Specially designed contact lenses may soon help optometrists and ophthalmologists monitor high eye pressure that can lead to vision loss from glaucoma.

That’s the conclusion of researchers in Spain who reported the development of a prototype pressure-monitoring lens at the 2010 annual meeting of the Association for Research in Vision and Ophthalmology (ARVO) held this week in Fort Lauderdale, Florida.

The pressure-sensing gas permeable contact indirectly measures intraocular pressure (IOP) by detecting changes on the surface of the cornea caused by the internal eye pressure. It does so with an incorporated sensor consisting of a polycarbonate film nanostructured with an organic molecular conductor, according to the researchers.

The sensor is capable of detecting IOP changes of less than 1.0 mmHg, they say. (Normal IOP is generally considered to be in the range of 8 to 20 mmHg.)

Pressure readings can be obtained in real time and collected in a computerized record.

Currently, the prototype pressure-sensing contact lens only has been tested with non-living pig eyes, but the researchers say the device can effectively monitor IOP and has the potential to someday be used to assist eye doctors in glaucoma treatment.

Drug-eluting contacts may soon be used to treat glaucoma, thanks in part to a breakthrough by researchers at the University of Florida in Gainesville.

The idea of using contact lenses that contain medicine to treat eye diseases such as glaucoma is not new. A major hurdle in the technology, however, has been finding a way to keep tears from washing away the medicine too quickly.

Anuj Chauhan, PhD, and colleagues may have found the answer — vitamin E. The researchers say that incorporating the antioxidant vitamin into the therapeutic contact lens makes the glaucoma medicine last almost 100 times longer than it does with current drug-eluting contacts.

Many ophthalmologists and optometrists feel medicine-containing contact lenses may solve a major problem in glaucoma treatment. Traditionally, eye drops have been used to apply glaucoma medicine to the eye. But many patients forget to use their drops as directed, which can cause the condition to progress, leading to serious vision loss, even blindness.

And even when eye drops are used as directed for glaucoma treatment, they often are not as effective as they should be. Some studies suggest that only about 1 to 5 percent of the applied drug reaches the target tissue in the eye, and the rest is distributed throughout the body by the circulatory system, possibly causing side effects.

Many eye doctors and glaucoma experts say the use of medicated contact lenses may eliminate these problems, leading to more effective glaucoma treatment.

A second possible benefit of adding vitamin E to medicine-containing contact lenses is that the vitamin may help prevent cataracts due to its antioxidant activity, according to the researchers. Vitamin E also blocks UV radiation, possibly leading to reduced eye damage from UV light.

Though the new vitamin E therapeutic contact lenses are not yet approved by the FDA, animal studies in beagle dogs are ongoing to determine the effectiveness of the lenses in treating glaucoma.

SOURCE:  Contact lenses loaded with vitamin E may treat glaucoma. (Press release issued by the American Chemical Society, March 24, 2010.)

Can artificial tears be safely used to re-wet contact lenses?

In some cases, eye drops that are designed to treat dry eyes may have formulations that are incompatible with contact lens wear. For this reason, contact lens wearers are well-advised to use only the contact lens solutions specifically recommended by their optometrist or ophthalmologist.

But a new study conducted by Allergan (Irvine, Calif.) has found that one of the company’s artificial tear products appears to work well as a contact lens lubricant. In fact, when compared with Allergan’s own brand of contact lens rewetting drops, the artificial tear actually outperformed the rewetting drop at improving contact lens comfort.

In the study, 166 contact lens wearers were randomly assigned to use the artificial tear product (Refresh Optive) and 79 wearers received the contact lens rewetting drop (Refresh Contacts). All subjects were instructed to use 1 to 2 drops of their respective product four times per day for three months.

At the end of the study period, among subjects who reported using contact lens rewetting drops prior to the study, more subjects that switched to using the Refresh Optive artificial tears during the study reported improvement in contact lens comfort than those who used the Refresh Contacts rewetting drops (53.2 percent vs. 34.2 percent).

But the researchers warned that contact lens wearers should not rush out and purchase the Refresh Optive product just yet for contact lens discomfort.

Contact lens care products are required to carry specific labeling, indicating that the product has been approved by the FDA for use in conjunction with contact lens wear.

Based on the results of the study, Allergan says it plans to investigate developing a new contact lens rewetting drop with a formulation similar to Refresh Optive, which is more viscous than Refresh Contacts.

SOURCE:  Artificial tear studied as contact lens lubricant. Ophthalmology Times. February 15, 2010.

UV-blocking silicone hydrogel contact lenses can reduce or eliminate harmful effects from the sun’s UV rays, according to a study published this month in Investigative Ophthalmology & Visual Science, an official journal of The Association for Research in Vision and Ophthalmology (ARVO).

Overexposure to UV light can cause harmful changes in the cornea, conjunctiva and lens, including cataracts, according to the investigators and authors of the article, “Prevention of UV-Induced Damage to the Anterior Segment Using Class I UV-Absorbing Hydrogel Contact Lenses.”

In the study, 12 rabbits were assigned to one of three treatment groups:

1. Those wearing a UV-blocking silicone hydrogel contact lens.
2. Those wearing a silicone hydrogel lens that doesn’t block UV.
3. Those wearing no contact lenses.

For five days, the animals were exposed to UV radiation capable of producing corneal changes. Only the rabbits who wore the UV-absorbing contacts were not affected by the exposure.

The UV-absorbing contact lenses used in the study were made of a silicone hydrogel material called senofilcon A. The material is used to produce Acuvue Oasys disposable contacts.

Heather Chandler, PhD, from Ohio State University’s College of Optometry, was lead investigator in the study. “The data generated from this study could support the use of UV-absorbing contact lenses and greatly impact the health of a large number of people,” Dr. Chandler said in an ARVO press release this week.

The study was supported by Vistakon, a division of Johnson & Johnson Vision Care, Inc.