Why can your prescription change over the years, even in adulthood?

Have you noticed that your glasses no longer correct your vision as well as they used to? Although it is often thought that an eye prescription stabilises in adulthood, changes in vision are more common than you might imagine. In this article from Barraquer Ophthalmology Centre, we explain why your prescription may change over the years, even in healthy adults, and when it is advisable to have an eye examination.

What do we mean by an eye prescription?

An eye prescription refers to the number of dioptres required in a lens to correct visual defects such as myopia, hyperopia, astigmatism or presbyopia. This measurement is obtained through an optometric examination and is expressed as positive or negative values, depending on the type of refractive error.

Why can an adult’s prescription change?

Although it is normal for the number of dioptres to increase during childhood and adolescence, changes can also occur in adulthood. During the first decades of life, the prescription usually evolves naturally due to genetic and environmental factors, such as the development of the eye, visual habits or the amount of time spent on close-up activities.

In most people, this progression tends to stabilise upon reaching adulthood, although the prescription does not always remain completely unchanged over the years. The main causes are explained below:

Physiological changes associated with age

• From the age of 40–45, presbyopia, or age-related long-sightedness, begins to appear. This is a progressive loss of the ability to focus on nearby objects.
• At more advanced ages, the crystalline lens loses transparency and elasticity, which can also affect the prescription.

Changes in eye health

• The development of cataracts can cause a change in refraction, often towards temporary myopia, known as “second sight”.
• Conditions such as keratoconus, corneal disorders or retinal diseases can also alter the prescription.

Metabolic or systemic changes

• Diabetes can cause temporary changes in vision due to fluctuations in blood glucose levels.
• Some medicines can also affect accommodation or the curvature of the cornea.

Eye strain and the digital environment

• Excessive screen use can contribute to symptoms such as blurred vision or difficulty focusing.
• These symptoms do not always indicate a genuine change in the number of dioptres, but they still require attention and possible optical adjustments.

What signs indicate that your prescription has changed?

Some warning signs include:

• Difficulty reading or seeing clearly at a distance.
• Frequent headaches at the end of the day.
• Eye strain when using screens.
• The need to move objects further away or bring them closer in order to focus.
• Double or blurred vision.

How can you maintain good eye health in adulthood?

Some key recommendations include:

• Have regular eye examinations, even if you do not have any symptoms.
• Ensure good lighting at home and at work.
• Follow the 20-20-20 rule: every 20 minutes, look at something 20 feet away for 20 seconds.
• Do not use glasses purchased without a professional prescription.

Changes in prescription are not exclusive to children or adolescents. In adults, they can also occur for many reasons, ranging from the natural ageing of the eye to systemic factors. At Barraquer, we are committed to providing an accurate diagnosis and personalised treatment so that you can continue to enjoy the best possible vision.

Dr Jose Lamarca, ophthalmologist at Barraquer Ophthalmology Centre