Presbyopia
During middle age, usually beginning in the 40s, people experience blurred vision at near points, such as when reading, sewing or working at the computer. There’s no getting around it — this happens to everyone at some point in life, even those who have never had a vision problem before.
Presbyopia Symptoms and Signs
When people develop presbyopia, they find they need to hold books, magazines, newspapers, menus and other reading materials at arm’s length in order to focus properly. When they perform near work, such as embroidery or handwriting, they may have headaches or eyestrain, or feel fatigued.
What Causes Presbyopia?
Presbyopia is caused by an age-related process. This is different from astigmatism, nearsightedness and farsightedness, which are related to the shape of the eyeball and caused by genetic factors, disease, or trauma. Presbyopia is generally believed to stem from a gradual loss of flexibility in the natural lens inside your eye.
The eye’s lens stiffens with age, so it is less able to focus when you view something up close. The result is blurred near vision.
These age-related changes occur within the proteins in the lens, making the lens harder and less elastic with the years. Age-related changes also take place in the muscle fibers surrounding the lens. With less elasticity, the eye has a harder time focusing up close. Other, less popular theories exist as well.
Presbyopia Treatment: Eyewear
Eyeglasses with bifocal or progressive addition lenses (PALs) are the most common correction for presbyopia. Bifocal means two points of focus: the main part of the spectacle lens contains a prescription for nearsightedness or farsightedness, while the lower portion of the lens holds the stronger near prescription for close work.
Progressive addition lenses are similar to bifocal lenses, but they offer a more gradual visual transition between the two prescriptions, with no visible lines between them.
Reading glasses are another choice. Unlike bifocals and PALs, which most people wear all day, reading glasses are typically worn just during close work. If you wear contact lenses, your eye doctor can prescribe reading glasses that you wear while your contacts are in. You may purchase readers over-the-counter at a retail store, or you can get higher-quality versions prescribed by your eye care practitioner.
Contact lenses
People who don’t want to wear eyeglasses often try contact lenses to improve their vision problems caused by presbyopia. This option may not work for you if you have certain conditions related to your eyelids, tear ducts or the surfaces of your eyes such as dry eye.
Several lens types are available:
- Bifocal contact lenses.Bifocal contact lenses provide distance and close-up correction on each contact. In one type of bifocal lens, the bottom, reading portion of the lens is weighted to keep the lens correctly positioned on your eye. Newer types of bifocal contact lenses offer one type of correction through the edges (periphery) of each lens and the other type of correction through the center of the lenses.
- Monovision contact lenses.With monovision contacts, you wear a contact lens for distance vision in one eye (usually your dominant eye) and a contact lens for close-up vision in the other eye.
- Modified monovision.With this option, you wear a bifocal or multifocal contact lens in one eye and a contact lens set for distance in the other (usually your dominant eye). You use both eyes for distance and one eye for reading.
Refractive surgery
Refractive surgery changes the shape of your cornea. For presbyopia, this treatment can be used to improve close-up vision in your nondominant eye. It’s like wearing monovision contact lenses. Even after surgery, you may need to use eyeglasses for close-up work.
Talk with your doctor about the possible side effects, as this procedure is not reversible. You might want to try monovision contact lenses for a while before you commit to surgery.
Refractive surgical procedures include:
- Conductive keratoplasty.This procedure uses radiofrequency energy to apply heat to tiny spots around the cornea. The heat causes the edge of the cornea to shrink slightly, increasing its curve (steepness) and focusing ability. The results of conductive keratoplasty are variable and may not be long lasting.
- Laser-assisted in situ keratomileusis (LASIK).With this procedure, your eye surgeon makes a thin, hinged flap deeper into your cornea. He or she then uses a laser to remove inner layers of your cornea to steepen its domed shape.
Recovery from LASIK surgery is usually more rapid and less painful than other corneal surgeries.
- Laser-assisted subepithelial keratectomy (LASEK).The surgeon creates an ultra-thin flap only in the cornea’s outer protective cover (epithelium). He or she then uses a laser to reshape the cornea’s outer layers, steepening its curve, and then replaces the epithelium.
- Photorefractive keratectomy (PRK).This procedure is similar to LASEK, except the surgeon completely removes the epithelium, then uses the laser to reshape the cornea. The epithelium is not replaced, but will grow back naturally, conforming to your cornea’s new shape.
Lens implants
Some ophthalmologists use a procedure in which they remove the lens in each eye and replace it with a synthetic lens. This is called an intraocular lens.
Several types of lens implants are available for correcting presbyopia. Some allow your eye to see things both near and at a distance. Some change position or shape within the eye (accommodative lens). But lens implants can cause a decrease in the quality of your near vision, and you may still need reading glasses.
Possible side effects include glare and blurring. In addition, this surgery carries with it the same risks as those associated with cataract surgery, such as inflammation, infection, bleeding and glaucoma.
Corneal inlays
Some people have had success with a presbyopia treatment that involves inserting a small plastic ring with a central opening, into the cornea of one eye. The opening acts like a pinhole camera and allows in focused light so that you can see close objects.
If you don’t like the results of your corneal inlay procedure, your eye surgeon can remove the rings, leaving you free to consider other treatment options.
Dr Vertika Kulshrestha
Sr. Specialist (ophthal)
Sanjeevani hospital, SSTPS