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.

A new investigation finds that some contact lens solutions do not provide protection from Acanthamoeba — a free-living organism commonly found in soil, freshwater lakes and streams, seawater, tap water and hot tubs — that can cause a painful vision-threatening form of keratitis.

In 2007, a multi-state outbreak of Acanthamoeba keratitis led to an investigation by the Centers for Disease Control and Prevention (CDC) and the U.S. Department of Health and Human Services. The investigators found an association with the use of Complete MoisturePlus multipurpose contact lens solution, manufactured by Abbott Medical Optics (formerly Advanced Medical Optics), which has since been withdrawn from the market.

Recently, researchers at CDC compared 11 different contact lens solutions for their ability to kill three Acanthamoeba species associated with the 2007 outbreak. Of the 11 solutions tested, only the two containing hydrogen peroxide showed any disinfection ability for cysts of two of the three Acanthamoeba species.

The researchers said a “systematic method for evaluating contact lens solutions will reduce the chance that inefficacious solutions are available.”

The study was reported in the July 2009 issue of the Journal of Clinical Microbiology.

Researchers at the University of California, Los Angeles (UCLA) recently performed an analysis of the types and prevalence of contact lens-related complications among patients seen in the university’s clinic.

Of the 846 eyes of 572 contact lens wearers evaluated in the study, approximately 50 percent of eyes had at least one contact lens-related complication, the researchers said. Among the findings of the study:

• Rigid gas permeable contacts had a statistically lower average number of complications than soft contact lenses.
• Conjunctival papillae and giant papillary conjunctivitis were the most prevalent complications among both gas permeable (GP) and soft contact lens wearers.
• Silicone hydrogel contact lenses had a slightly lower (though not statistically significant) rate of complications than regular soft lenses.
• Extended wear contacts had a slightly higher complication rate compared with daily wear lenses.
• Use of contact lens solutions not recommended by the wearer’s eye doctor — including generic and private label solutions — was associated with the highest rate of complications for both GP and soft contact lenses.

Conjunctival papillae are bumpy lesions on the inner surface of the eyelids that can affect contact lens comfort. Giant papillary conjunctivitis (GPC) is an allergic inflammation of these papillae characterized by redness, itching and contact lens intolerance.

The researchers said the significant prevalence of contact lens-related complications identified by this study — regardless of lens design, material and wearing schedule — highlights the importance of routine professional eye care for all contact lens wearers.

The full report of the study appears in the July 2009 issue of Eye & Contact Lens: Science and Clinical Practice.

The front surface of the eye returns to its original shape relatively quickly after discontinuation of overnight orthokeratology, according to a study published in the British Journal of Ophthalmology. 

Researchers in Japan conducted the study to investigate the reversibility of the orthokeratology procedure used for the temporary non-surgical correction of myopia. The procedure, also called “ortho-k,” reshapes the cornea (the front surface of the eye) with specially designed rigid gas permeable contact lenses worn during sleep.

The prospective study followed 17 subjects who underwent the ortho-k procedure for a period of 12 months. 

Prior to the procedure, several baseline eye measurements were taken, including refraction, corneal topography, wavefront aberrometry, uncorrected visual acuity (UCVA) and contrast sensitivity. These tests were then repeated 12 months after commencement of ortho-k, and one week and one month after discontinuation of the procedure.

The researchers found that all measures of corneal shape, refractive error and visual performance returned to baseline levels within one week of discontinuation of overnight ortho-k.

They concluded the effects of orthokeratology are completely reversible, and that the cornea fully recovers its original parameters relatively quickly after ortho-k is discontinued. 

Source: Recovery of corneal irregular astigmatism, ocular higher-order aberrations, and contrast sensitivity after discontinuation of overnight orthokeratology. British Journal of Ophthalmology. February 2009.