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How to Integrate Aspheric Presbyopia- Correcting IOLs Into Your Practice
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Possessing knowledge on the advances in IOLs, cataract surgery, and laser-based vision correction is not sufficient; the physician must know how to incorporate all of these new tools into their practice. There are several strategies ophthalmologists may utilize that will facilitate the incorporation of aspheric presbyopia-correcting IOLs into their practice.
Toric Lenses
For ophthalmologists who wish to integrate aspheric-correcting IOLs into their practice, a reasonable first step would be to incorporate toric lenses to manage astigmatism, because the surgical technique is straightforward, and the concept is easy for patients to understand. In order to undertake toric IOLs successfully, a variety of alterations in practice must occur that involves all employees, such as learning to handle cash-paying procedures that refractive practices utilize. Proper training in this area will facilitate the incorporation of more complicated procedures into practice.
There are several strategies that will facilitate the incorporation of aspheric presbyopia-correcting IOLs into practice.
— Kerry D. Solomon, MD
If toric lenses are incorporated into practice, it is important to differentiate between candidates for toric lenses and candidates for other lenses, such as presbyopia-correcting lenses. One effective means of accomplishing this is to educate the patient in advance and then have a conversation with them. Have the staff interview them or give them a questionnaire. If these actions are performed, the physician will be able to review the information and make a recommendation regarding management strategies. Although many surgeons are hesitant to make a recommendation, beginning with circular conversations with the patients about what they want to do only complicates matters. Moreover, when patients are indecisive, many will then ask to bring a family member into the office, requiring the physician to review options a second time, lengthening the process. Thus it is also advisable to tell patients in advance to bring a family member with them. In summary, providing information and asking questions in advance, as well as encouraging patients to bring family members with them, greatly facilitates the process in the office.
A patient who presents with 0.75 D or more of astigmatism would be a candidate for toric lenses. Patients who present with between 1 D and 1.5 D would be good candidates for either ReSTOR or AcrySof Toric lenses. In patients with 1.5 D of astigmatism, limbal relaxing incisions (LRIs) should be performed.
As previously mentioned, alignment is crucial. There is a bubble marker now available that can serve as a valuable tool in achieving proper alignment. This can be done on patients in the holding area, while they are still sitting up. The patients then do not need to be taken to a slit lamp. It can be done by the nurses and staff. The patient looks straight ahead, the bubble is centered, and the 3, 6, and 9 o’clock marks are made for the surgeon, who then only needs to mark the specific axis for orientation before beginning the procedure.
LRIs
It is beneficial to incorporate LRIs into practice as well. While lasers are probably more accurate than LRIs in low degrees of astigmatism, correction of 1 D to 1.5 D does not require significant incisions. LRIcalculator.com should be utilized, especially for the beginning surgeon. It utilizes two nomograms, from Eric Donnenfeld, MD and Louis Nichamin, MD. The physician enters the astigmatism data and selects a nomogram and LRIcalculator.com will then instruct where to place incisions.
Presbyopia-correcting lenses
Aspheric presbyopia-correcting IOLs can enable patients to reach the goal of astigmatism <0.5 D. The +4.0 D platform is currently available, and a +3.0 D lens has recently been approved. The +3.0 D has similar traits, including a ReSTOR Aspheric +4.0 D Platform, identical asphericity, identical energy distribution profile, and an identical shape factor. The design modifications of the +3.0 D lens include modified add power from +4.0 D to +3.0 D, nine diffractive rings (as compared to 12 diffractive rings), and slightly wider ring spacing to modify the add power with the same overall diameter diffractive structure.
Figure 2.
Presbyopic IOLs: OCT Analysis OCT analysis should be performed on all patients who are candidates for premium lenses as a screening process, as it may affect the decision a surgeon would make regarding the type of treatment for a particular patient. Source: Kerry D. Solomon, MD. |
Although the new model is the same ReSTOR lens with the same natural chromophore and apodized diffractive optics, it will provide new options. The +3.0 D lens will enable surgeons to tailor treatment to meet their patients’ specific presbyopia-correcting needs. For example, it will allow individuals to read at slightly greater distances, approximately 16-18 inches, and provide a depth of field in a range of vision that is broader than can be provided by the +4.0 D lens. Patients will get slightly less magnification with the +3.0 D lens that could make focusing on very small objects or fine print more difficult, but their ability to focus on objects in intermediate ranges will be greater. Diffractive step height profile and energy distribution are virtually identical between +4.0 D and +3.0 D lenses.
Presbyopic IOLs: Patient Selection
In the beginning stages of implementing presbyopic IOLs into practice, avoid patients with low degrees of myopia. These patients are accustomed to excellent near vision, and thus should be avoided as candidates, especially when performing procedures off-label, such as refractive lens exchange. Patients with hyperopia and moderate levels of myopia are good candidates to begin integrating into practice. Patients with extremely high levels of myopia should be avoided because there is a higher risk of retinal detachment.1,2
Presbyopic IOLs: OCT Analysis
Analysis of premium lens candidates via optical coherence tomography (OCT) should be performed on all patients as a screening process, for a number of reasons. OCT analysis may change how a patient should be treated. For example, if an individual is found to have a small epiretinal membrane, he or she may have other contributing factors and must have a retinal consult before moving forward. Such patients may not be viable candidates for diffractive or multi-focal lenses, and may require an accommodative lens since the others could decrease their quality of vision. Another option may be an aspheric monofocal lens. Moreover, patients are normally treated with steroids and NSAIDs 3 days before surgery. Patients with epiretinal membranes are at much higher risk for cystoid macular edema (CME), and thus should be treated for a week before surgery, and treatment should be continued for a minimum of 4 weeks and a maximum of 8 weeks. It is much better for patients to be aware of this preoperatively rather than postoperatively, thus this issue should be addressed in advance, underscoring the importance of OCT analysis as a screening process.
Presbyopic IOLs: Meticulous Outcomes
Providing information in advance and encouraging patients to bring family members with them greatly facilitates the process in the office.
— Kerry D. Solomon, MD
During the screening process, it is also important to pay careful attention to the lids, lashes, and ocular surface. Issues such as blepharitis, rosacea, evaporative dry eye, and aqueous insufficiency are some of the reasons that patients need extra attention after surgery. It is much more effective to address these issues beforehand, through treatments such as warm compresses, oral nutrition, omega-3 fatty acids, and antibiotics, rather than afterward.
Other Considerations for the Clinic
Grounding patients’ expectations is essential prior to treating them. There are several manners in which this goal can be met, such as by avoiding discussions of clinical success data. For example, if patients are told there is an 80% chance they will never need glasses again, they will have high expectations for the outcome of the procedure. If they come back to the clinic and need glasses when using the computer, they will view their procedure as a failure. Following surgery, patients often require glasses for reading fine print, using computers, seeing in low-light conditions, and driving at night. Instead, it is better to tell them that after the procedure, they should be able to do most of their daily activities without glasses. If a patient is then able to perform most of their daily activities without glasses, they will view the procedure as a success.
Pearls for Incorporating Aspheric IOLs into Practice:
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Additional methods for preparing individuals for IOLs include providing them with information about the types of lenses available before discussing those options in person. There are also questionnaires patients can complete prior to office visits that can motivate them to consider key factors. Also, having family members accompany them to the clinic can assist them in the decision process.
In conclusion, there are several steps that can be taken when incorporating presbyopia-correcting aspheric IOLs into practice. Incorporating toric IOLs, LRIs, and OCT analyses are important steps to take in this process. Grounding patients’ expectations and providing them with educational materials in advance can help increase their satisfaction with treatment.
References
- Boberg-Ans G, Villumsen J, Henning V. Retinal detachment after phacoemulsification cataract extraction. Journal of Cataract and Refractive Surgery. 2003 Jul;29(7):1333-8.
- Solomon K, Fernández de Castro L. Retinal detachment risk in myopes. In: Chang D, eds. Mastering Refractive IOLs: The Art and Science. Thorofare, NJ: SLACK Incorporated;2008:735-736.
Case PresentationsCase 3: Consider a 63-year old woman who has experienced a painless decrease in vision over the last year. She has a glare at night. Her optometrist has requested that she be seen for cataract surgery. Upon examination of the patient it is observed that she has a nuclear sclerotic cataract. Her visual acuity is 20/60 OD with a refraction of -3.75 D +0.50 D x 5º; 20/50 OS with a refraction of -4.00 D +0.25 D x 175º. Keratometry and _pachymetry readings are normal. What is your recommendation? Kerry D. Solomon, MD: Due to the patient’s age, attention must be paid to her ocular surface, eyelids, and lashes if a premium lens or cataract surgery are to be considered. Surgery should not be performed until corneal topography is obtained. Looking at the patient’s refraction, she does not have much astigmatism. If her topography is consistent with her K readings, a toric lens is a possible solution. Astigmatism must be corrected at the level of the cornea, and she clearly has 2 D in the right and 1 D in the left. An assumption could also be made that she has some astigmatism in her cataract that is offsetting the astigmatism in her cornea. It must be made clear to the patient that this is an assumption and if wrong she will have to come back for another procedure to reorient a toric lens along the proper axis. If the retina and cornea are healthy, a multifocal lens would also be reasonable. She does not have large pupils at night, but she has a low degree of myopia. She is used to having good near vision. However, unlike a refractive lens exchange, she has cloudy vision due to the cataract. In summary, she would do well with a toric lens with the right indications, or a multifocal lens with the right indications. Stephen S. Lane, MD: The bottom line here is that there are a lot of possibilities. Many cases will not have an absolute answer and will depend on the patient. Case 4: Consider a 55-year old patient with keratoconus who complains of decreased vision over the last year. There has been documentation of 20/25 best corrected vision with spectacles in the past, but it now has decreased to 20/60 OD and 20/40 OS. His slit lamp examination shows cataracts in each eye, more significant in the right than the left. His retina, eyelids, and ocular surface are all normal. Cataract surgery is planned. What type of IOL would you recommend? Solomon: You would not select an aspheric lens for this patient. A non-aspheric lens would probably be better. I do not use toric lenses in keratoconic patients, because if they are contact lens-tolerant, they are going to get their best corrected vision with spherical contact lenses. If toric lenses are implanted, their best corrected vision would be decreased with contact lenses postoperatively. If a patient desires to be less dependent on contact lenses, then toric lenses would be reasonable. However, the patient must understand that an irregular astigmatism on the cornea will not be corrected with a contact lens, and he may still need contact lenses afterward. However, I will have decreased the need for contact lenses with the toric IOL. All in all, my tendency is not to use a toric lens, but to use a multifocal lens and have the patient resume contact lens wear. Lane: A Bausch & Lomb aspheric lens that does not induce any spherical aberration would be a reasonable choice as well. Trying to address keratoconus with a toric lens is not a good idea, as it essentially creates a bitoric optical system that is difficult to correct. Daniel S. Durrie, MD: A 55-year old with keratoconus is much different than a 25-year old with keratoconus, as age and sunlight crosslink the cornea. The patient has 20/25 best corrected vision and +3 nuclear sclerosis. Simply getting rid of the cataract would improve his vision. A standard IOL without a toric or an aspheric IOL would be very successful in this patient. Case 5: Consider a 48-year old female who has experienced deteriorating near and distance vision over the past several years. She had radial keratotomy (RK) in 1985. _Her visual acuity is 20/25 OD with a refraction of +5.25 - 4.00 x 85º; 20/25 OS with a refraction of +7.75 -5.00 x 100º. How would you approach this case? Karl G. Stonecipher, MD: This is within the realm of what you can treat on-label, “in the box.” A surface treatment with these types of patients is generally successful. However, this particular patient has had significant fluctuation in vision and must be considered differently. On the other hand, I have implanted toric lenses in these types of patients with the goal of reducing the astigmatism even though they do see well. I would go with a refractive lensectomy approach with the plan to have the patient come back and treat the residual refractive error, again on the surface of the photorefractive keratectomy (PRK). The topography was abnormal, so I decided to perform surface ablation to normalize the topography. We performed a standard wavefront-optimized PRK with mitomycin. Examination at 1 year after surgery showed dramatic improvement. Thus, PRK can in fact be done over RK. Solomon: I believe we will be seeing more and more patients coming to us for cataract surgery that have had previous refractive surgery, such as RK, PRK, and LASIK, to name a few. I recommend the ASCRS website for advice on these types of patients. It will provide you with a number of formulas and options to choose from. In my experience the Masket formula or the modified Masket for post-LASIK works very well, and the modified Masket for post-myopic LASIK also works very well if the information is available. Case 6: Consider a 41-year old female, who has been a successful monovision contact lens wearer for many years. She has bilateral nuclear sclerotic cataracts. Her manifest refraction shows some cylinder. Topography results showed that the ocular surface is normal. All in all, a virtually normal exam except for the cataracts and the corneal astigmatism. She wants cataract surgery and does not want to wear glasses for distance or near after surgery. What are our options? Lane: We could do cataract surgery with either crystalens, ReSTOR, ReZoom, or toric IOLs. We could also fit her for a toric lens. We could also mix and match. This patient received bilateral Toric lenses. The right eye for distance, the left eye with a -2 goal, which is what she had been as a monovision patient with her contact lenses. She ended up with 20/20 distance vision and near vision. She was happy with the results and she no longer needed contact lenses. Moreover, she doesn’t have the potential optical aberrations that can occur with multifocal IOLs. She doesn’t have the risk of fluctuation of the near vision not being exactly right, that may occur with one of the accomodating lenses. Solomon: I would have done the same. She has success with monovision and should continue with monovision. Monovision requires some compromises and if someone was adapted to those compromises, I would not change anything. There are, however, going to be some patients who say they are not happy with monovision. In those situations the surgeon must have a conversation with the patient. Often they actually are happy with monovision and just are not happy with contact lenses. If, however, they truly are not happy with monovision itself then presbyopia- correcting lenses should be considered. Case 7: Consider a 61-year old male with decreased vision in his right eye and poor depth perception. He has a history of reduced ocular blood flow. He had been seen by multiple clinics and retina doctors. He had a brother with branch retinal vein occlusion (BRVO). He was put on travaprost to reduce the IOP and therefore improve this reduced blood flow to the optic nerve in the left eye. Intraocular pressure (IOP) was normal (14 mm Hg OD, 10 mm Hg OS). He came in desiring new lenses to see distance and near, which he has heard about from one of his friends. He was 20/100 in the right eye; 20/50 in the left eye. His manifest refraction shows a moderate amount of astigmatism and mild-to-moderate myopia in each eye. Examining his cylinder reaction keratometrically shows results consistent with what was observed in his refraction. His bilateral nuclear sclerosis was worse in the right eye than the left eye. The vision in his left eye has always been less than 20/20, fluctuating between 20/25 and 20/40, due to the reduced blood flow. His visual fields were normal and full in each eye. His OCTs were normal. Topography showed a fairly regular astigmatism. What are the options for this particular patient? Lane: I think the options would be to implant a monofocal in the right eye only, implant either a multifocal or accomodating lens in the right eye only, or to implant a multifocal or accomodating IOL in each eye, with or without LRIs, LASIK, or PRK as a touch-up. We chose multifocal lenses. He underwent one procedure including LRIs in late January, and the fellow eye in early February. Again, he had a fair amount of cylinder at his refraction and everything else was fairly stable. Two or three months later, he was uncorrected at about 20/50 and 20/30 in the right and left eyes, respectively. His near vision was still suboptimal because of the refractive error. He still has some residual cylinder and some residual myopia. His best corrected vision was near 20/20 in each eye and everything else was normal. We then performed custom PRK OU because of concern for raising the IOP with the suction ring. We achieved satisfactory refractive results with good distance, near vision, and, most importantly, a happy patient, leading to happy doctors. DiscussionWhat is the incidence of epiretinal membranes? How do you handle them? Stonecipher: Many of my retinal colleagues report an incidence of 5% to 10%. I find myself performing more OCTs preoperatively. It is better to be able to tell a patient before surgery that he or she has a membrane as opposed to them finding out after surgery and having them think it is your fault. Solomon: Upon examination of all of our patients that were about to undergo cataract surgery, approximately 1000 eyes, we found that the incidence of epiretinal membranes was about 10%. Approximately two-thirds of them were missed on slit lamp exams. It is not always easy to detect an epiretinal membrane preoperatively. The presence of an epiretinal membrane is not necessarily a contraindication to a multifocal lens. I see it as a yellow flag, as it renders patients at high risk for cystoid macular edema (CME). It will affect my plans and I would definitely have a conversation with the patient. If patients accept the plan, undergo surgery, and develop CME, it is better when they are prepared for it. Should NSAIDs be used preoperatively? Solomon: If you are not pretreating your patients with NSAIDs, you are doing them a disservice. Pretreatment with NSAIDs is not for prevention of postoperative inflammation or inhibition of miosis. This treatment is for CME prophylaxis. Even small amounts of retinal thickening after surgery may have a long lasting effect, especially if multifocal lenses are being utilized. Where can the preoperative bubble markers be obtained? Solomon: There are a few options. Mastel, Inc. (Rapid City, SD) and ASICO, Llc. (Westmont, IL) make them. Duckworth & Kent, Ltd. (Hertfordshire, England) is also coming out with one. Should OCT be performed before or after the patient makes the decision to get a premium IOL? Lane: In my practice OCT is completed before I see the patient. It is another test that is part of the work-up in addition to the K readings and topography. Some may ask what is the point of OCT in patients with standard myopia. OCT is a tool that is easy to use, and it can detect retinal thinning in some patients, and other issues in patients with high degrees of myopia that would otherwise be missed, as it would go unnoticed in other examinations. I believe OCT is something that will gradually be accepted as a standard work-up, especially in surgical candidates. If someone is trusting a surgeon to change his or her vision for life, the surgeon should want to take all possible precautions. Solomon: We used to do that in my practice and stopped about a year ago, because we saw it as charging patients for services that are not otherwise part of the normal routine. We now will obtain OCTs on those patients who we decide are candidates for premium lenses. We let these patients know there is going to be additional testing. It is not part of our normal routine, and this is not part of the fee that we normally charge. We do the same with topography-it is done only with premium lens patients. If you are considering a corneal refractive procedure following cataract surgery, do you create your flap before cataract surgery? Solomon: That depends on what the refractive error is. With the options available today, many patients will have overall residual refractive error reduced. I am more frequently performing PRK on these postoperative patients. LASIK is an option, but I think it depends on the refractive error. |