In the context of the Dutch National Research Agenda, experts at Maastricht UMC+ answer questions about science in the 'A conversation with...' column. This time, ophthalmologist Prof. Rudy Nuijts, Professor of Cornea Transplantation and Refractive Surgery, deals with the following question:
"There are a number of risk factors relating to cataracts. Among other things, high cholesterol, smoking, and exposure to too much UV light can cause clouding of the lens. We also know that the drug prednisone may cause cataracts. So you can somewhat reduce the risk of cataracts by paying attention to your lifestyle. As you get older, however, your eyesight may begin to deteriorate anyway, and once that has happened there is currently little option other than cataract surgery. That involves your own cloudy lens being replaced surgically with an artificial lens. But there have recently been some interesting and innovative developments in the world of research that may change that situation, including stem cell research.
Let's first take a look at some basic facts. A healthy eye contains a lens in which there are cells with transparent proteins. Those proteins are arranged in such a way that they allow light to pass through, resulting in a clear image. The shape of the lens can also be changed by the little muscles of the eye, so that the image remains in constant focus. As you get older, or because of other factors, the proteins in the lens may clump together or fall apart. What you see therefore becomes increasingly cloudy: a cataract develops. In the worst case, blindness may even occur. Surgery is then needed. Even just in Maastricht, we perform 2500 of these cataract operations annually, while in the Netherlands as a whole the total is some 180,000 a year.
During the operation, a tiny incision is first made in the cornea and a circular opening in the lens capsule, so that the surgeon can get at the lens. The lens is then pulverised and sucked out with a kind of little vacuum cleaner. It is then replaced by an artificial lens. The technology has now advanced to the stage that various different types of artificial lenses are available depending on the patient's symptoms. A multifocal lens can be inserted, for example, so that the patient doesn't need to wear spectacles or contact lenses. At Maastricht UMC+, we also use a special laser technique so as to make very precise incisions in the cornea and the opening in the lens capsule which are then also perfectly round or symmetrical. This is different to the standard method, in which the surgeon makes the incisions by hand. With that method, however, it is virtually impossible to make a perfectly circular opening in the lens capsule. Laser technology therefore makes it possible to position the artificial lens in the eye far more accurately Although we achieve excellent results when inserting artificial lenses, it would naturally be fantastic to be able to restore the sight of a cataract patient without an artificial aid. That innovation now seems to be on its way. Very recently, scientists have succeeded in treating congenital cataracts in twelve children (aged under two) with stem cells. With babies like that, it's often difficult to place an artificial lens. However, the researchers had discovered that a thin layer of lens epithelial stem cells is located in the lens. In the children with congenital cataracts, they removed the cloudy cells and left the layer of stem cells in place. After about eight months, the lens had largely recovered, with clear cells developing, and sight had partly returned. The researchers say that the result is in fact better than inserting an artificial lens. One caveat is that the lens in a baby's eye is still developing, unlike that of someone aged 50. Nevertheless, this is a development with great prospects for the future.
Another remarkable result was achieved with the substance lanosterol, which is one of the main ingredients in Nivea cream. A Chinese-American research team demonstrated in animal models that a lanosterol solution was capable of reversing clouding of the lens. It apparently reverses protein clumping so that within a few weeks the lens was significantly clearer again. But to what extent this also applies to humans is still uncertain. Intake of vitamin C from food also appears to have a beneficial effect. There are recent indications that that vitamin can reduce the risk of cataracts in people aged 60 and over by a third over a ten-year period. But there is unfortunately still no real remedy other than surgery, although a healthy lifestyle can certainly help reduce the risk of cataracts. In any case, modern technological developments and the current expertise of eye surgeons do make it possible for the patient to regain clear eyesight, without that being too much of a hindrance."
More information about cataracts?
- Research and treatment for eye conditions, including cataracts, takes place at the Maastricht UMC+ at the University Clinic for Ophthalmology.
- In addition to cataracts, there is another eye problem, namely glaucoma. This does not directly affect the lens but there is damage to the optic nerve.
- Prof. Rudy Nuijts was recently appointed best ambassador of Maastricht Convention City. He has seen to it that some 1500 ophthalmologists will come to Maastricht in 2017 for the 2017 Winter Meeting of the European Society of Cataract and Refractive Surgeons (ESCRS), a conference at which the latest innovations and developments in the field of cataract and refractive surgery will be discussed.