Presbyopic Lenses: Case by Case
PRESBYOPIC LENS OPTIONS
Presbyopic Lenses: Case by Case
Practitioners can meet the diverse contact lens demands of presbyopes by knowing the lens options.
By Nina Sera, OD, & Neil A. Pence, OD
Dr. Sera is a graduate of the Illinois College of Optometry and a Cornea and Contact Lens resident at the Indiana University School of Optometry.
Dr. Pence is director of the Contact Lens Research Clinic, Indiana University School of Optometry in Bloomington, Indiana. He is a consultant or advisor to B&L, CIBA Vision and Vistakon and has received research funding from AMO.
Presbyopic patients are increasing in number every year, and they present interesting challenges with contact lens fitting. As the demands for alternatives to managing presbyopia increase, more patients are inquiring about multifocal or bifocal contact lenses.
Presbyopic patients are a diverse group who have many visual demands and require a variety of corrections. Traditionally, monovision contact lenses were the most prevalent form of presbyopic contact lens correction. When suited for monovision, patients can function comfortably with the dominant eye corrected for distance vision and the nondominant eye corrected for near vision. The issue with monovision is the decrease and/or loss of binocular vision and depth perception, especially noticeable when patients need higher add powers. Many innovative multifocal alternatives have been introduced that are successful in managing presbyopia while maintaining functional binocular vision over a greater range of distances. Following are reports of patients who have had their presbyopic demands successfully met with contact lenses.
A 44-year old female professor had noticed progressive near blur with her current contact lenses and spectacles, especially when looking back and forth from her students to her notes while teaching. She currently did not wear a bifocal prescription or over-the-counter reading glasses, and she wanted to try multifocal contact lenses to avoid removing her spectacles while teaching.
Her spectacle prescription was OD –4.25DS and OS –5.75 –0.50 × 045 with a +1.50D add. She was wearing Acuvue Oasys (Vistakon) to address contact lens-related dryness issues she had experienced, and she was satisfied with the comfort of her lenses.
Her current lenses were OD –4.00DS and OS –5.25DS, with 20/20 visual acuities at distance. Considering the patient's needs and satisfaction with her current contact lenses, we fit her with Acuvue Oasys for Presbyopia (Vistakon), utilizing a –4.25DS OD and –5.50DS OS, both with the Mid Add (+1.75D). Visual acuities were 20/20 OU for distance and 20/25 OU at near. The patient was pleased while in the office, and at her follow-up visit she expressed her pleasure that she was able to work in the classroom without spectacles. She was very comfortable in general with the new lenses.
In this case, the patient was a presbyope who wanted contact lenses to halt the inconvenience of having to remove/replace spectacles while constantly shifting her vision from distance and near. She also wanted to maintain her comfort with the Acuvue Oasys material for her dry eye-related symptoms. Considering her visual demands, environment, current visual correction, and ocular health issues, we elected to continue using the Acuvue Oasys material. Thus, the patient was an excellent candidate for the Acuvue Oasys for Presbyopia contact lens.
This case is also an excellent example of a patient who is perfectly happy with her multifocal lens experience even though the near acuity was not a "perfect" 20/20. Visual comfort, especially with presbyopic contact lens options, is about achieving balance and allowing patients to determine success as opposed to basing it exclusively on the acuity chart.
A 40-year-old female nurse wearing OD –5.25 –1.25 × 160 and OS –5.00 –1.25 × 010 had no initial complaints of blur at near. At age 42, she switched to monovision with OD –5.25 –1.25 × 160 and OS –4.00 –1.25 × 010. Two years later the add increased by +0.25DS OS, and three years later increased to an overall add of +1.75D, with a –3.25 –1.25 × 010 lens power OS. At age 52, her near demand increased by an additional +0.50DS. We attempted a –2.00 –1.25 × 010 OS (equivalent to a +2.25D add) without success. The patient complained of vision loss at intermediate distances, such as when viewing the computer or dashboard of the car, and of feeling that her vision was just "less good, less comfortable" overall.
Considering her complaints and the need to increase her add, we attempted Proclear Multifocal Toric (CooperVision) lenses. We used a –5.00 –1.25 × 160, +1.50D add "D" lens OD and a –4.50 –1.25 × 010, +2.00D add "N" lens OS. She enjoyed success with this combination and was much more comfortable with her vision at all distances.
This case is an example of a patient who started wearing contact lenses for early presbyopia in a monovision system with her dominant right eye focused for distance vision. She was successful with monovision for a number of years until her add increased to where the disparity between the two eyes became too high to tolerate. We then fit her with the Proclear Multifocal Toric, which provided a mild modified monovision system, greatly decreasing the disparity between the two eyes. These toric lenses are provided in dominant (D lens, center distance, surround near) and nondominant (N lens, center near, surround distance) designs, each with progressive aspheric intermediate transition zones. This combination allowed the patient to have some overlap in prescription between the two eyes, greatly decreasing the large disparity experienced with straight monovision and allowing more comfortable vision at distance, intermediate, and near.
A 53-year-old female nurse noticed increased blur while working at the computer and while reading charts. Her spectacle prescription was –1.25DS OU with a +2.00D add. She had been wearing GP multifocals (Essential II Multifocals from Blanchard Contact Lens) with the following lens parameters:
- Base curve radius (BCR): 7.80mm OD, 7.90mm OS
- Power: –1.25D OD, –1.75D OS
- Overall diameter (OAD): 9.50mm OD, 9.50mm OS
- Concentric S-Form Add (CSA): +2.00D OD, +2.00D OS
This lens is a posterior surface aspheric design, and the CSA adds additional asphericity to the front surface to increase the add power effect. Visual acuities with the GP multifocals at distance were 20/20– OU and at near were 20/100 OD, 20/40 OS, and 20/60 OU. Evaluating the fit, we found that the right lens centered well in primary gaze without any translation on down gaze, and the left lens decentered inferiorly after a blink in primary gaze and likewise did not translate on down gaze. We refit the patient with a flatter BCR OD (8.0mm), –0.75D power and a steeper BCR OS (7.8mm), –1.75D power with a +2.50D CSA OU and no change in OAD OU. The lenses centered well on the patient's eyes in primary gaze and translated well on down gaze for improved reading effectiveness. Visual acuities at distance were 20/20 OU and at near were 20/25 OU, and the patient was satisfied with the results. She had some difficulty seeing very fine detail, such as medicine bottle labels, and we suggested +1.00D reading glasses to wear over her contact lenses for very occasional wear when improved near vision was required.
It's important with most GP multifocal designs that the lenses center well in primary gaze to optimize distance vision. Generally, some translation upward is desirable on down gaze so that areas designated more for the add power are positioned in front of the pupil. Lens decentration will cause halos or ghosting, and no lens translation will result in decreased near and intermediate vision effectiveness. Steepening the BCR will usually allow the lens to center better on the eye, and flattening the base curve may allow the lower edge of the lens to be pushed up more by the lower eyelid when looking down due to the resulting increase in edge clearance. While the add power may appear high compared to her spectacle add power, this is not an unusual case when fitting many GP multifocal designs.
A 53-year-old female had previously attempted monovision contact lenses, but had been unhappy with her vision and did not continue wearing them. The patient was not able to handle the difference in prescription between the two eyes and stated a desire for improved depth perception when playing tennis as well as the ability to read comfortably with contact lenses.
Her spectacle prescription was: +1.00 –0.25 × 090 with a +2.25D add OU with 20/20 visual acuities at distance and near, and she was OD dominant. We fit the patient with PureVision Multifocals (Bausch & Lomb) +0.50DS, high add OU. Distance visual acuities were 20/20 and near 20/25. The patient returned for a follow-up visit and was very content with her distance and near vision while wearing the multifocal lenses. She also stated improvement when playing tennis compared to being uncorrected.
This is a great example of a patient for whom one form of presbyopic contact lens correction was attempted without success, and the patient gave up on the idea of being able to wear contact lenses. Eventually the frustrations of multifocal spectacles led her to try contact lenses once again. With the need for a +2.25D add power, she is not an ideal candidate for multifocal lenses, and having been a previous "failure," she probably would not be encouraged to attempt contact lenses in many offices. The fact that she was successfully fit relatively easily with PureVision Multifocals is a great reminder to not pre-judge success and failure, and to allow all your patients the opportunity to experience the benefits of contact lenses.
|Presbyopic Lens Fitting Pearls|
- Due to the limitations of monovision, always present the contact lens multifocal option to every interested presbyopic patient. Monovision wearers not totally satisfied with their correction are excellent multifocal candidates.
- Determine what a patient's primary goals are and attempt to meet them. A patient with a primary goal of seeing well at the computer and secondarily at near may require a different multifocal lens than someone whose priority is distance vision and secondary is reading.
- Remember that blur may be present with some distances, but visual comfort is most important; allow patients to determine success as opposed to basing it exclusively on the acuity chart. Have several different multifocal designs available to satisfy varying patient needs.
- With the knowledge that tear volume decreases with age, include lens designs and materials that target borderline dry eye patients as options for these individuals.
- Never indicate to patients that glasses will not be necessary with contact lens multifocals. If you successfully meet their primary needs, they may still require occasional spectacle use for small print or critical distance tasks.
- Numerous GP multifocal designs have recently been introduced, available in high add powers, often with some or all of the add on the front surface to correct moderate presbyopes who have critical vision demands.
- It is important for GP multifocal lenses to center well and to exhibit some translation on downward gaze. If excessive movement is present with primary gaze, steepen the base curve radius.
It is important to consider all of a presbyopic patient's needs when determining the most suitable approach with regard to contact lenses. A few factors to consider when selecting an appropriate modality would be individual visual demands and requirements, current visual correction, ocular health, the options available and, most importantly, the patient's ultimate goals with contact lens wear. Visual demands and requirements to consider would be occupation, leisure activities, positions of gaze, and typical environmental and lighting conditions the patient encounters. A patient who requires clear and comfortable vision while working on the computer and reading small print may require a different modality than one who requires seeing well at distance and occasionally desires to be able to read a magazine. If a patient has any ocular surface diseases or conditions that may affect contact lens wear such as allergies or dry eyes, you may initially consider a daily disposable lens or a material specifically recommended for dry eyes.
Most of all, patient expectations and goals are key. Inquiring about tasks and activities a patient wants to do while wearing contact lenses, wearing time, flexibility with wear, and realistic expectations all contribute to a successful multifocal contact lens wearer.
In general, distance vision must be sufficient for patients to be comfortable with their correction choices. There are certainly exceptions, when near demands are critical enough to warrant sacrificing more distance vision. It is not uncommon, however, to have patients state a strong desire for excellent near acuity and acknowledge in the office their understanding that distance vision will be compromised, only to return having realized that they really are bothered by the decreased distance vision. More often, patients will accept a little less precise near vision in return for distance vision being less affected by the bifocal/multifocal powers.
Patients are successful wearers if they are able to perform the majority of daily activities comfortably. Supplementing the contact lenses with occasional readers or driving glasses over them, or using other vision alternatives for a few tasks, should be considered normal practice and not somehow an acknowledgement of failure.
It is important to listen to a patient's definition of success and to realize that you can achieve an acceptable vision correction in most cases. Knowing the presbyopic lens options, making use of alternatives, and listening to patients can make any practitioner a successful presbyopic contact lens fitter. CLS
Contact Lens Spectrum, Issue: May 2009