Clinical Pearls for Fitting Soft Multifocals
The Association of Optometric Contact Lens Educators offers troubleshooting tips and fitting advice.
By Vinita Allee Henry, OD, FAAO
Dr. Henry is a clinical professor, co-chief of the Contact Lens Service and director of residencies at the University of Missouri-St. Louis, College of Optometry. Her research is primarily in contact lens designs, materials and solutions.
In the 1980s, soft contact lenses were introduced to correct presbyopia. The first lenses produced were expensive and lacked durability. Disposable and frequent replacement multifocal lenses have made soft multifocals more cost effective and convenient for wearers.
The introduction of silicone hydrogel materials and new designs opens a new direction to optimize ocular health, vision and ability to wear lenses for extended or continuous wear. The baby boomer population is increasing, and many of these current contact lens wearers are not willing to give up contact lens wear for spectacles or readers. Current multifocal lenses are easier to fit and are showing an upward trend in use.
In 1974, the Association of Optometric Contact Lens Educators (AOCLE) was formed. This organization consists of contact lens educators from the 19 schools and colleges of optometry currently educating students. Its goal is to enhance and foster education in the area of cornea and contact lenses (aocle.org). The commitment to contact lens excellence and education within this group is of the highest quality. I surveyed AOCLE members to gather clinical pearls for fitting soft multifocal contact lenses and coordinated their responses in the information that follows.
Patient motivation and education are important to fitting soft multifocals. Patient education begins with a thorough explanation of patient options. This includes discussing bifocal spectacles, distance-only contact lenses with reading glasses, monovision and multifocal contact lenses — GP and soft. The education should emphasize that these are specialty lenses that require more time to fit and might require trying more than one lens design to achieve success.
Good candidates for soft multifocals include patients who currently wear contact lenses successfully, who dislike wearing spectacles, who equate old age with bifocal spectacles and who demonstrate motivation to find the contact lenses that work for them.
In addition, you can't overestimate your own role. Becoming familiar with the lens designs, lens materials and fitting guides, in addition to enthusiastically trying the lenses with prospective multifocal patients, aids success.
In the past, soft monovision wear has been successful as practitioners have been wary of trying designs that require more chair time, especially when the results had been less than optimal. The new designs are much easier to fit and chair time is less. Patients enjoy improved stereoacuity and more usable vision when both eyes are viewing binocularly at distance and near. Studies show that when comparing monovision to multifocal lenses, even in the same material with similar visual acuity results, patients prefer multifocals 3 to 1 over monovision (Benjamin, 2007 and Richdale et al, 2006).
Table 1 shows some basic fitting steps for soft multifocals. When selecting a lens for a presbyopic patient, the following tests are important: keratometry readings, refractive error, add power, dominant eye determination, tear break-up time (TBUT), wearing time and ocular health.
Once you've selected the lenses, allow them to settle 15-to-20 minutes before testing visual acuity. Use normal room illumination, although using a lamp at near may increase near acuity. Perform acuity testing binocularly with the over-refraction and perform the over-refraction monocularly to determine the best powers for the patient's visual needs. Don't use a phoropter to perform the over-refraction. Flippers with ±0.25D and ±0.50D lenses are invaluable when performing over-refraction on a multifocal patient.
Rather than using a 20/20 line on a nearpoint card, use a reading card with various print types to simulate the real world and allow patients to determine whether vision is satisfactory. Visual acuity of 20/20 at near may not be necessary for the patient's primary near vision tasks. Adds of unequal powers may provide better overall distance, intermediate and near vision.
|Basic Fitting Steps|
The AOCLE offers additional fitting pearls in Table 2. Notice the importance of patient selection and education in these pearls. Potential soft multifocal patients must meet the same requirements as soft spherical or toric patients. There should be no significant ocular health issues of the anterior segment (corneal dystrophy, keratoconus). A tear breakup time of 10 seconds or greater is preferred. Current contact lens wearers, dissatisfied monovision patients, early presbyopes and patients with an active lifestyle make good candidates for soft multifocals.
It's important to review a patient's visual tasks and hobbies to select the right lens. A patient who uses the computer all day, a truck driver and an accountant may have very different primary visual tasks that require a lens that performs well for the particular distance they use most. Presbyopes may benefit from a handling tint, a lens that is easy to handle or a lens that has approval for extended or continuous wear.
Patience is an important virtue on the part of both patient and practitioner. Some patients will require greater education on lens designs and expectations. Emphasize that just because one lens doesn't work, that doesn't mean none will. Generally, good education prior to starting the fitting process results in a patient who is more motivated and less frustrated.
After educating the patient, select a lens that matches the patient's needs. The lens should center and fit like other soft contact lenses. Assess visual acuity at the patient's primary visual distances. Many occupations require the use of a computer, so most patients will benefit from sitting in front of a computer and viewing information that simulates their work material.
Perform an over-refraction and assess the clear range of vision for the specified visual distances. Encourage patients to bring particular work materials or hobbies with them if they can to check visual acuity for everyday tasks. For example, a seamstress may want to bring some sewing along to try. Patients and practitioners should not feel that the fit is a failure if over-the-contact-lens readers are needed for long-term, detailed near tasks. Educate patients that it's beneficial to be able to complete most everyday tasks with the contact lenses only (sports, shopping, reading a menu, etc.)
When performing an over-refraction, small changes in the sphere value will make a big difference. Often you can manipulate the distance sphere value to provide good vision without having to increase or decrease the add. Many patients end up with a lower add in the dominant eye and a higher add in the non-dominant eye. This results in better visual acuity at all distances.
Determining the dominant eye by sighting through a triangle made by the hands is helpful, but two other tests that help confirm the result are having a patient sight a camera and using plus lenses. When performing the plus lens test, place a +1.50D to +2.00D lens in front of one eye, and then the other eye, while viewing a distance target. Ask the patient which eye has blurry vision with the lens. The eye that is blurry with the lens is the dominant eye. Many practitioners rely more on this test than the sighting test to confirm the dominant eye.
After the testing is complete, patients should trial the lenses in their real world environment for three-to-four days before you make any changes necessary to meet their visual needs.
The AOCLE respondents advised reviewing the manufacturer fitting guides and becoming familiar with the steps to fit the lenses. Manufacturers include troubleshooting tips in most fitting guides. In addition, the manufacturers have Web sites that aid in fitting and troubleshooting. Several of the sites have calculators that aid in lens selection.
If the initial lens does not provide satisfactory vision, it's important to determine whether the vision needs to be corrected at distance or near. Correct distance vision before near vision in cases where both are not good. Simply adding 0.25D steps in plus or minus with flippers over one eye or both will make large changes. If the problem is at distance, determine which eye has reduced distance vision monocularly. After determining which eye is reduced, try adding +0.25D over the eye. If that fails to provide satisfactory vision, try reducing the add power in the dominant eye.
If near vision is not adequate, check monocular acuities and add +0.25D distance power in the eye with reduced vision. If greater than +0.50D is needed with the flippers, increase the add in the non-dominant eye.
It's important to remember that you should check any power added to the distance at near and vice versa. In soft multifocals, with the exception of one translating design (Triton, Gelflex Laboratories), the lenses are simultaneous vision. Any power added to the lens is effective in both distance and near powers. For example, a patient wearing a –1.00D lens with a low add PureVision Multi-Focal (Bausch & Lomb) that takes a –0.25D over-refraction to obtain 20/20 visual acuity at distance will require that near vision be checked with the –0.25D flipper in place to see if near vision is affected.
If a lens design is not working, discontinue that design and try another. Although one design may be successful on many patients, there are some patients who find satisfactory vision only in an alternate design. Having several fitting sets on hand helps provide variety to the fitting choices. Patient education about different designs can minimize frustration in the fitting process if a lens design isn't working. This reassures the patient that there are various lens designs and that you just need to find the right design for that patient.
Finally, some patients will benefit from a GP multifocal lens, so provide that as an option, especially if all the soft multifocal options have failed. Some patients find that GP lenses improve visual quality, especially for patients who have corneal astigmatism. See Table 3 for a summary of troubleshooting tips by AOCLE practitioners.
The following case examples are based on fitting experiences of AOCLE practitioners and the author.
Case 1. A patient came to the office reporting blurry near vision. She had worn soft contact lenses for many years and didn't want to return to glasses. Her refraction was: OD –6.50DS, OS –6.00DS and add +1.00D. Her previous lenses were –6.00D OU. The patient had many questions and doubts as to whether multifocal contact lenses would work for her.
The lenses selected were Biomedics EP (CooperVision), OD –6.00D and OS –5.75D. It's not necessary to specify an add power for this lens. The patient had 20/20 distance vision and 20/20- near vision. When viewing a reading card with various reading samples, she was satisfied with her near vision. She uses a computer at her work and was satisfied with her intermediate vision.
She returned within a week for a follow up and reported that she was experiencing difficulty reading her cookbooks and was uncomfortable that her eyes now have unequal powers for distance. She felt that the lenses might be decreasing her vision OS.
Visual acuity was still 20/20 at distance OD, OS, OU and her near vision was good. She mentioned that she has poor lighting in her kitchen, so her practitioner educated her that good lighting may be needed for small print. She admitted that she had been able to use the lenses for all her tasks except perhaps in her kitchen or reading a small print book for long periods.
Patience and reassurance on the part of the practitioner and some tips to aid her near vision complaints (good lighting, readers over the contact lenses) appeared to relieve her complaints. The practitioner also educated her on how the left eye is fully corrected and that over-minusing that eye to –6.00D will only affect her near vision. After reassurance, the patient appeared happy and satisfied with her new multifocal contact lenses.
Case 2. A 66-year-old patient had been wearing a PureVision (B&L) Multi-Focal on her near eye and a soft toric lens on the opposite eye in a modified monovision. She wanted to have multifocals for both eyes.
Refraction revealed that her astigmatism was less than 1.00D, so she was fit with PureVision Multi-Focals in the high add power on both eyes. The patient reported high satisfaction with the new lenses and good visual acuity. At the follow-up visit, she mentioned that she is much more satisfied with the multifocal lenses OU than she was with the previous modified monovision.
Case 3. A long-term soft lens patient was interested in multifocals. She was fit with Frequency MF (CooperVision). At the follow-up visit, she reported dissatisfaction with her near vision. Over-refraction with +0.50D flippers revealed that she needed a higher add on the non-dominant eye.
The patient appeared very frustrated with the length of the visit. Upon discussion, she expressed that she was sorry for being such a difficult patient. She related that her previous fits were simple. The practitioner then stopped to discuss the multifocal fitting process, explaining that these are specialty lenses and it may require slightly more time to find the final lens. The practitioner also mentioned that having her try the lens in her real world setting and then tweaking the prescription helps obtain the best lens for her. She became reassured that she's not a difficult patient and that hers was a fairly customary multifocal fitting experience. The patient's countenance changed and she enthusiastically became a part of the fitting process. She became very satisfied with her new contact lenses.
|Fitting Tips from AOCLE Practitioners|
Case 4. A long-term soft toric monovision patient requested soft toric multifocals. To complicate the fitting, he has a busy work schedule and never has much time to allow for a fitting. He had a history of struggling to obtain the correct astigmatic correction for optimal visual acuity. His practitioner was less than enthusiastic about changing lenses that were working, but after educating the patient on what's available and that it may take some time to complete the fit, the patient and practitioner decided to move forward.
The patient was fit in Proclear Multifocal Toric lenses (CooperVision). Although his dominant eye is his left eye, his vision was less than 20/20 at distance in that eye because of irregular astigmatism. The practitioner decided to fit the D lens on his right eye (non-dominant), which has 20/20 distance acuity, and the N lens on his left eye (dominant). Despite the fact that this patient didn't look like a promising soft multifocal candidate, he is quite happy with his vision and the fit is successful.
Case 5. For several years, a patient had been wearing Acuvue Bifocal lenses (Vistakon) and was satisfied with her vision. At a recent visit, she was no longer happy with her near and distance vision. Altering her distance or add powers did not improve vision. A trial pair of PureVision Multi-Focal lenses was attempted on the patient. Although little change in her refraction was noted, the patient expressed better satisfaction with the new lenses. After a follow-up visit, she reported satisfaction and improved vision with the change in lens design. This is an example of when one lens design is not successful for a patient, changing to a new lens design with little to no power change may result in a successful fit.
Case 6. A 60-year-old lawyer presented for a soft multifocal contact lens fitting. He was particular about his distance visual acuity. He was fit with the Proclear Multifocal lens, with the D lens in his dominant eye and the N lens in his non-dominant eye. Although he reported good distance visual acuity at follow up, he desired better near vision. The practitioner tried two N lenses, and the patient returned very satisfied with distance and near vision with both eyes. Although this patient may be an exception to the rule, it's an important point that you may need to find creative alternatives for some patients.
|Troubleshooting Tips from AOCLE Practitioners|
If fitting soft multifocals has appeared to be a daunting task, now is a good time to try fitting presbyopic patients into this lens modality. The new designs and lens materials are successful for presbyopic patients. Chair time is reduced, and satisfaction with the lenses is good. Baby boomers like to invest in products that keep them looking youthful, and multifocal lenses are an excellent option for theses patients. As you work with the lens designs, your confidence will increase and creative solutions such as unequal adds, mixing lens designs and modified monovision will become straightforward. CLS
Acknowledgements: The author would like to acknowledge and thank the individuals of the Association of Optometric Contact Lens Educators for sharing their experiences.
To obtain references for this article, please visit http://www.clspectrum.com/references.asp and click on document #152.