Presbyopia and Laser Eye Surgery

Written by John Taylor

Laser-assisted refractive surgery can help improve a variety of vision problems, such as myopia, hyperopia and astigmatism, but one problem it can't solve is presbyopia, an age related condition that contributes to the deterioration of one's ability to see objects at all ranges.

Presbyopia, which is Greek for "elder eyes," is the gradual deterioration of eyesight caused by age. How this deterioration happens is not known, but research suggests that over time the eye's crystalline lens loses elasticity and combined with gradual changes in the lens' curvature, the eye loses focusing power. Symptoms of presbyopia induce trouble reading small print, especially when there's not much light, headaches or eye strain after reading for an extended period of time and temporarily blurred vision when shifting between looking at something up close or far away. Presbyopia is much less affecting in bright light, where the iris shrinks thus increasing the eye's ability to focus.

Presbyopia affects millions of Americans, and the condition is expected to be more widespread as the demographic age of the average American continues to shift upward.

The traditional treatment for presbyopia is the use of reading or bifocal glasses. Bifocals separate the eyeglasses into top and bottom segments. The top segment is used for far away seeing while the bottom is used for up close vision. A number of surgical techniques have been developed in recent years to help patients with presbyopia see without the use of glasses.

While LASIK and other laser-assisted refractive surgeries can improve vision impacted myopia, hyperopia, and/or astigmatism, these procedures can't restore both near and far vision to an eye affected by presbyopia. What LASIK and other laser eye surgeries such as LASEK and PRK can do is create a condition called monovision. In monovision, one eye is modified for distance sight, while the other is modified for use up close.

While in general both eyes are used for seeing, one eye tends to be dominant over the other for "sighting," that is, seeing long distance objects. For patients with presbyopia, surgeons will take the dominant eye and perform laser-assisted refractive surgery on it to enable it to see objects that are far away. The non-dominant eye is left slightly myopic, so it will be able to focus on up close objects. One potential drawback of monovision is a reported decline in the patients' depth perception. Folks with monovision may also experience blurred vision in their "near" eye when looking in car mirros or they may also experience blurred vision in the "far" eye when their vision is blocked by an object.

Surgeons are a little wary of this technique because some patients cannot tolerate monovision. Many require patients to try monovision by first using a pair of contact lenses that will produce monovision first to ensure that the patient can adapt to monovision.

Although laser-assisted refractive surgery's only option for presbyopes is currently the procedure to create monovision, research continues on a procedure called PresbyLASIK. This procedure would create multifocal abalations in the cornea, in effect turning your eye into a pair of bifocal glasses.

In the PresbyLASIK procedure, the surgeon will use an excimer laser to sculpt different parts of your cornea for up close, far away and intermediate sight. Your brain will adjust and then select whichever area that's necessary to see objects. This procedure is currently in clinical trials in the U.S. and is awaiting FDA approval.

There are some surgical options to deal with presbyopia that do not include the use of lasers. One such procedure is scleral expansion bands. In this procedure, four tiny plastic bracers are inserted beneath the sclera's surface. The bracers separate the muscles that focus the lens and the lense, increasing muscle tension and allowing stronger focusing. This procedure is still in the clinical trial phase, however.

A more common option is refractive lense exchange, in which the lens of the eye is removed and swapped with an artificial lens. This operation has been approved by the FDA as an off-label procedure.

While presbyopia poses a challenge for doctors trying to find a surgical solution to the problem, it appears that laser-assisted refractive surgery will soon produce some promising options. If you feel that you may be a good candidate for the options currently available on the market, you should consult with your eye doctor.