Presbyopia

Presbyopia is the gradual loss of your eyes' ability to focus on nearby objects. It's a natural, often annoying part of aging. Presbyopia usually makes itself felt in the early to mid-40s and continues to worsen until about age 65.

You may become aware of presbyopia when you start keeping books and newspapers nearby so you can read them. A basic eye exam can confirm presbyopia. You can correct the situation with glasses or contact lenses. You may also consider surgery.

Symptoms
Presbyopia develops gradually. You may notice these symptoms for the first time after age 40:

• A tendency to keep reading material further apart to make letters clearer
• Blurry reading vision
• Eye fatigue or headaches after reading or working closely
• You may notice that these symptoms are worse if you are tired or in a dimly lit area.

When to see a doctor
See an ophthalmologist if blurred near vision prevents you from reading, doing close-up tasks, or enjoying other normal activities. 

A regular examination can be performed by the ophthalmologist

The American Academy of Ophthalmology recommends that healthy adults with no known vision problems or eye disease undergo a complete eye examination according to the following schedule:

• Every 2 to 4 years from 40 to 54 years old
• Every one to three years between the ages of 55 and 64
• Every 1 to 2 years after the age of 65

If you have diabetes, a family history of eye disease, high blood pressure, or other risks of heart or vascular disease, you'll likely need more regular eye exams. You'll also likely need more regular checkups if you already have prescription glasses or contact lenses, or if you've had surgery to correct vision.

Causes

Your eyes have two components that focus images

The cornea is the clear dome-shaped front surface of your eye.
The lens is a transparent structure behind the iris. 

The lens, unlike the cornea, is somewhat flexible and can change shape with the help of a circular muscle surrounding it. When you look at something in the distance, the circular muscle relaxes. When you look at something close, the muscle contracts, allowing the relatively elastic lens to curl up and change its focusing power.
To be able to see, light must pass through the cornea and lens. They refract light so that light is focused directly on the retina at the back of your eye. This translates light into signals sent to the brain, which allow you to perceive images.

Presbyopia is caused by a hardening of the lens of your eye, which occurs with aging. As your lens becomes less elastic, it can no longer change shape to focus on close-up images. As a result, these images appear out of focus.

Risk factors
Some factors may make you more likely to develop presbyopia, including:

• Age. Age is the biggest risk factor for presbyopia. Almost everyone experiences some degree of presbyopia after the age of 40.
• Other medical conditions. Hyperopia or having certain diseases – such as diabetes, multiple sclerosis or cardiovascular disease – can increase the risk of premature presbyopia, which is presbyopia in people under 40.
• Medications. Some medications are associated with early presbyopic symptoms, including antidepressants, antihistamines and diuretics.