The causes of different cataracts are different, and the causes of senile cataracts are not yet unified, but are mostly thought to be related to aging. For some early cataracts, the development of the disease may be slowed down after medication, and the vision of individual patients may be slightly improved, while for patients with intermediate cataracts, neither the vision nor the degree of lens clouding is improved after medication. In the middle stage of cataract, neither vision nor lens clouding will improve after medication. At present, there are no less than dozens of drugs commonly used in clinical practice, such as eye drops or oral Chinese and Western medicines. The following is a brief introduction, hoping to have certain therapeutic effect on your early cataract: Zhang Jian, Ophthalmology Department, Xuanwu Hospital, Capital Medical University
Cataract treatment drugs generally have the following categories.
1.Auxiliary nutritional drugs.
2.Drugs related to quinone doctrine.
3.Antioxidant damage drugs.
4.Aldose reductase inhibitors.
5.Chinese herbal medicine.
6.Acupuncture in Chinese medicine.
1.Adjunctive nutritional drugs.
Comparing the metabolism of cataract crystals with normal crystals, it is found that their components such as multivitamins, certain trace elements and inorganic salt ions are significantly reduced. The drugs aiming at supplementing these nutrients are vitamins, trace elements and inorganic substances.
(1) Vitamins.
Certain vitamins are high in normal human atrial crystals, while they are often in a deficient state in aged crystals. Therefore, vitamin supplementation is used as an adjuvant drug treatment for cataract to stop or delay the occurrence of senile and glycogenic cataract. A variety of vitamin preparation eye drops are available abroad.
①Vitamin C: maintains the reduced state of sulfhydryl groups in enzyme molecules and keeps them active, and as a crystal scavenger and antioxidant, it can actively scavenge free radicals. In addition, it is also involved in hexose phosphate bypass metabolism. Preparations include vitamin C Faure (VitCFaure) eye drops, etc.
②Vitamin E: a fat-soluble antioxidant that protects the crystal lipid membrane from damage by free radicals and maintains crystal transparency. It can reduce oxygen and lipid radicals to H2O2 and lipid peroxides, and then decompose them into non-toxic substances.
B vitamins: The main source of energy in crystals is anaerobic B vitamin enzymes of glucose. For example, VitB2 is a precursor of FAD, a coenzyme of GSH, which plays a hydrogen-delivery role in the physiological oxidation process and reduces GSSH to GSH, and its deficiency can lead to a decrease in the concentration of reduced GSH. Preparations such as Opacinan eye solution (containing VitB2, B3, B5, B6, etc.).
(2) Trace elements category.
Carotenoids: They are relevant to the prevention and treatment of cataracts by.
① prevent abnormal biochemical changes in the organism and scavenge various oxygen and other reactive free radicals.
② can convert the form of sulfhydrylase which is sensitive to radiation damage into thiocondensate which has resistance activity to radiation damage.
(3) Regulation of DNA synthesis and increased synthesis of proteins that have inactivating effects on a variety of free radicals.
(3) Inorganic species.
Ionic balance is the basic factor to maintain a stable internal environment of the crystal. All types of cataracts are accompanied by different degrees of ion distribution disorder, which is related to the disruption of the cation pump mechanism that depends on Na+-K+-ATPase. Low potassium and magnesium diets induce cataracts in rabbit eyes. Supplementation with inorganic ions to treat cataracts with ionic disorders is a reasonable concept. On the one hand, it attempts to replace a certain component in the crystal, and on the other hand, it serves as the main method of dehydration to reduce crystal swelling. High calcium not only causes crystal protein aggregation, activates neutral protein hydrolase, promotes crystal protein degradation and causes crystal clouding, but also inhibits Na+-K+-ATPase activity. Animal experiments have confirmed that the use of calcium channel blockers (cardiac painkillers, isoptin, etc.) restricts the entry of calcium ions into crystal cells and effectively prevents cataract formation. Therefore, calcium antagonists are expected to be effective drugs for cataract prevention and treatment.
2. Drugs related to the quinone doctrine.
The abnormal metabolism of tryptophan and tyrosine in the body produces quinoneimine acid, whose unsaturation can react with the sulfhydryl groups on some soluble proteins in the crystal to form insoluble compounds, leading to crystal clouding. Some scholars believe that quinone bodies are the stimulating substances of age-related cataracts. Anti-quinone agents are synthesized based on the idea of competitively inhibiting the binding of quinones to crystalline proteins, protecting the active sulfhydryl groups in crystals and preventing degenerative damage to crystalline proteins. Commonly used drugs such as cathelin and focalin. The former is the most widely used chemically synthesized anti-cataract drug in clinical practice. It has a stronger affinity for hydroxyl groups than quinone bodies and prevents the oxidative degeneration of crystalline soluble proteins by quinone bodies. It also acts as a redox agent to prevent the inhibition of ATPase by quinone body and lipid peroxidation. It also has redox effect, can promote crystal metabolism and maintain crystal transparency.
3.Anti-oxidation damage drugs.
Among various pathogenic factors, it is generally believed that oxidative damage to the crystal plays an important role and is the initial factor in cataract formation. It can lead to various biochemical changes in the crystal and atrial water, such as changes in the permeability of the crystal cell membrane and imbalance of the ion balance inside and outside the cell, etc. These changes further lead to increased oxidation of the crystal, causing the oxidation of crystal proteins and lipids and the appearance of crystal clouding. Oxidative damage is involved in the formation of especially senile cataracts. Therefore, most of the current drug research on cataract prevention and treatment starts from improving the antioxidant function of the crystal, using antioxidants or antioxidant enzyme activators to remove or neutralize the oxidation products of the crystal and stop or reverse the biochemical changes in the crystal.
(1) Glutathione.
Crystals can synthesize glutathione during the metabolic process. Normal clear crystals contain high levels of reduced glutathione. Its main effects are currently studied as.
①containing free sulfhydryl groups, empowering and protecting a variety of enzyme systems participating in metabolism, regulating and maintaining a stable internal environment of the body and ocular tissues, especially the crystal.
(ii) Acting as a reducing agent, protecting the sulfhydryl components of crystalline proteins from oxidation and maintaining the conformational stability of crystalline proteins and some enzymes required for their activity.
(iii) Plays an important role in crystal amino acid and ion transport.
④Converts oxidized VitC into reduced VitC. The content of free amino acids in the crystal decreases with the development of senile cataract, such as glutamate and glycine are significantly reduced, which can affect the synthesis of glutathione, so the concentration of glutathione in the crystal is significantly reduced when cataract is formed. It is proved that glutathione can delay the formation of galactosomal and radiolucent cataract and maintain the transparency of the crystal. Theoretically the administration of glutathione can achieve the purpose of cataract prevention and treatment. At present, glutathione preparations are available clinically for the treatment of senile cataract by local spotting combined with intramuscular injection, and the combination with VitE is more effective for cortical cataract. However, the drug is unstable and easy to decompose.
(2) Taurine.
Taurine is a sulfhydryl amino acid. Crystals have the ability to accumulate taurine, so human crystals contain a large amount of taurine, accounting for about 50% of non-protein hydrolyzed amino acids in crystals. It was found that during the development of different types of cataracts, the taurine content in the crystal decreased significantly, and it was especially significant in the early stage of cataract, which may be related to the biochemical changes in that period. Crystal ex vivo culture study found that taurine could inhibit the lipid peroxidation reaction triggered by galactose and prevent the clouding of crystals; taurine could reduce the damage of diabetic cataract crystals,. Taurine can reduce the damage of diabetic cataract crystal, and also has a significant inhibitory effect on experimental sodium selenite cataract, the intensity of which is proportional to the dose. Taurine supplementation can maintain crystal transparency and the stability of crystalline proteins, and the mechanism may be related to antioxidant and osmolarity regulation. Currently, taurine is used as eye drops for the prevention and treatment of age-related cataracts in the initial stage. Recent studies have found that taurine is closely related to zinc. Zinc is an antioxidant and regulates cell membrane permeability. It is hypothesized that there is a taurine zinc complex which is important for protecting the normal structure and function of cells. Taurine as a supplement with zinc has the potential to improve the osmotic pressure regulation of the crystal, enhance the antioxidant capacity and alleviate the development of cataract.
(3) Aspirin (acetylsalicylic acid).
Aspirin is the most commonly used drug for antipyretic, analgesic, anti-inflammatory and anti-rheumatism. Epidemiological surveys have shown that patients who take this drug for a long time have a low incidence of cataracts. Therefore, it is believed that the drug has a preventive and curative effect on cataracts. It has been concluded from in vitro and in vivo experimental studies that, the mechanisms by which aspirin inhibits cataractogenesis are as follows.
(i) Binding to lysine residues in crystallin and inhibition of the non-enzymatic glycosylation reaction of crystallin with glucose (Maillard reaction).
(ii) Inhibition of lipid peroxidation reactions.
(iii) Inhibition of carbamylation reaction of crystallin.
④inhibition of metal ion-induced catalytic oxidation reactions.
⑤ lowering of blood glucose effect.
(6) Inhibition of membrane cyclooxygenase; inactivation of calcium channels on crystal cell membranes. Therefore, this drug has certain development prospects in preventing crystal protein polymerization reaction caused by oxidation.
(4) SOD (superoxide dismutase).
This enzyme can scavenge superoxide anion radicals, while having anti-cataract effects, and can be combined with injectable type of copper and zinc, named Orgotein.
4. Aldose reductase inhibitors.
Aldose reductase is a key enzyme in the production of experimental glycogenic cataracts. With the involvement of NADPH, it converts hexose into the corresponding polyglycols. These sugar alcohols do not easily pass through the cell membrane and accumulate intracellularly to produce a hyperosmotic state, causing osmotic swelling of the lens fibers and cataract formation. Inhibit the activity of aldose reductase to prevent or delay the development of glycogenic cataract in experimental animals to varying degrees. Carbinol, phacolysine and bendazac are representative drugs of aldose reduction inhibitors. Most experimental studies with aldose reductase inhibitors have focused more on the complications of diabetes and the toxicity of the drugs is a major concern. Studies on the application of these drugs for cataracts are also immature in terms of mechanism and preventive treatment, and most of these drugs have been eliminated due to high side effects or inaccurate efficacy.
Other classes of drugs.
5. Traditional Chinese medicine.
Chinese herbal medicine treatment is administered through systemic diagnosis and treatment. Many ophthalmologists emphasize that the disease is mostly characterized by deficiency, which is related to the liver, kidney and spleen, among which the liver and kidney yin deficiency is the closest. There are also people who use the method of activating blood to dispel obstruction to treat this disease, which is quite effective and complements the shortcomings of the previous people in the treatment rules. Chinese medicine eye drops include musk pearl eye drops, etc.
6, Chinese medicine acupuncture.
Commonly used acupuncture points are eye-mind, after the ball, Zanzhu, fish waist, hegu, foot Sanli, Sanyinjiao, etc.
The efficacy of Chinese medicine in the prevention and treatment of immature cataract still has some problems to be solved.
(1) How to improve the efficacy of cataract treatment.
(2) Lack of scientific and rigorous diagnosis.
(3) Lack of identification of effective ingredients.
(4) The mechanism of action of the treatment needs to be further studied.
(5) The efficacy of cataract treatment by Chinese herbal medicine alone or in combination needs to be further confirmed.
(6) There are few studies comparing the effectiveness of cataract treatment between drugs. Therefore, it is one of the objectives of further research on cataract treatment drugs by comparing the therapeutic effects between drugs to find more effective cataract treatment drugs.