Surgical options for presbyopes, including laser vision correction and premium IOL implantation, have expanded rapidly over the last 10 years––and for good reason. Demand for the surgical correction of presbyopia has been increasing exponentially.
This growth can be attributed to two major factors. The first––and most obvious––consideration is that an ever-growing portion of the American population has presbyopia. The generation of patients that is now starting to experience presbyopia has a much lower tolerance for the life-altering effects of aging than previous generations. Often, these patients will spend tens of thousands of dollars to counteract the effects of aging. The restriction of spectacle wear for reading, as well as the age-associated stigma that accompanies reading glasses, has become a driving force for many middle-aged patients. Couple this with our increased dependence on computers, tablets and smartphones, and presbyopia quickly becomes more of a functional impairment than ever before.
The second major driving force behind the growth of presbyopia correction devices and procedures is outstanding visual results. The quality of vision that results from modern presbyopic surgery has become markedly better during the last decade. Ten years ago, many of these procedures were associated with decreased night vision, debilitating glare and halos, poor acuity at various distances, and unimpressive patient satisfaction rates.
With contemporary advances in our understanding of optics, devices, surgical procedures, ocular anatomy and patient selection criteria, we are now able to provide exceptional postoperative visual outcomes.
Caring for the Ocular Surface
Before recommending any form of refractive surgery, you must optimize the patient’s ocular surface quality. This fundamental consideration cannot be stressed enough. In fact, you shouldn’t consider any corneal procedure until the patient’s ocular surface is in good shape.
A poor tear film will decrease contrast sensitivity and lead to inconsistent vision.1 Further, attempting to begin ocular surface treatment postoperatively can be a fruitless task because of decreased tear production secondary to neuropathy. Encountering just a few of these postoperative problems will forever change your mentality about addressing any amount of pre-existing ocular surface disease.
Below are three of the most common ocular surface conditions that you likely will have to manage before and sometimes after a refractive procedure:
• Blepharitis. Considering that blepharitis is one of the most common causes of postoperative complications, it is surprising how frequently the condition is still routinely overlooked.2 Patients with blepharitis must be informed that they have a chronic condition that will need to be treated both pre- and postoperatively. Any amount of lid margin inflammation or gland secretion turbidity should be treated before surgery. Preoperative treatments include combination antibiotic/steroid drops, topical azithromycin and oral tetracycline analogues.3 Long-term management includes topical azithromycin, pulse-dosed steroids, warm compresses/lid scrubs, low-dose tetracycline analogues and oral omega-3 fatty acid supplementation.3
• Dry Eye. Dry eye––both preoperatively and postoperatively––has always been a fundamental concern for patients who wish to undergo LASIK or cataract surgery. There is no question that moderate to severe dry eye is a contraindication for refractive surgery; however, mild dry eye has become unavoidable in many of our patients. For those at a high risk of dry eye, consider the use of pharmacological prophylactic treatment (e.g., Restasis [cyclosporine, Allergan]) as well as recommend omega-3 fatty acid supplementation and artificial tears.4 In fact, we recommend omega-3 supplementation to all LASIK and cataract patients, unless there is a medical contraindication. This general recommendation also holds true for asymptomatic patients with low tear prism height as well as patients with mild superficial punctate corneal staining.
Take note that multiple reports have indicated that Restasis may speed visual recovery––as well as yield other benefits––following LASIK.5-7 Topical steroids also can be used to speed postoperative recovery, but typically are not used long term following surgery.
• Allergy. Although the symptoms of allergic conjunctivitis typically can be controlled with an antihistamine/mast cell stabilizer eye drop, consider preoperative treatment with topical corticosteroids. Corticosteroids shut down the entire inflammatory cascade, yielding a better environment for surgery and ensuring good control of moderate allergy that can be difficult to manage with antihistamines alone. After the immediate postoperative period, initiate antihistamine drops as needed.
• LASIK. For patients with a history of monovision contact lens wear and clear crystalline lenses, monovision LASIK can be an excellent option. Contact lens-wearing presbyopes are also at an increased risk for dry eye, blepharitis and ocular allergy. Keep in mind that patients who experience contact lens intolerance likely will inquire about LASIK. (This complaint often indicates pre-existing ocular surface disease, which should be treated aggressively.) Additionally, elderly patients must be informed that their age group alone puts them at increased risk for unrelated cataract formation, and several years or decades could pass before cataracts start to affect their vision.
• Lens exchange options. When the natural crystalline lens is unable to morph sufficiently to provide a functional amount of accommodation, it becomes a primary source of visual impairment. Historically, we used to wait until the lens thickened and opacified, which would often result in significant lifestyle restrictions. Further, we used to delay cataract surgery as long as possible due to the invasive nature and associated risks of the procedure. In the meantime, accommodative loss was seen as inevitable, and reading glasses were the only realistic option.
|Five Key Points About Monovision LASIK for Presbyopes|
| 1. If the patient has never worn monovision before, always insist on a
monovision contact lens trial to assess patient satisfaction.
2. Do not recommend offering monovision LASIK to hyperopes. If you make a
hyperopic eye myopic, the optics seem to deteriorate dramatically and
the patients are rarely impressed.
3. Although monovision allows some patients to read at near all day
long, it is still a good idea to offer these patients a binocular
reading prescription to ease monocular strain.
4. Any myopic vision change that occurs several years after LASIK most
likely is a lenticular change, and further corneal refractive surgery
will only make the patient happy temporarily.
5. Advanced age alone puts these patients at a higher risk of
postoperative dry eye. So, consider treating all presbyopic LASIK
patients for dry eye.
To date, Medicare still uses a guideline of 20/50 best-corrected visual acuity or significant lifestyle impairment before it will assist in covering the cost of cataract surgery. This has conditioned many surgeons to only consider cataract surgery at that threshold, believing that the risks of surgery are then sufficiently offset by the potential benefit.
Fortunately, advancements in lens optics––as well as surgical instruments and techniques––now produce excellent visual results with considerably fewer complications. Additionally, surgeons are more willing to offer patients lens replacement surgery solely for refractive purposes (often termed clear lens exchange or refractive lens exchange [RLE]).
Although the natural loss of contrast, acuity and accommodation was begrudgingly accepted by the previous generation, many current presbyopes are not willing to accept unsatisfactory outcomes. As doctors, our attitude toward decreased vision has begun to evolve as well. Without question, we would recommend new correction if patients’ spectacles or contacts reduced their vision by several lines of acuity. So, why should a compromised crystalline lens be any different?
When counseling patients on lens exchange options, the benefits vary by case. Still, the potential limitations of each lens must be stressed. For a patient with debilitating cataracts, vision often remains poor no matter what form of correction he or she uses––so any lens that clears the individual’s vision will have limitations that are comparatively small.
In contrast, if a patient has a relatively clear lens and sees well with glasses, postoperative visual limitations must be stressed exhaustively, because the individual is accustomed to seeing clear, distortion-free images. A patient’s postoperative satisfaction level is often directly related to his or her degree of preoperative visual impairment.
|Cataract and Refractive Lens Exchange Questionnaire|
As previously mentioned, every lens technology has its own benefits and limitations. But, it is important to understand that, despite which technology you use, there are some universal expectations that must be addressed. Establishing proper expectations is critical to ensuring patient satisfaction. Patients who have unrealistic expectations, or are overly critical of their vision, should be guided away from RLE. Patient personality and expectations are such a critical factor that our surgeon, Steven Dell, M.D., developed a specific patient entrance questionnaire that is now widely used across the country (see “Cataract and Refractive Lens Exchange Questionnaire.”).
Poor candidates for IOL surgery include those patients with scarred corneas or poor ocular health, including individuals with severe ocular surface disease, degenerative corneal disease and retinal disease.
Patient prescriptions also play a large role in postoperative satisfaction. Hyperopes with no accommodative capacity, for instance, do not see well at any distance without correction. They are the easiest to make happy with this surgery. High myopes are a close second.
On the other hand, the prescription that you need to be most cautious with is mild, mixed astigmatism. These patients exhibit functional distance and some functional near vision, so bilateral implantation will not greatly change their lifestyle.
For the same reason––but to a lesser degree––emmetropes and mild myopes are somewhere in between. They both see well at one distance but not the other without glasses. Although proper expectations are the most important presurgical factor, the patients’ prescriptions are highly suggestive of their postoperative satisfaction.
Premium IOL Technologies
There are two different premium IOL technologies approved in the United States for presbyopic correction: accommodative and multifocal. At this time, neither lens technology is available in toric form––so any patient with more than a few diopters of corneal astigmatism will need to consider monofocal toric IOLs.
The Crystalens (Bausch + Lomb) is the only available accommodating IOL in the United States. The two available multifocal IOLs are the AcrySof ReSTOR (Alcon) and the Tecnis (Abbott Medical Optics). All three primary lens platforms have undergone multiple enhancements and refinements during the last decade.
Here is a closer look at the available presbyopia-correcting IOL designs:
• Accommodating IOLs exhibit one distinct advantage over multifocal IOLs: only one focal point. This optical feature is superior to multifocal lenses because all available light is focused to a single point, yielding better contrast sensitivity. Typically, these IOLs give the patient exceptional intermediate visual quality and are the lens of choice for tech-savvy patients who spend much of their time using computers and tablets.
Accommodating lenses are also less likely to produce glare, halo and general visual distortion. Superior vision quality also makes this lens a logical choice for patients, such as pilots, occupational drivers or competitive athletes, who require high-quality distance vision. Because the dominant eye is much more sensitive to visual distortion, surgeons often document better patient satisfaction when accommodating lenses are used in the dominant eye.8
However, accommodating lenses also have several disadvantages. Although intermediate vision typically is good, traditional reading distance (40cm) often is not as clear as that generated by multifocal IOLs. So, an accommodative IOL is not the lens of choice for someone who likes to read for hours in bed.
|Premium IOLs at a Premium Cost|
patients must be made aware that no medical insurance providers cover
the cost of either accommodating or multifocal IOLs. For insured
patients with qualifying cataracts, a premium upgrade costs about $2,000
per lens. (Insurance typically covers the cost of surgery and
implantation for a conventional monofocal lens.) For patients who are
paying entirely out of pocket, the procedure can cost between $4,000 and
$6,000 per eye. Remember, out-of-pocket expenses always result in
higher patient expectations.|
Also, the accommodative effects of these lenses may take weeks to months to be appreciated, and patients must be counseled that patience is required during this time.
Finally, because accommodative IOLs are translating lenses, they are also prone to a slight anterior shift if the posterior capsule starts to opacify. If this happens, the patient will become more myopic. Fortunately, the myopic shift can be corrected by performing a posterior YAG capsulotomy, which allows the lens to fall back into its proper position.
• Multifocal IOLs produce superior vision at traditional reading distances of 30cm to 40cm. This makes them ideal choices for patients who read novels or do a lot of detailed near work. The near viewing benefits of these lenses are often experienced as soon as the morning after surgery. Although these lenses produce multiple focal points, we find that patient satisfaction with these lenses is extremely high and does not correlate at all to previous success with multifocal contact lenses. The typical patient will report surprisingly good near and distance vision at the one-day postoperative follow-up.
A drawback of multifocal lenses is that they are more likely to cause minor glare and distortion. Such visual artifacts are rarely debilitating, however.
Because multifocal IOLs have two primary focal points––far and near––the patient may experience inadequate visual quality at intermediate distances. All patients with bilateral implantation should be informed that they might need reading glasses at computer distance.
Additionally, because these lenses split the available light, they are highly susceptible to visual degradation from a poor ocular surface and mild posterior capsule opacification. So, be sure to treat any surface disease aggressively and closely examine the posterior capsule in any patient who presents with visual complaints.
No single prebyopic IOL technology is superior to another. In fact, my surgeon has found success in combining technologies. In our office, we prefer to implant an accommodating lens in the dominant eye and a multifocal lens in the non-dominant eye. We believe that this combination gives the patient all the benefits of each technology, while providing usable vision at almost all distances.
Dr. Dell promotes the mix-matching of these IOL technologies. (In fact, he has coined the term “full-focus cataract surgery” for this combination approach.) His patients often are very happy and have no issues secondary to different optical technologies in each eye. However, some doctors, as well as patients, are not comfortable with the idea of mixing IOLs.
Sometimes, the patient’s anatomy dictates the choice of IOL. If the individual has any amount of corneal disease that affects light transmission, the surgeon should avoid the use of multifocal IOLs because of the light-splitting effects. Patients with a corneal disease, like Fuchs’ endothelial dystrophy, likely will experience amplified visual degradation from a multifocal lens. Patients with mild macular diseases or restricted visual fields also are poor candidates for multifocal lenses, because of distortion and decreased light reception. Fortunately, in my experience, patients with any of the aforementioned limitations often do well with accommodating IOLs.
|Suggestions on What to Tell Your Patients About RLE|
| • “These IOLs work very well, but none of them deliver the natural,
precise accommodation that you experienced when you were young. This is
the best technology that we have at this point and it will give you
increased freedom from glasses and contacts.”
• “While you will likely be able to see very well at multiple distances
and reduce your dependence on glasses, you will notice that some
distances are not clear and you may still need spectacles for certain
activities.” (Just be certain never to tell patients that they can go
ahead and throw away their glasses. Although you’ll learn that most of
your RLE patients will not use spectacles for near or far, never
overpromise something and allow it to become a coveted expectation.)
• “There is a summation effect between the eyes. That means that these
technologies seem to work much better once both eyes undergo correction.
Keep in mind that you will likely experience some strained and awkward
vision while waiting for the second eye to be corrected.” (Binocular
implantation yields much happier patients than monocular implantation.)
• “Although we typically are very accurate with the placement of these
lenses, they may shift position as you heal. To maximize the benefit of
the lens, we may need to refine your vision with LASIK surgery once your
eye is stable.” (Many surgeons do not charge extra for a LASIK
procedure after RLE.)
We are now just starting to experience rapid growth in RLE interest among patients who previously underwent corneal refractive surgery. Patients with a history of radial keratotomy or LASIK should only be considered for RLE following extensive counseling. Surgically altered corneas have less predictable outcomes, and the unnatural curvature makes it more difficult to calculate the proper IOL power. Most surgeons will not put multifocal IOLs in these patients because they can compound the image degradation caused by the cornea. Accommodating IOLs, however, work relatively well in these patients, with the understanding that results are more variable than those experienced by an unadulterated cornea.
Also, I have learned to use brand-name NSAID medications on a routine basis in these patients. Topical NSAIDs and analgesics have been shown to be effective for the prevention of cystoid macular edema (CME).9 Angiographic CME has been shown to develop in up to 30% of all cataract surgeries.10
Although vision degradation is not always noticed in patients with conventional monofocal IOL implants, the risk of permanent or prolonged visual decline secondary to CME is more of a concern. This is because these patients have a higher expectation for visual recovery and the technology may be affected more adversely than a premium IOL.
A significant reason to only use branded NSAIDs is improved patient tolerance. For generic medications, the FDA requires only that they contain the same active ingredient(s) as their premium counterparts. Generics are not required to demonstrate safety, efficacy, absorption or tolerance––which are all affected by different preservatives, buffers, fillers, pH and manufacturing processes.
Additionally, caution should be exercised with the use of generic NSAIDs due to a recent report that documented corneal ectasia following generic diclofenac use.11 I have seen similar corneal tolerance and efficacy issues with generic bromfenac. Ultimately, I believe that NSAIDs are critical to the outcome of these surgeries, so I often insist on the use of branded medications.
Presbyopia-correcting surgeries have allowed us to provide our patients with unprecedented levels of visual satisfaction. The increased demand for spectacle-free viewing in the ever-aging population has forced optometrists to become more familiar with these surgical technologies.
These procedures also highlight the importance of effective surgical comanagement. Comanaging optometrists understand patients’ visual demands and ocular histories, which are essential considerations in proper technology selection.
Dr. Cunningham is the director of research and optometry at Dell Laser Consultants in Austin, Texas. He has received research support and/or is a consultant to Abbott Medical Optics, Alcon, Allergan, Bausch + Lomb and Ista Pharmaceuticals.
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