystoid macular edema (a retina problem), ocular surface disease (chronic dry eye, for example) and posterior capsular opacification. Treating these problems may eliminate the need for additional refractive surgery.
• If laser vision correction is needed because of residual refractive error after IOL surgery, Dr. Hardten prefers all-laser LASIK for eyes with healthy corneas. For eyes with corneal disease or a cornea with unusual shape, he prefers PRK.
• Perform laser vision correction after IOL surgery only in cases of favorable reward/risk ratio for additional surgery.
• LASIK or PRK may be a better choice for correcting residual astigmatism after implantation of a toric IOL than trying to rotate the lens surgically.
• Sometimes, multifocal IOLs in the eye can affect the accuracy of measurements used to program an excimer laser for wavefront-guided LASIK. Conventional (non-wavefront) LASIK or PRK may be a better choice after IOL surgery in these cases.

Though premium IOLs for presbyopia correction usually provide good distance and near vision for most people, there will be some patients who will need additional surgery to achieve acceptable vision without glasses, according to Dr. Hardten.

The surgical enhancement rate for presbyopic IOL patients in his practice currently is 12 percent, he says.

SOURCE:  Tap the potential of premium IOLs. Review of Ophthalmology. June 2010.

Monovision is the practice of fully correcting one eye so it sees perfectly well for distance vision, and making the other (usually non-dominant) eye mildly nearsighted so it provides acceptable near vision without reading glasses.

Monovision has been around for years, being performed with contact lenses to enable people over age 45 who have presbyopia to have functional vision at all distances without being dependent on reading glasses.

Recently, monovision also is being offered by refractive surgeons with LASIK and with refractive IOLs used in cataract surgery.

This week, eye surgeon John A. Hovanesian, MD, (Laguna Hills, Calif.) discussed monovision cataract surgery in his blog on the Ocular Surgery News website.

According to Dr. Hovanesian, the monovision procedure has several advantages over the use of multifocal IOLs in cataract surgery, Including:

• A “trial run” of monovision with contact lenses prior to cataract surgery rarely is needed.
• High-quality vision at all distances can be achieved with only a mild amount of nearsightedness in the non-dominant eye, making adaptation to monovision quite easy.
• Monovision typically does not cause depth perception problems.
• Monovision can yield better contrast sensitivity than monofocal IOLs for activities like driving at night.
• Monovision allows cataract surgeons to choose from a variety of premium monofocal IOLs, including aspheric lenses designed to reduce glare.
• Monovision typically is less expensive than cataract surgery with multifocal IOLs, which can require thousands of dollars in out-of-pocket costs for patients.

For the best results with monovision, it’s important that the distance vision of the dominant eye is perfect. In some cases, this means enhancement refractive procedures (i.e. LASIK or PRK) may be required after cataract surgery.

Dr. Hovanesian said that after considering its advantages, he plans to offer surgical monovision to more of his cataract patients in the future.

Also, many refractive surgeons prefer not to perform LASIK on older patients who have or may soon have cataracts that would make the benefits of LASIK short-lived.

For these patients, many eye surgeons are turning to an elective vision correction procedure called refractive lens exchange, or RLE. In this procedure, the lens inside the eye is removed and replaced with a man-made intraocular lens (IOL) — like in cataract surgery.

In the March 2010 issue of EyeWorld, two experienced refractive surgeons discussed the advantages of RLE and the techniques they prefer when performing the procedure.

Stanley Berke, MD, associate clinical professor of ophthalmology and visual sciences at Albert Einstein College of Medicine (New York, N.Y.) says RLE is a good choice for patients who desire vision correction surgery but are poor candidates for LASIK because their corneas are too thin, they have too much nearsightedness or farsightedness or because of other risk factors.

Jason Stahl, MD, assistant clinical professor of ophthalmology at Kansas University Medical Center (Kansas City, Kan.) says that normal age-related lens changes in the eyes of people in their late 40s and 50s can cause light scatter that degrades vision, even before a cataract forms in the lens.

Replacing the aging lens with an IOL via the refractive lens exchange procedure can improve vision in these patients, he says.

Dr. Stahl says RLE offers older patients who desire vision correction surgery a number of advantages:

1. When using an accommodating IOL or a multifocal IOL, RLE can restore both distance and near vision in a person who has presbyopia.
2. RLE can eliminate the need for cataract surgery in the future.
3. RLE stabilizes the optics of the eye, reducing the risk of changes in a person’s eyeglass prescription and visual acuity because of increasing refractive errors.

Both surgeons emphasized that patient education about the RLE procedure, including risks and potential outcomes, are essential so patients have realistic expectations about what the surgery can and cannot do for them.

They also said a thorough pre-operative exam is necessary to rule out eye problems other than normal age-related lens changes that could affect visual outcomes, and post-operative care is needed to avoid unwanted complications.

In some cases, a follow-up refractive procedure such as LASIK or PRK may be needed to fine-tune the refractive result for optimal uncorrected visual acuity.

SOURCE:  Considering refractive lens exchange. EyeWorld. March 2010.

Researchers in Spain and Portugal evaluated the stereoacuity of 15 farsighted subjects who elected to undergo RLE in both eyes for the correction of farsightedness and presbyopia. None of the participants in the study had cataracts prior to surgery.

Stereoacuity, a sensitive measure of a person’s 3-dimensional vision and ability to perceive depth, was measured with a standard clinical test (Titmus stereotest) before and after RLE surgery.

All participants in the study had excellent stereoacuity scores prior to surgery. After bilateral RLE surgery, 95 percent of patients receiving AcrySof ReSTOR multifocal IOLs in both eyes maintained the same level of stereoacuity they had prior to surgery.

The authors of the study concluded that refractive lens exchange with bilateral AcrySof ReSTOR multifocal IOLs does not affect the depth perception of farsighted patients with normal binocular vision prior to surgery.

SOURCE:  Stereoacuity after refractive lens exchange with AcrySof ReSTOR intraocular lens implantation. Journal of Refractive Surgery. November, 2009.

In the article, Dr. Chu and other prominent cataract and refractive surgeons discuss the advantages of premium IOLs and factors surrounding the usage of these and other new eye surgery technologies.

Premium intraocular lenses include multifocal IOLs and accommodating IOLs to correct presbyopia and reduce the need for reading glasses, toric IOLs to correct astigmatism and aspheric IOLs designed to reduce glare and improve night vision.

Educating patients and managing their expectations about premium IOLs

Surgeon David F. Chang, MD, (Los Altos, CA) advises surgeons to educate patients about premium IOLs prior to surgery and to use concise, clearly understandable language about visual expectations after surgery.

Premium IOLs cost more than regular intraocular lenses, and the difference in cost typically is not covered by insurance and becomes an added out-of-pocket expense for patients, increasing their cataract surgery cost. The premium price of these lenses often leads patients to expect premium visual outcomes, says Richard L. Lindstrom, MD (Bloomington, MN).

John A. Hovanesian, MD, (Laguna Hills, CA) and Eric. D. Donnenfeld, MD, (Rockville Centre, NY) said that surgeons should discuss all available premium lens options with patients, including the strengths and weaknesses of each lens, and that it is critical for the surgeon to personally believe in the technology if they are to offer it to patients.

Refining outcomes after IOL surgery

Because people who choose premium refractive IOLs for cataract surgery or lens-based refractive surgery such as refractive lens exchange (RLE) often have high visual expectations, laser surgery is sometimes needed after premium IOL surgery to fine-tune visual outcomes, says Dr. Chu.

Dr. Lindstrom cited a recent study indicating that more than 95 percent of patients were satisfied with their visual outcomes after LASIK surgery, noting that many of these patients, too, needed a laser enhancement to achieve their best visual outcomes.

Popularity of premium IOLs is increasing

Apparently, many refractive surgeons are finding that the added benefits of premium IOLs outweigh the challenges of the new lenses, as recent research shows more surgeons in the U.S. are offering premium lens implants to their patients:

• According to a survey of cataract and refractive surgeons reported by Market Scope, 71 percent of surgeons responding said they offered premium IOLs to their patients in 2008, up from approximately 59 percent in 2007.
• Market Scope also estimates that 210,000 presbyopia-correcting IOLs were used for cataract surgery or other vision correction procedures in the U.S. in 2008, up from 153,000 in 2007.

Eye surgeons also are more frequently recommending premium IOLs for the correction of high myopia in patients seeking elective vision correction surgery.

In a 2008 survey of American Society of Cataract and Refractive Surgery (ASCRS) members, more surgeons responding to the survey preferred premium IOLs (40 percent) to LASIK (23 percent) for the correction of high myopia.

SOURCE:  Surgeons considering premium IOLs must overcome fear of change, challenge. Ocular Surgery News, U.S. Edition. October 25, 2009.

Toric intraocular lenses (IOLs) are specially designed lens implants that contain both sphere and cylinder powers to correct astigmatism. Use of toric IOLs may reduce the need for a secondary surgical procedure called limbal relaxing incisions (LRI) after refractive cataract surgery and RLE.

Toric IOL study: Design and methods

The study included 32 eyes of 19 consecutive patients that underwent RLE with implantation of the AcrySof Toric IOL (Alcon Laboratories). All eyes had more than 1.00 diopter (D) of corneal astigmatism prior to surgery.

Data gathered pre-operatively and six months after surgery included uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA) and refractive sphere and cylinder powers.

Patients also completed a questionnaire to evaluate their overall satisfaction, presence of visual phenomena and their level of spectacle independence after surgery.

Toric IOL study: Results

Results at six months following surgery included:

• 100 percent of eyes had UCVA of 20/32 or better.
• 84.3 percent of eyes had UCVA of 20/25 or better.
• 100 percent of eyes had BCVA of 20/25 or better.
• Mean refractive cylinder was reduced from -2.46 D pre-operatively to -0.53 D after surgery.
• 50 percent of eyes had no change in BCVA after surgery compared to pre-operative BCVA.
• Four eyes (12.5 percent) gained one line of BCVA and 11 eyes (34.4 percent) gained two or more lines of BCVA after surgery.
• One eye (3.1 percent) lost one line of BCVA after surgery.

All patients reported being satisfied with their vision following the RLE procedure, with none reporting significant visual phenomena.

Conclusions

The researchers concluded RLE with toric IOL implantation produced good visual and refractive outcomes for the correction of both spherical (nearsighted or farsighted) and cylindrical (astigmatism) refractive errors.

SOURCE:  Refractive lens exchange with foldable toric intraocular lens. American Journal of Ophthalmology. July 2009.

In the June 2009 issue of Optometric Management, optometrist Justin Holt, OD, updates his colleagues on the latest premium IOLs available for patients who need cataract surgery or who desire lens-based refractive surgery, such as refractive lens exchange (RLE) or phakic IOL implantation.

The blending of cataract and refractive surgery

According to Dr. Holt, today’s cataract patients are also refractive surgery patients: They typically want as much freedom from glasses as possible after surgery, with the least amount of visual side effects.

He says while there is no single “perfect” IOL, people today have more options in premium lens implants than ever before, and it’s up to eye doctors to help their patients choose the IOL that best suits their needs.

Among the choices available…

Aspheric IOLs

Aspheric IOLs change in shape from the center of the lens to the periphery, a feature that is designed to sharpen vision and reduce an optical defect called spherical aberration.

Aspheric IOLs produce sharper vision than conventional IOLs, especially in low light conditions, according to manufacturers of the lenses.

Most aspheric lenses are monofocal (single power) lenses, so reading glasses typically are still needed after surgery, unless the lenses are implanted in both eyes to create a monovision correction (one eye corrected for distance vision and the other eye for near).

Also, aspheric lenses do not correct astigmatism. So eyeglasses or a second surgical procedure, such as limbal relaxing incisions (LRI), LASIK, LASEK, Epi-LASIK or PRK may be needed after surgery for patients with pre-existing astigmatism.

Examples of aspheric IOLs include:

• AcrySof SN60WF (Alcon)
• SofPort Advanced Optics (Bausch & Lomb)
• Tecnis Z9000 (Abbott Medical Optics)

Toric IOLs

Toric IOLs are premium intraocular lenses that contain both a spherical power (to correct nearsightedness or farsightedness) and a cylindrical power, which makes one meridian of the lens more curved than any other, to correct astigmatism.

Computer-applied markings on toric IOLs allow cataract surgeons and refractive surgeons to rotate the lens into the proper position within the eye so it is aligned perfectly to correct corneal astigmatism.

Toric IOLs can correct mild and moderate pre-existing astigmatism without the need for LRI or additional refractive surgery. Reading glasses may still be needed after surgery, however, unless lenses are implanted in both eyes for monovision.

The AcrySof Toric IOL (Alcon) is an example of a toric intraocular lens.

Presbyopia-correcting IOLs

Presbyopia-correcting IOLs are premium intraocular lenses that reduce the need for reading glasses after cataract or refractive surgery.

There are two types of  IOLs that correct presbyopia: accommodating IOLs and multifocal IOLs.

Accommodating IOLs

Accommodating IOLs are monofocal intraocular lenses that have a flexible surrounding structure (the “haptic”) that allows the central portion of the lens (the “optic”) to move slightly forward within the eye in response to focusing effort, thereby improving near vision.

The Crystalens IOLs (Bausch & Lomb) currently are the only FDA-approved accommodating IOLs used in the United States.

Multifocal IOLs

Multifocal IOLs, like multifocal or bifocal contact lenses, contain more than one power to correct vision at multiple distances simultaneously.

While the multiple refracting zones of multifocal IOLs provide a wider range of vision than conventional monofocal IOLs, they also cause some light scatter, which initially may cause visual symptoms such as halos at night, Dr. Holt says.

As patients adapt to multifocal IOLs over a period of days to months, however, these symptoms typically become less bothersome and may disappear altogether.

Adaptation to multifocal IOLs is similar to adapting to the limitations of a monovision correction produced by monofocal IOLs or contact lenses, Dr. Holt says.

Examples of currently available multifocal IOLs include:

• AcrySof IQ ReSTOR (Alcon)
• ReZoom (Abbott Medical Optics)
• Tecnis Multifocal IOL (Abbott Medical Optics)

Phakic IOLs

Phakic IOLs are refractive intraocular lenses designed to be implanted without removal of the eye’s natural lens to correct large amounts of myopia.

Patients who opt for phakic IOLs typically are younger than age 45 and may not be good candidates for LASIK or other laser vision correction procedures.

Phakic IOLs can be implanted in front of the pupil (anterior chamber phakic IOLs) or behind it (posterior chamber phakic IOLs).

Anterior chamber phakic IOLs are attached to the front of the iris and are therefore somewhat visible. Posterior chamber phakic IOLs, on the other hand, are virtually invisible behind the pupil.

Desirable features of phakic IOLs include:

1. Because the natural lens is left intact, young patients retain their normal focusing ability and are not forced to wear reading glasses prematurely.
2. Phakic IOLs can be removed if cataract surgery becomes necessary later in the patient’s life.
3. In many cases, phakic IOLs can safely correct higher amounts of myopia than LASIK and other types of laser vision correction.

FDA-approved phakic IOLs include the Visian ICL, a posterior chamber phakic IOL manufactured by STAAR Surgical (Monrovia, Calif.) and the Verisyse Phakic IOL, an anterior chamber lens manufactured by Abbott Medical Optics (Santa Ana, Calif.).

Education and patient expectations are key

Dr. Holt advised his fellow eye doctors to appropriately screen and educate their patients about currently available premium IOLs.

A good understanding of the features, benefits and limitations of current IOL technology and having realistic post-operative expectations are key to patient satisfaction after surgery, he says.

SOURCE:  Understanding the latest IOL technology. Optometric Management. June 2009.

Their findings suggest aspheric IOLs may produce noticeably better vision for tasks in low-light conditions, such as driving at night.

Aberrations and visual performance

The quality of vision after cataract surgery is influenced by optical abberations of the eye. Spherical aberration, in particular, can cause glare and halos around lights during tasks such as night driving.

Spherical aberration and other optical abberations of the eye — also called “higher-order aberrations,” or HOA — usually cannot be corrected by eyeglasses or contact lenses.

Recently, several manufacturers of lens implants used in cataract surgery and refractive lens exchange (RLE) have introduced aspheric IOLs designed to reduce spherical aberration and improve visual performance.

Unlike conventional spherical IOLs, which have the same curvature across the entire lens surface, aspheric IOLs have a surface curve that becomes flatter toward the lens periphery. This gradually changing curve is designed to more closely mimic the performance of the eye’s natural lens and reduce spherical aberration.

Aspheric vs. spherical IOLs: Study design

In the Italian study, 100 people with bilateral cataracts were randomly assigned to receive either aspheric or spherical IOLs in both eyes.

Two brands of aspheric IOLs and two brands of spherical IOLs were included in the study. The aspheric IOLs were the AcrySof SN60WF (Alcon) and the Tecnis Z9000 (Abbott Medical Optics). The spherical IOLs were the AcrySof SN60AT (Alcon) and the Sensar AR40e (Abbott Medical Optics).

Participants had the same type of IOL implanted in both eyes.

All eyes were evaluated for a period of two years after surgery. Quality of vision was assessed via visual acuity, contrast sensitivity and wavefront aberration measurements.

Aspheric vs. spherical IOLS: Study results

After analyzing the study data, the researchers found:

• Both types of aspheric IOLs evaluated in the study reduced total spherical aberration, compared to the spherical IOLs.
• Though there was no significant difference in best spectacle-corrected visual acuity (BSCVA) among the four groups of eyes, eyes receiving either of the aspheric IOLs exhibited significantly better contrast sensitivity than eyes receiving the spherical IOLs.

Conclusions

The researchers concluded that both the aspheric AcrySof IOL and the aspheric Tecnis IOL provide “improved functional vision” compared to spherical IOLs, and this is due to their ability to reduce spherical aberration.

Results of the study suggest that though aspheric IOLs may not produce significantly better visual acuity in bright daylight conditions, they may offer noticeably superior vision in low light conditions such as night driving.

SOURCE:  Contrast sensitivity evaluation of aspheric and spherical intraocular lenses two years after implantation. Journal of Refractive Surgery. July 2009.

The RLE procedure is essentially the same as procedure used for modern cataract surgery. The only difference is that the lens being removed from the eye is clear, not clouded by cataracts.

Many surgeons are reluctant to perform RLE for purely refractive reasons due to the potential for serious complications, such as glaucoma and retinal detachment. Other surgeons, however, point out the low incidence of such complications in both RLE and modern cataract surgery.

RLE safety and effectiveness: Study design

To investigate the safety and effectiveness of refractive lens exchange for the treatment of moderate and high hyperopia, researchers in Indonesia treated 153 eyes with the procedure.

The mean refraction of the eyes prior to surgery was +5.29 diopters (D) and the mean age of the patients was 52 years.

Three different IOLs were investigated, including multifocal IOLs for the treatment of presbyopia. Mean follow-up after surgery was more than five years.

RLE safety and effectiveness: Study results

Amit Tarafdar, MD reported the results of the study at he joint meeting of the Asia-Pacific Academy of Ophthalmology and the American Academy of Ophthalmology held recently in Bali.

Findings of the study included:

• Mean refraction after surgery improved to 0.04 D, compared to +5.29 D prior to the procedure.
• Uncorrected visual acuity (UCVA) at near was 20/20 in more than 90 percent of the subjects.
• There were no occurrences of intra-operative or post-operative complications and no instances of detached retina folowing surgery.

“Clear lensectomy (and RLE) for hyperopia is predictable and extremely safe,” Dr. Tarafdar said. “Results are acceptable for monofocal lenses and extremely good for multifocal lenses.”

Surgeons prefer RLE for high hyperopia, but not high myopia

In related news, a recent survey of refractive surgeons in the American Society of Cataract and Refractive Surgery (ASCRS) found that a majority of surgeons prefer RLE for the surgical treatment of high (+5.00 D) hyperopia, compared with only 9 percent of respondents preferring LASIK for these patients. (Thirty percent of those surveyed said they prefer not to perform either type of surgery on these patients.)

But it is a different story for the correction of high myopia. For patients with -10.00 D of nearsightedness, 40 percent of surgeons surveyed say they prefer phakic IOL implantation, 20 percent prefer LASIK and only two percent prefer RLE.

The difference is due to the higher risk of retinal detachment and other RLE complications among eyes with high myopia compared to eyes with high hyperopia.

SOURCE:  RLE shown safe and effective in moderate, high hyperopia. Ocular Surgery News website (OSNsupersite.com). May 16, 2009.