Presbyopia

Our ability to see an object requires our eye’s cornea and lens to refract the light entering our eyes and focus it on our retina. The lens is flexible and can change its shape. When looking at nearby objects, the circular muscle around the lens constricts, allowing the stretchable lens to change its curvature and focal point. With aging, the lens loses its flexibility and becomes less elastic. It cannot change its shape sufficiently to focus on the close-up range. This condition is called presbyopia.

Presbyopia occurs gradually starting at the age of early or mid-40 and continues to deteriorate until age 65. Presbyopia in people younger than 40 is known as premature presbyopia.

People who begin to experience problems focusing on small or close-up objects or need to read a book at arm’s length should have an eye exam to confirm presbyopia. Eyeglasses, contact lenses, or surgery can correct this condition.

Symptoms of presbyopia

• Difficulty reading small print or focusing on objects close to you
• Eyestrain, headaches, fatigue from reading
• Squinting
• Need brighter light to read or see clearly

Causes

Eye lenses become less flexible due to aging and cannot change shapes to focus on nearby objects.

Risk factors

• Older age: Presbyopia usually develops in people 40 years old or above.
• Female
• Previous eye surgery
• An unhealthy eating habit
• Decompression sickness in scuba divers who resurface too quickly. 

Certain diseases can cause premature presbyopia. For example:

• Eye injury
• Diabetes
• Multiple sclerosis
• Myasthenia gravis
• Anemia, a low level of normal red blood cells
• Cardiovascular disease
• Vascular insufficiency
• Hyperopia

Diagnosis

A basic eye exam with pupil dilation and refraction assessment can confirm the diagnosis. Adults should have eye exams as follows:

• Under 40: every 5-10 years.
• 40-54 years old: every 2-4 years.
• 55-64 years old: every 1-3 years
• 65 years old and above: every 1-2 years
• If you wear glasses or contact lenses or have a risk of developing eye diseases, have an eye exam yearly.

Treatment

• Corrective eyeglasses
  • Nonprescription reading glasses are available with power from +1.00 diopter(D) to +3.00 D. People who do not have nearsightedness, farsightedness, or astigmatism before developing presbyopia can wear over-the-counter reading glasses.
  • If nonprescription reading glasses do not work, get a pair of prescription glasses.
  • Bifocals have a visible horizontal line separating the lenses. The lens above is for distance vision, and the lens below is for reading.  
  • Trifocals are for a close-up, middle-distance computer screen, and distance visions. They have two visible horizontal lines across the lenses.
  • Progressive multifocal has different focusing strengths on a single lens.
  • Office progressives are for computer-distance and close work. It is suitable for people who don't need glasses driving or walking.
• Contact lenses
  • Bifocal contact lenses*** are available in soft and hard materials. They have two focal points, near and far.
  • Multifocal contact lenses have three focal points – near, middle, and far, available in soft and hard materials.
  • Monovision contact lenses include one lens for near vision and the other for far vision; you wear one on each eye. It may take up to 2 weeks for your brain to adjust.
  • Modified monovision contact lenses have one lens for either near or far vision and a multifocal lens for the other eye.

Contact lenses are not for people with tear duct problems, dry eye, or other eyelid or eye surface conditions.

• Refractive lens exchange (RLE) This technique replaces the natural lens with an implant that corrects presbyopia.
• Corneal inlays. This method inserts an inlay, a tiny plastic ring, into one of your corneas to create a pinhole camera effect. You will be able to see near and distant objects more clearly. (Not yet available in Thailand.)

Prevention

Though presbyopia is unavoidable, there are certain things you can do to improve your eye health and decrease the risk of developing age-related eye diseases. 

• Have a regular eye exam, especially when you are 40 or above. 
• Keep your medical conditions, such as hypertension and diabetes, well-controlled. These conditions can lead to vision problems. 
• Wear sunglasses to protect your eyes from UV radiation.
• Use protective eyewear when painting, mowing the lawn, using chemical products, or playing sports.
• Turn up the light for clearer vision.
• Eating more fruits and vegetables having high levels of vitamin A, beta carotene, and antioxidants can help maintain a healthy vision.
• Seek immediate medical care if you develop blurry vision, double vision, or sudden vision loss.