Facts You Should Know About Presbyopia
- As people get older, their eyes gradually lose the ability to rapidly change their focus from distance to near. This condition, known as presbyopia, affects everyone.
- Symptoms of presbyopia include difficulty seeing things up close, requiring a person to move the reading material further away to make it clearer. Other symptoms potentially include headaches, eye strain, and eye fatigue.
- Although presbyopia is not preventable or curable, there are a number of approaches available to treat the symptoms of presbyopia.
What Is Presbyopia?
- Presbyopia is a common type of vision disorder that occurs as you age. The definition of presbyopia is the loss of the ability to see clearly at a normal near working distance while fully corrected for distance vision.
- Presbyopia affects 100% of the population as they grow older, with symptoms commonly appearing between the ages of 40 and 50. Presbyopia is one of the earliest and most predictable signs of middle age.
- Presbyopia does not occur suddenly. It is the consequence of the slow and progressive universal decline in the amplitude of accommodation (change of focus) with age. The young eye has the remarkable ability to focus over a broad range from infinity to 2.6 inches within less than a second. This process, called accommodation, is facilitated by a change in the shape of the lens of the eye.
- Presbyopia occurs in both eyes and is symmetrical in its development.
What Causes Presbyopia?
- The lens of the eye is a transparent structure that changes it shape due to the contraction or relaxation of the ciliary muscle within the eye. The autonomic nervous system controls this muscle to increase the optical power of the lens during accommodation.
- According to the most commonly held theory, presbyopia results from the gradual loss of the elasticity of the lens with advancing age. The older lens does not change its shape to the same degree as the young lens. Therefore, the process of accommodation is gradually lost with time.
What Are Presbyopia Symptoms and Signs?
- The typical symptom of presbyopia is increasing difficulty with clearly seeing near objects. This is commonly manifested by problems reading fine print, threading a needle, or seeing the hands of a wristwatch.
- This symptom is worse under conditions of reduced illumination. It can also seem more noticeable when tired or when taking certain medications. Commonly, a person with presbyopia will notice that bringing the object that one is trying to see closer makes it even more blurred.
The presbyopic person will often push the reading material or other near object further away from his eyes to make it clearer. In addition, adding light or moving the materials toward a better illuminated area will help.
- If a person has been nearsighted (myopic) and has been wearing glasses all the time, presbyopia will cause similar symptoms. Myopic people will find that their near work is much more easily seen when they take their glasses off.
- Presbyopia may also cause the symptoms of eye strain, headache when reading, and eye fatigue.
What Tests Diagnose Presbyopia?
The diagnosis of presbyopia is made by recognition of the typical symptom of difficulty with near vision in a middle-aged person. Although the amplitude of accommodation can be accurately measured by testing, it is rarely necessary to do so. A very simple test to prove the diagnosis is having the symptoms of presbyopia relieved by reading glasses.
What Is the Treatment for Presbyopia?
- In people who have no underlying refractive error (no myopia, hyperopia, or astigmatism), the usual treatment is reading glasses. These glasses will make far vision blurry when worn. Therefore, most people opt to either put them on only when performing close work, wear bifocals, or progressive lens glasses with a clear upper portion or wear half-glasses that allow them to see over the glasses.
- A much lesser used alternative is to wear a contact lens in one eye to correct that eye for near. One eye is now used for far vision while the eye with the contact lens, usually the non-dominant eye, is used for close work. This is called monovision. Monovision is difficult for many people to become accustomed to since, at near, the eye with the contact lens is clear and the other blurred while at distance, the eye with the contact lens is blurred while the other one is clear.
- In people who have pre-existing myopia (nearsightedness) previously treated with glasses will usually be instructed to take their glasses off for near work. If this becomes cumbersome, they may be given bifocals or progressive lenses which allow good vision in each eye both for far and near.
- People who have been wearing contact lenses for the correction of myopia can obtain reading glasses, similar to patients without refractive error, which can be worn over their contact lenses. Reducing the power of the contact lens in the non-dominant eye may also be used to provide monovision if one does not wish to wear glasses.
- Patients who have been wearing glasses for the correction of hyperopia or astigmatism prior to the onset of presbyopia are treated with either two pairs of glasses, one for far and one for near or with a bifocal or progressive multifocal pair of glasses.
Can Surgery Correct Presbyopia?
- There have been countless innovative attempts to correct presbyopia surgically, either through surgery on the sclera, ciliary body, intracorneal inlays and multifocal laser modeling of the cornea. These are designed to structurally increase the accommodative ability of the eye or convert the eye into an optically multifocal system. None have been successful enough to become generally accepted.
- Various forms of laser surgery including LASIK and PRK can induce monovision, where one eye is made myopic, allowing that eye to see near objects clearly. The other eye remains the distance seeing eye. As above, this will be difficult for many people to become accustomed to since one eye is now clear for near but blurred for distance. Since the operated eye cannot focus any more than prior to the surgery, the operated eye remains presbyopic, but has become permanently nearsighted through the surgery, providing an optical correction for the presbyopia.
- In patients with cataract, multifocal lenses can be implanted at the time of cataract removal surgery. Although side effects are common, most patients having this done are satisfied with the outcome.
- Clear lens extraction with multifocal lens implantation extraction offers another optical approach to presbyopia in patients without cataract.
Are There Exercises or Remedies That Help Presbyopia?
- Various claims have been made over the centuries that exercises or other techniques can prevent or cure presbyopia. Although some of these have made their originator wealthy, none have any scientific validity.
- Increasing illumination for near work, including reading, can reduce the symptom of presbyopia by increasing contrast and decreasing the size of the pupil, providing increased depth of field.
- Depth of field can also be increased by using eye drops to make the pupils smaller, thereby temporarily decreasing presbyopic symptoms. Side effects of such drops make this choice unacceptable to most people.
What Is the Prognosis of Presbyopia?
Presbyopia occurs in all eyes, whether healthy or unhealthy. Using one's eyes does not hasten its progression. Presbyopia itself does not result in any loss of the structural integrity of the eye.
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Jain, S., et al. "Monovision outcomes in presbyopic individuals after refractive surgery." Ophthalmology 108 (2001): 1430-1433.