Presbyopia: Rethinking approach to better meet patients’ needs

July 21, 2020

Just as evolving technology is changing patients' visual demands, eye-care providers should increase their awareness and efforts to fill current gaps.

Presbyopia has long been both a challenging and frustrating condition for patients and physicians alike.

The problem has only magnified in recent years by society’s growing dependence on digital devices. Satisfying patients' full range of visual needs is now more challenging than ever.

Consider the statistics: Adults spend an average of more than 11 hours per day interacting with some form of media, including checking their smartphones every 10 minutes.1

Related: Researchers reaching for the stars to cure presbyopia

Even baby boomers are changing the way they communicate—they are seven times more likely to text than talk, and they use smartphones and tablets nearly 4 hours a day.1

The numbers are staggering: About 1.8 billion people globally have presbyopia,2 and 128 million people in the United States suffer from near vision loss.3

Although individuals have varying degrees of difficulty due to presbyopia, most report difficulty reading as part of their everyday activities.

A survey of 797 patients aged 40-55 years revealed that 96% of respondents claimed at least one daily activity is "somewhat affected" by presbyopia symptoms, while near one-half said the impact is “extreme.”4

What does this mean in practical terms?

Patients find workarounds to deal with near-vision loss, including keeping flashlights in every room, relying on magnifying mirrors, and placing special labels on pill bottles. They report needing help to read driving directions, printing out electronic documents, and enlarging text on their devices.

Related: Technology puts focus on presbyopia laser correction

No matter how creatively patients address their presbyopia, they are as a group unhappy. They struggle regularly with their near-vision loss, sometimes to the point of feeling helpless.

Although choices for near-vision correction include glasses, contact lenses, monovision corneal laser refractive surgery, corneal inlays, and IOLs, 90% of patients aged 40-55 years remain frustrated or irritated with presbyopia.

In part, this is due to the fact that even though nearly two-thirds of patients with presbyopia seek help from their eye-care provider, barely one-half report obtaining the information they needed, with just 15% of those surveyed indicating that they received printed educational material.5

Eye-care providers are falling short in managing patients with presbyopia. With increasing technology and treatment options, it is imperative that eye-care providers increase efforts to engage patients, educate them, and to provide solutions that more completely address patients’ needs and concerns.

Related: Presbyopia-correcting IOLs enhance customization


Achieving pseudoaccommodation

Surgical approaches
The various surgical approaches to treating presbyopia harness a variety of mechanisms for extending depth of field.

These include corneal-based approaches with excimer lasers, conductive keratoplasty, and corneal inlays as well as lens-based approaches with a variety of presbyopia-correcting IOL options.

Regardless of the actual technique, in the absence of movement and true accommodation, pseudoaccommodation leverages the eye's optical properties to increase depth of field through a variety of mechanisms, including:

  • higher-order aberrations (e.g., spherical aberration and coma)
  • residual astigmatism
  • diffractive/nondiffractive IOL technologies
  • refractive index change
  • pinhole effect/small-aperture optics

Small-aperture optics
Small-aperture optics or the pinhole effect is a method of pseudoaccommodation that increases the depth of field without the need for ciliary muscle engagement.

This occurs with miosis, or iris constriction and pupil size reduction. This mechanism and the resulting improvement in the depth of field can be utilized to relieve presbyopia symptoms.

The position of the pinhole is key to increasing the depth of field without constricting the peripheral visual field. If a pinhole is placed in front of the eye, like on the spectacle plane, the visual field is greatly reduced.

Related: How pinhole camera effect in small-aperture implant corrects presbyopia

A pinhole on the corneal plane has lesser peripheral field impact. A small aperture near the iris plane or small pupil would be ideal to provide increased depth of field while maintaining a full visual field.

Pupillary miosis can improve near vision, but distance vision can be lost when a pupil gets too small. Therefore, there is no specific number that describes the optimal pupil size for all individuals.

Rather, the best way to think about pupil size is as a percentage of the natural pupil size. This approach accounts for factors such as lighting and pupil size variability for each individual eye.

Studies shows that in all lighting conditions, pupils that are 40% to 50% of their natural pupil size will maximize near-vision improvement without sacrificing relative distance visual quality (see Figure 1).

Therefore, achieving an optimal pupil range allows for maximum image quality for both far and near vision.

Related: Study targets topical medication adherence, visual field progression

Conclusion
Presbyopia is an increasingly common age-related condition that affects almost all older patients on a daily basis, bringing frustration and irritation to the majority of sufferers.

Techniques that harness the principle of small-aperture optics and the pinhole effect, particularly utilizing the pupil, may hold promise for an improved approach to presbyopia correction.

This optimal method would place a pinhole at the iris plane to extend the depth of field without impairing the visual field.

As eye-care providers, we should more assertively educate and treat our older patients for this near-ubiquitous condition.

About the author
Daniel H. Chang, MD
Cataract and refractive surgeon, Empire Eye and Laser Center, Bakersfield, California
dchang@empireeyeandlaser.com

Financial disclosure: Dr. Chang is a consultant for Allergan and Johnson & Johnson Vision

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References
1. Nielsen Total Audience Report Q1 2018. https://www.nielsen.com/us/en/insights/report/2018/q1-2018-total-audience-report/. Accessed June 12, 2020.

2. Fricke TR, Tahhan N, Resnikoff S, et al. Global prevalence of presbyopia and vision impairment from uncorrected presbyopia: systematic review, meta-analysis, and modelling. Ophthalmology. 2018;125(10):1492-1499. doi: 10.1016/j.ophtha.2018.04.013.

3. Zebardast N, Friedman DS, Vitale S. The prevalence and demographic associations of presenting near-vision impairment among adults living in the United States. Am J Ophthalmol. 2017;174: 134–144. doi: 10.1016/j.ajo.2016.11.004

4. Data on file, Allergan. Survey of 797 patients aged 40-55 years.

5. Data on file, Allergan; Full Quantitative Summary. Survey of 1339 patients aged 40-55 years.