Cataract surgery - New drops for inflamed eyes
By Sven Siebenand / The cataract is not uncommon. Around 550,000 cataract surgeries are performed annually by doctors in Germany. The treatment of postoperative inflammation is often with non-steroidal anti-inflammatory drugs. With immediate effect Bromfenac, a new representative of this class, is available.
The turbidity of the eye lens experts usually call cataract. But also common is the colloquial name cataract. But the whole thing has nothing in common with a colorless bird. Rather, the name is derived from two typical hallmarks of the disease: gray, because the pupil looks like this in the advanced stage of the disease, and rigid because of the staring eyesight of the visually impaired. The main symptom of cataracts is the slowly progressive vision loss. In addition, patients complain more and more about blurry images, their visual acuity subsides and the sensitivity to glare increases.
There is usually no way around an operation. After the procedure inflammatory processes on the eye can occur. Because shortly after cataract extraction patients are more prone to it because of the surgical interruption of the blood-eye barrier. Anti-inflammatory drugs make it possible to minimize the risk of surgery-induced ocular inflammatory complications, such as cystoid macular edema.
Fast absorption due to high lipophilicity
With Bromfenac (Yellox® 0.9 mg / ml eye drops) a new non-steroidal anti-inflammatory drug for ophthalmology is now available. COX inhibition disruptes the production of prostaglandins involved in the inflammatory process. The active ingredient was created by bromination of the NSAID Amfenac. As stated by manufacturer Bausch + Lomb, twice daily use of the new eye drops for two weeks leads to the control of the inflammation. So far available drugs in Germany provide for a four-week therapy with three to four times daily use. The reason: Bromfenac is characterized by a particularly high lipophilicity. This leads to improved penetration and absorption by the cornea and the underlying eye tissues. After single administration of the ophthalmic solution, absorption takes place within 15 minutes. The already reached peak concentrations in the aqueous humor persist for more than twelve hours; Thus, a twice-daily application to maintain the anti-inflammatory activity is sufficient. Patients who regularly use other eye drops should maintain a time interval of at least five minutes between doses.
Stem cells against the cataract
New method makes the eye to form a new lens itself
Physicians have developed a new healing method for cataracts: instead of replacing the clouded lens with an artificial lens, they cause eye cells that occur in the eye to generate a new lens themselves. In a pilot study, this gave children with a natural cataract their eyesight within a few months, as the researchers report in the journal "Nature".
Cataract is one of the most common causes of blindness worldwide. In this disease, the lens diminishes more and more, until finally no more light reaches the retina. While cataracts are most prevalent among older people, many children in developing countries are affected by this eye disease.
So far, there is only one treatment for the cataract: The clouded lens is removed by a cut in the cornea and instead used an artificial lens made of plastic. However, this procedure can cause inflammation and scarring and can not be performed on children under the age of two.
Stem cells in the lens case
Kang Zhang of the University of California at San Diego and his colleagues have therefore been looking for a gentler therapeutic method. Your idea: Why not make the inherently existing in the eye stem cells to produce even a new lens. Lens epithelial stem cells, which reproduce lens cells throughout our lives, sit in the envelope of the eye lens.
Clouded eye lens in a cataract patient.
So far, this lens cover was removed in gray-star surgery, because you wanted to prevent disordered growths of this tissue. But Zhang and his colleagues have now developed a microsurgical method in which only a very small incision is made laterally in the eye. Through this, the clouded lens material is sucked in without damaging the lens cover.
Lenticular tissue grows by itself
The remainder now happens by itself - through the self-healing power of the body: "Four to five weeks after the procedure, new lens tissue grew symmetrically from the sides of the lens capsule into the interior," the researchers report. After seven weeks, a translucent, biconvex lens had emerged from this tissue. Their refraction was as good in testing as that of a normal, healthy eye lens.
But would this work for humans? To find out, Zhang and his colleagues conducted a pilot study of 12 infants suffering from an innate cataract. The clouded lens was also gently removed so that the stem cells could become active.
First tests with children successful
And indeed: Three months after the procedure, a new, healthy lens had formed in the children as well. Thin at first, she grew to the normal shape and strength of a healthy eye lens over the course of eight months. "The children's eyes regained their function as soon as the new lens completely filled the eye capsule," the researchers report.
The visual acuity of the children improved as much as by the conventional implantation of an artificial lens, as an eye test showed. At the same time, however, fewer complications such as inflammation and scarring have occurred because of the smaller incision than in conventionally treated patients.
Cataract: drug could replace surgery
So far only one operation could prevent the blindness by cataract. Now researchers have discovered a possible alternative. A substance could prevent the lens opacity and even improve afterwards.
Cataract is the leading cause of blindness. Half of all people over the age of 70 are affected by lens opacification worldwide. So far, only surgery using an artificial lens implant could prevent cataract blindness. But possibly the disease can also be treated with medication in the future. A research team led by PhD Jason Gestwicki of the University of Michigan, Ann Arbor, has recently discovered an active ingredient that prevents and even improves the opacification of the lens in the laboratory and in mice. Their results published the researchers in the journal "Science".
Drug prevents clumping of proteins
The refractive power of the eye lens is generated by highly concentrated proteins. These proteins must remain in a dissolved state so that the lens remains transparent. This is ensured by the two protective proteins A-crystallin (cryAA) and B-crystallin (cryAB). If these crystals fail, the proteins clump together and the lens becomes cloudy. The team around Gestwicki was now looking for substances that stabilize the protective proteins and thus prevent misfolding.
They found a substance that prevented the formation of protein clots in the laboratory and even dissolved existing lumps. The researchers first tested this substance on genetically modified mice that developed early cataracts due to a cryAB defect. As it turned out, the condition of the lenses could be significantly improved by the treatment within two weeks. In addition, the researchers confirmed the effect also on mice with a cryAA defect as well as on ordinary mice that develop the cataract due to age.
Finally, the scientists tested the substance in the content of eye lenses that had been removed from older people. Again, it was found that the amount of all soluble proteins could be increased, after all, by 18 percent. According to the study authors, the drug may thus be a promising lead to non-surgical therapy, both in hereditary and age-related cataracts.
Cataract treatment: What's new?
According to the Oxford Dictionary, the word "cataract" derives from the Latin word "cataracta", meaning "waterfall", and the Greek word "cataractes", which means "falling down". Cataract is a condition in which there is a progressive clouding of the natural eye lens. The latter works much like the lens of a camera, bundling the light, throwing it onto the retina for a clear view. Moreover, it can change its curvature and refractive power to be able to see clearly at any distance. The eye lens consists mainly of water and crystalline proteins, which are arranged in a precise pattern which causes their transparency. The crystalline proteins clump together, altering their geometric arrangement and forming insoluble amyloids, making the lens dull.
Cataract is the leading cause of blindness worldwide and the leading cause of visual impairment in over-40s. In 2010, 5% of patients aged 50-54 years and 68% of those over 80 years old had cataracts, according to the US National Eye Institute. According to estimates by the association "Prevent Blindness America" in the USA, by the year 2020, 30 million Americans will be suffering from cataracts. Visual impairment results in high costs for both the patient and the healthcare system.
The efficacy of cataract extraction was confirmed in a prospective, longitudinal, population-based cohort study in 190 patients in Sweden with a 15-year follow-up. Fifteen years after surgery, the corrected distance vision had deteriorated on average from 20/20 to 20/25. In elderly patients, the decrease in subjective vision was higher. The most common reason for this was age-related macular degeneration, followed by glaucoma.
Advances in cataract surgery
In the first stages of the disease visual acuity can be improved by using glasses, contact lenses, enlarging with bifocal eyeglasses or adjusting the light intensity. If these non-surgical measures are no longer sufficient, a cataract surgery is required.
Cataract surgery is the most common surgical procedure in the US. According to the American Society of Cataract and Refractive Surgery, more than 3 million surgical procedures are performed every year, with a success rate of at least 98%. Cataract can be removed manually (extracapsular cataract extraction) or by phacoemulsification using radiofrequency ultrasound with or without femtolaser (FL) -assisted surgery. In most cases, an intraocular lens (IOL) is inserted into the capsular bag. Often, the procedure is performed on an outpatient basis.
Today's cataract surgery is safe and effective. Nonetheless, ophthalmologists and industry are constantly striving to optimize results by improving the material of the IOL, the diagnostic instruments, the laser and phacoemulsification technology, or the properties of the IOL.
Recently, the "U.S. Food and Drug Administration (FDA) has approved some FL to assist surgeons in cataract surgery. With their ultra-fast 10-15 second frequency and low energy consumption, they may cause less damage to the surrounding tissue. The lasers can be used to make the first incision on the eye, open the anterior capsule, fragment the lens nucleus, and make precise incisions on the cornea in patients with astigmatism.
They allow for more precise incisions than manual technique, as well as a well-tuned and uniform central capsulotomy with less displacement and tilting of the IOL and better centering, resulting in a more accurate postoperative refraction. In addition, optical coherence tomography (OCT), which is integrated into some FLs, improves operational safety in difficult cases with poor visibility. The use of FL may be particularly useful in patients with endothelial corneal dystrophy, where the least or no ultrasound energy should be used. In the future, the FLs are likely to be smaller and connectable to the surgical microscope, allowing a combination of cataract surgery with corneal and vitreous surgery. Nonetheless, FL can not replace all stages of surgery. The removal of the lens nucleus, rinsing of the cortex and capsule, and the use of the IOL must continue to be performed by a surgeon..