Prevention and Treatment-with Reference to Chinese Medicine
Cataract is the term for clouding of the lens of the eye; if the cloudiness is sufficient to inhibit transmission of images to the retina, then vision is partly or fully obstructed. Mild cloudiness, the most common condition associated with cataracts, does not need surgical intervention for correction, but can often be compensated for by using corrective lenses; more severe cloudiness is usually treated by surgery, removing the original lens and replacing with an artificial lens.
Cataract surgery is part of ancient medical arts; it was one of the earliest of surgical procedures, even in the Orient, traced back over 2,000 years. It is likely that the reliance on surgery had the effect of limiting efforts to develop non-surgical treatment methods; similarly, it is likely that non-surgical methods that had been tried were relatively unsatisfactory, making surgery seem an appropriate alternative. Therefore, when examining suggested non-surgical treatments, one should be careful about expectations for dramatic effects on vision. Further, when reviewing treatment options, cataracts should be differentiated from "nebulae" which are described as clouding the vision but refer to films that form on the surface of the eye (cornea).
Cataracts occur most often in the elderly-sometimes referred to as senile cataracts which affect 25% of those over the age of 65. They are especially common in those with diabetes. Some drug therapies induce cataract formation. Nearly 1.5 million cataract surgeries are performed in the U.S. each year.
The lens of the eye is a small oval structure consisting of a thin, clear capsule enveloping a fluid protein. The protein is clear and colorless at birth, but over the years it discolors and clouds gradually. It first yellows, then turns brown, and finally, cloudy. Often, it is not diagnosed until the fluid becomes so cloudy that it interferes with vision, but, in fact, the process is usually gradual (rapid development may be induced by elevation of blood sugar or use of some drugs). A cataract is not a growth, nor is it a film over the eye.
Initially, the cataract changes the focusing power of the eye-by dispersing the light that passes through it-so that a change of corrective lenses can satisfactorily improve vision. However, clarity will gradually decline if the condition progresses so that vision becomes increasingly difficult despite the best possible corrective lenses; this is when surgery is recommended.
The discoloration and clouding of the lens protein fluid arises from a number of processes. One is cross-linking of the proteins, which converts them to thicker, darker colored materials. Cross-linking of proteins is caused by exposure to UV light, by oxidative chemical reactions, and by addition of glucose to the proteins (glycosylation) that promotes cross-linking. Therefore, using good quality UV-blocking sunglasses to protect the eyes, having an antioxidant-rich diet (and avoiding smoking, which increases oxidation reactions), taking additional antioxidants, and keeping blood sugar well-regulated can all help slow the development of cataracts. Topical application of antioxidants has been tried in many countries as a means of preventing further development of cataracts and even reversing them; these methods are rarely used in the U.S. in routine ophthalmology care. In addition to protein cross-linking, breakdown of the normal proteins of the lens may also occur, especially if calcium levels in the lens increase (the cause of such change in calcium is not yet established). A calcium-activated protease can break down the proteins into smaller units, rearranging the protein matrix and scattering the incoming light. Enzyme inhibitors are considered potentially useful in preventing and treating cataracts: inhibitors of aldose reductase may slow cataract formation in diabetics by preventing glycosylation of the proteins and protease inhibitors may prevent the breakdown of the lens protein. Such inhibitors have been derived from herbs and developed as new drugs. As examples of herbs of potential use, salvia and licorice are potent inhibitors of aldose reductase; the flavonoids from pueraria and scute also serve this function (1).
It is difficult to reverse the clouding of the lens that has already occurred, but there may be mechanisms within the lens that help restore the protein fluid so that if the destructive processes cease, some degree of improvement may occur. Efforts should be made to begin prevention measures early: as soon as cataracts can be detected (during routine eye exams) and even sooner where risk factors can be identified (high exposure to UV light; diabetes). The previously-mentioned preventive practices-sunglasses, good diet, not smoking, taking antioxidants, regulating blood sugar-should be standard for people over the age of 40. Wearing sunglasses to protect the eyes can also slow development of floaters; other therapies, such as relying on antioxidants, may similarly be useful for restraining formation of floaters, which also involve changes in the protein fluid (in the central portion of the eye ball; see: Floaters and their treatment with Chinese herbs).
Below, some herb formulas will be mentioned as potentially helpful for preventing and treating cataracts; many of the ingredients are used in "anti-aging" formulations and could be taken regularly as part of a program of preventive health care that might help preserve vision.
It is estimated (by Pro Ro Nata, Inc., a consulting firm) that traditional Chinese medicine products for eye disorders accounted for 41 million dollars (U.S.) of business in 2002, with 80% sold over the counter in pharmacies, the rest prescribed at hospitals and clinics. Cataracts are a major target of therapy, with 40% of the ophthalmic drug market (including non-TCM therapies). Unfortunately, little is known about the success rate for these treatments. Both internal and topical therapies are used.
In the English-Chinese Encyclopedia of Practical Traditional Chinese Medicine (2), there is a chapter on diseases of the lens. Three basic formulations (well-known traditional prescriptions) are recommended for senile cataract on the basis of differential diagnosis of syndromes, as follows (the number of grams used for a daily dose of decoction is indicated in parentheses after the common names of the herbs):
|Liver/Kidney Deficiency||Spleen Qi Deficiency||Yin Deficiency and Damp Heat|
|Qi Ju Dihuang Tang||Yiqi Congming Tang||Ganlu Yin|
Baked Licorice (3)
Rehmannia, raw (9)
According to the text: "Medication [referring to these herb therapies] may be effective in the incipient stage [of cataract]; when there is notable opacity of the lens, medication will not work, and so surgical treatment should be considered." In the book Traditional Chinese Treatment for Senile Diseases (3), the etiology of cataracts is described as based in deficiency, leading to inadequate nourishment of the eyes. It is evident from the wording of the text that its contents are derived primarily from the same sources as that used for the above-mentioned Encyclopedia. The three formulas described above are listed (with slight variation on the dosage of individual ingredients), along with two other formulas for additional diagnostic categories:
|Liver/Kidney Yin Deficiency||Liver Deficiency and Spleen Damp|
|Buyin Bushen Tang||Siwu Tang + Erchen Tang|
Black sesame (12)
Cassia seed (12)
Morus fruit (12)
Both texts also mention the use of eye drops, two items being listed are Phacolysin and Catalin. Catalin is a brand name for the drug pirenoxine sodium (see illustration and explanation below), which is probably the most widely-used eye drop for early stage cataracts, with more than 50 years of use and distribution in 40 countries. It is produced by 20 manufacturers in China; the brand Catalin is made in Japan. Phacolysin (also called Phacolin) is a complex anti-oxidant (see structure diagram left); it has been used both topically and internally as a therapy for eye disorders.
In addition to Pirenoxine eye drops, the main OTC cataract products in China include Zhangyanming Tablets (there are several of these, including Zhangyan Mingmu Pian, Neizhang Yanming Pian, etc.; they are tonics for kidney and liver with herbs for nourishing the eyes and promoting circulation) and Shihu Yeguang Wan (produced by many factories; the item entering the U.S. is called Dendrobium Night Sight Pills). These products are indicated for early and mid-stage cataracts, as well as for nebulae.
In Japan, Rehmannia Eight Formula (Bawei Dihuang Wan, also called Jingui Shenqi Wan) is recommended for treatment of several disorders of aging, including diabetes and cataracts. The modified version, Achyranthes, Plantago, and Rehmannia Formula (Rehmannia Eight Formula with achyranthes, niuxi, and plantago seed, cheqian, added, called Niu Che Shenqi Wan; in Japan, called Goshajinkigan) is especially used for complications of diabetes, such as diabetic neuropathy and cataracts. The formula appears to be effective for reducing corneal sensitivity in diabetes patients, indicating an influence on the eye (4).
In an article from Japan, published in the American Journal of Chinese Medicine (5), three physicians report on a successful case of cataract treatment with a traditional herb formula. This involved a 68-year-old woman with diabetes having a cataract in one eye. The cataract had been present for more than four years at the time of treatment with the herb formula. She was given Achyranthes, Plantago, and Rehmannia Formula. She had been taking Catalin eye drops and Tathion eye drops (glutathione eye drops, another antioxidant strategy), with only slight effect, but when she began taking the herb formula, her vision began to rapidly improve within 10 days, and continued to improve over three months of therapy. The affected eye then remained in improved condition thereafter, with continued use of the herbs (dried extract granules, 7.5 grams per day).
Sample of pirenoxine eyedrops (a modified phenoxazine carboxylic acid, see structure diagram, right) for cataract; this is labeled Catalin (in Japan); it is also sold as Clarvisan, Clarvisor, and under other names; a Chinese version is called Baineiting.
N-acetylcarnosine, is an antioxidant provided as an eye drop; the pictured product is called Can-C; carnosine is also sold as Bright Eyes and NuEyes, and under other names. Carnosine is a dipeptide (alanine-histidine) researched mainly in Russia as a treatment for cataracts. In one study (6), it was claimed that after 6 months, 89% of all eyes treated with the drops had an improvement of glare sensitivity; 41% had improvement of the transmissivity of the lens, and 90% of the eyes showed improvement in visual acuity. The improvements were said to be retained during two years of follow-up with continued use of the eye drops. Carnosine may specifically inhibit glycosylation of the lens proteins.
A Swiss product called Quinax (dihydroazapentacen or azapentacene polysulfonate) is used as a treatment for cataracts. According to one research report from Poland (7): "An observation of (on average) 5 years duration showed that systematic application of the drug prevents the development of early senile cataract and distinctly slows down the progress of the condition in the group of patients without the risk factors. Non systematic application of the compound also slows down the progress of the condition in the group of early cataract. The drug was ineffective in patients with an advanced diabetic cataract."