Presbyopia is an eye defect that occurs later in life and is a result of the natural degeneration of the eye lens. The first symptoms of presbyopia appear around age 40, and it is reported that at around age 60, the situation stabilises and is no longer appreciable. It is not a defect of the eye in the true sense of the word, but rather a natural consequence of the aging process.
The first symptom of presbyopia is usually farsightedness, as people find they need reading glasses. They may discover there is a need for glasses for „middle distances“ as well. Problems with nearsightedness usually show up later. Now with new technology, most people prefer contact lenses over glasses thanks to their comfort and easy handling.
With the first signs of farsightedness, most people notice difficulty reading text in front of them. Reading can be especially difficult in low-light conditions, causing eye strain, and vision can also become blurred when transitioning from focusing on close to far distances. Presbyopia symptoms are less noticeable during the day in bright light conditions because the iris closes to a smaller diameter.
Presbyopia can be corrected with contact lenses or glasses. Multifocal contact lenses can eliminate the need for reading glasses. These lenses are designed with different zones for near vision and distance vision, and the brain naturally trains itself to use the different zones to focus objects at various distances. Presbyopia should always be diagnosed by an optometrist, who can then suggest the most effective lenses for each patient.
In this picture, you can see how the visual error of presbyopia works. Light rays entering the eye are focused behind the retina, and the resulting images appear blurry. You can also see the blurred vision associated with presbyopia compared with the clear vision of a normal eye.