MedicineWorld.Org
Your gateway to the world of medicine
Home
News
Cancer News
About Us
Cancer
Health Professionals
Patients and public
Contact Us
Disclaimer

Medicineworld.org: Soft Contacts Designed for Cone-Shaped Cornea

Back to ophthalmology news Blogs list Cancer blog  


Subscribe To Ophthalmology News RSS Feed  RSS content feed What is RSS feed?

Soft Contacts Designed for Cone-Shaped Cornea

Soft Contacts Designed for Cone-Shaped Cornea
Geunyoung Yoon (PHOTO CREDIT: University of Rochester)
Custom-designed contacts improved vision for subjects with keratoconic eyes and offer hope of nonsurgical therapy instead of corneal transplants. University of Rochester scientists describe the custom design techniques and results of visual acuity tests in a paper published in April in Optics Letters.

Keratoconic eyes are rare but disabling. From the side, the eyes look more pointed or cone-shaped than round. The apex shift from visual axis in the cornea causes people with the condition to see halos and double and triple images. About 1 in 2,000 people suffer from the disease, commonly in both eyes.

"The condition shows up in a relatively small population, but it causes huge optical problems," says Geunyoung Yoon, assistant professor in the Departments of Ophthalmology and Biomedical Engineering, the Center for Visual Science, and the Institute of Optics. "These people have problems so severe, they can't tolerate glasses. They can't take laser vision correction because they have a very thin cornea around the apex, so it's not an option. The only available therapy is to wear hard contact lenses or corneal transplant with a donored cornea if the disease is severe. And with the corneal transplant, there is a rejection rate".

All three subjects reported their vision significantly improved with the custom-designed soft contact lenses.

The researchers tested several designs of custom lenses on the subjects' eyes for both high-contrast and low-contrast visual acuity. They compared vision with the custom-designed soft lenses to vision with conventional lenses and rigid gaccording tomeable lenses, or hard contact lenses. Corrections with the custom lenses resulted in an average improvement of 2.1 lines in visual acuity, or from 20/48 to 20/29, over the use of the conventional defocus and astigmatism corrections alone.

Conventional soft contact lenses do not work for keratoconic eyes, as they merely conform to the conical cornea shape. The custom-designed lenses, conversely, have irregular front surface profiles designed to correct for specific aberrations of the cornea and crystalline lens. The researchers designed the front profiles by measuring with wavefront sensors exactly how light enters the subjects' eyes through the misshapen cornea. In collaboration with Bausch & Lomb, an oscillating tool lathe sculpted the front surface of the lens.

Keeping the lenses exactly in place is still a challenge, as blinking notoriously shifts contacts. The researchers used existing stabilizing techniques, such as making the lenses bottom-heavy, to coax them into correct orientation.

Other authors include David R. Williams, director of the Center for Visual Science; Ramkumar Sabesan, doctoral candidate of the Institute of Optics; Tae Moon Jeong and Luis Carvalho, former postdoctoral fellows at Yoon's lab; and Ian G. Cox of Bausch & Lomb.


Posted by: Mike    Source




Did you know?
Custom-designed contacts improved vision for subjects with keratoconic eyes and offer hope of nonsurgical therapy instead of corneal transplants. University of Rochester scientists describe the custom design techniques and results of visual acuity tests in a paper published in April in Optics Letters.

Medicineworld.org: Soft Contacts Designed for Cone-Shaped Cornea

Cancer terms| History of cancer| Imaging techniques| Cancer Main| Bladder cancer news| Cervix cancer news| Colon cancer news| Esophageal cancer news| Gastric cancer news| Health news| Lung cancer news| Breast cancer news| Ovarian cancer news| Cancer news| Pancreatic cancer news| Prostate cancer news| Endometrial cancer news| General info| What is cancer?| Cancer causes| Is cancer hereditary?| Types of cancer| Cancer statistics| Breast cancer main| Breast cancer symptoms| Colon cancer main| Anal cancer| Bladder cancer main| Lung cancer general| Lung cancer main| Non small cell| Small cell| Ovarian cancer main| Treatment of ovarian cancer| Prostate cancer main| Updates in oncology| Acute myeloid leukemia|

Copyright statement
The contents of this web page are protected. Legal action may follow for reproduction of materials without permission.