Reader and Industry Forum
What the Future Holds for Presbyopic Contact Lenses
BY KEITH PARKER, NCLEC
The future of presbyopic contact lenses is very clear when we take a close-up look. The quality of optics available in all ranges of soft and GP lens manufacturing have improved tremendously. However, the improvement of verification and evaluation equipment is what has been responsible for the vast improvements in consistent manufacturing and in production of multi-optic designs.
Where We Are Now
Using precision manufacturing to control the placement of the multi-optic zones is now the norm in most custom contact lens manufacturing laboratories. This means that we can effectively produce sophisticated optics in very specific zones within a confined area of a contact lens.
The improvement of refractive analysis through high-tech automated refractive evaluation systems allows a fitter to pinpoint desired functional acuity requirements and visual demands for a particular patient. This information is provided to a manufacturing consultant to produce a lens with the specific amount of power distributed within the lens zones to accommodate the physical dynamics of that patient’s pupil and visual axis.
To summarize so far, manufacturing advancements and high-tech refractive analysis allow for the delivery of exceptional optics in both GP and soft contact lenses.
So what’s next on the horizon for multifocal lens technology?
1. Peripheral Visual Alignment Now that we better understand the role of peripheral refractive positioning in the development of refractive error, we should see an increase in the use of presbyopic designs for controlling myopia progression. Center-distance, near-peripheral-zone lens designs will allow practitioners to provide specific powers to designated areas of the retina.
Studies continue to show that many children may benefit from the use of presbyopic designs to aid in the development of their visual system (Berntsen and Kramer, 2013; Walline et al, 2013). The ease of fitting young children has increased in both GP and soft lenses, making multifocal lenses for children a viable option.
2. Young Presbyopes Young presbyopes are getting younger due to the increased use of hand-held visual devices. We all live in a computer world. Near vision is the primary visual range that too many of us utilize all day long. The needs for low-add multifocal options have therefore increased and will continue to do so.
3. Older Presbyopes Older presbyopes are more active than ever before. They do not want to give up contact lenses just because of their advancement in presbyopia. The ability to provide higher adds and specific zone sizes positioned in line with the visual axis allows almost any patient who is willing to work through the fitting process to be successful with multifocal contact lenses.
Barriers to Success
As mentioned previously, manufacturing precision optics within specific zones is now a reality. However, the age-old problem of positioning the optical axis of the contact lens precisely in line with the visual axis of individual patients is still a barrier to success. The natural blinking dynamics needed in healthy lens wear create a mechanical concern of inconsistent visual performance.
Properly fitting contact lenses by selecting the correct lens diameter based on the size of the cornea will improve the overall fitting relationship. Understanding the need to identify each patient’s horizontal visible iris diameter will aid in obtaining this proper fitting relationship. Continuing to ask manufacturers to custom make lenses based on Ks and prescription alone is a barrier.
Contact lens rotational stability has always been a barrier. Traditional corneal contact lenses must move on the eye to provide needed tear exchange for ocular health. Placing optics in a specific zone is ineffective if the lens moves or rotates more than desired. Minimal movement of the lens with normal blinking/lens wear will be a barrier due to inconsistent vision.
Continued developments in both soft and GP multifocal lens technology are helping to resolve these issues. Newer mass-produced soft multifocal designs are more stable and come with fitting guides that help in achieving the best possible fit. Custom soft multifocals can be designed with varying zone sizes and precise parameters and powers.
Corneal GP designs are constantly improving and easier to fit. They also offer the crisp GP lens optics at distance and near.
More scleral lenses are becoming available in multifocal options. These lenses move very little on the eye and so offer the stability to help optimally placed optics remain in place for the duration of the wearing period.
Finally, a clear prosthetic optical shell designed by taking an impression of the front surface of the eye is now available, producing an optimally aligned fitting relationship to each individual ocular surface. This design does not rotate or move because it matches the contours of the individual eye, which allow multifocal optics to be placed consistently in line with the patient’s visual axis for more consistent visual performance.
Presbyopic contact lenses will continue to play an increasingly important role in providing functional vision for many types of patients both young and old. As technology and research come together, a new visual customization will evolve. It is clear to see that the future is bright for this modality. And, as we look up close, we can see the successful distance on our patients’ horizon. CLS
For references, please visit www.clspectrum.com/references and click on document #244.
Keith Parker is president of Advanced Vision Technologies and co-founder of EyePrint Prosthetics LLC. He is a past president of the Contact Lens Manufacturers Association (CLMA) and currently continues to serve on the CLMA Board of Directors.