The leading cause of visual loss in adults age 55 and older, cataracts occur when the normally clear ocular lens in an eye becomes cloudy. As the cataract progresses, a person’s vision becomes blurrier, requiring surgery to replace the lens.

“The natural lens has an onion-like structure with layers of arch-like fibers,” explains Dr. Kai-Tak Wan, assistant professor of mechanical and aerospace engineering at UMR. “These layers deform in concert to allow accommodate focusing on objects.”

Once the lens is replaced, a patient’s focus is fixed because an artificial lens is less flexible than a natural lens and limits the range of focus.

“After surgery, patients need to wear glasses to correct their vision, either for nearsightedness or farsightedness,” Wan adds.

Wan and Dr. Nathan Ravi, director of ophthalmology for Veterans Affairs Medical Center at Barnes Jewish Hospital, are using lenses from pigs and human cadavers to characterize the force needed to stretch lenses and allow for the maximum range of focus. The same technique is also used to characterize prosthetic lenses.

Wan and Ravi expect to develop a new prosthetic hydrogel that simulates the optical and mechanical properties of a natural lens.

The study of the mechanical behavior of lenses has significant impact on other eye problems, including presbyopia, a condition that describes the eye’s gradual loss of its ability to change focus from distance to near.

An estimated 440,000-plus Missouri residents age 40 and older either have a cataract or have had cataract surgery, according to the National Institutes of Health.

Note: If no author is given, the source is cited instead.

• Eye Care
• Today's Healthcare
• Disability
• Diseases and Conditions
• Cosmetic Surgery
• Healthy Aging

• Eyeglass prescription
• Hyperopia
• Cataract
• Astigmatism (eye)
• Refractive surgery
• Myopia