Researchers are developing contact lenses that darken automatically in sunlight, similar to photochromic lenses available for prescription glasses. The contacts are treated with sun-sensitive dyes that darken when exposed to ultraviolet light, which is harmful to eyes.

Earlier attempts to make photochromic contacts were few and unsuccessful. Now, researchers at the Institute of Bioengineering and Nanotechnology (IBN) in Singapore are making headway by using a contact lens material that contains a network of nano-sized tunnels that can be filled with photosensitive dyes. The structure of the flexible lens material allows the dye to react quickly and uniformly throughout the lens, according to the researchers.

Edwin Chow, IBN senior research scientist, says this technology has a faster response time than photochromic eyeglass lenses (such as Transitions lenses) currently on the market. While photochromic lenses can take minutes to fully react to light, the new photochromic contacts can respond in 10 to 20 seconds, he says.

Next the research team will test the contact lenses in animals. IBN Director Jackie Ying believes the contacts could be available commercially outside the United States within a year. Approval for use in the U.S. may take longer due to safety testing required by the Food and Drug Administration (FDA).

The study was reported this month in Technology Review, published by the Massachusetts Institute of Technology (MIT).

This week, Unilens Vision Inc. (Largo, Fla.) launched C-VUE Advanced Toric Multifocal contact lenses. These specialty lenses correct both astigmatism and presbyopia.

According to the 1999-2004 National Health and Nutrition Examination Survey (NHANES), approximately 36 percent of Americans ages 20 and older have astigmatism. Presbyopia is an age-related vision problem that affects virtually everyone some time after age 40.

Eye doctors can customize the new C-VUE Advanced Toric Multifocal lenses for their patients by specifying astigmatic and multifocal powers, multifocal zone size, lens diameter, base curve and more. The monthly disposable contact lenses also feature advanced hydration properties for all-day comfort, according to the company.

Unilens Vision Inc. offers a free trial program and a 120-day performance guarantee. The lenses are available exclusively from independent eye care professionals. Read more at www.unilens.com.

SynergEyes, Inc. (Carlsbad, Calif.) announced today that its new ClearKone hybrid contact lens for correction of vision problems associated with keratoconus is now available in the United States, Canada and Puerto Rico.

The new ClearKone lens is the second SynergEyes hybrid contact lens specifically designed for people with keratoconus — a degenerative disorder in which structural changes in the clear anterior portion of the eye cause the cornea to bulge forward into a cone shape.

Keratoconus frequently causes vision problems that cannot be corrected with conventional eyeglasses or soft contact lenses.

The company launched SynergEyes KC hybrid lenses in 2006, which have proven successful in restoring vision for certain types of keratoconic eyes. The ClearKone lens is designed to fit a much broader spectrum of cone-shaped corneas, according to the company.

Hybrid contact lenses feature a rigid, gas permeable central portion, surrounded by a ring of soft contact lens material. The lenses are designed to provide the sharp vision of gas permeable contact lenses and the all-day comfort and convenience of soft lenses, says Kellie Kaseburg, Vice President of Global Marketing for SynergEyes.

SynergEyes ClearKone and SynergEyes KC are the only FDA-approved hybrid contact lenses specifically designed for keratoconus vision correction in the United States. The company also makes hybrid contacts for the correction of nearsightedness, farsightedness and astigmatism in normal eyes.

You can learn more about SynergEyes hybrid contact lenses by visiting the company’s website.

Soon people who need to use medications frequently for eye infections, glaucoma and other health problems may be able to wear contact lenses that provide a sustained release of the medicine they need.

Researchers at Massachusetts Eye and Ear Infirmary, Harvard Medical School and Massachusetts Institute of Technology recently developed and tested prototype drug-eluting contacts with promising results. If these contact lenses are proven successful and commercially viable, they may be a more convenient and reliable drug delivery system than eye drops.

The lenses were created by coating films containing test compounds with a soft contact lens material by using ultraviolet light polymerization.

One compound tested was ciprofloxacin (or “Cipro”), an antibacterial drug with multiple applications. After a brief initial burst, the prototype drug-eluting lenses demonstrated a controlled release of Cipro for more than 4 weeks, and the lenses inhibited ciprofloxacin-sensitive Staphylococcus aureus bacteria at all time-points tested.

Though additional testing is needed, the researchers concluded that it appears contact lenses like those produced in the study could be used successfully for ocular drug delivery with widespread therapeutic applications.

The full report of the study appears in the July 2009 issue of Investigative Ophthalmology & Visual Science.