An illuminating piece written by Dr. Brian Chou in Contact Lens Spectrum sheds some more light on silicone-hydrogels:
“Like many of my colleagues, when CIBA Vision first launched its Night & Day contact lens, I prescribed it for a large number of patients for continuous wear. Indeed, many patients successfully wear this lens. But an unexpected number of my patients came back, complaining of symptoms such as light sensitivity, redness, burning, itching and foreign body sensation…”
“Nevertheless, certain practitioners have already professed silicone hydrogels as the new standard of care even for daily wear. I believe such a claim is unfounded and mistaken…For the vast majority of patients, it’s still perfectly reasonable, if not compassionate, to prescribe advanced hydrogel lenses.”
“When a lens remains on the eye for a long, continuous period, metabolic debris, including CO2 and lactate, forms under the lens. With insufficient tear exchange, especially without daily lens removal, these and other waste products accumulate. Exotoxins produced by normal eyelid flora may also accumulate and are effective in inciting inflammatory reactions.
So, how do higher Dk materials designed for continuous wear improve removal of post-lens ocular waste? They don’t! I see this as a problem with how some manufacturers position silicone hydrogel lenses to practitioners, as well as to consumers. Although oxygen transmission is crucial for successful lens wear, it’s not the only factor. Good physiology, comfort, handling, vision and convenience are also important, if not more so. Unfortunately, high oxygen transmission doesn’t guarantee that the lens adequately meets all these criteria.”
Bravo to this optometrist for seeing through a whole lot of marketing mumbo-jumbo!
Though it’s got a bit of jargon to sift through, you can read the entire piece here (PDF) or here (HTML).
For those in the San Diego area looking for an optometrist who won’t try to stuff you into silicone-hydrogels, you can try Dr. Chou (full disclosure: I only know that he is in San Diego because it says so in the article. I’ve never had any contact with the guy.).
His bio:
Dr. Chou is a partner at Carmel Mountain Vision Care, a group optometric practice in San Diego. A graduate of UC Berkeley School of Optometry, he completed fellowship training in refractive surgery management at Jules Stein Eye Institute, UCLA School of Medicine. Dr. Chou has authored over 50 eye care manuscripts including the book, Spanish Terminology for the Eyecare Team. He received the Nuemueller Award in Optics from the American Academy of Optometry and is on the editorial board for Review of Contact Lenses.
Dr. Chou is a consultant to CooperVision, Ophthonix, and the California Board of Optometry.
