Presbyopia is defined as the gradual loss of ability to see objects from up close. While such vision changes mostly affect individuals over the age of 40, an increasing prevalence of detrimental refractory vision changes has more recently been noted amongst younger individuals.

The statistics on vision are alarming:

• Over 70% of US workers need vision correction
• Myopia affects nearly 34% of the world’s population
• Nearly 61% of Americans need some type of corrective vision eyewear for myopia
• 31% of Americans require vision correction caused by presbyopia
• When uncorrected, refractive errors are the primary contributor of moderate and severe vision impairment

Presbyopia a Common Vision Issue

In a previous blog post, we discussed presbyopia. To briefly summarize, presbyopia is caused by a combination of reduced flexibility of the eye lens and weakened eye muscles, which interfere with the ability of the lens to focus.

Presbyopia, which is a refractive type of vision loss, causes vision distortion and an inability to see things clearly from up close. A common sign indicating that an individual may be experiencing presbyopia is the need to extend printed materials (books, prescription bottles, cooking instructions on food labels) further from the eyes – hence the term 'short-arm syndrome'.

Presbyopia has long been perceived as an age-related disorder. Today, however, increasing numbers of young adults are being diagnosed with presbyopia or other vision disorders. According to some clinical reports, computer programmers and "techies" around the world are experiencing increased vision distortion at younger ages.

Common Presbyopia Solutions

The number of options for treating presbyopia has increased over the years, and include:

• Spectacles and contact lenses (bifocal or multifocal)
• GP contact lenses
• Laser surgery
• Corneal inlay
• Intraocular implants and Fullrange optics

Spectacles and Contact Lenses

Eyeglasses are typically the first step individuals take to increase vision capabilities. Individuals experiencing early stages of presbyopia often turn to generic, non-prescription reading glasses. Both spectacles and contact lenses are relatively inexpensive options that are also available with a variety of prescriptions, including bifocal and multifocal lens options.

Bifocal spectacles are divided into two sections, with the prescription for short-distance vision on the top of the lens and the prescription for long-distance vision on the top. However, many find it difficult to adjust and adapt to bifocal eyeglasses or prefer not to wear eyeglasses at all.

Bifocal contact lenses function in a similar way to traditional bifocal spectacles. However, they appear to be more beneficial in restoring vision due to a dual prescription basis for near vision and distance.  Today, multifocal contact lenses are developed with a number of variations.

Gas permeable (GP) contact lenses may work better to correct presbyopia than glasses, soft contacts, or surgery. GP contact lenses are among the most popular with users and are manufactured using firm, durable plastic that transmits oxygen. This means that oxygen flows through to the cornea, which is optimal for eye health. They're manufactured with silicone to enhance flexibility and are also larger, so the edges fit closer to the eye surface, making them more comfortable, improving vision, resisting deposits, and offering enhanced durability. This type of contact lens doesn't contain water as do soft contact lenses and is therefore less likely to succumb to bacteria. 

Potential patients interested in GP contact lenses should be aware that it does take some time for the eye to adapt to them. This is because they are not soft lenses - but within a short amount of time, they start to feel more natural in the eye.

GP lenses can also be adapted to people diagnosed with presbyopia using a number of different multifocal or bifocal designs. They're also beneficial for individuals diagnosed with keratoconus, which affects the shape of the cornea and causes severe vision distortion.

These lenses are also recommended for orthokeratology (Ortho-K procedures). Ortho-k is a new procedure that may enhance and improve vision for some individuals without contacts or glasses. The GP lenses are worn at night during sleep to reshape the cornea.

Eye Surgery

Laser surgery, also known as refractive surgery, is an accepted methodology used to correct a number of refractive errors including presbyopia and astigmatism. Traditionally, bifocal eyeglasses were often the first course of treatment. Today laser surgery is considered safe and is becoming more popular, all the more so for people who cannot or will not use glasses or contacts. The primary surgical option turned to laser in situ Keratomileusis or LASIK.  LASIK procedures reshape the cornea so it's better able to focus light on the retina. The procedure corrects refractive "errors" for astigmatism, nearsightedness (myopia), and farsightedness (presbyopia).

More recent developments in refractive eye surgery include optical coherence tomography (OCT), which uses more advanced technologies and diagnostics. Full range imaging of the eye accommodates optimal optical views and imaging of the anterior portion of the eye, enhancing imaging and diagnostics that better serve development of vision care technologies and products for patients. 

Such technologies enhance the ability and advantages of precise measurements in developing vision solutions for patients. Precise measurements and observation of changes in the shape and thickness of the lens are essential to making highly accurate diagnoses.

These technologies and the employment of real-time imaging for eye accommodations contribute to the potential for simultaneous imaging of the surface of the cornea to posterior surfaces of the lens as the eye changes accommodation, measuring distances of reflective surfaces, lens thickness, and curvature. Improved diagnostics also improve options for patients.

Corneal inlays are also a surgical solution for vision correction. A new generation of corneal inlays raised the statistics of successful outcomes in the treatment of presbyopia. As corneal inlays are additive and do not cause removal of tissue, there is also room for future correction as required. With new biocompatible materials and innovative technologies, corneal inlays today are thin with small diameters, high nutrient permeability and allow for implanting in various depths within the stromal tissue, according to specific inlay model and vision correction requirements.  All these advantages make a strong case for corneal inlays within the treatment spectrum[1].

Intraocular implants - IOL

Intraocular implants are specifically designed to replace the eye lens. These small lenses are available in numerous options:

• Monofocal – The most common IOL, this implant adapts to help the eye focus on distant objects and improve ability to see far objects more clearly. These implants can be used in the mono-vision method, but this will not suffice for reading distances as monovision patients are more than 7 times more likely to need glasses, so this will not give these patients freedom from glasses[2].
• Accommodating – Much like multifocal IOLs, this type is also flexible and functions much like normal eye lenses do, focusing on objects of varying distances at once. To date (and at the time of writing), accommodating lenses have not yet been proven to work in the long term.
• Multifocal – Offer vision at varying distances – some offer near and intermediate vision, while others offer only extended depth of focus for intermediate vision without adequate near vision. There are several different lenses available, some of which are based on refractive optics and others on diffractive optics. As these lenses maintain several focuses within the eye at the same time, optical phenomena such as glare or halo may occur, which the patient will need to get used to. The ease with which the patient accommodates to these phenomena is related to the optical design and the lens material. Multifocal lenses have been studied for a long time using different methods that include the measurement of acuity through the defocus curve and the measurement of contrast and stray light.

Recent studies have reported that individuals who have undergone IOL procedures following cataract extractions may not need glasses, but may experience the 'halo effect'. Multifocal IOLs offer two or more additional points of focus. The halo effect may be reduced by placing different monofocal lenses in each eye, as needed for optimal focusing capability for near and distance vision.

IOL implants for presbyopia following cataract surgery have also been studied at intervals following surgery for near and distance visual acuity. Multifocal IOLs were reported to offer better results for near visual acuity than monofocal IOLs. In addition, they reduce the future need for spectacles for both near and far distance than those with the monofocal IOL. However, monofocal IOLs reported minimal 'halo effect'.

Conclusion

An increasing number of people worldwide are suffering today from multiple types of vision impairment including presbyopia, and from younger ages. Moreover, people are no longer waiting to correct their vision and are looking for solutions earlier on in a desire to improve their quality of life and be spectacle-free. This leads them to turn to the varied solutions available for vision correction, as well as technological advances that have brought about many innovations in this field.

Contact Hanita Lenses for more information about our FullRange options for presbyopia correction.

[1] A Review of Presbyopia Treatment with Corneal Inlays, Moarefi, A.M., Bafna S., Wiley W. Ophthalmol Ther (2017) 6:55–65

DOI 10.1007/s40123-017-0085-7

[2] William W. Culbertson. Monovision vs Multifocal IOLs for Spectacle Independence After Cataract Surgery - Medscape - Mar 03, 2014