Article

Presbyopic Success with Multifocal Scleral Lenses

Presbyopia is inevitable and everyone who lives long enough will eventually become presbyopic with age. In fact, there are more than 130 million Americans over age 45,1 suggesting the prevalence of presbyopia is quite high, and it is expected to grow as the population continues to age. According to a study of contact lens wearers, 91% of wearers age 35 to 55 are committed to continuing contact lens wear.2 Multiple studies have indicated that multifocal contact lenses are preferred over monovision contact lenses.3,4 Patients prefer multifocal contact lens visual performance for most activities,5 even when visual acuity is better with monovision contact lenses.5 The advantages of multifocal contact lenses are numerous, including the ability to provide simultaneous vision. Educating patients about presbyopia prior to its onset is beneficial. Not only will patients think you’re a genius, but it makes for an easier transition to multifocal contact lenses.

Good Candidates

Many patients wish to remain free of spectacles for as much of their lives as possible. However, numerous studies have demonstrated that contact lens dropout ranges from 15% to more than 20%,6-10 even with current advances in contact lens technology. Contact lens dropout often occurs in the presbyopic population, around 40 years of age. The reason for contact lens dropout is multifactorial, according to the Tear Film and Ocular Surface Society (TFOS).11 Contact lens discomfort, which eventually leads to dropout, may be due to environmental factors or the lens itself. After age 45, vision and comfort are almost equally stated as reasons for contact lens dropout.12 The distinguishing factors of dry eye and contact lens dropout may blend. The prevalence of dry eye disease may be under-diagnosed and varies between 7% to 34%13-14 depending on how the disease is diagnosed, which population is surveyed, and the study citation.

Dry eye is one of the most common reasons for patients to visit their eyecare practitioners. Nearly 40% of people are experiencing dry eye symptoms on a regular basis,15 and studies suggest that dry eye disease may have a considerable impact on quality of life (QOL).16-17 A study by Schiffman and colleagues18 evaluated utility assessment scores to quantify the QOL of dry eye disease (DED) in patients. Moderate dry eye had a utility score of 0.78, which is in the same range reported for moderate angina (0.75),18 where perfect health has a utility score of 1.0, whereas death has a utility score of 0.

The distinguishing factors of dry eye and contact lens dropout may blend. In practice, we see that patients with clinical signs and symptoms of dry eye disease are more likely to experience contact lens discomfort.19 With advancing age, dry eye becomes increasingly prevalent, which may exacerbate contact lens discomfort.

Fortunately, scleral lenses are a comfortable option and they provide excellent optics. Scleral lenses can correct refractive error such as myopia, hyperopia, and astigmatism, and multiple multifocal options are available. Even in the past few years, numerous multifocal designs have been introduced for patients with corneal irregularity, ocular surface disease, and normal, healthy eyes. A supplemental benefit is that the post-lens fluid reservoir of scleral lenses bathes the ocular surface and helps soothe ocular surface disease and dry eye.

In practice, I like to offer multifocal scleral lenses to all appropriate candidates. These may include patients with corneal irregularities such as keratoconus, those with severe dry eye, such as patients who have Sjögren’s disease, or those with refractive error who experience discomfort with other lens modalities and are interested in continuing contact lens wear.

Case History, Evaluation, and Lens Selection

A detailed history is beneficial when fitting scleral multifocal lenses. Specific questions will identify the ideal lens correction. These questions include the following: Is there a previous history of contact lens wear? Have monovision or multifocal lenses been tried previously? Did a specific aspect of contact lens wear work — or not work? What is the motivation to wear contact lenses? Is part-time or full-time wear desired? Are contact lenses going to be used for work, sports, social occasions, or a combination of settings? How much time is spent on digital devices per day? Is there a significant amount of nighttime driving?

When selecting a multifocal scleral lens, there is no single lens design that can meet the visual needs of every patient. However, there are common factors to improve the chances of success with certain lens designs.

Determining best-corrected vision in each eye and binocularity will aid in lens selection. Multifocal scleral lenses can be fit on one eye only; however, there will be improved vision and depth perception with multifocal lenses in both eyes.

Eye dominance is especially useful when troubleshooting multifocal scleral lenses. There are multiple methods to determine eye dominance. Sighting dominance is when patients look through a hole between their hands. The eye selected is the dominant eye. Sensory dominance is when a lens is placed over each eye. The eye that does not tolerate the lens due to blur is the dominant eye. In a study of 72 emmetropes, sighting method with a hole in the card was compared to sensory method (+1.50 lens blur test).20 Right eye dominance was 71% with the sighting method and 54% with the sensory method. Of interest, laterality was in agreement only 50% of the time.

Pupil size and best-corrected vision in each eye help guide scleral multifocal lens selection. If vision is reduced in one eye, a modified multifocal fit may be beneficial. A multifocal can be used in the eye with better vision, and a single vision near lens may be used in the eye with reduced vision. Visual requirements are another factor when selecting lens design.

Once a scleral lens is fit and an over-refraction is performed, discuss the preferred lens design with the laboratory consultant. Most multifocal scleral lenses are ordered empirically, without a diagnostic lens fitting set.

It is important to set and manage realistic expectations when fitting multifocal scleral lenses. It is best to under-promise and over-deliver. The lenses may correct most, but not all, of their visual needs. Some specific activities may need reading glasses. Prior to prescribing lenses, it is important to discuss the fitting process. With multifocal scleral lenses, some manufacturers recommend fitting single vision distance lenses first to obtain an ideal fit and vision, and then proceeding with multifocal scleral lenses. Discuss the number of visits expected to obtain a successful fit and vision. The number of visits may vary; however, it may require more than two to three visits to achieve success.

Multifocal Lens Designs

Dual aspheric designs are advantageous to obtain binocular vision. These are better for lower adds (generally up to +2.00D), or those who require good distance vision while enjoying the advantages of a multifocal lens. An aspheric design is helpful to use in the dominant eye with a different design in the non-dominant eye.

Center-distance lenses are good for emerging presbyopes who want clear distance vision, as these lenses don’t induce distance blur. This design is preferred for people who require good distance vision such as pilots, drivers, and athletes as the distance portion of the lens is over the visual axis.

Center-near lenses are the design used in the majority of current soft multifocal contact lenses. The advantage of this design is improved near acuity. Center-near designs are valuable for people who require close distance work, especially digital device users who do most of their work up close. Different add powers may be used in each eye. Typically, a lower add power is used in the dominant eye and a higher add power is used in the non-dominant eye.

Problem Solving

Once a scleral lens is ideally fit, an over-refraction is performed. Generally, as scleral lenses settle, it is important to push plus power. With multifocal scleral lenses, it is especially important to push plus both monocularly and binocularly. Even 0.25 or 0.50D more plus power in each eye for distance can significantly improve binocular vision at intermediate and near distances. It is helpful to evaluate each eye monocularly to confirm that the patient is not over-minused.

For emerging presbyopes who are heavy users of digital devices, consider aspheric multifocal lenses in both eyes. Most people use digital devices each day and often use more than one device at a time. Studies demonstrate that the blink rate decreases to 66% less than normal while staring at a computer.20 Computer vision syndrome is a highly prevalent condition, affecting 75% of people who work on computers 21 and is more common in people over age 40.

If critical distance vision is required, consider a modified multifocal fit with a distance lens in the dominant eye and an aspheric multifocal lens in the non-dominant eye. If an aspheric multifocal design isn’t providing clear enough near vision, switch to a different design, such as distance-center or near-center multifocal design in the non-dominant eye. If glare or haloes are experienced with near vision, alter the add zone, especially in the non-dominant eye.

Use the minimal add power to obtain clear, comfortable vision at all distances. Do not use any additional add power than is absolutely necessary. An add power that is too high will require a closer working distance and blur distance vision.

Demonstrate binocular vision outside of the examination room in free space. Use different tasks to show distance, intermediate, and near vision in free space binocularly. A smart phone is a useful tool when demonstrating multifocality.

If vision with multifocal scleral lenses is good for the majority of the time, but not for specific tasks, investigate what those tasks are. Perhaps it is difficult to read a medicine bottle in a restaurant with dim lighting. It is acceptable for patients to use over-the-counter reading glasses for specific tasks. Also encourage the use of additional light if needed.

Discuss the importance of multifocal scleral lens adaptation. It may take up to 2 weeks to adapt to the lenses. This adaptation time requires patience. In a study evaluating clinical and electrophysiological predictive markers of monovision and multifocal contact lenses, there were no differences between the two types of correction.22 However, visual evoked potential of the P100 wave may be beneficial and the best indicator of stereopsis. This can be used to predict visual comfort when correcting presbyopia.

Embrace the Potential

There is huge potential for multifocal lenses — including scleral lenses — globally. In fact, less than 10% of presbyopes are fit with multifocal lenses in the United States.22 Scleral lenses provide superb vision and comfort and may be an option for presbyopic patients. Fitting these lenses is a great opportunity for patients and practitioners alike and is a tremendous opportunity to aid in the development of a scleral lens practice. ■

References

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