What Causes Presbyopia?
Every good pair of eyes eventually gets old and with age comes a condition called presbyopia. Presbyopia, which usually begins to set in some time around 40, occurs when the lens of the eye begins to stiffen, making near vision (such as reading books, menus, and computer screens) blurry. You may have this age-related farsightedness if you notice yourself holding the newspaper further and further away in order to make out the words, and you may begin to experience headaches or eyestrain as well.
The good news is, presbyopia is very common. It happens to most of us eventually and these days there are a number of good options to correct it. First of all, let’s take a look at what causes the condition.
As the eye ages, the natural lens begins to lose its elasticity as the focusing muscles (the ciliary muscles) surrounding the lens have difficulty changing the shape of the lens. The lens is responsible for focusing light that comes into the eye onto the retina for clear vision. The hardened or less flexible lens causes the light which used to focus on the retina to shift its focal point behind the retina when looking at close objects. This causes blurred vision.
Presbyopia is a progressive condition that gets worse with time. It is a refractive error just like myopia (nearsightedness), hyperopia (farsightedness) and astigmatism.
Signs of Presbyopia Include:
- Blurred near vision
- Difficulty focusing on small print or close objects
- Eyestrain, headaches or fatigue, especially when reading or doing close work
- Holding reading material at a distance to see properly
- Needing brighter light to see close objects
Presbyopia can be diagnosed through an eye exam.
Treatments for Presbyopia
There are a number of options for presbyopia treatment which include glasses, contact lenses or surgery.
The most common form of correction is eyeglasses. Reading glasses adjust the focal point of the target to reduce the focusing demand on the eyes. A side effect of the convex lenses is that they also magnify the target. For some, reading glasses are sufficient to improve close vision. Others, especially those with another refractive error, require more complex lenses.
Bifocal or multifocal lenses, including progressive addition lenses (PALs), offer a solution for those with nearsightedness or farsightedness. These lenses have two or more prescriptions within the same lens, usually in different areas, to allow correction for distance vision and near vision within the same lens. While bifocals and standard multifocals typically divide the lenses into two hemispheres (or more), requiring the patient to look in the proper hemisphere depending on where they are focusing, with an unattractive contour calling attention to the presbyopia portion of the lens, progressive lenses provide a progressive transition of lens power creating a smooth, gradual change. Some people prefer progressive lenses for aesthetic reasons as they don’t have a visible line dividing the hemispheres.
Like glasses, contact lenses are also available in bifocal and multifocal lenses. Alternatively, some eye doctors will prescribe monovision contact lens wear, which divides the vision between your eyes. Typically it fits your dominant eye with a single vision lens for distance vision and your weaker eye with a single vision lens for near vision. Sometimes your eye doctor will prescribe modified monovision which uses a multifocal lens in the weaker eye to cover intermediate and near vision. Newer contact lens technology is making both lenses multifocal, and therefore doctors are becoming less dependent on monovision. Sometimes monovision takes a while to adjust to.
Based on your prescription, your eye doctor will help you decide which option is best for you and assist you through the adjustment period to determine whether this is a feasible option. Since there are so many baby boomers with presbyopia nowadays, the contact lens choices have expanded a lot within recent years.
There are a few surgical treatments available for presbyopia. These include monovision LASIK surgery (which is a refractive surgery that works similar to monovision glasses or contact lenses), corneal inlays or onlays (implants placed on the cornea), refractive lens exchange (similar to cataract surgery, this replaces the old, rigid lens with a manufactured intraocular lens), and conductive keratoplasty (which uses radio waves to reshape the cornea in a noninvasive procedure).
Medication – On the Horizon
There are currently clinical trials with promising early results that are testing eye drops that restore the flexibility of the human lens. It could be possible that in the near future eye drop prescriptions could be used to reduce the amount of time that people have to use reading glasses or contact lenses.
These procedures vary in cost, recovery and outcome. If you are interested in surgery, schedule a consultation with a knowledgeable doctor to learn all of the details of the different options.
As people are living longer, presbyopia is affecting a greater percentage of the population and more research is being done into treatments for the condition. So if your arm is getting tired from holding books so far away, see your eye doctor to discuss the best option for you.