Presbyopia
What is Presbyopia?
Presbyopia is an eye condition that will happen to some degree to everyone some time in life. People with presbyopia have a hard time focusing up close and find themselves having to hold up reading material at arms length to focus. They may also have headaches and eye strain when doing work close up.
There is no cure for presbyopia but there are a lot of procedures to help correct presbyopia to allow improved near vision. There are many new treatments still being researched and trials for treatment of presbyopia are currently underway. As the Baby Boomer generation ages, the need for treatment of presbyopia will increase.
Presbyopia Causes
As we age, the lens of the eyes becomes rigid, loses its flexibility, and thus its ability to focus as well. The exact cause of presbyopia is still under research and debate. One theory is that the fibers in the lens become stiffened and are unable to change shape as well. Another theory is that the lens grows too big and is not able to change shape as well. Other factors such as trauma, occupation, and lifestyle may be factors as well.
Presbyopia Treatments
People with presbyopia usually need treatment for both close up vision and distance vision. Usually eyeglasses and contacts are the obvious choice. A few surgical techniques are available with several still under testing and trials.
There are four different types of eyeglasses available. Reading glasses are worn when working close up. Bifocals are eyeglasses with two points of focus for near vision and distant vision. The top part of bifocal lens is used to correct other eye conditions like myopia or astigmatism while the bottom part is used to correct close up vision. Trifocals have three focusing points; one for near vision, one for immediate vision, and one for distant vision. Progressive addition lenses (PALs) uses different focus points but gradually changes them so that no visual sections are as noticeable as in bifocals and trifocals. Bifocal and monovision contacts are also available. In monovision, one eye is corrected for near vision and the other for distant vision. The brain gradually adapts to using one eye for certain tasks depending on distance.
Current surgery for presbyopia includes Laser assisted in situ keratomileusis, or LASIK, and CK, Conductive keratoplasty. These techniques all give the patient monovision so it is better to try out monovision with contacts before surgery, especially in the case of LASIK where changes to the cornea are permanent. LASIK involves permanently changing the shape of the cornea in one eye allowing better near vision while leaving the other eye alone. LTK and CK use different techniques but both aim to change the shape of the cornea using thermal conduction of specific areas in the cornea. CK treatment is on the rise because Refractec, a company involved in CK technology, received approval on March 22, 2004 from the FDA for their new technology for correcting presbyopia.
There are also several treatments that are still under testing and trials in the US. Surgical Reversal of Presbyopia (SRP) is a technique under development by PresbyCorp. In this procedure Scleral Expansion Bands (SEBs) are inserted into the sclera which causes muscle fibers that focus the lens, to tighten. SRP is still under major trials because risks include eye infections, erosion of SEBs, decreased blood circulation in the eye and some other factors. Anterior ciliary sclerotomy (ACS) is a treatment where several incisions are made in a radial pattern around the eye. This extra space supposedly allows the lens to change shape easier. After sometime however regression occurs and vision returns to before the surgery. SurgiLight is a company involved with Laser Presbyopia Reversal (LAPR). In LAPR, an infrared laser is applied to the sclera to make it smaller. Another treatment being tested is the total removal of the lens with a replacement artificial one such as Crystalens or ReSTOR. The artificial lens is connected to muscle fibers that were responsible for moving and focusing the original lens. With new treatments, advancement in technology, and the increased need for a cure for presbyopia, people facing the problem should have many options.
[Page updated 1/2011]
