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The new year is upon us and, like every year, we realize that the aging process continues to progress. Presbyopia is a mainstay of each of our practices, and it has the potential to be a burden or an opportunity depending on how we look at our patients and the treatment options available to them.
Presbyopia is a combined process of the crystalline lens hardening and the process of the ciliary muscles/zonules weakening. In addition to the accommodative issues that patients experience, presbyopia brings with it a reduction in contrast sensitivity, the need for additional light, increased light scatter, and a reduced ability to cope with glare.1 This process affects everyone at different ages, but clinically, we typically see the symptomatic start of presbyopia begin when patients are in their early 40s. We must keep in mind, however, that the structural changes as a result of presbyopia begin much earlier. As such, patients modify their behavior or adjust to this visual change by adapting. Often, these adaptations can result in eyestrain, headaches, dry eyes, or decreased visual performance. By incorporating the ideal visual correction at the appropriate time and for the tasks that patients undertake, we can better meet their needs.
OPTIONS FOR VISUAL CORRECTION
When it comes to correction options for presbyopic patients, many of us first think of progressive addition spectacle lenses (PALs). With hundreds of PAL designs on the market, this is an understandable option for patients. These lenses offer our patients superior vision without the image jump that is common with traditional bifocals. PALs provide our patients with superior vision at most distances due to the progressive power shifts as patients look through the lens. Like with single-vision lenses, at any one location in the lens, patients’ vision is isolated to that single-power profile, which allows them to have ideal vision at that single point of the lens. Although ideal if the patient is aligning the area of wanted vision with the location of the lens, this can be problematic if the patient is not gazing through the portion of the lens that lines up with the distance that they wish to view. Depending on the spectacle lens design, this is most often experienced at a computer distance when a patient has not placed his or her computer at the appropriate height. Therefore, he or she either has to modify their head position or look through an improper portion of the lens that does not provide the most ideal vision. In our offices, we fix this problem by either working with the patients viewing distance and computer position, or more preferably for visual comfort, prescribe a computer-specific PAL, which has their computer distance in the primary gaze and near correction in inferior gaze. This allows the patient to have a proper head position and ideal visual function.
DISADVANTAGES OF PALs
Although visually superior to bifocal or trifocal lenses, PAL lenses have their downsides as well. In addition to improper visual height adjustments and viewing distances, patients wearing PALs often struggle with peripheral aberrations.2 This is due to the inherent design distortions that exist in the inferior periphery of PAL designs. As most of us have experienced, some patients notice these aberrations more significantly than other patients, especially when making quick head movements where the vision is described as “swimming.” Most of the newer PAL designs have nearly eliminated the peripheral aberrations or made them so insignificant that patients do not notice. If patients do become aware of this swimming movement, we find that by having them learn to make slower head movements in combination with adaptation periods can help to alleviate these symptoms.
NEW PROGRESSIVE TECHNOLOGY
For many practices, PALs are the mainstay of the visual correction for presbyopic patients. They certainly provide patients with phenomenal vision, but they have some disadvantages. By becoming familiar with newer progressive technology, incorporating designs for specific tasks, and with proper education, we can provide our patients with ideal vision for their desired tasks.
Contact lenses may provide many patients with the vision correction they desire. Contact lens correction for presbyopia has been available for many years, but it is now increasing in popularity, and its design technology is improving.
Historically, monovision was the mainstay for presbyopic patients. Typically, patients are started in monovision in their early or emerging years of presbyopia. This is an easier transition, as patients are often able to maintain stereoacuity despite the minimal amount of blur that they have at distance from their nondominant eye, or near from their dominant eye. As patients age and they are given an increasing add power in their nondominant eye, their power shift becomes more significant, and they begin to lose their stereo ability. This is a gradual process over years, so many patients may not notice this loss. Patients eventually will begin to notice that, despite their clarity of vision at distance and near, their midrange vision begins to blur. This is because the powers of the lenses are monofocal and do not award them with a range of vision that they would achieve with multifocal contact lenses or PALs. Patients may also develop aniso- metropia. A study at the University of Houston College of Optometry found that after 12 months of using monovision correction, 29% of subjects had higher than 0.50 D of anisometropia. Some patients had as high as 1.25 D of anisometropia at the completion of the study.3
MULTIFOCAL CONTACT LENSES
When given a choice between monovision and multifocal contact lenses, most patients will opt for the latter. In a study at the Ohio State University College of Optometry, individuals were randomized to monovision or multifocal lenses. After 1 month, patients’ visual acuity at high and low contrast was measured, and then the patients were crossed over to the other modality. After 1 more month of lens wear, patients’ visual acuity was again checked, and they were asked for their preference of lens. Although patients achieved slightly better low contrast acuity through the monovision lenses, 76% chose to wear multifocal lenses.4 In another 1-month crossover study completed at the University of Alabama Birmingham School of Optometry, patients were fit with monovision and multifocal lenses. Nearly 70% of the participants in this study preferred multifocal contact lenses to monovision.5
With the improved technology of multifocal contact lenses, we have several design concepts to work with for our patients. Lenses are available with center-near as well as center-distance designs. These employ concentric rings, asphericity, or a combination of the two and graduated designs that transition from near to distance or distance to near. Historically, many of us have struggled with fitting guides and lens designs, concluding that multifocal lenses are complicated and difficult to fit. With the current lineup of lenses available and with the new modified fitting guides that manufacturers offer, soft multifocal contact lens fitting has never been easier. In a study of a new lens design including 294 practitioners and 2,455 patients, it was found that fewer than four lenses were required to obtain a successful fit. This was achieved over a period of 2.4 visits. About 95% of practitioners agreed that the lenses were easy to fit—in fact, 64.3% said they were as easy to fit as spherical lenses.6
PATIENTS’ DESIRES AND EDUCATION
When they question us about multifocal contact lenses, we find that most patients are interested in the modality because of its benefits for their near vision. Patients struggle with the range of vision with their monovision lenses, the hassle of over-the-counter readers over their spherical lenses, or the frustration of multiple pairs of glasses and head bobbing with PALs. In discussing multifocal contacts with patients, we share with them that the lenses will provide a better range of vision than they achieve with monovision or with spherical contact lenses. Initially upon lens insertion, we block out the distance acuity chart and highlight the visual tasks that the patient is most interested in. We have them view their cell phones and/or computer screens while wearing the lenses. Patients tend to be shocked by the added visual benefits that they achieve.
Next, we slowly begin to work our way down the distance acuity chart, not by presenting every line, but by showing them individual lines starting with the 20/50 line. Around the 20/40 line, we congratulate the patient on being legal to drive in our states of practice while continuing down the chart. Usually around the 20/40 or 20/30 line, patients begin to notice that something is different from when they are using their usual glasses or distance contact lenses. We are surprised at how often these patients will have a visual acuity of 20/25 or 20/20 OU. Then, we step back and explain to the patient that he or she is no longer wearing monofocal lenses, and the new lenses have the added benefit of providing all ranges of vision at all times. This has benefits in that it allows patients to have a larger range of vision, but may have some drawbacks in that their vision is initially different due to the clarity at many focal lengths. We assure our patients that some cortical adaptation will take place, and we continue to progress down the eye chart.
In our offices, we usually gauge success when we are able to achieve a distance vision binocularly of 20/25 or 20/20 and near tasking to the patient’s desired level. We have found that this method of highlighting the strengths for patients has increased our success rates and has helped them understand the benefits of multifocal lenses.
With all presbyopic corrections, whether bifocals, trifocals, progressives, single-vision contact lenses with readers, monovision, or multifocal contact lenses, patients have great visual potential. All the modalities have their strengths, and all have their weaknesses. Fitting patients into any of these options earlier in their presbyopic years will result in the most success, as visual transitions from distance to near are less abrupt for emerging presbyopes to adapt to.
With the advent of newer technology, we have great opportunities to advance the visual and lifestyle activities of our patients. By finding out what is important to them visually, we can customize their correction to meet their needs.
Mile Brujic, OD, is a partner at Premier Vision Group in Bowling Green, Ohio. Dr. Brujic may be reached at (419) 352-2502; email@example.com.
David Kading, OD, is a partner with the Specialty Eye Group in Kirkland, Washington. Dr. Kading may be reached at (425) 821-8900; firstname.lastname@example.org.
- Keeney A, Hagman R, Cosmo F. Dictionary of Ophthalmic Optics. London, UK;Butterworth– Heinemann;1995:240.
- Heiting G, Mattison-Shupnick M. Progressive lenses replace bifocals for age-defying appearance. http://www. allaboutvision.com/lenses/progressives.htm. Accessed January 3, 2013.
- Wick B, Westin E. Change in refractive anisometropia in presbyopic adults wearing monovision contact lens correction. Optom Vis Sci. 1999;76(1):33-39.
- Richdale K, Mitchell GL, Zadnik K. Comparison of multifocal and monovision soft contact lens corrections in patients with low-astigmatic presbyopia. Optom Vis Sci. 2006;83(5):266-273.
- BenjaminWJ. Comparing multifocals and monovision. Contact Lens Spectrum. February 2007. http://www. clspectrum.com/articleviewer.aspx?articleid=100637. Accessed January 3, 2013.
- Rappon J, Bergenske P. Air Optix Aqua Multifocal contact lenses in practice. Contact Lens Spectrum. 2010;25(3):S7-S9.