La presbyopia is a physiological condition that arises with advancing age and is characterised by the gradual loss of the eye's accommodative capacity, usually occurring after the age of 40.1
The pathophysiology of presbyopia still remains poorly understood. According to the prevailing hypothesis, with increasing age the crystalline lens would progressively lose its elastic properties and this would lead to a decrease in accommodative capacity. Other studies, however, support the theory that presbyopia is caused by an increase in the volume and equatorial diameter of the crystalline lens, usually during the fifth decade of life.1
The use of portable devices, for both professional and leisure activities, is a phenomenon that has become ubiquitous in modern society, globally. Individuals of all ages use portable electronic devices (such as smartphones and tablets) for written communication (text messaging, e-mail) and Internet access. This results in the replacement of printed paper materials by electronic devices, which have become an integral part of everyday life. New technologies and the increasing use of digital media are also changing people's postural and behavioural habits, with consequences on the viewing styles and postures assumed by people who use smartphones for prolonged periods of time.2
In most industrialised countries, smartphones have been popular among young adults for years, but recently there has been a significant growth in the adoption of digital technology also by of the older generations. In Italy, 48% of people over 50 years old own a smartphone and a similar trend can be seen in the rest of Europe and the US. Consequently, people of different ages may experience different visual problems when using smartphones.2
However, little is still known about the prevalence and determinants of smartphone-related difficulties in individuals with presbyopia.2Â
Parameters affecting viewing distance with smartphones
The reference reading distance for optometric examinations is 40 cm, this is in fact considered a typical reading distance for paper media. It has not yet been clearly established whether this reading distance can also be applied to new portable electronic devices.2
A recent observational study analysed several parameters that could influence the viewing distance with smartphones in different age groups.
On average, participants in the group with presbyopia held smartphones at a greater distance than young adults, with an increase in distance of 10%. The difference was 4 cm, with a reduction of 0.29 diopters in the need for accommodation.2 Studies conducted so far have also hypothesised that people with presbyopia who have difficulty reading their smartphones compensate by adjusting the brightness of the screen and the font size, instead of changing their usual viewing distance, as is the case with paper media. Some authors have observed that screen size affects viewing distance and, in particular, the smaller the screen, the smaller is the distance of use.2
The authors also hypothesised that changes in ophthalmic lens design (particularly for the correction of presbyopia) might be necessary to facilitate modern visual requirements.2
New generation intraocular lenses, such as EDOF with wavefront technology, are designed to meet the needs of even presbyopes who are confronted with smartphones and computer media on a daily basis. In fact, these lenses are characterised by the ability to create a single continuous focus that allows high-quality vision at all distances, minimising dysphotopsia (visual disturbances that may arise following cataract surgery). This translates into independence from glasses for most daily activities, including computer and mobile phone use.
Bibliography:
Dr. Carmelo Chines
Direttore responsabile
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