Presbyopia is the gradual reduction in the amount that the eye can change its focus. The changes are the result of the continued growth of the biological lens inside the eye, and are a normal part of ageing.
Presbyopia usually becomes noticeable between the ages of 40 and 50 as an inability to focus on near objects. People in this age group often find that they have to hold things further away to see them clearly.
Presbyopia can be corrected by an optical prescription specifically designed for close work. This can be provided in many forms, including reading glasses, bifocals, trifocals and progressive lenses (multifocals).
What is presbyopia?
Presbyopia is a common condition that makes vision difficult at a normal reading distance. It is not a disease.
How will presbyopia affect my vision?
Close tasks such as reading and sewing become difficult, particularly in poor light. For example, you may find that you are holding your newspaper further away from your eyes to make the print clearer. Presbyopia does not affect distance vision. You may also have difficulty concentrating when reading or you may find periods of close work result in sore eyes, headaches or tiredness.
What causes presbyopia?
It is important to understand how your eyes change their focus for viewing close objects. Normally they are focused for distance vision. Inside the eye there is a lens about the size of a pea. To focus on close objects, a special muscle in the eye changes the shape of the lens. This process is called accommodation.
With age the lens loses its flexibility and is less able to change its shape. This is a completely normal ageing change, just like stiffening joints or greying hair. The loss in lens flexibility is the reason that close focusing becomes more difficult.
Who is likely to become presbyopic?
Everyone experiences the ageing process that causes presbyopia. The condition cannot be prevented.
Does presbyopia come on quickly?
No. Presbyopia is usually first noticed around the age of 40 to 45 years. Although difficulties with close work may seem to come on suddenly, the ageing process that causes presbyopia is gradual and has been going on since childhood. Between the ages of 45 and 65, the amount of presbyopia increases, making near work more difficult. From 65 years onwards, there are unlikely to be any further significant changes to vision due to presbyopia.
How is presbyopia treated?
Presbyopia is corrected by a spectacle prescription designed especially for close distances, in the form of spectacles or contact lenses. It is important that the prescription is calculated for the distance at which you do your close tasks. It is not possible to treat presbyopia by surgery.
Through discussion with your optometrist, you will be able to decide on the best way of preparing your prescription. The correction for presbyopia will make near objects clear but distant objects blurry. This means that if you have a pair of spectacles just for reading, you will not be able to watch television while wearing them.
Having different prescriptions for distance and reading can be a nuisance, especially if you have to change spectacles all the time. One way around the problem is the use of bifocals. These are special lenses that have a prescription for distance vision in the top half of the lens and the prescription for near vision (reading) in the lower half. Another form of spectacles used to correct presbyopia is ‘look-overs’ (half-glasses). Other options include the use of trifocals, progressive lenses and some special contact lens prescriptions.
Does presbyopia mean that my eyes are deteriorating?
No. Although your close focusing system is not functioning as well as it used to, once presbyopia has been corrected with spectacles you will be able to see close things as well as you always did. Presbyopia does not represent a threat to your eyes’ health.
When should I have my prescription for presbyopia renewed?
Between the ages of 45 and 65 years, your prescription is likely to change significantly. It is sensible to have your eyes examined every two to three years to review your correction and your general eye health. If you experience vision problems within two or three years of your previous examination, you should make a review appointment with your optometrist. Your optometrist will advise you of the most appropriate period between consultations.
Will wearing spectacles weaken my eyes?
No. Presbyopia will continue regardless of whether spectacles are worn. Wearing spectacles will not accelerate or slow the development of presbyopia.
(Article provided courtesy of the Optometrists Association Australia www.optometrists.asn.au)