Presbyopia

Presbyopia refers to the gradual loss of the ability to see nearby things. The condition starts to manifest around the age of 40 and is often first reported as difficulty reading. However, premature presbyopia may begin around the age of 36 years. Unless you have nearsightedness also, you will not have difficulty seeing distant objects.

The most common symptom of presbyopia include:

• Having difficulty reading, especially small print. You may have to hold the printed material a bit farther from your eyes to be able to read.
• Finding it difficult to check your phone, see or recognise people in photos
• Needing brighter lights to read
• Difficulty doing any work with fine details up close
• Difficulty reading for prolonged periods of time due to gradual blurring of vision
• Squinting, eye strain and headache after reading for a while

The symptoms may be more pronounced when you are tired.

If you have presbyopia, you may notice blurry vision in the morning at first which will get better within a few minutes. Alternatively, you may notice your vision getting more blurry later in the day.

Presbyopia vs hyperopia or hypermetropia

Both presbyopia and hyperopia are characterised by difficulty in perceiving nearby objects clearly. However, the two conditions are a bit different from each other. Here is how:

• Presbyopia occurs due to the reducing flexibility of the eye lens with age while hyperopia occurs when the image of an object forms beyond the cornea. Shorter than normal size of the eyeball, weak lens or cornea are some causes of hyperopia. 
• Those with presbyopia have difficulty seeing nearby objects but those with hyperopia may have difficulty seeing even objects that are farther away. Anything seen from a distance of 20 feet may appear blurred to a hyperopic person.
• Those with presbyopia are often seen reading from farther than normal distance, while those with hyperopia usually hold the reading material at normal reading distance.
• Hyperopic people are able to read in normal lights while those with presbyopia need bright light (brighter than room light) to read.

Normally, your eye lens changes its shape to focus on nearby and far-off objects. It turns flatter and thinner to help you see objects that are far away. And it becomes more curved and thicker to help you see nearby objects. Your eye muscles help the lens to change its shape. 

However, with age, your eye lens loses its flexibility and becomes harder and your eye muscles also become weak. As a result, your eye lens is not able to change its shape as effectively and you start to have difficulty in looking at nearby objects. You would still be able to see far off objects clearly if you are not near-sighted, though.

Age is one of the major risk factors for presbyopia. Almost every person notices some level of presbyopia by the age of 40. Some other factors that increase your risk of developing presbyopia include:

• Diabetes
• Cardiovascular diseases
• Myopia or uncorrected hyperopia
• Nutritional deficiency
• Need to use near vision a lot such as due to computer work
• Eye disease or trauma
• Alcohol intake
• Smoking
• As a side effect of some drugs, including antianxiety, antipsychotic and antidepressant medications
• Females are generally seen to develop presbyopia earlier than males. This is suggested to be either due to menopause or the fact that women tend to do something to correct the condition earlier.
• Chronic amino acid deficiency
• Anaemia
• High average environmental temperature
• Exposure to toxins like hair dyes
• Over or prolonged exposure to the sun and hence UV light

There is no way to prevent presbyopia. However, you can keep your eyes healthy and reduce your risk of developing the condition early in the following ways:

• Get regular eye exams to make sure that any changes in your vision may be noticed clearly. It will also help your doctor identify eye conditions early on. 
• Take a healthy and balanced diet. Include a lot of green leafy vegetables and fresh fruits in your meals as these foods contain vitamin A and antioxidants which help maintain eye health.
• If you have a chronic health condition including diabetes or cardiovascular disease, make sure to get proper treatment.
• Workout regularly 
• Quit smoking and reduce your alcohol intake
• Make sure to keep yourself hydrated
• Wear sunglasses every time you go out, especially if you spend a lot of time in the sun.
• Read in adequate lighting to reduce eye strain.
• Always wear protective eyeglasses when needed such as while with chemicals including household cleaners and playing certain kinds of sports.
• Visit a doctor at the earliest if you notice symptoms like blurry vision, double vision, flashes, halos or black spots, vision loss in one eye, eye pain.

A lot of people notice the condition themselves as they start to observe reading difficulties. Presbyopia is usually diagnosed through an eye exam. Your doctor will ask you to read letters or text at a distance comfortable to you. He/she may ask you to see through corrective lenses to check your refractive error and prescribe glasses of appropriate power. 

Before the test, your doctor may ask you to put in eye drops to dilate your pupils. This will lead to temporary light sensitivity. Make sure to bring a family member or a close friend along for the appointment, as you may not be able to drive if your eyes are dilated for a test.

There is no treatment for presbyopia. Your doctor will suggest prescription glasses or contact lenses. Surgery and lens implants are also recommended in some cases though they come with their own set of side effects. Let us have a look at these options one by one:

• Eyeglasses: Eyeglasses for presbyopia can be worn with or without glasses for other vision problems. If your vision is fine otherwise, ask your doctor if you can use over-the-counter (OTC) glasses.
  OTC glasses have power between +1.00 D and +3.00 D (dioptre). If your doctor allows you to buy them, try reading through a glass of every power to see which one is best for you.
  However, if you do not want to use OTC glasses or already are using eyeglasses for other vision problems, your doctor may recommend one of the following prescription glasses:
  • Reading glasses: Your doctor will recommend reading glasses if you don’t otherwise have a vision problem. These glasses can be worn while you are reading or doing close or fine work. 
  • Bifocal lenses: Bifocal lenses have two different powers in a single spectacle. The one on the top has a prescription for far off objects while the one in the bottom has a prescription for near vision.
  • Trifocal lenses: Trifocal lenses have three zones: one with far off vision, one for intermediate vision and one for near vision. The zones have visible horizontal lines in-between them.
  • Varifocal/multifocal or progressive lenses: These lenses are like bifocal or trifocal lenses but they have no visible lines of demarcations between the zones. Those who do not like the clear lines between the various zones in bifocal or trifocal lenses, and can afford them, may opt for progressive lenses.
• Contact lenses: If you have already been using contact lenses for a vision problem, you can get specialised contacts to help you with presbyopia along with your existing problem. Here are some types of contact lenses you can choose from:
  • Bifocal contact lenses: Bifocal contact lenses have two different focal points that help you see both nearby and far off objects. Some types of bifocal lenses have a weighted lower region to keep the lens in the right position when you wear them. Other lenses have one area of correction in the centre and the other area in the periphery. 
  • Monovision contact lenses: Monovision contact lenses consist of a set in which one lens helps you see far off objects while the other lens aids in seeing nearby objects. It can take some time to adjust to these lenses.
  • Multifocal contact lenses: Multifocal contact lenses have more than two focal points; for example, one for close vision, one for intermediate and one for far vision. 
  • Modified monovision contact lenses: Modified monovision contact lenses include a pair of lenses, with one lens to help you see distant objects and the other one is a multifocal or bifocal lens to help you see at all distances.

You can also wear reading glasses over the contact lenses if your doctor okays it.

• Refractive surgery: There are various types of surgeries that can be performed to correct presbyopia. These include:
  • Photorefractive keratectomy (PRK): Photorefractive keratectomy is a surgery in which the epithelial (outermost) layer of the cornea is removed. The cornea regrows over time, confirming to its new shape.
  • LASEK: Laser is a modified PRK in which the corneal epithelium is not cut out. Instead, the surgeon makes a flap of the epithelium and reshapes the inner layer then puts the flap back over in its original place. In both the LASEK and PRK procedures to correct presbyopia, one eye lens is shaped to help you see far off things better while the other lens is shaped to help you see nearby things, just like monovision contact lenses. These procedures affect your spatial vision and your brain cannot usually adjust to the change properly.
  • LASIK: LASIK is similar to LASEK, only in this one, the flap is made deeper into the cornea before cutting and reshaping the inner layers. Reduced vision quality, less contrast sensitivity, especially at higher frequencies, and seeing halos at night are some of the major concerns associated with a LASIK surgery.
  • INTRACOR: INTRACOR involves cutting rings in the cornea (to reshape it) using a laser. Studies indicate that this procedure does not change the refractive power of the eye by much and often the person still needs glasses and may find it difficult to see things in the distance. It might also cause scarring in the cornea and affect your eyesight.

Surgeries are usually recommended for people who also have near or farsightedness or astigmatism along with presbyopia. If you only have presbyopia and no other eye condition, it is best not to opt for eye surgery. 

• Lens replacement: Lens replacement involves replacing your natural eye lens with a synthetic one. The new lens may be monofocal or multifocal and can correct all types of vision problems including nearsightedness or farsightedness and astigmatism along with presbyopia. However, these implants won’t give you the natural vision quality, so you may still need reading glasses. Light sensitivity, glare, blurry vision are some possible side effects associated with the surgery. It may also lead to increased risk of cataracts, glaucoma, and bleeding inside the eye.
• Corneal inlays: Corneal inlays are tiny devices that are fit inside the cornea to correct presbyopia. The device is usually implanted in only one eye. In case you have a vision problem like myopia or hypermetropia, you will also need a corrective procedure like LASIK along with getting the corneal inlay implanted. Corneal inlays are not used for those with cataract or dry eye.
  ​According to the American Academy of Ophthalmology, there are two types of corneal inlays:
  • Small aperture inlays: This type of inlay is ring-shaped, with an aperture like that of a camera. The aperture adjusts the amount of light that enters into the eye and also helps narrow your field of vision. 
  • Refractive corneal inlays: This type of inlays work like multifocal lenses and have different areas that provide various levels of magnification to your eye. Refractive corneal inlays are not yet approved by the US Food and Drug Administration (FDA).